Merge branch 'develop' into usize_32_or_std
This commit is contained in:
Julien Cretin
@@ -12,6 +12,11 @@
|
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// See the License for the specific language governing permissions and
|
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// limitations under the License.
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||||
|
||||
//! Flash storage for testing.
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//!
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//! [`BufferStorage`] implements the flash [`Storage`] interface but doesn't interface with an
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//! actual flash storage. Instead it uses a buffer in memory to represent the storage state.
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|
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use crate::{Storage, StorageError, StorageIndex, StorageResult};
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use alloc::borrow::Borrow;
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use alloc::boxed::Box;
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@@ -23,9 +28,9 @@ use alloc::vec;
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/// for tests and fuzzing, for which it has dedicated functionalities.
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///
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/// This storage tracks how many times words are written between page erase cycles, how many times
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/// pages are erased, and whether an operation flips bits in the wrong direction (optional).
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/// Operations panic if those conditions are broken. This storage also permits to interrupt
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/// operations for inspection or to corrupt the operation.
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/// pages are erased, and whether an operation flips bits in the wrong direction. Operations panic
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/// if those conditions are broken (optional). This storage also permits to interrupt operations for
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/// inspection or to corrupt the operation.
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#[derive(Clone)]
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pub struct BufferStorage {
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/// Content of the storage.
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@@ -59,8 +64,13 @@ pub struct BufferOptions {
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/// How many times a page can be erased.
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pub max_page_erases: usize,
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/// Whether bits cannot be written from 0 to 1.
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pub strict_write: bool,
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/// Whether the storage should check the flash invariant.
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///
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/// When set, the following conditions would panic:
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/// - A bit is written from 0 to 1.
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/// - A word is written more than [`Self::max_word_writes`].
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/// - A page is erased more than [`Self::max_page_erases`].
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pub strict_mode: bool,
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}
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/// Corrupts a slice given actual and expected value.
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@@ -105,15 +115,13 @@ impl BufferStorage {
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///
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/// Before each subsequent mutable operation (write or erase), the delay is decremented if
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/// positive. If the delay is elapsed, the operation is saved and an error is returned.
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/// Subsequent operations will panic until the interrupted operation is [corrupted] or the
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/// interruption is [reset].
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/// Subsequent operations will panic until either of:
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/// - The interrupted operation is [corrupted](BufferStorage::corrupt_operation).
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/// - The interruption is [reset](BufferStorage::reset_interruption).
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///
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/// # Panics
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///
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/// Panics if an interruption is already armed.
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///
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/// [corrupted]: struct.BufferStorage.html#method.corrupt_operation
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/// [reset]: struct.BufferStorage.html#method.reset_interruption
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pub fn arm_interruption(&mut self, delay: usize) {
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self.interruption.arm(delay);
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}
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@@ -125,10 +133,8 @@ impl BufferStorage {
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/// # Panics
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///
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/// Panics if any of the following conditions hold:
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/// - An interruption was not [armed].
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/// - An interruption was not [armed](BufferStorage::arm_interruption).
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/// - An interruption was armed and it has triggered.
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///
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/// [armed]: struct.BufferStorage.html#method.arm_interruption
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pub fn disarm_interruption(&mut self) -> usize {
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self.interruption.get().err().unwrap()
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}
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@@ -137,16 +143,14 @@ impl BufferStorage {
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///
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/// # Panics
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///
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/// Panics if an interruption was not [armed].
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///
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/// [armed]: struct.BufferStorage.html#method.arm_interruption
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/// Panics if an interruption was not [armed](BufferStorage::arm_interruption).
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pub fn reset_interruption(&mut self) {
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let _ = self.interruption.get();
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}
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/// Corrupts an interrupted operation.
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///
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/// Applies the [corruption function] to the storage. Counters are updated accordingly:
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/// Applies the corruption function to the storage. Counters are updated accordingly:
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/// - If a word is fully written, its counter is incremented regardless of whether other words
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/// of the same operation have been fully written.
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/// - If a page is fully erased, its counter is incremented (and its word counters are reset).
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@@ -154,13 +158,10 @@ impl BufferStorage {
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/// # Panics
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///
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/// Panics if any of the following conditions hold:
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/// - An interruption was not [armed].
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/// - An interruption was not [armed](BufferStorage::arm_interruption).
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/// - An interruption was armed but did not trigger.
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/// - The corruption function corrupts more bits than allowed.
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/// - The interrupted operation itself would have panicked.
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///
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/// [armed]: struct.BufferStorage.html#method.arm_interruption
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/// [corruption function]: type.BufferCorruptFunction.html
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pub fn corrupt_operation(&mut self, corrupt: BufferCorruptFunction) {
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let operation = self.interruption.get().unwrap();
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let range = self.operation_range(&operation).unwrap();
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@@ -212,9 +213,13 @@ impl BufferStorage {
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///
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/// # Panics
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///
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/// Panics if the maximum number of erase cycles per page is reached.
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/// Panics if the [maximum number of erase cycles per page](BufferOptions::max_page_erases) is
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/// reached.
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fn incr_page_erases(&mut self, page: usize) {
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assert!(self.page_erases[page] < self.max_page_erases());
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// Check that pages are not erased too many times.
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if self.options.strict_mode {
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assert!(self.page_erases[page] < self.max_page_erases());
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}
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self.page_erases[page] += 1;
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let num_words = self.page_size() / self.word_size();
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for word in 0..num_words {
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@@ -235,7 +240,8 @@ impl BufferStorage {
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///
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/// # Panics
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///
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/// Panics if the maximum number of writes per word is reached.
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/// Panics if the [maximum number of writes per word](BufferOptions::max_word_writes) is
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/// reached.
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fn incr_word_writes(&mut self, index: usize, value: &[u8], complete: &[u8]) {
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let word_size = self.word_size();
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for i in 0..value.len() / word_size {
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@@ -252,7 +258,10 @@ impl BufferStorage {
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continue;
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}
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let word = index / word_size + i;
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assert!(self.word_writes[word] < self.max_word_writes());
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// Check that words are not written too many times.
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if self.options.strict_mode {
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assert!(self.word_writes[word] < self.max_word_writes());
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}
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self.word_writes[word] += 1;
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}
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}
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@@ -306,8 +315,8 @@ impl Storage for BufferStorage {
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self.interruption.tick(&operation)?;
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// Check and update counters.
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self.incr_word_writes(range.start, value, value);
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// Check strict write.
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if self.options.strict_write {
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// Check that bits are correctly flipped.
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if self.options.strict_mode {
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for (byte, &val) in range.clone().zip(value.iter()) {
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assert_eq!(self.storage[byte] & val, val);
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}
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@@ -472,7 +481,7 @@ mod tests {
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page_size: 16,
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max_word_writes: 2,
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max_page_erases: 3,
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strict_write: true,
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strict_mode: true,
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};
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// Those words are decreasing bit patterns. Bits are only changed from 1 to 0 and at least one
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// bit is changed.
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@@ -12,6 +12,10 @@
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// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
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//! Store wrapper for testing.
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//!
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//! [`StoreDriver`] wraps a [`Store`] and compares its behavior with its associated [`StoreModel`].
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use crate::format::{Format, Position};
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#[cfg(test)]
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use crate::StoreUpdate;
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@@ -181,6 +185,12 @@ pub enum StoreInvariant {
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},
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}
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impl From<StoreError> for StoreInvariant {
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fn from(error: StoreError) -> StoreInvariant {
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StoreInvariant::StoreError(error)
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}
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}
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impl StoreDriver {
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/// Provides read-only access to the storage.
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pub fn storage(&self) -> &BufferStorage {
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@@ -249,6 +259,10 @@ impl StoreDriverOff {
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}
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/// Powers on the store without interruption.
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///
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/// # Panics
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///
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/// Panics if the store cannot be powered on.
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pub fn power_on(self) -> Result<StoreDriverOn, StoreInvariant> {
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Ok(self
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.partial_power_on(StoreInterruption::none())
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@@ -301,31 +315,15 @@ impl StoreDriverOff {
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})
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}
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/// Returns a mapping from delay time to number of modified bits.
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/// Returns the number of storage operations to power on.
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///
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/// For example if the `i`-th value is `n`, it means that the `i`-th operation modifies `n` bits
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/// in the storage. For convenience, the vector always ends with `0` for one past the last
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/// operation. This permits to choose a random index in the vector and then a random set of bit
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/// positions among the number of modified bits to simulate any possible corruption (including
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/// no corruption with the last index).
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pub fn delay_map(&self) -> Result<Vec<usize>, (usize, BufferStorage)> {
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let mut result = Vec::new();
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loop {
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let delay = result.len();
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let mut storage = self.storage.clone();
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storage.arm_interruption(delay);
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match Store::new(storage) {
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Err((StoreError::StorageError, x)) => storage = x,
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Err((StoreError::InvalidStorage, mut storage)) => {
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storage.reset_interruption();
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return Err((delay, storage));
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}
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Ok(_) | Err(_) => break,
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}
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result.push(count_modified_bits(&mut storage));
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}
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result.push(0);
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Ok(result)
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/// Returns `None` if the store cannot power on successfully.
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pub fn count_operations(&self) -> Option<usize> {
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let initial_delay = usize::MAX;
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let mut storage = self.storage.clone();
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storage.arm_interruption(initial_delay);
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let mut store = Store::new(storage).ok()?;
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Some(initial_delay - store.storage_mut().disarm_interruption())
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}
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}
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@@ -412,29 +410,15 @@ impl StoreDriverOn {
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})
|
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}
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|
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/// Returns a mapping from delay time to number of modified bits.
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/// Returns the number of storage operations to apply a store operation.
|
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///
|
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/// See the documentation of [`StoreDriverOff::delay_map`] for details.
|
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///
|
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/// [`StoreDriverOff::delay_map`]: struct.StoreDriverOff.html#method.delay_map
|
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pub fn delay_map(
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&self,
|
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operation: &StoreOperation,
|
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) -> Result<Vec<usize>, (usize, BufferStorage)> {
|
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let mut result = Vec::new();
|
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loop {
|
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let delay = result.len();
|
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let mut store = self.store.clone();
|
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store.storage_mut().arm_interruption(delay);
|
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match store.apply(operation).1 {
|
||||
Err(StoreError::StorageError) => (),
|
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Err(StoreError::InvalidStorage) => return Err((delay, store.extract_storage())),
|
||||
Ok(()) | Err(_) => break,
|
||||
}
|
||||
result.push(count_modified_bits(store.storage_mut()));
|
||||
}
|
||||
result.push(0);
|
||||
Ok(result)
|
||||
/// Returns `None` if the store cannot apply the operation successfully.
|
||||
pub fn count_operations(&self, operation: &StoreOperation) -> Option<usize> {
|
||||
let initial_delay = usize::MAX;
|
||||
let mut store = self.store.clone();
|
||||
store.storage_mut().arm_interruption(initial_delay);
|
||||
store.apply(operation).1.ok()?;
|
||||
Some(initial_delay - store.storage_mut().disarm_interruption())
|
||||
}
|
||||
|
||||
/// Powers off the store.
|
||||
@@ -506,8 +490,8 @@ impl StoreDriverOn {
|
||||
/// Checks that the store and model are in sync.
|
||||
fn check_model(&self) -> Result<(), StoreInvariant> {
|
||||
let mut model_content = self.model.content().clone();
|
||||
for handle in self.store.iter().unwrap() {
|
||||
let handle = handle.unwrap();
|
||||
for handle in self.store.iter()? {
|
||||
let handle = handle?;
|
||||
let model_value = match model_content.remove(&handle.get_key()) {
|
||||
None => {
|
||||
return Err(StoreInvariant::OnlyInStore {
|
||||
@@ -516,7 +500,7 @@ impl StoreDriverOn {
|
||||
}
|
||||
Some(x) => x,
|
||||
};
|
||||
let store_value = handle.get_value(&self.store).unwrap().into_boxed_slice();
|
||||
let store_value = handle.get_value(&self.store)?.into_boxed_slice();
|
||||
if store_value != model_value {
|
||||
return Err(StoreInvariant::DifferentValue {
|
||||
key: handle.get_key(),
|
||||
@@ -528,7 +512,7 @@ impl StoreDriverOn {
|
||||
if let Some(&key) = model_content.keys().next() {
|
||||
return Err(StoreInvariant::OnlyInModel { key });
|
||||
}
|
||||
let store_capacity = self.store.capacity().unwrap().remaining();
|
||||
let store_capacity = self.store.capacity()?.remaining();
|
||||
let model_capacity = self.model.capacity().remaining();
|
||||
if store_capacity != model_capacity {
|
||||
return Err(StoreInvariant::DifferentCapacity {
|
||||
@@ -544,8 +528,8 @@ impl StoreDriverOn {
|
||||
let format = self.model.format();
|
||||
let storage = self.store.storage();
|
||||
let num_words = format.page_size() / format.word_size();
|
||||
let head = self.store.head().unwrap();
|
||||
let tail = self.store.tail().unwrap();
|
||||
let head = self.store.head()?;
|
||||
let tail = self.store.tail()?;
|
||||
for page in 0..format.num_pages() {
|
||||
// Check the erase cycle of the page.
|
||||
let store_erase = head.cycle(format) + (page < head.page(format)) as Nat;
|
||||
@@ -619,22 +603,3 @@ impl<'a> StoreInterruption<'a> {
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Counts the number of bits modified by an interrupted operation.
|
||||
///
|
||||
/// # Panics
|
||||
///
|
||||
/// Panics if an interruption did not trigger.
|
||||
fn count_modified_bits(storage: &mut BufferStorage) -> usize {
|
||||
let mut modified_bits = 0;
|
||||
storage.corrupt_operation(Box::new(|before, after| {
|
||||
modified_bits = before
|
||||
.iter()
|
||||
.zip(after.iter())
|
||||
.map(|(x, y)| (x ^ y).count_ones() as usize)
|
||||
.sum();
|
||||
}));
|
||||
// We should never write the same slice or erase an erased page.
|
||||
assert!(modified_bits > 0);
|
||||
modified_bits
|
||||
}
|
||||
|
||||
@@ -12,6 +12,8 @@
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
//! Storage representation of a store.
|
||||
|
||||
#[macro_use]
|
||||
mod bitfield;
|
||||
|
||||
@@ -20,18 +22,20 @@ use self::bitfield::Length;
|
||||
use self::bitfield::{count_zeros, num_bits, Bit, Checksum, ConstField, Field};
|
||||
use crate::{usize_to_nat, Nat, Storage, StorageIndex, StoreError, StoreResult, StoreUpdate};
|
||||
use alloc::vec::Vec;
|
||||
use core::borrow::Borrow;
|
||||
use core::cmp::min;
|
||||
use core::convert::TryFrom;
|
||||
|
||||
/// Internal representation of a word in flash.
|
||||
///
|
||||
/// Currently, the store only supports storages where a word is 32 bits.
|
||||
/// Currently, the store only supports storages where a word is 32 bits, i.e. the [word
|
||||
/// size](Storage::word_size) is 4 bytes.
|
||||
type WORD = u32;
|
||||
|
||||
/// Abstract representation of a word in flash.
|
||||
///
|
||||
/// This type is kept abstract to avoid possible confusion with `Nat` if they happen to have the
|
||||
/// same representation. This is because they have different semantics, `Nat` represents natural
|
||||
/// This type is kept abstract to avoid possible confusion with [`Nat`] if they happen to have the
|
||||
/// same representation. This is because they have different semantics, [`Nat`] represents natural
|
||||
/// numbers while `Word` represents sequences of bits (and thus has no arithmetic).
|
||||
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
|
||||
pub struct Word(WORD);
|
||||
@@ -46,7 +50,7 @@ impl Word {
|
||||
///
|
||||
/// # Panics
|
||||
///
|
||||
/// Panics if `slice.len() != WORD_SIZE`.
|
||||
/// Panics if `slice.len()` is not [`WORD_SIZE`] bytes.
|
||||
pub fn from_slice(slice: &[u8]) -> Word {
|
||||
Word(WORD::from_le_bytes(<WordSlice>::try_from(slice).unwrap()))
|
||||
}
|
||||
@@ -59,47 +63,49 @@ impl Word {
|
||||
|
||||
/// Size of a word in bytes.
|
||||
///
|
||||
/// Currently, the store only supports storages where a word is 4 bytes.
|
||||
/// Currently, the store only supports storages where the [word size](Storage::word_size) is 4
|
||||
/// bytes.
|
||||
const WORD_SIZE: Nat = core::mem::size_of::<WORD>() as Nat;
|
||||
|
||||
/// Minimum number of words per page.
|
||||
///
|
||||
/// Currently, the store only supports storages where pages have at least 8 words.
|
||||
const MIN_NUM_WORDS_PER_PAGE: Nat = 8;
|
||||
/// Currently, the store only supports storages where pages have at least 8 [words](WORD_SIZE), i.e.
|
||||
/// the [page size](Storage::page_size) is at least 32 bytes.
|
||||
const MIN_PAGE_SIZE: Nat = 8;
|
||||
|
||||
/// Maximum size of a page in bytes.
|
||||
///
|
||||
/// Currently, the store only supports storages where pages are between 8 and 1024 [words].
|
||||
///
|
||||
/// [words]: constant.WORD_SIZE.html
|
||||
/// Currently, the store only supports storages where pages have at most 1024 [words](WORD_SIZE),
|
||||
/// i.e. the [page size](Storage::page_size) is at most 4096 bytes.
|
||||
const MAX_PAGE_SIZE: Nat = 4096;
|
||||
|
||||
/// Maximum number of erase cycles.
|
||||
///
|
||||
/// Currently, the store only supports storages where the maximum number of erase cycles fits on 16
|
||||
/// bits.
|
||||
/// Currently, the store only supports storages where the [maximum number of erase
|
||||
/// cycles](Storage::max_page_erases) fits in 16 bits, i.e. it is at most 65535.
|
||||
const MAX_ERASE_CYCLE: Nat = 65535;
|
||||
|
||||
/// Minimum number of pages.
|
||||
///
|
||||
/// Currently, the store only supports storages with at least 3 pages.
|
||||
/// Currently, the store only supports storages where the [number of pages](Storage::num_pages) is
|
||||
/// at least 3.
|
||||
const MIN_NUM_PAGES: Nat = 3;
|
||||
|
||||
/// Maximum page index.
|
||||
///
|
||||
/// Thus the maximum number of pages is one more than this number. Currently, the store only
|
||||
/// supports storages where the number of pages is between 3 and 64.
|
||||
/// Currently, the store only supports storages where the [number of pages](Storage::num_pages) is
|
||||
/// at most 64, i.e. the maximum page index is 63.
|
||||
const MAX_PAGE_INDEX: Nat = 63;
|
||||
|
||||
/// Maximum key index.
|
||||
///
|
||||
/// Thus the number of keys is one more than this number. Currently, the store only supports 4096
|
||||
/// keys.
|
||||
/// Currently, the store only supports 4096 keys, i.e. the maximum key index is 4095.
|
||||
const MAX_KEY_INDEX: Nat = 4095;
|
||||
|
||||
/// Maximum length in bytes of a user payload.
|
||||
///
|
||||
/// Currently, the store only supports values smaller than 1024 bytes.
|
||||
/// Currently, the store only supports values at most 1023 bytes long. This may be further reduced
|
||||
/// depending on the [page size](Storage::page_size), see [`Format::max_value_len`].
|
||||
const MAX_VALUE_LEN: Nat = 1023;
|
||||
|
||||
/// Maximum number of updates per transaction.
|
||||
@@ -108,9 +114,15 @@ const MAX_VALUE_LEN: Nat = 1023;
|
||||
const MAX_UPDATES: Nat = 31;
|
||||
|
||||
/// Maximum number of words per virtual page.
|
||||
const MAX_VIRT_PAGE_SIZE: Nat = div_ceil(MAX_PAGE_SIZE, WORD_SIZE) - CONTENT_WORD;
|
||||
///
|
||||
/// A virtual page has [`CONTENT_WORD`] less [words](WORD_SIZE) than the storage [page
|
||||
/// size](Storage::page_size). Those words are used to store the page header. Since a page has at
|
||||
/// least [8](MIN_PAGE_SIZE) words, a virtual page has at least 6 words.
|
||||
const MAX_VIRT_PAGE_SIZE: Nat = MAX_PAGE_SIZE / WORD_SIZE - CONTENT_WORD;
|
||||
|
||||
/// Word with all bits set to one.
|
||||
///
|
||||
/// After a page is erased, all words are equal to this value.
|
||||
const ERASED_WORD: Word = Word(!(0 as WORD));
|
||||
|
||||
/// Helpers for a given storage configuration.
|
||||
@@ -120,33 +132,31 @@ pub struct Format {
|
||||
///
|
||||
/// # Invariant
|
||||
///
|
||||
/// - Words divide a page evenly.
|
||||
/// - There are at least 8 words in a page.
|
||||
/// - There are at most `MAX_PAGE_SIZE` bytes in a page.
|
||||
/// - [Words](WORD_SIZE) divide a page evenly.
|
||||
/// - There are at least [`MIN_PAGE_SIZE`] words in a page.
|
||||
/// - There are at most [`MAX_PAGE_SIZE`] bytes in a page.
|
||||
page_size: Nat,
|
||||
|
||||
/// The number of pages in the storage.
|
||||
///
|
||||
/// # Invariant
|
||||
///
|
||||
/// - There are at least 3 pages.
|
||||
/// - There are at most `MAX_PAGE_INDEX + 1` pages.
|
||||
/// - There are at least [`MIN_NUM_PAGES`] pages.
|
||||
/// - There are at most [`MAX_PAGE_INDEX`] + 1 pages.
|
||||
num_pages: Nat,
|
||||
|
||||
/// The maximum number of times a page can be erased.
|
||||
///
|
||||
/// # Invariant
|
||||
///
|
||||
/// - A page can be erased at most `MAX_ERASE_CYCLE` times.
|
||||
/// - A page can be erased at most [`MAX_ERASE_CYCLE`] times.
|
||||
max_page_erases: Nat,
|
||||
}
|
||||
|
||||
impl Format {
|
||||
/// Extracts the format from a storage.
|
||||
///
|
||||
/// Returns `None` if the storage is not [supported].
|
||||
///
|
||||
/// [supported]: struct.Format.html#method.is_storage_supported
|
||||
/// Returns `None` if the storage is not [supported](Format::is_storage_supported).
|
||||
pub fn new<S: Storage>(storage: &S) -> Option<Format> {
|
||||
if Format::is_storage_supported(storage) {
|
||||
Some(Format {
|
||||
@@ -162,21 +172,12 @@ impl Format {
|
||||
/// Returns whether a storage is supported.
|
||||
///
|
||||
/// A storage is supported if the following conditions hold:
|
||||
/// - The size of a word is [`WORD_SIZE`] bytes.
|
||||
/// - The size of a word evenly divides the size of a page.
|
||||
/// - A page contains at least [`MIN_NUM_WORDS_PER_PAGE`] words.
|
||||
/// - A page contains at most [`MAX_PAGE_SIZE`] bytes.
|
||||
/// - There are at least [`MIN_NUM_PAGES`] pages.
|
||||
/// - There are at most [`MAX_PAGE_INDEX`]` + 1` pages.
|
||||
/// - A word can be written at least twice between erase cycles.
|
||||
/// - The maximum number of erase cycles is at most [`MAX_ERASE_CYCLE`].
|
||||
///
|
||||
/// [`WORD_SIZE`]: constant.WORD_SIZE.html
|
||||
/// [`MIN_NUM_WORDS_PER_PAGE`]: constant.MIN_NUM_WORDS_PER_PAGE.html
|
||||
/// [`MAX_PAGE_SIZE`]: constant.MAX_PAGE_SIZE.html
|
||||
/// [`MIN_NUM_PAGES`]: constant.MIN_NUM_PAGES.html
|
||||
/// [`MAX_PAGE_INDEX`]: constant.MAX_PAGE_INDEX.html
|
||||
/// [`MAX_ERASE_CYCLE`]: constant.MAX_ERASE_CYCLE.html
|
||||
/// - The [`Storage::word_size`] is [`WORD_SIZE`] bytes.
|
||||
/// - The [`Storage::word_size`] evenly divides the [`Storage::page_size`].
|
||||
/// - The [`Storage::page_size`] is between [`MIN_PAGE_SIZE`] words and [`MAX_PAGE_SIZE`] bytes.
|
||||
/// - The [`Storage::num_pages`] is between [`MIN_NUM_PAGES`] and [`MAX_PAGE_INDEX`] + 1.
|
||||
/// - The [`Storage::max_word_writes`] is at least 2.
|
||||
/// - The [`Storage::max_page_erases`] is at most [`MAX_ERASE_CYCLE`].
|
||||
fn is_storage_supported<S: Storage>(storage: &S) -> bool {
|
||||
let word_size = usize_to_nat(storage.word_size());
|
||||
let page_size = usize_to_nat(storage.page_size());
|
||||
@@ -185,7 +186,7 @@ impl Format {
|
||||
let max_page_erases = usize_to_nat(storage.max_page_erases());
|
||||
word_size == WORD_SIZE
|
||||
&& page_size % word_size == 0
|
||||
&& (MIN_NUM_WORDS_PER_PAGE * word_size <= page_size && page_size <= MAX_PAGE_SIZE)
|
||||
&& (MIN_PAGE_SIZE * word_size <= page_size && page_size <= MAX_PAGE_SIZE)
|
||||
&& (MIN_NUM_PAGES <= num_pages && num_pages <= MAX_PAGE_INDEX + 1)
|
||||
&& max_word_writes >= 2
|
||||
&& max_page_erases <= MAX_ERASE_CYCLE
|
||||
@@ -198,28 +199,28 @@ impl Format {
|
||||
|
||||
/// The size of a page in bytes.
|
||||
///
|
||||
/// We have `MIN_NUM_WORDS_PER_PAGE * self.word_size() <= self.page_size() <= MAX_PAGE_SIZE`.
|
||||
/// This is at least [`MIN_PAGE_SIZE`] [words](WORD_SIZE) and at most [`MAX_PAGE_SIZE`] bytes.
|
||||
pub fn page_size(&self) -> Nat {
|
||||
self.page_size
|
||||
}
|
||||
|
||||
/// The number of pages in the storage, denoted by `N`.
|
||||
/// The number of pages in the storage, denoted by N.
|
||||
///
|
||||
/// We have `MIN_NUM_PAGES <= N <= MAX_PAGE_INDEX + 1`.
|
||||
/// We have [`MIN_NUM_PAGES`] ≤ N ≤ [`MAX_PAGE_INDEX`] + 1.
|
||||
pub fn num_pages(&self) -> Nat {
|
||||
self.num_pages
|
||||
}
|
||||
|
||||
/// The maximum page index.
|
||||
///
|
||||
/// We have `2 <= self.max_page() <= MAX_PAGE_INDEX`.
|
||||
/// This is at least [`MIN_NUM_PAGES`] - 1 and at most [`MAX_PAGE_INDEX`].
|
||||
pub fn max_page(&self) -> Nat {
|
||||
self.num_pages - 1
|
||||
}
|
||||
|
||||
/// The maximum number of times a page can be erased, denoted by `E`.
|
||||
/// The maximum number of times a page can be erased, denoted by E.
|
||||
///
|
||||
/// We have `E <= MAX_ERASE_CYCLE`.
|
||||
/// We have E ≤ [`MAX_ERASE_CYCLE`].
|
||||
pub fn max_page_erases(&self) -> Nat {
|
||||
self.max_page_erases
|
||||
}
|
||||
@@ -234,19 +235,18 @@ impl Format {
|
||||
MAX_UPDATES
|
||||
}
|
||||
|
||||
/// The size of a virtual page in words, denoted by `Q`.
|
||||
/// The size of a virtual page in words, denoted by Q.
|
||||
///
|
||||
/// A virtual page is stored in a physical page after the page header.
|
||||
///
|
||||
/// We have `MIN_NUM_WORDS_PER_PAGE - 2 <= Q <= MAX_VIRT_PAGE_SIZE`.
|
||||
/// We have [`MIN_PAGE_SIZE`] - 2 ≤ Q ≤ [`MAX_VIRT_PAGE_SIZE`].
|
||||
pub fn virt_page_size(&self) -> Nat {
|
||||
self.page_size() / self.word_size() - CONTENT_WORD
|
||||
}
|
||||
|
||||
/// The maximum length in bytes of a user payload.
|
||||
///
|
||||
/// We have `(MIN_NUM_WORDS_PER_PAGE - 3) * self.word_size() <= self.max_value_len() <=
|
||||
/// MAX_VALUE_LEN`.
|
||||
/// This is at least [`MIN_PAGE_SIZE`] - 3 [words](WORD_SIZE) and at most [`MAX_VALUE_LEN`].
|
||||
pub fn max_value_len(&self) -> Nat {
|
||||
min(
|
||||
(self.virt_page_size() - 1) * self.word_size(),
|
||||
@@ -254,57 +254,50 @@ impl Format {
|
||||
)
|
||||
}
|
||||
|
||||
/// The maximum prefix length in words, denoted by `M`.
|
||||
/// The maximum prefix length in words, denoted by M.
|
||||
///
|
||||
/// A prefix is the first words of a virtual page that belong to the last entry of the previous
|
||||
/// virtual page. This happens because entries may overlap up to 2 virtual pages.
|
||||
///
|
||||
/// We have `MIN_NUM_WORDS_PER_PAGE - 3 <= M < Q`.
|
||||
/// We have [`MIN_PAGE_SIZE`] - 3 ≤ M < Q.
|
||||
pub fn max_prefix_len(&self) -> Nat {
|
||||
self.bytes_to_words(self.max_value_len())
|
||||
}
|
||||
|
||||
/// The total virtual capacity in words, denoted by `V`.
|
||||
/// The total virtual capacity in words, denoted by V.
|
||||
///
|
||||
/// We have `V = (N - 1) * (Q - 1) - M`.
|
||||
/// We have V = (N - 1) × (Q - 1) - M.
|
||||
///
|
||||
/// We can show `V >= (N - 2) * (Q - 1)` with the following steps:
|
||||
/// - `M <= Q - 1` from `M < Q` from [`M`] definition
|
||||
/// - `-M >= -(Q - 1)` from above
|
||||
/// - `V >= (N - 1) * (Q - 1) - (Q - 1)` from `V` definition
|
||||
///
|
||||
/// [`M`]: struct.Format.html#method.max_prefix_len
|
||||
/// We can show V ≥ (N - 2) × (Q - 1) with the following steps:
|
||||
/// - M ≤ Q - 1 from M < Q from [M](Format::max_prefix_len)'s definition
|
||||
/// - -M ≥ -(Q - 1) from above
|
||||
/// - V ≥ (N - 1) × (Q - 1) - (Q - 1) from V's definition
|
||||
pub fn virt_size(&self) -> Nat {
|
||||
(self.num_pages() - 1) * (self.virt_page_size() - 1) - self.max_prefix_len()
|
||||
}
|
||||
|
||||
/// The total user capacity in words, denoted by `C`.
|
||||
/// The total user capacity in words, denoted by C.
|
||||
///
|
||||
/// We have `C = V - N = (N - 1) * (Q - 2) - M - 1`.
|
||||
/// We have C = V - N = (N - 1) × (Q - 2) - M - 1.
|
||||
///
|
||||
/// We can show `C >= (N - 2) * (Q - 2) - 2` with the following steps:
|
||||
/// - `V >= (N - 2) * (Q - 1)` from [`V`] definition
|
||||
/// - `C >= (N - 2) * (Q - 1) - N` from `C` definition
|
||||
/// - `(N - 2) * (Q - 1) - N = (N - 2) * (Q - 2) - 2` by calculus
|
||||
///
|
||||
/// [`V`]: struct.Format.html#method.virt_size
|
||||
/// We can show C ≥ (N - 2) × (Q - 2) - 2 with the following steps:
|
||||
/// - V ≥ (N - 2) × (Q - 1) from [V](Format::virt_size)'s definition
|
||||
/// - C ≥ (N - 2) × (Q - 1) - N from C's definition
|
||||
/// - (N - 2) × (Q - 1) - N = (N - 2) × (Q - 2) - 2 by calculus
|
||||
pub fn total_capacity(&self) -> Nat {
|
||||
// From the virtual capacity, we reserve N - 1 words for `Erase` entries and 1 word for a
|
||||
// `Clear` entry.
|
||||
self.virt_size() - self.num_pages()
|
||||
}
|
||||
|
||||
/// The total virtual lifetime in words, denoted by `L`.
|
||||
/// The total virtual lifetime in words, denoted by L.
|
||||
///
|
||||
/// We have `L = (E * N + N - 1) * Q`.
|
||||
/// We have L = (E × N + N - 1) × Q.
|
||||
pub fn total_lifetime(&self) -> Position {
|
||||
Position::new(self, self.max_page_erases(), self.num_pages() - 1, 0)
|
||||
}
|
||||
|
||||
/// Returns the word position of the first entry of a page.
|
||||
///
|
||||
/// The init info of the page must be provided to know where the first entry of the page
|
||||
/// starts.
|
||||
pub fn page_head(&self, init: InitInfo, page: Nat) -> Position {
|
||||
Position::new(self, init.cycle, page, init.prefix)
|
||||
}
|
||||
@@ -335,12 +328,12 @@ impl Format {
|
||||
}
|
||||
|
||||
/// Builds the storage representation of an init info.
|
||||
pub fn build_init(&self, init: InitInfo) -> WordSlice {
|
||||
pub fn build_init(&self, init: InitInfo) -> StoreResult<WordSlice> {
|
||||
let mut word = ERASED_WORD;
|
||||
INIT_CYCLE.set(&mut word, init.cycle);
|
||||
INIT_PREFIX.set(&mut word, init.prefix);
|
||||
WORD_CHECKSUM.set(&mut word, 0);
|
||||
word.as_slice()
|
||||
INIT_CYCLE.set(&mut word, init.cycle)?;
|
||||
INIT_PREFIX.set(&mut word, init.prefix)?;
|
||||
WORD_CHECKSUM.set(&mut word, 0)?;
|
||||
Ok(word.as_slice())
|
||||
}
|
||||
|
||||
/// Returns the storage index of the compact info of a page.
|
||||
@@ -368,36 +361,36 @@ impl Format {
|
||||
}
|
||||
|
||||
/// Builds the storage representation of a compact info.
|
||||
pub fn build_compact(&self, compact: CompactInfo) -> WordSlice {
|
||||
pub fn build_compact(&self, compact: CompactInfo) -> StoreResult<WordSlice> {
|
||||
let mut word = ERASED_WORD;
|
||||
COMPACT_TAIL.set(&mut word, compact.tail);
|
||||
WORD_CHECKSUM.set(&mut word, 0);
|
||||
word.as_slice()
|
||||
COMPACT_TAIL.set(&mut word, compact.tail)?;
|
||||
WORD_CHECKSUM.set(&mut word, 0)?;
|
||||
Ok(word.as_slice())
|
||||
}
|
||||
|
||||
/// Builds the storage representation of an internal entry.
|
||||
pub fn build_internal(&self, internal: InternalEntry) -> WordSlice {
|
||||
pub fn build_internal(&self, internal: InternalEntry) -> StoreResult<WordSlice> {
|
||||
let mut word = ERASED_WORD;
|
||||
match internal {
|
||||
InternalEntry::Erase { page } => {
|
||||
ID_ERASE.set(&mut word);
|
||||
ERASE_PAGE.set(&mut word, page);
|
||||
ID_ERASE.set(&mut word)?;
|
||||
ERASE_PAGE.set(&mut word, page)?;
|
||||
}
|
||||
InternalEntry::Clear { min_key } => {
|
||||
ID_CLEAR.set(&mut word);
|
||||
CLEAR_MIN_KEY.set(&mut word, min_key);
|
||||
ID_CLEAR.set(&mut word)?;
|
||||
CLEAR_MIN_KEY.set(&mut word, min_key)?;
|
||||
}
|
||||
InternalEntry::Marker { count } => {
|
||||
ID_MARKER.set(&mut word);
|
||||
MARKER_COUNT.set(&mut word, count);
|
||||
ID_MARKER.set(&mut word)?;
|
||||
MARKER_COUNT.set(&mut word, count)?;
|
||||
}
|
||||
InternalEntry::Remove { key } => {
|
||||
ID_REMOVE.set(&mut word);
|
||||
REMOVE_KEY.set(&mut word, key);
|
||||
ID_REMOVE.set(&mut word)?;
|
||||
REMOVE_KEY.set(&mut word, key)?;
|
||||
}
|
||||
}
|
||||
WORD_CHECKSUM.set(&mut word, 0);
|
||||
word.as_slice()
|
||||
WORD_CHECKSUM.set(&mut word, 0)?;
|
||||
Ok(word.as_slice())
|
||||
}
|
||||
|
||||
/// Parses the first word of an entry from its storage representation.
|
||||
@@ -459,31 +452,31 @@ impl Format {
|
||||
}
|
||||
|
||||
/// Builds the storage representation of a user entry.
|
||||
pub fn build_user(&self, key: Nat, value: &[u8]) -> Vec<u8> {
|
||||
pub fn build_user(&self, key: Nat, value: &[u8]) -> StoreResult<Vec<u8>> {
|
||||
let length = usize_to_nat(value.len());
|
||||
let word_size = self.word_size();
|
||||
let footer = self.bytes_to_words(length);
|
||||
let mut result = vec![0xff; ((1 + footer) * word_size) as usize];
|
||||
result[word_size as usize..][..length as usize].copy_from_slice(value);
|
||||
let mut word = ERASED_WORD;
|
||||
ID_HEADER.set(&mut word);
|
||||
ID_HEADER.set(&mut word)?;
|
||||
if footer > 0 && is_erased(&result[(footer * word_size) as usize..]) {
|
||||
HEADER_FLIPPED.set(&mut word);
|
||||
*result.last_mut().unwrap() = 0x7f;
|
||||
}
|
||||
HEADER_LENGTH.set(&mut word, length);
|
||||
HEADER_KEY.set(&mut word, key);
|
||||
HEADER_LENGTH.set(&mut word, length)?;
|
||||
HEADER_KEY.set(&mut word, key)?;
|
||||
HEADER_CHECKSUM.set(
|
||||
&mut word,
|
||||
count_zeros(&result[(footer * word_size) as usize..]),
|
||||
);
|
||||
)?;
|
||||
result[..word_size as usize].copy_from_slice(&word.as_slice());
|
||||
result
|
||||
Ok(result)
|
||||
}
|
||||
|
||||
/// Sets the padding bit in the first word of a user entry.
|
||||
pub fn set_padding(&self, word: &mut Word) {
|
||||
ID_PADDING.set(word);
|
||||
pub fn set_padding(&self, word: &mut Word) -> StoreResult<()> {
|
||||
ID_PADDING.set(word)
|
||||
}
|
||||
|
||||
/// Sets the deleted bit in the first word of a user entry.
|
||||
@@ -492,13 +485,16 @@ impl Format {
|
||||
}
|
||||
|
||||
/// Returns the capacity required by a transaction.
|
||||
pub fn transaction_capacity(&self, updates: &[StoreUpdate]) -> Nat {
|
||||
pub fn transaction_capacity<ByteSlice: Borrow<[u8]>>(
|
||||
&self,
|
||||
updates: &[StoreUpdate<ByteSlice>],
|
||||
) -> Nat {
|
||||
match updates.len() {
|
||||
// An empty transaction doesn't consume anything.
|
||||
0 => 0,
|
||||
// Transactions with a single update are optimized by avoiding a marker entry.
|
||||
1 => match &updates[0] {
|
||||
StoreUpdate::Insert { value, .. } => self.entry_size(value),
|
||||
StoreUpdate::Insert { value, .. } => self.entry_size(value.borrow()),
|
||||
// Transactions with a single update which is a removal don't consume anything.
|
||||
StoreUpdate::Remove { .. } => 0,
|
||||
},
|
||||
@@ -508,9 +504,9 @@ impl Format {
|
||||
}
|
||||
|
||||
/// Returns the capacity of an update.
|
||||
fn update_capacity(&self, update: &StoreUpdate) -> Nat {
|
||||
fn update_capacity<ByteSlice: Borrow<[u8]>>(&self, update: &StoreUpdate<ByteSlice>) -> Nat {
|
||||
match update {
|
||||
StoreUpdate::Insert { value, .. } => self.entry_size(value),
|
||||
StoreUpdate::Insert { value, .. } => self.entry_size(value.borrow()),
|
||||
StoreUpdate::Remove { .. } => 1,
|
||||
}
|
||||
}
|
||||
@@ -523,7 +519,10 @@ impl Format {
|
||||
/// Checks if a transaction is valid and returns its sorted keys.
|
||||
///
|
||||
/// Returns `None` if the transaction is invalid.
|
||||
pub fn transaction_valid(&self, updates: &[StoreUpdate]) -> Option<Vec<Nat>> {
|
||||
pub fn transaction_valid<ByteSlice: Borrow<[u8]>>(
|
||||
&self,
|
||||
updates: &[StoreUpdate<ByteSlice>],
|
||||
) -> Option<Vec<Nat>> {
|
||||
if usize_to_nat(updates.len()) > self.max_updates() {
|
||||
return None;
|
||||
}
|
||||
@@ -550,7 +549,7 @@ impl Format {
|
||||
///
|
||||
/// # Preconditions
|
||||
///
|
||||
/// - `bytes + self.word_size()` does not overflow.
|
||||
/// - `bytes` + [`Self::word_size`] does not overflow.
|
||||
pub fn bytes_to_words(&self, bytes: Nat) -> Nat {
|
||||
div_ceil(bytes, self.word_size())
|
||||
}
|
||||
@@ -564,7 +563,7 @@ const COMPACT_WORD: Nat = 1;
|
||||
|
||||
/// The word index of the content of a page.
|
||||
///
|
||||
/// Since a page is at least 8 words, there is always at least 6 words of content.
|
||||
/// This is also the length in words of the page header.
|
||||
const CONTENT_WORD: Nat = 2;
|
||||
|
||||
/// The checksum for a single word.
|
||||
@@ -711,21 +710,21 @@ bitfield! {
|
||||
|
||||
/// The position of a word in the virtual storage.
|
||||
///
|
||||
/// With the notations defined in `Format`, let:
|
||||
/// - `w` a virtual word offset in a page which is between `0` and `Q - 1`
|
||||
/// - `p` a page offset which is between `0` and `N - 1`
|
||||
/// - `c` the number of erase cycles of a page which is between `0` and `E`
|
||||
/// With the notations defined in [`Format`], let:
|
||||
/// - w denote a word offset in a virtual page, thus between 0 and Q - 1
|
||||
/// - p denote a page offset, thus between 0 and N - 1
|
||||
/// - c denote the number of times a page was erased, thus between 0 and E
|
||||
///
|
||||
/// Then the position of a word is `(c*N + p)*Q + w`. This position monotonically increases and
|
||||
/// The position of a word is (c × N + p) × Q + w. This position monotonically increases and
|
||||
/// represents the consumed lifetime of the storage.
|
||||
///
|
||||
/// This type is kept abstract to avoid possible confusion with `Nat` and `Word` if they happen to
|
||||
/// have the same representation. Here is an overview of their semantics:
|
||||
/// This type is kept abstract to avoid possible confusion with [`Nat`] and [`Word`] if they happen
|
||||
/// to have the same representation. Here is an overview of their semantics:
|
||||
///
|
||||
/// | Name | Semantics | Arithmetic operations | Bit-wise operations |
|
||||
/// | ---------- | --------------------------- | --------------------- | ------------------- |
|
||||
/// | `Nat` | Natural numbers | Yes (no overflow) | No |
|
||||
/// | `Word` | Word in flash | No | Yes |
|
||||
/// | [`Nat`] | Natural numbers | Yes (no overflow) | No |
|
||||
/// | [`Word`] | Word in flash | No | Yes |
|
||||
/// | `Position` | Position in virtual storage | Yes (no overflow) | No |
|
||||
#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
|
||||
pub struct Position(Nat);
|
||||
@@ -756,9 +755,9 @@ impl Position {
|
||||
/// Create a word position given its coordinates.
|
||||
///
|
||||
/// The coordinates of a word are:
|
||||
/// - Its word index in its page.
|
||||
/// - Its word index in its virtual page.
|
||||
/// - Its page index in the storage.
|
||||
/// - The number of times that page was erased.
|
||||
/// - The number of times its page was erased.
|
||||
pub fn new(format: &Format, cycle: Nat, page: Nat, word: Nat) -> Position {
|
||||
Position((cycle * format.num_pages() + page) * format.virt_page_size() + word)
|
||||
}
|
||||
@@ -921,11 +920,11 @@ pub fn is_erased(slice: &[u8]) -> bool {
|
||||
|
||||
/// Divides then takes ceiling.
|
||||
///
|
||||
/// Returns `ceil(x / m)` in mathematical notations (not Rust code).
|
||||
/// Returns ⌈x / m⌉, i.e. the lowest natural number r such that r ≥ x / m.
|
||||
///
|
||||
/// # Preconditions
|
||||
///
|
||||
/// - `x + m` does not overflow.
|
||||
/// - x + m does not overflow.
|
||||
const fn div_ceil(x: Nat, m: Nat) -> Nat {
|
||||
(x + m - 1) / m
|
||||
}
|
||||
@@ -1077,4 +1076,15 @@ mod tests {
|
||||
0xff800000
|
||||
);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn position_offsets_fit_in_a_halfword() {
|
||||
// The store stores in RAM the entry positions as their offset from the head. Those offsets
|
||||
// are represented as u16. The bound below is a large over-approximation of the maximal
|
||||
// offset. We first make sure it fits in a u16.
|
||||
const MAX_POS: Nat = (MAX_PAGE_INDEX + 1) * MAX_VIRT_PAGE_SIZE;
|
||||
assert!(MAX_POS <= u16::MAX as Nat);
|
||||
// We also check the actual value for up-to-date documentation, since it's a constant.
|
||||
assert_eq!(MAX_POS, 0xff80);
|
||||
}
|
||||
}
|
||||
|
||||
@@ -42,15 +42,20 @@ impl Field {
|
||||
|
||||
/// Sets the value of a bit field.
|
||||
///
|
||||
/// # Preconditions
|
||||
/// # Errors
|
||||
///
|
||||
/// - The value must fit in the bit field: `num_bits(value) < self.len`.
|
||||
/// - The value must only change bits from 1 to 0: `self.get(*word) & value == value`.
|
||||
pub fn set(&self, word: &mut Word, value: Nat) {
|
||||
debug_assert_eq!(value & self.mask(), value);
|
||||
pub fn set(&self, word: &mut Word, value: Nat) -> StoreResult<()> {
|
||||
if value & self.mask() != value {
|
||||
return Err(StoreError::InvalidStorage);
|
||||
}
|
||||
let mask = !(self.mask() << self.pos);
|
||||
word.0 &= mask | (value << self.pos);
|
||||
debug_assert_eq!(self.get(*word), value);
|
||||
if self.get(*word) != value {
|
||||
return Err(StoreError::InvalidStorage);
|
||||
}
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Returns a bit mask the length of the bit field.
|
||||
@@ -82,8 +87,8 @@ impl ConstField {
|
||||
}
|
||||
|
||||
/// Sets the bit field to its value.
|
||||
pub fn set(&self, word: &mut Word) {
|
||||
self.field.set(word, self.value);
|
||||
pub fn set(&self, word: &mut Word) -> StoreResult<()> {
|
||||
self.field.set(word, self.value)
|
||||
}
|
||||
}
|
||||
|
||||
@@ -135,15 +140,15 @@ impl Checksum {
|
||||
|
||||
/// Sets the checksum to the external increment value.
|
||||
///
|
||||
/// # Preconditions
|
||||
/// # Errors
|
||||
///
|
||||
/// - The bits of the checksum bit field should be set to one: `self.field.get(*word) ==
|
||||
/// self.field.mask()`.
|
||||
/// - The checksum value should fit in the checksum bit field: `num_bits(word.count_zeros() +
|
||||
/// value) < self.field.len`.
|
||||
pub fn set(&self, word: &mut Word, value: Nat) {
|
||||
pub fn set(&self, word: &mut Word, value: Nat) -> StoreResult<()> {
|
||||
debug_assert_eq!(self.field.get(*word), self.field.mask());
|
||||
self.field.set(word, word.0.count_zeros() + value);
|
||||
self.field.set(word, word.0.count_zeros() + value)
|
||||
}
|
||||
}
|
||||
|
||||
@@ -290,7 +295,7 @@ mod tests {
|
||||
assert_eq!(field.get(Word(0x000000f8)), 0x1f);
|
||||
assert_eq!(field.get(Word(0x0000ff37)), 6);
|
||||
let mut word = Word(0xffffffff);
|
||||
field.set(&mut word, 3);
|
||||
field.set(&mut word, 3).unwrap();
|
||||
assert_eq!(word, Word(0xffffff1f));
|
||||
}
|
||||
|
||||
@@ -305,7 +310,7 @@ mod tests {
|
||||
assert!(field.check(Word(0x00000048)));
|
||||
assert!(field.check(Word(0x0000ff4f)));
|
||||
let mut word = Word(0xffffffff);
|
||||
field.set(&mut word);
|
||||
field.set(&mut word).unwrap();
|
||||
assert_eq!(word, Word(0xffffff4f));
|
||||
}
|
||||
|
||||
@@ -333,7 +338,7 @@ mod tests {
|
||||
assert_eq!(field.get(Word(0x00ffff67)), Ok(4));
|
||||
assert_eq!(field.get(Word(0x7fffff07)), Err(StoreError::InvalidStorage));
|
||||
let mut word = Word(0x0fffffff);
|
||||
field.set(&mut word, 4);
|
||||
field.set(&mut word, 4).unwrap();
|
||||
assert_eq!(word, Word(0x0fffff47));
|
||||
}
|
||||
|
||||
|
||||
345
libraries/persistent_store/src/fragment.rs
Normal file
345
libraries/persistent_store/src/fragment.rs
Normal file
@@ -0,0 +1,345 @@
|
||||
// Copyright 2021 Google LLC
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||||
// you may not use this file except in compliance with the License.
|
||||
// You may obtain a copy of the License at
|
||||
//
|
||||
// http://www.apache.org/licenses/LICENSE-2.0
|
||||
//
|
||||
// Unless required by applicable law or agreed to in writing, software
|
||||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
//! Support for fragmented entries.
|
||||
//!
|
||||
//! This module permits to handle entries larger than the [maximum value
|
||||
//! length](Store::max_value_length) by storing ordered consecutive fragments in a sequence of keys.
|
||||
//! The first keys hold fragments of maximal length, followed by a possibly partial fragment. The
|
||||
//! remaining keys are not used.
|
||||
|
||||
use crate::{Storage, Store, StoreError, StoreHandle, StoreResult, StoreUpdate};
|
||||
use alloc::vec::Vec;
|
||||
use core::ops::Range;
|
||||
|
||||
/// Represents a sequence of keys.
|
||||
#[allow(clippy::len_without_is_empty)]
|
||||
pub trait Keys {
|
||||
/// Returns the number of keys.
|
||||
fn len(&self) -> usize;
|
||||
|
||||
/// Returns the position of a key in the sequence.
|
||||
fn pos(&self, key: usize) -> Option<usize>;
|
||||
|
||||
/// Returns the key of a position in the sequence.
|
||||
///
|
||||
/// # Preconditions
|
||||
///
|
||||
/// The position must be within the length: `pos` < [`Self::len`].
|
||||
fn key(&self, pos: usize) -> usize;
|
||||
}
|
||||
|
||||
impl Keys for Range<usize> {
|
||||
fn len(&self) -> usize {
|
||||
self.end - self.start
|
||||
}
|
||||
|
||||
fn pos(&self, key: usize) -> Option<usize> {
|
||||
if self.start <= key && key < self.end {
|
||||
Some(key - self.start)
|
||||
} else {
|
||||
None
|
||||
}
|
||||
}
|
||||
|
||||
fn key(&self, pos: usize) -> usize {
|
||||
debug_assert!(pos < Keys::len(self));
|
||||
self.start + pos
|
||||
}
|
||||
}
|
||||
|
||||
/// Reads the concatenated value of a sequence of keys.
|
||||
pub fn read(store: &Store<impl Storage>, keys: &impl Keys) -> StoreResult<Option<Vec<u8>>> {
|
||||
let handles = get_handles(store, keys)?;
|
||||
if handles.is_empty() {
|
||||
return Ok(None);
|
||||
}
|
||||
let mut result = Vec::with_capacity(handles.len() * store.max_value_length());
|
||||
for handle in handles {
|
||||
result.extend(handle.get_value(store)?);
|
||||
}
|
||||
Ok(Some(result))
|
||||
}
|
||||
|
||||
/// Reads a range from the concatenated value of a sequence of keys.
|
||||
///
|
||||
/// This is equivalent to calling [`read`] then taking the range except that:
|
||||
/// - Only the needed chunks are read.
|
||||
/// - The range is truncated to fit in the value.
|
||||
pub fn read_range(
|
||||
store: &Store<impl Storage>,
|
||||
keys: &impl Keys,
|
||||
range: Range<usize>,
|
||||
) -> StoreResult<Option<Vec<u8>>> {
|
||||
let range_len = match range.end.checked_sub(range.start) {
|
||||
None => return Err(StoreError::InvalidArgument),
|
||||
Some(x) => x,
|
||||
};
|
||||
let handles = get_handles(store, keys)?;
|
||||
if handles.is_empty() {
|
||||
return Ok(None);
|
||||
}
|
||||
let mut result = Vec::with_capacity(range_len);
|
||||
let mut offset = 0;
|
||||
for handle in handles {
|
||||
let start = range.start.saturating_sub(offset);
|
||||
let length = handle.get_length(store)?;
|
||||
let end = core::cmp::min(range.end.saturating_sub(offset), length);
|
||||
offset += length;
|
||||
if start < end {
|
||||
result.extend(&handle.get_value(store)?[start..end]);
|
||||
}
|
||||
}
|
||||
Ok(Some(result))
|
||||
}
|
||||
|
||||
/// Writes a value to a sequence of keys as chunks.
|
||||
pub fn write(store: &mut Store<impl Storage>, keys: &impl Keys, value: &[u8]) -> StoreResult<()> {
|
||||
let handles = get_handles(store, keys)?;
|
||||
let keys_len = keys.len();
|
||||
let mut updates = Vec::with_capacity(keys_len);
|
||||
let mut chunks = value.chunks(store.max_value_length());
|
||||
for pos in 0..keys_len {
|
||||
let key = keys.key(pos);
|
||||
match (handles.get(pos), chunks.next()) {
|
||||
// No existing handle and no new chunk: nothing to do.
|
||||
(None, None) => (),
|
||||
// Existing handle and no new chunk: remove old handle.
|
||||
(Some(_), None) => updates.push(StoreUpdate::Remove { key }),
|
||||
// Existing handle with same value as new chunk: nothing to do.
|
||||
(Some(handle), Some(value)) if handle.get_value(store)? == value => (),
|
||||
// New chunk: Write (or overwrite) the new value.
|
||||
(_, Some(value)) => updates.push(StoreUpdate::Insert { key, value }),
|
||||
}
|
||||
}
|
||||
if chunks.next().is_some() {
|
||||
// The value is too long.
|
||||
return Err(StoreError::InvalidArgument);
|
||||
}
|
||||
store.transaction(&updates)
|
||||
}
|
||||
|
||||
/// Deletes the value of a sequence of keys.
|
||||
pub fn delete(store: &mut Store<impl Storage>, keys: &impl Keys) -> StoreResult<()> {
|
||||
let updates: Vec<StoreUpdate<Vec<u8>>> = get_handles(store, keys)?
|
||||
.iter()
|
||||
.map(|handle| StoreUpdate::Remove {
|
||||
key: handle.get_key(),
|
||||
})
|
||||
.collect();
|
||||
store.transaction(&updates)
|
||||
}
|
||||
|
||||
/// Returns the handles of a sequence of keys.
|
||||
///
|
||||
/// The handles are truncated to the keys that are present.
|
||||
fn get_handles(store: &Store<impl Storage>, keys: &impl Keys) -> StoreResult<Vec<StoreHandle>> {
|
||||
let keys_len = keys.len();
|
||||
let mut handles: Vec<Option<StoreHandle>> = vec![None; keys_len as usize];
|
||||
for handle in store.iter()? {
|
||||
let handle = handle?;
|
||||
let pos = match keys.pos(handle.get_key()) {
|
||||
Some(pos) => pos,
|
||||
None => continue,
|
||||
};
|
||||
if pos >= keys_len {
|
||||
return Err(StoreError::InvalidArgument);
|
||||
}
|
||||
if let Some(old_handle) = &handles[pos] {
|
||||
if old_handle.get_key() != handle.get_key() {
|
||||
// The user provided a non-injective `pos` function.
|
||||
return Err(StoreError::InvalidArgument);
|
||||
} else {
|
||||
return Err(StoreError::InvalidStorage);
|
||||
}
|
||||
}
|
||||
handles[pos] = Some(handle);
|
||||
}
|
||||
let num_handles = handles.iter().filter(|x| x.is_some()).count();
|
||||
let mut result = Vec::with_capacity(num_handles);
|
||||
for (i, handle) in handles.into_iter().enumerate() {
|
||||
match (i < num_handles, handle) {
|
||||
(true, Some(handle)) => result.push(handle),
|
||||
(false, None) => (),
|
||||
// We should have `num_handles` Somes followed by Nones.
|
||||
_ => return Err(StoreError::InvalidStorage),
|
||||
}
|
||||
}
|
||||
Ok(result)
|
||||
}
|
||||
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
use crate::test::MINIMAL;
|
||||
|
||||
#[test]
|
||||
fn read_empty_entry() {
|
||||
let store = MINIMAL.new_store();
|
||||
assert_eq!(read(&store, &(0..4)), Ok(None));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn read_single_chunk() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
let value = b"hello".to_vec();
|
||||
assert_eq!(store.insert(0, &value), Ok(()));
|
||||
assert_eq!(read(&store, &(0..4)), Ok(Some(value)));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn read_multiple_chunks() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
let value: Vec<_> = (0..60).collect();
|
||||
assert_eq!(store.insert(0, &value[..52]), Ok(()));
|
||||
assert_eq!(store.insert(1, &value[52..]), Ok(()));
|
||||
assert_eq!(read(&store, &(0..4)), Ok(Some(value)));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn read_range_first_chunk() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
let value: Vec<_> = (0..60).collect();
|
||||
assert_eq!(store.insert(0, &value[..52]), Ok(()));
|
||||
assert_eq!(store.insert(1, &value[52..]), Ok(()));
|
||||
assert_eq!(
|
||||
read_range(&store, &(0..4), 0..10),
|
||||
Ok(Some((0..10).collect()))
|
||||
);
|
||||
assert_eq!(
|
||||
read_range(&store, &(0..4), 10..20),
|
||||
Ok(Some((10..20).collect()))
|
||||
);
|
||||
assert_eq!(
|
||||
read_range(&store, &(0..4), 40..52),
|
||||
Ok(Some((40..52).collect()))
|
||||
);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn read_range_second_chunk() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
let value: Vec<_> = (0..60).collect();
|
||||
assert_eq!(store.insert(0, &value[..52]), Ok(()));
|
||||
assert_eq!(store.insert(1, &value[52..]), Ok(()));
|
||||
assert_eq!(read_range(&store, &(0..4), 52..53), Ok(Some(vec![52])));
|
||||
assert_eq!(read_range(&store, &(0..4), 53..54), Ok(Some(vec![53])));
|
||||
assert_eq!(read_range(&store, &(0..4), 59..60), Ok(Some(vec![59])));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn read_range_both_chunks() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
let value: Vec<_> = (0..60).collect();
|
||||
assert_eq!(store.insert(0, &value[..52]), Ok(()));
|
||||
assert_eq!(store.insert(1, &value[52..]), Ok(()));
|
||||
assert_eq!(
|
||||
read_range(&store, &(0..4), 40..60),
|
||||
Ok(Some((40..60).collect()))
|
||||
);
|
||||
assert_eq!(
|
||||
read_range(&store, &(0..4), 0..60),
|
||||
Ok(Some((0..60).collect()))
|
||||
);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn read_range_outside() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
let value: Vec<_> = (0..60).collect();
|
||||
assert_eq!(store.insert(0, &value[..52]), Ok(()));
|
||||
assert_eq!(store.insert(1, &value[52..]), Ok(()));
|
||||
assert_eq!(
|
||||
read_range(&store, &(0..4), 40..100),
|
||||
Ok(Some((40..60).collect()))
|
||||
);
|
||||
assert_eq!(read_range(&store, &(0..4), 60..100), Ok(Some(vec![])));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn write_single_chunk() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
let value = b"hello".to_vec();
|
||||
assert_eq!(write(&mut store, &(0..4), &value), Ok(()));
|
||||
assert_eq!(store.find(0), Ok(Some(value)));
|
||||
assert_eq!(store.find(1), Ok(None));
|
||||
assert_eq!(store.find(2), Ok(None));
|
||||
assert_eq!(store.find(3), Ok(None));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn write_multiple_chunks() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
let value: Vec<_> = (0..60).collect();
|
||||
assert_eq!(write(&mut store, &(0..4), &value), Ok(()));
|
||||
assert_eq!(store.find(0), Ok(Some((0..52).collect())));
|
||||
assert_eq!(store.find(1), Ok(Some((52..60).collect())));
|
||||
assert_eq!(store.find(2), Ok(None));
|
||||
assert_eq!(store.find(3), Ok(None));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn overwrite_less_chunks() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
let value: Vec<_> = (0..60).collect();
|
||||
assert_eq!(store.insert(0, &value[..52]), Ok(()));
|
||||
assert_eq!(store.insert(1, &value[52..]), Ok(()));
|
||||
let value: Vec<_> = (42..69).collect();
|
||||
assert_eq!(write(&mut store, &(0..4), &value), Ok(()));
|
||||
assert_eq!(store.find(0), Ok(Some((42..69).collect())));
|
||||
assert_eq!(store.find(1), Ok(None));
|
||||
assert_eq!(store.find(2), Ok(None));
|
||||
assert_eq!(store.find(3), Ok(None));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn overwrite_needed_chunks() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
let mut value: Vec<_> = (0..60).collect();
|
||||
assert_eq!(store.insert(0, &value[..52]), Ok(()));
|
||||
assert_eq!(store.insert(1, &value[52..]), Ok(()));
|
||||
// Current lifetime is 2 words of overhead (2 insert) and 60 bytes of data.
|
||||
let mut lifetime = 2 + 60 / 4;
|
||||
assert_eq!(store.lifetime().unwrap().used(), lifetime);
|
||||
// Update the value.
|
||||
value.extend(60..80);
|
||||
assert_eq!(write(&mut store, &(0..4), &value), Ok(()));
|
||||
// Added lifetime is 1 word of overhead (1 insert) and (80 - 52) bytes of data.
|
||||
lifetime += 1 + (80 - 52) / 4;
|
||||
assert_eq!(store.lifetime().unwrap().used(), lifetime);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn delete_empty() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
assert_eq!(delete(&mut store, &(0..4)), Ok(()));
|
||||
assert_eq!(store.find(0), Ok(None));
|
||||
assert_eq!(store.find(1), Ok(None));
|
||||
assert_eq!(store.find(2), Ok(None));
|
||||
assert_eq!(store.find(3), Ok(None));
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn delete_chunks() {
|
||||
let mut store = MINIMAL.new_store();
|
||||
let value: Vec<_> = (0..60).collect();
|
||||
assert_eq!(store.insert(0, &value[..52]), Ok(()));
|
||||
assert_eq!(store.insert(1, &value[52..]), Ok(()));
|
||||
assert_eq!(delete(&mut store, &(0..4)), Ok(()));
|
||||
assert_eq!(store.find(0), Ok(None));
|
||||
assert_eq!(store.find(1), Ok(None));
|
||||
assert_eq!(store.find(2), Ok(None));
|
||||
assert_eq!(store.find(3), Ok(None));
|
||||
}
|
||||
}
|
||||
@@ -1,4 +1,4 @@
|
||||
// Copyright 2019-2020 Google LLC
|
||||
// Copyright 2019-2021 Google LLC
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||||
// you may not use this file except in compliance with the License.
|
||||
@@ -12,191 +12,191 @@
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
// TODO(ia0): Add links once the code is complete.
|
||||
// The documentation is easier to read from a browser:
|
||||
// - Run: cargo doc --document-private-items --features=std
|
||||
// - Open: target/doc/persistent_store/index.html
|
||||
|
||||
//! Store abstraction for flash storage
|
||||
//!
|
||||
//! # Specification
|
||||
//!
|
||||
//! The store provides a partial function from keys to values on top of a storage
|
||||
//! interface. The store total capacity depends on the size of the storage. Store
|
||||
//! updates may be bundled in transactions. Mutable operations are atomic, including
|
||||
//! when interrupted.
|
||||
//! The [store](Store) provides a partial function from keys to values on top of a
|
||||
//! [storage](Storage) interface. The store total [capacity](Store::capacity) depends on the size of
|
||||
//! the storage. Store [updates](StoreUpdate) may be bundled in [transactions](Store::transaction).
|
||||
//! Mutable operations are atomic, including when interrupted.
|
||||
//!
|
||||
//! The store is flash-efficient in the sense that it uses the storage lifetime
|
||||
//! efficiently. For each page, all words are written at least once between erase
|
||||
//! cycles and all erase cycles are used. However, not all written words are user
|
||||
//! content: lifetime is also consumed with metadata and compaction.
|
||||
//! The store is flash-efficient in the sense that it uses the storage [lifetime](Store::lifetime)
|
||||
//! efficiently. For each page, all words are written at least once between erase cycles and all
|
||||
//! erase cycles are used. However, not all written words are user content: Lifetime is also
|
||||
//! consumed with metadata and compaction.
|
||||
//!
|
||||
//! The store is extendable with other entries than key-values. It is essentially a
|
||||
//! framework providing access to the storage lifetime. The partial function is
|
||||
//! simply the most common usage and can be used to encode other usages.
|
||||
//! The store is extendable with other entries than key-values. It is essentially a framework
|
||||
//! providing access to the storage lifetime. The partial function is simply the most common usage
|
||||
//! and can be used to encode other usages.
|
||||
//!
|
||||
//! ## Definitions
|
||||
//!
|
||||
//! An _entry_ is a pair of a key and a value. A _key_ is a number between 0
|
||||
//! and 4095. A _value_ is a byte slice with a length between 0 and 1023 bytes (for
|
||||
//! large enough pages).
|
||||
//! An _entry_ is a pair of a key and a value. A _key_ is a number between 0 and
|
||||
//! [4095](format::MAX_KEY_INDEX). A _value_ is a byte slice with a length between 0 and
|
||||
//! [1023](format::Format::max_value_len) bytes (for large enough pages).
|
||||
//!
|
||||
//! The store provides the following _updates_:
|
||||
//! - Given a key and a value, `Insert` updates the store such that the value is
|
||||
//! - Given a key and a value, [`StoreUpdate::Insert`] updates the store such that the value is
|
||||
//! associated with the key. The values for other keys are left unchanged.
|
||||
//! - Given a key, `Remove` updates the store such that no value is associated with
|
||||
//! the key. The values for other keys are left unchanged. Additionally, if there
|
||||
//! was a value associated with the key, the value is wiped from the storage
|
||||
//! (all its bits are set to 0).
|
||||
//! - Given a key, [`StoreUpdate::Remove`] updates the store such that no value is associated with
|
||||
//! the key. The values for other keys are left unchanged. Additionally, if there was a value
|
||||
//! associated with the key, the value is wiped from the storage (all its bits are set to 0).
|
||||
//!
|
||||
//! The store provides the following _read-only operations_:
|
||||
//! - `Iter` iterates through the store returning all entries exactly once. The
|
||||
//! iteration order is not specified but stable between mutable operations.
|
||||
//! - `Capacity` returns how many words can be stored before the store is full.
|
||||
//! - `Lifetime` returns how many words can be written before the storage lifetime
|
||||
//! is consumed.
|
||||
//! - [`Store::iter`] iterates through the store returning all entries exactly once. The iteration
|
||||
//! order is not specified but stable between mutable operations.
|
||||
//! - [`Store::capacity`] returns how many words can be stored before the store is full.
|
||||
//! - [`Store::lifetime`] returns how many words can be written before the storage lifetime is
|
||||
//! consumed.
|
||||
//!
|
||||
//! The store provides the following _mutable operations_:
|
||||
//! - Given a set of independent updates, `Transaction` applies the sequence of
|
||||
//! updates.
|
||||
//! - Given a threshold, `Clear` removes all entries with a key greater or equal
|
||||
//! to the threshold.
|
||||
//! - Given a length in words, `Prepare` makes one step of compaction unless that
|
||||
//! many words can be written without compaction. This operation has no effect
|
||||
//! on the store but may still mutate its storage. In particular, the store has
|
||||
//! the same capacity but a possibly reduced lifetime.
|
||||
//! - Given a set of independent updates, [`Store::transaction`] applies the sequence of updates.
|
||||
//! - Given a threshold, [`Store::clear`] removes all entries with a key greater or equal to the
|
||||
//! threshold.
|
||||
//! - Given a length in words, [`Store::prepare`] makes one step of compaction unless that many
|
||||
//! words can be written without compaction. This operation has no effect on the store but may
|
||||
//! still mutate its storage. In particular, the store has the same capacity but a possibly
|
||||
//! reduced lifetime.
|
||||
//!
|
||||
//! A mutable operation is _atomic_ if, when power is lost during the operation, the
|
||||
//! store is either updated (as if the operation succeeded) or left unchanged (as if
|
||||
//! the operation did not occur). If the store is left unchanged, lifetime may still
|
||||
//! be consumed.
|
||||
//! A mutable operation is _atomic_ if, when power is lost during the operation, the store is either
|
||||
//! updated (as if the operation succeeded) or left unchanged (as if the operation did not occur).
|
||||
//! If the store is left unchanged, lifetime may still be consumed.
|
||||
//!
|
||||
//! The store relies on the following _storage interface_:
|
||||
//! - It is possible to read a byte slice. The slice won't span multiple pages.
|
||||
//! - It is possible to write a word slice. The slice won't span multiple pages.
|
||||
//! - It is possible to erase a page.
|
||||
//! - The pages are sequentially indexed from 0. If the actual underlying storage
|
||||
//! is segmented, then the storage layer should translate those indices to
|
||||
//! actual page addresses.
|
||||
//! - It is possible to [read](Storage::read_slice) a byte slice. The slice won't span multiple
|
||||
//! pages.
|
||||
//! - It is possible to [write](Storage::write_slice) a word slice. The slice won't span multiple
|
||||
//! pages.
|
||||
//! - It is possible to [erase](Storage::erase_page) a page.
|
||||
//! - The pages are sequentially indexed from 0. If the actual underlying storage is segmented,
|
||||
//! then the storage layer should translate those indices to actual page addresses.
|
||||
//!
|
||||
//! The store has a _total capacity_ of `C = (N - 1) * (P - 4) - M - 1` words, where
|
||||
//! `P` is the number of words per page, `N` is the number of pages, and `M` is the
|
||||
//! maximum length in words of a value (256 for large enough pages). The capacity
|
||||
//! used by each mutable operation is given below (a transient word only uses
|
||||
//! capacity during the operation):
|
||||
//! - `Insert` uses `1 + ceil(len / 4)` words where `len` is the length of the
|
||||
//! value in bytes. If an entry was replaced, the words used by its insertion
|
||||
//! are freed.
|
||||
//! - `Remove` doesn't use capacity if alone in the transaction and 1 transient
|
||||
//! word otherwise. If an entry was deleted, the words used by its insertion are
|
||||
//! freed.
|
||||
//! - `Transaction` uses 1 transient word. In addition, the updates of the
|
||||
//! transaction use and free words as described above.
|
||||
//! - `Clear` doesn't use capacity and frees the words used by the insertion of
|
||||
//! the deleted entries.
|
||||
//! - `Prepare` doesn't use capacity.
|
||||
//! The store has a _total capacity_ of C = (N - 1) × (P - 4) - M - 1 words, where:
|
||||
//! - P is the number of words per page
|
||||
//! - [N](format::Format::num_pages) is the number of pages
|
||||
//! - [M](format::Format::max_prefix_len) is the maximum length in words of a value (256 for large
|
||||
//! enough pages)
|
||||
//!
|
||||
//! The _total lifetime_ of the store is below `L = ((E + 1) * N - 1) * (P - 2)` and
|
||||
//! above `L - M` words, where `E` is the maximum number of erase cycles. The
|
||||
//! lifetime is used when capacity is used, including transiently, as well as when
|
||||
//! compaction occurs. Compaction frequency and lifetime consumption are positively
|
||||
//! correlated to the store load factor (the ratio of used capacity to total capacity).
|
||||
//! The capacity used by each mutable operation is given below (a transient word only uses capacity
|
||||
//! during the operation):
|
||||
//!
|
||||
//! It is possible to approximate the cost of transient words in terms of capacity:
|
||||
//! `L` transient words are equivalent to `C - x` words of capacity where `x` is the
|
||||
//! average capacity (including transient) of operations.
|
||||
//! | Operation/Update | Used capacity | Freed capacity | Transient capacity |
|
||||
//! | ----------------------- | ---------------- | ----------------- | ------------------ |
|
||||
//! | [`StoreUpdate::Insert`] | 1 + value length | overwritten entry | 0 |
|
||||
//! | [`StoreUpdate::Remove`] | 0 | deleted entry | see below\* |
|
||||
//! | [`Store::transaction`] | 0 + updates | 0 + updates | 1 |
|
||||
//! | [`Store::clear`] | 0 | deleted entries | 0 |
|
||||
//! | [`Store::prepare`] | 0 | 0 | 0 |
|
||||
//!
|
||||
//! \*0 if the update is alone in the transaction, otherwise 1.
|
||||
//!
|
||||
//! The _total lifetime_ of the store is below L = ((E + 1) × N - 1) × (P - 2) and above L - M
|
||||
//! words, where E is the maximum number of erase cycles. The lifetime is used when capacity is
|
||||
//! used, including transiently, as well as when compaction occurs. Compaction frequency and
|
||||
//! lifetime consumption are positively correlated to the store load factor (the ratio of used
|
||||
//! capacity to total capacity).
|
||||
//!
|
||||
//! It is possible to approximate the cost of transient words in terms of capacity: L transient
|
||||
//! words are equivalent to C - x words of capacity where x is the average capacity (including
|
||||
//! transient) of operations.
|
||||
//!
|
||||
//! ## Preconditions
|
||||
//!
|
||||
//! The following assumptions need to hold, or the store may behave in unexpected ways:
|
||||
//! - A word can be written twice between erase cycles.
|
||||
//! - A page can be erased `E` times after the first boot of the store.
|
||||
//! - When power is lost while writing a slice or erasing a page, the next read
|
||||
//! returns a slice where a subset (possibly none or all) of the bits that
|
||||
//! should have been modified have been modified.
|
||||
//! - Reading a slice is deterministic. When power is lost while writing a slice
|
||||
//! or erasing a slice (erasing a page containing that slice), reading that
|
||||
//! slice repeatedly returns the same result (until it is overwritten or its
|
||||
//! page is erased).
|
||||
//! - To decide whether a page has been erased, it is enough to test if all its
|
||||
//! bits are equal to 1.
|
||||
//! - When power is lost while writing a slice or erasing a page, that operation
|
||||
//! does not count towards the limits. However, completing that write or erase
|
||||
//! operation would count towards the limits, as if the number of writes per
|
||||
//! word and number of erase cycles could be fractional.
|
||||
//! - The storage is only modified by the store. Note that completely erasing the
|
||||
//! storage is supported, essentially losing all content and lifetime tracking.
|
||||
//! It is preferred to use `Clear` with a threshold of 0 to keep the lifetime
|
||||
//! tracking.
|
||||
//! - A word can be written [twice](Storage::max_word_writes) between erase cycles.
|
||||
//! - A page can be erased [E](Storage::max_page_erases) times after the first boot of the store.
|
||||
//! - When power is lost while writing a slice or erasing a page, the next read returns a slice
|
||||
//! where a subset (possibly none or all) of the bits that should have been modified have been
|
||||
//! modified.
|
||||
//! - Reading a slice is deterministic. When power is lost while writing a slice or erasing a
|
||||
//! slice (erasing a page containing that slice), reading that slice repeatedly returns the same
|
||||
//! result (until it is overwritten or its page is erased).
|
||||
//! - To decide whether a page has been erased, it is enough to test if all its bits are equal
|
||||
//! to 1.
|
||||
//! - When power is lost while writing a slice or erasing a page, that operation does not count
|
||||
//! towards the limits. However, completing that write or erase operation would count towards
|
||||
//! the limits, as if the number of writes per word and number of erase cycles could be
|
||||
//! fractional.
|
||||
//! - The storage is only modified by the store. Note that completely erasing the storage is
|
||||
//! supported, essentially losing all content and lifetime tracking. It is preferred to use
|
||||
//! [`Store::clear`] with a threshold of 0 to keep the lifetime tracking.
|
||||
//!
|
||||
//! The store properties may still hold outside some of those assumptions, but with
|
||||
//! an increasing chance of failure.
|
||||
//! The store properties may still hold outside some of those assumptions, but with an increasing
|
||||
//! chance of failure.
|
||||
//!
|
||||
//! # Implementation
|
||||
//!
|
||||
//! We define the following constants:
|
||||
//! - `E < 65536` the number of times a page can be erased.
|
||||
//! - `3 <= N < 64` the number of pages in the storage.
|
||||
//! - `8 <= P <= 1024` the number of words in a page.
|
||||
//! - `Q = P - 2` the number of words in a virtual page.
|
||||
//! - `K = 4096` the maximum number of keys.
|
||||
//! - `M = min(Q - 1, 256)` the maximum length in words of a value.
|
||||
//! - `V = (N - 1) * (Q - 1) - M` the virtual capacity.
|
||||
//! - `C = V - N` the user capacity.
|
||||
//! - [E](format::Format::max_page_erases) ≤ [65535](format::MAX_ERASE_CYCLE) the number of times
|
||||
//! a page can be erased.
|
||||
//! - 3 ≤ [N](format::Format::num_pages) < 64 the number of pages in the storage.
|
||||
//! - 8 ≤ P ≤ 1024 the number of words in a page.
|
||||
//! - [Q](format::Format::virt_page_size) = P - 2 the number of words in a virtual page.
|
||||
//! - [M](format::Format::max_prefix_len) = min(Q - 1, 256) the maximum length in words of a
|
||||
//! value.
|
||||
//! - [V](format::Format::virt_size) = (N - 1) × (Q - 1) - M the virtual capacity.
|
||||
//! - [C](format::Format::total_capacity) = V - N the user capacity.
|
||||
//!
|
||||
//! We build a virtual storage from the physical storage using the first 2 words of
|
||||
//! each page:
|
||||
//! We build a virtual storage from the physical storage using the first 2 words of each page:
|
||||
//! - The first word contains the number of times the page has been erased.
|
||||
//! - The second word contains the starting word to which this page is being moved
|
||||
//! during compaction.
|
||||
//! - The second word contains the starting word to which this page is being moved during
|
||||
//! compaction.
|
||||
//!
|
||||
//! The virtual storage has a length of `(E + 1) * N * Q` words and represents the
|
||||
//! lifetime of the store. (We reserve the last `Q + M` words to support adding
|
||||
//! emergency lifetime.) This virtual storage has a linear address space.
|
||||
//! The virtual storage has a length of (E + 1) × N × Q words and represents the lifetime of the
|
||||
//! store. (We reserve the last Q + M words to support adding emergency lifetime.) This virtual
|
||||
//! storage has a linear address space.
|
||||
//!
|
||||
//! We define a set of overlapping windows of `N * Q` words at each `Q`-aligned
|
||||
//! boundary. We call `i` the window spanning from `i * Q` to `(i + N) * Q`. Only
|
||||
//! those windows actually exist in the underlying storage. We use compaction to
|
||||
//! shift the current window from `i` to `i + 1`, preserving the content of the
|
||||
//! store.
|
||||
//! We define a set of overlapping windows of N × Q words at each Q-aligned boundary. We call i the
|
||||
//! window spanning from i × Q to (i + N) × Q. Only those windows actually exist in the underlying
|
||||
//! storage. We use compaction to shift the current window from i to i + 1, preserving the content
|
||||
//! of the store.
|
||||
//!
|
||||
//! For a given state of the virtual storage, we define `h_i` as the position of the
|
||||
//! first entry of the window `i`. We call it the head of the window `i`. Because
|
||||
//! entries are at most `M + 1` words, they can overlap on the next page only by `M`
|
||||
//! words. So we have `i * Q <= h_i <= i * Q + M` . Since there are no entries
|
||||
//! before the first page, we have `h_0 = 0`.
|
||||
//! For a given state of the virtual storage, we define h\_i as the position of the first entry of
|
||||
//! the window i. We call it the head of the window i. Because entries are at most M + 1 words, they
|
||||
//! can overlap on the next page only by M words. So we have i × Q ≤ h_i ≤ i × Q + M . Since there
|
||||
//! are no entries before the first page, we have h\_0 = 0.
|
||||
//!
|
||||
//! We define `t_i` as one past the last entry of the window `i`. If there are no
|
||||
//! entries in that window, we have `t_i = h_i`. We call `t_i` the tail of the
|
||||
//! window `i`. We define the compaction invariant as `t_i - h_i <= V`.
|
||||
//! We define t\_i as one past the last entry of the window i. If there are no entries in that
|
||||
//! window, we have t\_i = h\_i. We call t\_i the tail of the window i. We define the compaction
|
||||
//! invariant as t\_i - h\_i ≤ V.
|
||||
//!
|
||||
//! We define `|x|` as the capacity used before position `x`. We have `|x| <= x`. We
|
||||
//! define the capacity invariant as `|t_i| - |h_i| <= C`.
|
||||
//! We define |x| as the capacity used before position x. We have |x| ≤ x. We define the capacity
|
||||
//! invariant as |t\_i| - |h\_i| ≤ C.
|
||||
//!
|
||||
//! Using this virtual storage, entries are appended to the tail as long as there is
|
||||
//! both virtual capacity to preserve the compaction invariant and capacity to
|
||||
//! preserve the capacity invariant. When virtual capacity runs out, the first page
|
||||
//! of the window is compacted and the window is shifted.
|
||||
//! Using this virtual storage, entries are appended to the tail as long as there is both virtual
|
||||
//! capacity to preserve the compaction invariant and capacity to preserve the capacity invariant.
|
||||
//! When virtual capacity runs out, the first page of the window is compacted and the window is
|
||||
//! shifted.
|
||||
//!
|
||||
//! Entries are identified by a prefix of bits. The prefix has to contain at least
|
||||
//! one bit set to zero to differentiate from the tail. Entries can be one of:
|
||||
//! - Padding: A word whose first bit is set to zero. The rest is arbitrary. This
|
||||
//! entry is used to mark words partially written after an interrupted operation
|
||||
//! as padding such that they are ignored by future operations.
|
||||
//! - Header: A word whose second bit is set to zero. It contains the following fields:
|
||||
//! - A bit indicating whether the entry is deleted.
|
||||
//! - A bit indicating whether the value is word-aligned and has all bits set
|
||||
//! to 1 in its last word. The last word of an entry is used to detect that
|
||||
//! an entry has been fully written. As such it must contain at least one
|
||||
//! bit equal to zero.
|
||||
//! - The key of the entry.
|
||||
//! - The length in bytes of the value. The value follows the header. The
|
||||
//! entry is word-aligned if the value is not.
|
||||
//! - The checksum of the first and last word of the entry.
|
||||
//! - Erase: A word used during compaction. It contains the page to be erased and
|
||||
//! a checksum.
|
||||
//! - Clear: A word used during the `Clear` operation. It contains the threshold
|
||||
//! and a checksum.
|
||||
//! - Marker: A word used during the `Transaction` operation. It contains the
|
||||
//! number of updates following the marker and a checksum.
|
||||
//! - Remove: A word used during the `Transaction` operation. It contains the key
|
||||
//! of the entry to be removed and a checksum.
|
||||
//! Entries are identified by a prefix of bits. The prefix has to contain at least one bit set to
|
||||
//! zero to differentiate from the tail. Entries can be one of:
|
||||
//! - [Padding](format::ID_PADDING): A word whose first bit is set to zero. The rest is arbitrary.
|
||||
//! This entry is used to mark words partially written after an interrupted operation as padding
|
||||
//! such that they are ignored by future operations.
|
||||
//! - [Header](format::ID_HEADER): A word whose second bit is set to zero. It contains the
|
||||
//! following fields:
|
||||
//! - A [bit](format::HEADER_DELETED) indicating whether the entry is deleted.
|
||||
//! - A [bit](format::HEADER_FLIPPED) indicating whether the value is word-aligned and has all
|
||||
//! bits set to 1 in its last word. The last word of an entry is used to detect that an
|
||||
//! entry has been fully written. As such it must contain at least one bit equal to zero.
|
||||
//! - The [key](format::HEADER_KEY) of the entry.
|
||||
//! - The [length](format::HEADER_LENGTH) in bytes of the value. The value follows the header.
|
||||
//! The entry is word-aligned if the value is not.
|
||||
//! - The [checksum](format::HEADER_CHECKSUM) of the first and last word of the entry.
|
||||
//! - [Erase](format::ID_ERASE): A word used during compaction. It contains the
|
||||
//! [page](format::ERASE_PAGE) to be erased and a [checksum](format::WORD_CHECKSUM).
|
||||
//! - [Clear](format::ID_CLEAR): A word used during the clear operation. It contains the
|
||||
//! [threshold](format::CLEAR_MIN_KEY) and a [checksum](format::WORD_CHECKSUM).
|
||||
//! - [Marker](format::ID_MARKER): A word used during a transaction. It contains the [number of
|
||||
//! updates](format::MARKER_COUNT) following the marker and a [checksum](format::WORD_CHECKSUM).
|
||||
//! - [Remove](format::ID_REMOVE): A word used inside a transaction. It contains the
|
||||
//! [key](format::REMOVE_KEY) of the entry to be removed and a
|
||||
//! [checksum](format::WORD_CHECKSUM).
|
||||
//!
|
||||
//! Checksums are the number of bits equal to 0.
|
||||
//!
|
||||
@@ -204,107 +204,105 @@
|
||||
//!
|
||||
//! ## Compaction
|
||||
//!
|
||||
//! It should always be possible to fully compact the store, after what the
|
||||
//! remaining capacity should be available in the current window (restoring the
|
||||
//! compaction invariant). We consider all notations on the virtual storage after
|
||||
//! the full compaction. We will use the `|x|` notation although we update the state
|
||||
//! of the virtual storage. This is fine because compaction doesn't change the
|
||||
//! status of an existing word.
|
||||
//! It should always be possible to fully compact the store, after what the remaining capacity
|
||||
//! should be available in the current window (restoring the compaction invariant). We consider all
|
||||
//! notations on the virtual storage after the full compaction. We will use the |x| notation
|
||||
//! although we update the state of the virtual storage. This is fine because compaction doesn't
|
||||
//! change the status of an existing word.
|
||||
//!
|
||||
//! We want to show that the next `N - 1` compactions won't move the tail past the
|
||||
//! last page of their window, with `I` the initial window:
|
||||
//! We want to show that the next N - 1 compactions won't move the tail past the last page of their
|
||||
//! window, with I the initial window:
|
||||
//!
|
||||
//! ```text
|
||||
//! forall 1 <= i <= N - 1, t_{I + i} <= (I + i + N - 1) * Q
|
||||
//! ```
|
||||
//! | | | | |
|
||||
//! | ----------------:| ----------:|:-:|:------------------- |
|
||||
//! | ∀(1 ≤ i ≤ N - 1) | t\_{I + i} | ≤ | (I + i + N - 1) × Q |
|
||||
//!
|
||||
//! We assume `i` between `1` and `N - 1`.
|
||||
//! We assume i between 1 and N - 1.
|
||||
//!
|
||||
//! One step of compaction advances the tail by how many words were used in the
|
||||
//! first page of the window with the last entry possibly overlapping on the next
|
||||
//! page.
|
||||
//! One step of compaction advances the tail by how many words were used in the first page of the
|
||||
//! window with the last entry possibly overlapping on the next page.
|
||||
//!
|
||||
//! ```text
|
||||
//! forall j, t_{j + 1} = t_j + |h_{j + 1}| - |h_j| + 1
|
||||
//! ```
|
||||
//! | | | | |
|
||||
//! | --:| ----------:|:-:|:------------------------------------ |
|
||||
//! | ∀j | t\_{j + 1} | = | t\_j + \|h\_{j + 1}\| - \|h\_j\| + 1 |
|
||||
//!
|
||||
//! By induction, we have:
|
||||
//!
|
||||
//! ```text
|
||||
//! t_{I + i} <= t_I + |h_{I + i}| - |h_I| + i
|
||||
//! ```
|
||||
//! | | | |
|
||||
//! | ----------:|:-:|:------------------------------------ |
|
||||
//! | t\_{I + i} | ≤ | t\_I + \|h\_{I + i}\| - \|h\_I\| + i |
|
||||
//!
|
||||
//! We have the following properties:
|
||||
//!
|
||||
//! ```text
|
||||
//! t_I <= h_I + V
|
||||
//! |h_{I + i}| - |h_I| <= h_{I + i} - h_I
|
||||
//! h_{I + i} <= (I + i) * Q + M
|
||||
//! ```
|
||||
//! | | | |
|
||||
//! | -------------------------:|:-:|:----------------- |
|
||||
//! | t\_I | ≤ | h\_I + V |
|
||||
//! | \|h\_{I + i}\| - \|h\_I\| | ≤ | h\_{I + i} - h\_I |
|
||||
//! | h\_{I + i} | ≤ | (I + i) × Q + M |
|
||||
//!
|
||||
//! Replacing into our previous equality, we can conclude:
|
||||
//!
|
||||
//! ```text
|
||||
//! t_{I + i} = t_I + |h_{I + i}| - |h_I| + i
|
||||
//! <= h_I + V + (I + i) * Q + M - h_I + i
|
||||
//! = (N - 1) * (Q - 1) - M + (I + i) * Q + M + i
|
||||
//! = (N - 1) * (Q - 1) + (I + i) * Q + i
|
||||
//! = (I + i + N - 1) * Q + i - (N - 1)
|
||||
//! <= (I + i + N - 1) * Q
|
||||
//! ```
|
||||
//! | | | |
|
||||
//! | ----------:|:-:| ------------------------------------------- |
|
||||
//! | t\_{I + i} | = | t_I + \|h_{I + i}\| - \|h_I\| + i |
|
||||
//! | | ≤ | h\_I + V + (I + i) * Q + M - h\_I + i |
|
||||
//! | | = | (N - 1) × (Q - 1) - M + (I + i) × Q + M + i |
|
||||
//! | | = | (N - 1) × (Q - 1) + (I + i) × Q + i |
|
||||
//! | | = | (I + i + N - 1) × Q + i - (N - 1) |
|
||||
//! | | ≤ | (I + i + N - 1) × Q |
|
||||
//!
|
||||
//! We also want to show that after `N - 1` compactions, the remaining capacity is
|
||||
//! available without compaction.
|
||||
//! We also want to show that after N - 1 compactions, the remaining capacity is available without
|
||||
//! compaction.
|
||||
//!
|
||||
//! ```text
|
||||
//! V - (t_{I + N - 1} - h_{I + N - 1}) >= // The available words in the window.
|
||||
//! C - (|t_{I + N - 1}| - |h_{I + N - 1}|) // The remaining capacity.
|
||||
//! + 1 // Reserved for Clear.
|
||||
//! ```
|
||||
//! | | | |
|
||||
//! | -:| --------------------------------------------- | --------------------------------- |
|
||||
//! | | V - (t\_{I + N - 1} - h\_{I + N - 1}) | The available words in the window |
|
||||
//! | ≥ | C - (\|t\_{I + N - 1}\| - \|h\_{I + N - 1}\|) | The remaining capacity |
|
||||
//! | + | 1 | Reserved for clear |
|
||||
//!
|
||||
//! We can replace the definition of `C` and simplify:
|
||||
//! We can replace the definition of C and simplify:
|
||||
//!
|
||||
//! ```text
|
||||
//! V - (t_{I + N - 1} - h_{I + N - 1}) >= V - N - (|t_{I + N - 1}| - |h_{I + N - 1}|) + 1
|
||||
//! iff t_{I + N - 1} - h_{I + N - 1} <= |t_{I + N - 1}| - |h_{I + N - 1}| + N - 1
|
||||
//! ```
|
||||
//! | | | | |
|
||||
//! | ---:| -------------------------------------:|:-:|:----------------------------------------------------- |
|
||||
//! | | V - (t\_{I + N - 1} - h\_{I + N - 1}) | ≥ | V - N - (\|t\_{I + N - 1}\| - \|h\_{I + N - 1}\|) + 1 |
|
||||
//! | iff | t\_{I + N - 1} - h\_{I + N - 1} | ≤ | \|t\_{I + N - 1}\| - \|h\_{I + N - 1}\| + N - 1 |
|
||||
//!
|
||||
//! We have the following properties:
|
||||
//!
|
||||
//! ```text
|
||||
//! t_{I + N - 1} = t_I + |h_{I + N - 1}| - |h_I| + N - 1
|
||||
//! |t_{I + N - 1}| - |h_{I + N - 1}| = |t_I| - |h_I| // Compaction preserves capacity.
|
||||
//! |h_{I + N - 1}| - |t_I| <= h_{I + N - 1} - t_I
|
||||
//! ```
|
||||
//!
|
||||
//! | | | | |
|
||||
//! | ---------------------------------------:|:-:|:-------------------------------------------- |:------ |
|
||||
//! | t\_{I + N - 1} | = | t\_I + \|h\_{I + N - 1}\| - \|h\_I\| + N - 1 | |
|
||||
//! | \|t\_{I + N - 1}\| - \|h\_{I + N - 1}\| | = | \|t\_I\| - \|h\_I\| | Compaction preserves capacity |
|
||||
//! | \|h\_{I + N - 1}\| - \|t\_I\| | ≤ | h\_{I + N - 1} - t\_I | |
|
||||
//!
|
||||
//! From which we conclude:
|
||||
//!
|
||||
//! ```text
|
||||
//! t_{I + N - 1} - h_{I + N - 1} <= |t_{I + N - 1}| - |h_{I + N - 1}| + N - 1
|
||||
//! iff t_I + |h_{I + N - 1}| - |h_I| + N - 1 - h_{I + N - 1} <= |t_I| - |h_I| + N - 1
|
||||
//! iff t_I + |h_{I + N - 1}| - h_{I + N - 1} <= |t_I|
|
||||
//! iff |h_{I + N - 1}| - |t_I| <= h_{I + N - 1} - t_I
|
||||
//! ```
|
||||
//! | | | | |
|
||||
//! | ---:| -------------------------------:|:-:|:----------------------------------------------- |
|
||||
//! | | t\_{I + N - 1} - h\_{I + N - 1} | ≤ | \|t\_{I + N - 1}\| - \|h\_{I + N - 1}\| + N - 1 |
|
||||
//! | iff | t\_I + \|h\_{I + N - 1}\| - \|h\_I\| + N - 1 - h\_{I + N - 1} | ≤ | \|t\_I\| - \|h\_I\| + N - 1 |
|
||||
//! | iff | t\_I + \|h\_{I + N - 1}\| - h\_{I + N - 1} | ≤ | \|t\_I\| |
|
||||
//! | iff | \|h\_{I + N - 1}\| - \|t\_I\| | ≤ | h\_{I + N - 1} - t\_I |
|
||||
//!
|
||||
//!
|
||||
//! ## Checksum
|
||||
//!
|
||||
//! The main property we want is that all partially written/erased words are either
|
||||
//! the initial word, the final word, or invalid.
|
||||
//! The main property we want is that all partially written/erased words are either the initial
|
||||
//! word, the final word, or invalid.
|
||||
//!
|
||||
//! We say that a bit sequence `TARGET` is reachable from a bit sequence `SOURCE` if
|
||||
//! both have the same length and `SOURCE & TARGET == TARGET` where `&` is the
|
||||
//! bitwise AND operation on bit sequences of that length. In other words, when
|
||||
//! `SOURCE` has a bit equal to 0 then `TARGET` also has that bit equal to 0.
|
||||
//! We say that a bit sequence `TARGET` is reachable from a bit sequence `SOURCE` if both have the
|
||||
//! same length and `SOURCE & TARGET == TARGET` where `&` is the bitwise AND operation on bit
|
||||
//! sequences of that length. In other words, when `SOURCE` has a bit equal to 0 then `TARGET` also
|
||||
//! has that bit equal to 0.
|
||||
//!
|
||||
//! The only written entries start with `101` or `110` and are written from an
|
||||
//! erased word. Marking an entry as padding or deleted is a single bit operation,
|
||||
//! so the property trivially holds. For those cases, the proof relies on the fact
|
||||
//! that there is exactly one bit equal to 0 in the 3 first bits. Either the 3 first
|
||||
//! bits are still `111` in which case we expect the remaining bits to be equal
|
||||
//! to 1. Otherwise we can use the checksum of the given type of entry because those
|
||||
//! 2 types of entries are not reachable from each other. Here is a visualization of
|
||||
//! the partitioning based on the first 3 bits:
|
||||
//! The only written entries start with `101` or `110` and are written from an erased word. Marking
|
||||
//! an entry as padding or deleted is a single bit operation, so the property trivially holds. For
|
||||
//! those cases, the proof relies on the fact that there is exactly one bit equal to 0 in the 3
|
||||
//! first bits. Either the 3 first bits are still `111` in which case we expect the remaining bits
|
||||
//! to be equal to 1. Otherwise we can use the checksum of the given type of entry because those 2
|
||||
//! types of entries are not reachable from each other. Here is a visualization of the partitioning
|
||||
//! based on the first 3 bits:
|
||||
//!
|
||||
//! | First 3 bits | Description | How to check |
|
||||
//! | ------------:| ------------------ | ---------------------------- |
|
||||
@@ -314,49 +312,48 @@
|
||||
//! | `100` | Deleted user entry | No check, atomically written |
|
||||
//! | `0??` | Padding entry | No check, atomically written |
|
||||
//!
|
||||
//! To show that valid entries of a given type are not reachable from each other, we
|
||||
//! show 3 lemmas:
|
||||
//! To show that valid entries of a given type are not reachable from each other, we show 3 lemmas:
|
||||
//!
|
||||
//! 1. A bit sequence is not reachable from another if its number of bits equal to
|
||||
//! 0 is smaller.
|
||||
//! 1. A bit sequence is not reachable from another if its number of bits equal to 0 is smaller.
|
||||
//! 2. A bit sequence is not reachable from another if they have the same number of bits equals to
|
||||
//! 0 and are different.
|
||||
//! 3. A bit sequence is not reachable from another if it is bigger when they are interpreted as
|
||||
//! numbers in binary representation.
|
||||
//!
|
||||
//! 2. A bit sequence is not reachable from another if they have the same number of
|
||||
//! bits equals to 0 and are different.
|
||||
//!
|
||||
//! 3. A bit sequence is not reachable from another if it is bigger when they are
|
||||
//! interpreted as numbers in binary representation.
|
||||
//!
|
||||
//! From those lemmas we consider the 2 cases. If both entries have the same number
|
||||
//! of bits equal to 0, they are either equal or not reachable from each other
|
||||
//! because of the second lemma. If they don't have the same number of bits equal to
|
||||
//! 0, then the one with less bits equal to 0 is not reachable from the other
|
||||
//! because of the first lemma and the one with more bits equal to 0 is not
|
||||
//! reachable from the other because of the third lemma and the definition of the
|
||||
//! checksum.
|
||||
//! From those lemmas we consider the 2 cases. If both entries have the same number of bits equal to
|
||||
//! 0, they are either equal or not reachable from each other because of the second lemma. If they
|
||||
//! don't have the same number of bits equal to 0, then the one with less bits equal to 0 is not
|
||||
//! reachable from the other because of the first lemma and the one with more bits equal to 0 is not
|
||||
//! reachable from the other because of the third lemma and the definition of the checksum.
|
||||
//!
|
||||
//! # Fuzzing
|
||||
//!
|
||||
//! For any sequence of operations and interruptions starting from an erased
|
||||
//! storage, the store is checked against its model and some internal invariant at
|
||||
//! each step.
|
||||
//! For any sequence of operations and interruptions starting from an erased storage, the store is
|
||||
//! checked against its model and some internal invariant at each step.
|
||||
//!
|
||||
//! For any sequence of operations and interruptions starting from an arbitrary
|
||||
//! storage, the store is checked not to crash.
|
||||
//! For any sequence of operations and interruptions starting from an arbitrary storage, the store
|
||||
//! is checked not to crash.
|
||||
|
||||
#![cfg_attr(not(feature = "std"), no_std)]
|
||||
#![feature(try_trait)]
|
||||
|
||||
#[macro_use]
|
||||
extern crate alloc;
|
||||
|
||||
#[cfg(feature = "std")]
|
||||
mod buffer;
|
||||
#[cfg(feature = "std")]
|
||||
mod driver;
|
||||
mod format;
|
||||
pub mod fragment;
|
||||
#[cfg(feature = "std")]
|
||||
mod model;
|
||||
mod storage;
|
||||
mod store;
|
||||
#[cfg(test)]
|
||||
mod test;
|
||||
|
||||
#[cfg(feature = "std")]
|
||||
pub use self::buffer::{BufferCorruptFunction, BufferOptions, BufferStorage};
|
||||
#[cfg(feature = "std")]
|
||||
pub use self::driver::{
|
||||
|
||||
@@ -12,13 +12,16 @@
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
//! Store specification.
|
||||
|
||||
use crate::format::Format;
|
||||
use crate::{usize_to_nat, StoreError, StoreRatio, StoreResult, StoreUpdate};
|
||||
use std::collections::HashMap;
|
||||
|
||||
/// Models the mutable operations of a store.
|
||||
///
|
||||
/// The model doesn't model the storage and read-only operations. This is done by the driver.
|
||||
/// The model doesn't model the storage and read-only operations. This is done by the
|
||||
/// [driver](crate::StoreDriver).
|
||||
#[derive(Clone, Debug)]
|
||||
pub struct StoreModel {
|
||||
/// Represents the content of the store.
|
||||
@@ -34,7 +37,7 @@ pub enum StoreOperation {
|
||||
/// Applies a transaction.
|
||||
Transaction {
|
||||
/// The list of updates to be applied.
|
||||
updates: Vec<StoreUpdate>,
|
||||
updates: Vec<StoreUpdate<Vec<u8>>>,
|
||||
},
|
||||
|
||||
/// Deletes all keys above a threshold.
|
||||
@@ -89,7 +92,7 @@ impl StoreModel {
|
||||
}
|
||||
|
||||
/// Applies a transaction.
|
||||
fn transaction(&mut self, updates: Vec<StoreUpdate>) -> StoreResult<()> {
|
||||
fn transaction(&mut self, updates: Vec<StoreUpdate<Vec<u8>>>) -> StoreResult<()> {
|
||||
// Fail if the transaction is invalid.
|
||||
if self.format.transaction_valid(&updates).is_none() {
|
||||
return Err(StoreError::InvalidArgument);
|
||||
|
||||
@@ -12,6 +12,8 @@
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
//! Flash storage abstraction.
|
||||
|
||||
/// Represents a byte position in a storage.
|
||||
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
|
||||
pub struct StorageIndex {
|
||||
@@ -65,12 +67,14 @@ pub trait Storage {
|
||||
/// The following pre-conditions must hold:
|
||||
/// - The `index` must designate `value.len()` bytes in the storage.
|
||||
/// - Both `index` and `value.len()` must be word-aligned.
|
||||
/// - The written words should not have been written too many times since last page erasure.
|
||||
/// - The written words should not have been written [too many](Self::max_word_writes) times
|
||||
/// since the last page erasure.
|
||||
fn write_slice(&mut self, index: StorageIndex, value: &[u8]) -> StorageResult<()>;
|
||||
|
||||
/// Erases a page of the storage.
|
||||
///
|
||||
/// The `page` must be in the storage.
|
||||
/// The `page` must be in the storage, i.e. less than [`Storage::num_pages`]. And the page
|
||||
/// should not have been erased [too many](Self::max_page_erases) times.
|
||||
fn erase_page(&mut self, page: usize) -> StorageResult<()>;
|
||||
}
|
||||
|
||||
|
||||
@@ -12,6 +12,8 @@
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
//! Store implementation.
|
||||
|
||||
use crate::format::{
|
||||
is_erased, CompactInfo, Format, Header, InitInfo, InternalEntry, Padding, ParsedWord, Position,
|
||||
Word, WordState,
|
||||
@@ -23,8 +25,12 @@ use crate::{usize_to_nat, Nat, Storage, StorageError, StorageIndex};
|
||||
pub use crate::{
|
||||
BufferStorage, StoreDriver, StoreDriverOff, StoreDriverOn, StoreInterruption, StoreInvariant,
|
||||
};
|
||||
use alloc::boxed::Box;
|
||||
use alloc::vec::Vec;
|
||||
use core::borrow::Borrow;
|
||||
use core::cmp::{max, min, Ordering};
|
||||
use core::convert::TryFrom;
|
||||
use core::option::NoneError;
|
||||
#[cfg(feature = "std")]
|
||||
use std::collections::HashSet;
|
||||
|
||||
@@ -51,17 +57,14 @@ pub enum StoreError {
|
||||
///
|
||||
/// The consequences depend on the storage failure. In particular, the operation may or may not
|
||||
/// have succeeded, and the storage may have become invalid. Before doing any other operation,
|
||||
/// the store should be [recovered]. The operation may then be retried if idempotent.
|
||||
///
|
||||
/// [recovered]: struct.Store.html#method.recover
|
||||
/// the store should be [recovered](Store::recover). The operation may then be retried if
|
||||
/// idempotent.
|
||||
StorageError,
|
||||
|
||||
/// Storage is invalid.
|
||||
///
|
||||
/// The storage should be erased and the store [recovered]. The store would be empty and have
|
||||
/// lost track of lifetime.
|
||||
///
|
||||
/// [recovered]: struct.Store.html#method.recover
|
||||
/// The storage should be erased and the store [recovered](Store::recover). The store would be
|
||||
/// empty and have lost track of lifetime.
|
||||
InvalidStorage,
|
||||
}
|
||||
|
||||
@@ -75,20 +78,26 @@ impl From<StorageError> for StoreError {
|
||||
}
|
||||
}
|
||||
|
||||
impl From<NoneError> for StoreError {
|
||||
fn from(error: NoneError) -> StoreError {
|
||||
match error {
|
||||
NoneError => StoreError::InvalidStorage,
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
/// Result of store operations.
|
||||
pub type StoreResult<T> = Result<T, StoreError>;
|
||||
|
||||
/// Progression ratio for store metrics.
|
||||
///
|
||||
/// This is used for the [capacity] and [lifetime] metrics. Those metrics are measured in words.
|
||||
/// This is used for the [`Store::capacity`] and [`Store::lifetime`] metrics. Those metrics are
|
||||
/// measured in words.
|
||||
///
|
||||
/// # Invariant
|
||||
///
|
||||
/// - The used value does not exceed the total: `used <= total`.
|
||||
///
|
||||
/// [capacity]: struct.Store.html#method.capacity
|
||||
/// [lifetime]: struct.Store.html#method.lifetime
|
||||
#[derive(Copy, Clone, PartialEq, Eq)]
|
||||
/// - The used value does not exceed the total: `used` ≤ `total`.
|
||||
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
|
||||
pub struct StoreRatio {
|
||||
/// How much of the metric is used.
|
||||
pub(crate) used: Nat,
|
||||
@@ -136,11 +145,20 @@ impl StoreHandle {
|
||||
self.key as usize
|
||||
}
|
||||
|
||||
/// Returns the value length of the entry.
|
||||
///
|
||||
/// # Errors
|
||||
///
|
||||
/// Returns [`StoreError::InvalidArgument`] if the entry has been deleted or compacted.
|
||||
pub fn get_length<S: Storage>(&self, store: &Store<S>) -> StoreResult<usize> {
|
||||
store.get_length(self)
|
||||
}
|
||||
|
||||
/// Returns the value of the entry.
|
||||
///
|
||||
/// # Errors
|
||||
///
|
||||
/// Returns `InvalidArgument` if the entry has been deleted or compacted.
|
||||
/// Returns [`StoreError::InvalidArgument`] if the entry has been deleted or compacted.
|
||||
pub fn get_value<S: Storage>(&self, store: &Store<S>) -> StoreResult<Vec<u8>> {
|
||||
store.get_value(self)
|
||||
}
|
||||
@@ -148,15 +166,15 @@ impl StoreHandle {
|
||||
|
||||
/// Represents an update to the store as part of a transaction.
|
||||
#[derive(Clone, Debug)]
|
||||
pub enum StoreUpdate {
|
||||
pub enum StoreUpdate<ByteSlice: Borrow<[u8]>> {
|
||||
/// Inserts or replaces an entry in the store.
|
||||
Insert { key: usize, value: Vec<u8> },
|
||||
Insert { key: usize, value: ByteSlice },
|
||||
|
||||
/// Removes an entry from the store.
|
||||
Remove { key: usize },
|
||||
}
|
||||
|
||||
impl StoreUpdate {
|
||||
impl<ByteSlice: Borrow<[u8]>> StoreUpdate<ByteSlice> {
|
||||
/// Returns the key affected by the update.
|
||||
pub fn key(&self) -> usize {
|
||||
match *self {
|
||||
@@ -168,12 +186,14 @@ impl StoreUpdate {
|
||||
/// Returns the value written by the update.
|
||||
pub fn value(&self) -> Option<&[u8]> {
|
||||
match self {
|
||||
StoreUpdate::Insert { value, .. } => Some(value),
|
||||
StoreUpdate::Insert { value, .. } => Some(value.borrow()),
|
||||
StoreUpdate::Remove { .. } => None,
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
pub type StoreIter<'a> = Box<dyn Iterator<Item = StoreResult<StoreHandle>> + 'a>;
|
||||
|
||||
/// Implements a store with a map interface over a storage.
|
||||
#[derive(Clone)]
|
||||
pub struct Store<S: Storage> {
|
||||
@@ -182,6 +202,14 @@ pub struct Store<S: Storage> {
|
||||
|
||||
/// The storage configuration.
|
||||
format: Format,
|
||||
|
||||
/// The position of the first word in the store.
|
||||
head: Option<Position>,
|
||||
|
||||
/// The list of the position of the user entries.
|
||||
///
|
||||
/// The position is encoded as the word offset from the [head](Store::head).
|
||||
entries: Option<Vec<u16>>,
|
||||
}
|
||||
|
||||
impl<S: Storage> Store<S> {
|
||||
@@ -193,13 +221,19 @@ impl<S: Storage> Store<S> {
|
||||
///
|
||||
/// # Errors
|
||||
///
|
||||
/// Returns `InvalidArgument` if the storage is not supported.
|
||||
/// Returns [`StoreError::InvalidArgument`] if the storage is not
|
||||
/// [supported](Format::is_storage_supported).
|
||||
pub fn new(storage: S) -> Result<Store<S>, (StoreError, S)> {
|
||||
let format = match Format::new(&storage) {
|
||||
None => return Err((StoreError::InvalidArgument, storage)),
|
||||
Some(x) => x,
|
||||
};
|
||||
let mut store = Store { storage, format };
|
||||
let mut store = Store {
|
||||
storage,
|
||||
format,
|
||||
head: None,
|
||||
entries: None,
|
||||
};
|
||||
if let Err(error) = store.recover() {
|
||||
return Err((error, store.storage));
|
||||
}
|
||||
@@ -207,31 +241,35 @@ impl<S: Storage> Store<S> {
|
||||
}
|
||||
|
||||
/// Iterates over the entries.
|
||||
pub fn iter<'a>(&'a self) -> StoreResult<StoreIter<'a, S>> {
|
||||
StoreIter::new(self)
|
||||
pub fn iter<'a>(&'a self) -> StoreResult<StoreIter<'a>> {
|
||||
let head = self.head?;
|
||||
Ok(Box::new(self.entries.as_ref()?.iter().map(
|
||||
move |&offset| {
|
||||
let pos = head + offset as Nat;
|
||||
match self.parse_entry(&mut pos.clone())? {
|
||||
ParsedEntry::User(Header {
|
||||
key, length: len, ..
|
||||
}) => Ok(StoreHandle { key, pos, len }),
|
||||
_ => Err(StoreError::InvalidStorage),
|
||||
}
|
||||
},
|
||||
)))
|
||||
}
|
||||
|
||||
/// Returns the current capacity in words.
|
||||
/// Returns the current and total capacity in words.
|
||||
///
|
||||
/// The capacity represents the size of what is stored.
|
||||
pub fn capacity(&self) -> StoreResult<StoreRatio> {
|
||||
let total = self.format.total_capacity();
|
||||
let mut used = 0;
|
||||
let mut pos = self.head()?;
|
||||
let end = pos + self.format.virt_size();
|
||||
while pos < end {
|
||||
let entry_pos = pos;
|
||||
match self.parse_entry(&mut pos)? {
|
||||
ParsedEntry::Tail => break,
|
||||
ParsedEntry::Padding => (),
|
||||
ParsedEntry::User(_) => used += pos - entry_pos,
|
||||
_ => return Err(StoreError::InvalidStorage),
|
||||
}
|
||||
for handle in self.iter()? {
|
||||
let handle = handle?;
|
||||
used += 1 + self.format.bytes_to_words(handle.len);
|
||||
}
|
||||
Ok(StoreRatio { used, total })
|
||||
}
|
||||
|
||||
/// Returns the current lifetime in words.
|
||||
/// Returns the current and total lifetime in words.
|
||||
///
|
||||
/// The lifetime represents the age of the storage. The limit is an over-approximation by at
|
||||
/// most the maximum length of a value (the actual limit depends on the length of the prefix of
|
||||
@@ -246,18 +284,22 @@ impl<S: Storage> Store<S> {
|
||||
///
|
||||
/// # Errors
|
||||
///
|
||||
/// Returns `InvalidArgument` in the following circumstances:
|
||||
/// - There are too many updates.
|
||||
/// Returns [`StoreError::InvalidArgument`] in the following circumstances:
|
||||
/// - There are [too many](Format::max_updates) updates.
|
||||
/// - The updates overlap, i.e. their keys are not disjoint.
|
||||
/// - The updates are invalid, e.g. key out of bound or value too long.
|
||||
pub fn transaction(&mut self, updates: &[StoreUpdate]) -> StoreResult<()> {
|
||||
/// - The updates are invalid, e.g. key [out of bound](Format::max_key) or value [too
|
||||
/// long](Format::max_value_len).
|
||||
pub fn transaction<ByteSlice: Borrow<[u8]>>(
|
||||
&mut self,
|
||||
updates: &[StoreUpdate<ByteSlice>],
|
||||
) -> StoreResult<()> {
|
||||
let count = usize_to_nat(updates.len());
|
||||
if count == 0 {
|
||||
return Ok(());
|
||||
}
|
||||
if count == 1 {
|
||||
match updates[0] {
|
||||
StoreUpdate::Insert { key, ref value } => return self.insert(key, value),
|
||||
StoreUpdate::Insert { key, ref value } => return self.insert(key, value.borrow()),
|
||||
StoreUpdate::Remove { key } => return self.remove(key),
|
||||
}
|
||||
}
|
||||
@@ -270,7 +312,9 @@ impl<S: Storage> Store<S> {
|
||||
self.reserve(self.format.transaction_capacity(updates))?;
|
||||
// Write the marker entry.
|
||||
let marker = self.tail()?;
|
||||
let entry = self.format.build_internal(InternalEntry::Marker { count });
|
||||
let entry = self
|
||||
.format
|
||||
.build_internal(InternalEntry::Marker { count })?;
|
||||
self.write_slice(marker, &entry)?;
|
||||
self.init_page(marker, marker)?;
|
||||
// Write the updates.
|
||||
@@ -278,7 +322,7 @@ impl<S: Storage> Store<S> {
|
||||
for update in updates {
|
||||
let length = match *update {
|
||||
StoreUpdate::Insert { key, ref value } => {
|
||||
let entry = self.format.build_user(usize_to_nat(key), value);
|
||||
let entry = self.format.build_user(usize_to_nat(key), value.borrow())?;
|
||||
let word_size = self.format.word_size();
|
||||
let footer = usize_to_nat(entry.len()) / word_size - 1;
|
||||
self.write_slice(tail, &entry[..(footer * word_size) as usize])?;
|
||||
@@ -287,7 +331,7 @@ impl<S: Storage> Store<S> {
|
||||
}
|
||||
StoreUpdate::Remove { key } => {
|
||||
let key = usize_to_nat(key);
|
||||
let remove = self.format.build_internal(InternalEntry::Remove { key });
|
||||
let remove = self.format.build_internal(InternalEntry::Remove { key })?;
|
||||
self.write_slice(tail, &remove)?;
|
||||
0
|
||||
}
|
||||
@@ -307,7 +351,9 @@ impl<S: Storage> Store<S> {
|
||||
if min_key > self.format.max_key() {
|
||||
return Err(StoreError::InvalidArgument);
|
||||
}
|
||||
let clear = self.format.build_internal(InternalEntry::Clear { min_key });
|
||||
let clear = self
|
||||
.format
|
||||
.build_internal(InternalEntry::Clear { min_key })?;
|
||||
// We always have one word available. We can't use `reserve` because this is internal
|
||||
// capacity, not user capacity.
|
||||
while self.immediate_capacity()? < 1 {
|
||||
@@ -373,7 +419,7 @@ impl<S: Storage> Store<S> {
|
||||
if key > self.format.max_key() || value_len > self.format.max_value_len() {
|
||||
return Err(StoreError::InvalidArgument);
|
||||
}
|
||||
let entry = self.format.build_user(key, value);
|
||||
let entry = self.format.build_user(key, value)?;
|
||||
let entry_len = usize_to_nat(entry.len());
|
||||
self.reserve(entry_len / self.format.word_size())?;
|
||||
let tail = self.tail()?;
|
||||
@@ -381,6 +427,7 @@ impl<S: Storage> Store<S> {
|
||||
let footer = entry_len / word_size - 1;
|
||||
self.write_slice(tail, &entry[..(footer * word_size) as usize])?;
|
||||
self.write_slice(tail + footer, &entry[(footer * word_size) as usize..])?;
|
||||
self.push_entry(tail)?;
|
||||
self.insert_init(tail, footer, key)
|
||||
}
|
||||
|
||||
@@ -398,7 +445,8 @@ impl<S: Storage> Store<S> {
|
||||
/// Removes an entry given a handle.
|
||||
pub fn remove_handle(&mut self, handle: &StoreHandle) -> StoreResult<()> {
|
||||
self.check_handle(handle)?;
|
||||
self.delete_pos(handle.pos, self.format.bytes_to_words(handle.len))
|
||||
self.delete_pos(handle.pos, self.format.bytes_to_words(handle.len))?;
|
||||
self.remove_entry(handle.pos)
|
||||
}
|
||||
|
||||
/// Returns the maximum length in bytes of a value.
|
||||
@@ -406,6 +454,17 @@ impl<S: Storage> Store<S> {
|
||||
self.format.max_value_len() as usize
|
||||
}
|
||||
|
||||
/// Returns the length of the value of an entry given its handle.
|
||||
fn get_length(&self, handle: &StoreHandle) -> StoreResult<usize> {
|
||||
self.check_handle(handle)?;
|
||||
let mut pos = handle.pos;
|
||||
match self.parse_entry(&mut pos)? {
|
||||
ParsedEntry::User(header) => Ok(header.length as usize),
|
||||
ParsedEntry::Padding => Err(StoreError::InvalidArgument),
|
||||
_ => Err(StoreError::InvalidStorage),
|
||||
}
|
||||
}
|
||||
|
||||
/// Returns the value of an entry given its handle.
|
||||
fn get_value(&self, handle: &StoreHandle) -> StoreResult<Vec<u8>> {
|
||||
self.check_handle(handle)?;
|
||||
@@ -437,7 +496,7 @@ impl<S: Storage> Store<S> {
|
||||
let init_info = self.format.build_init(InitInfo {
|
||||
cycle: 0,
|
||||
prefix: 0,
|
||||
});
|
||||
})?;
|
||||
self.storage_write_slice(index, &init_info)
|
||||
}
|
||||
|
||||
@@ -460,7 +519,9 @@ impl<S: Storage> Store<S> {
|
||||
|
||||
/// Recovers a possible compaction interrupted while copying the entries.
|
||||
fn recover_compaction(&mut self) -> StoreResult<()> {
|
||||
let head_page = self.head()?.page(&self.format);
|
||||
let head = self.get_extremum_page_head(Ordering::Less)?;
|
||||
self.head = Some(head);
|
||||
let head_page = head.page(&self.format);
|
||||
match self.parse_compact(head_page)? {
|
||||
WordState::Erased => Ok(()),
|
||||
WordState::Partial => self.compact(),
|
||||
@@ -470,14 +531,15 @@ impl<S: Storage> Store<S> {
|
||||
|
||||
/// Recover a possible interrupted operation which is not a compaction.
|
||||
fn recover_operation(&mut self) -> StoreResult<()> {
|
||||
let mut pos = self.head()?;
|
||||
self.entries = Some(Vec::new());
|
||||
let mut pos = self.head?;
|
||||
let mut prev_pos = pos;
|
||||
let end = pos + self.format.virt_size();
|
||||
while pos < end {
|
||||
let entry_pos = pos;
|
||||
match self.parse_entry(&mut pos)? {
|
||||
ParsedEntry::Tail => break,
|
||||
ParsedEntry::User(_) => (),
|
||||
ParsedEntry::User(_) => self.push_entry(entry_pos)?,
|
||||
ParsedEntry::Padding => {
|
||||
self.wipe_span(entry_pos + 1, pos - entry_pos - 1)?;
|
||||
}
|
||||
@@ -610,7 +672,7 @@ impl<S: Storage> Store<S> {
|
||||
///
|
||||
/// In particular, the handle has not been compacted.
|
||||
fn check_handle(&self, handle: &StoreHandle) -> StoreResult<()> {
|
||||
if handle.pos < self.head()? {
|
||||
if handle.pos < self.head? {
|
||||
Err(StoreError::InvalidArgument)
|
||||
} else {
|
||||
Ok(())
|
||||
@@ -640,20 +702,22 @@ impl<S: Storage> Store<S> {
|
||||
|
||||
/// Compacts one page.
|
||||
fn compact(&mut self) -> StoreResult<()> {
|
||||
let head = self.head()?;
|
||||
let head = self.head?;
|
||||
if head.cycle(&self.format) >= self.format.max_page_erases() {
|
||||
return Err(StoreError::NoLifetime);
|
||||
}
|
||||
let tail = max(self.tail()?, head.next_page(&self.format));
|
||||
let index = self.format.index_compact(head.page(&self.format));
|
||||
let compact_info = self.format.build_compact(CompactInfo { tail: tail - head });
|
||||
let compact_info = self
|
||||
.format
|
||||
.build_compact(CompactInfo { tail: tail - head })?;
|
||||
self.storage_write_slice(index, &compact_info)?;
|
||||
self.compact_copy()
|
||||
}
|
||||
|
||||
/// Continues a compaction after its compact page info has been written.
|
||||
fn compact_copy(&mut self) -> StoreResult<()> {
|
||||
let mut head = self.head()?;
|
||||
let mut head = self.head?;
|
||||
let page = head.page(&self.format);
|
||||
let end = head.next_page(&self.format);
|
||||
let mut tail = match self.parse_compact(page)? {
|
||||
@@ -667,8 +731,12 @@ impl<S: Storage> Store<S> {
|
||||
let pos = head;
|
||||
match self.parse_entry(&mut head)? {
|
||||
ParsedEntry::Tail => break,
|
||||
// This can happen if we copy to the next page. We actually reached the tail but we
|
||||
// read what we just copied.
|
||||
ParsedEntry::Partial if head > end => break,
|
||||
ParsedEntry::User(_) => (),
|
||||
_ => continue,
|
||||
ParsedEntry::Padding => continue,
|
||||
_ => return Err(StoreError::InvalidStorage),
|
||||
};
|
||||
let length = head - pos;
|
||||
// We have to copy the slice for 2 reasons:
|
||||
@@ -676,11 +744,13 @@ impl<S: Storage> Store<S> {
|
||||
// 2. We can't pass a flash slice to the kernel. This should get fixed with
|
||||
// https://github.com/tock/tock/issues/1274.
|
||||
let entry = self.read_slice(pos, length * self.format.word_size());
|
||||
self.remove_entry(pos)?;
|
||||
self.write_slice(tail, &entry)?;
|
||||
self.push_entry(tail)?;
|
||||
self.init_page(tail, tail + (length - 1))?;
|
||||
tail += length;
|
||||
}
|
||||
let erase = self.format.build_internal(InternalEntry::Erase { page });
|
||||
let erase = self.format.build_internal(InternalEntry::Erase { page })?;
|
||||
self.write_slice(tail, &erase)?;
|
||||
self.init_page(tail, tail)?;
|
||||
self.compact_erase(tail)
|
||||
@@ -688,14 +758,31 @@ impl<S: Storage> Store<S> {
|
||||
|
||||
/// Continues a compaction after its erase entry has been written.
|
||||
fn compact_erase(&mut self, erase: Position) -> StoreResult<()> {
|
||||
let page = match self.parse_entry(&mut erase.clone())? {
|
||||
// Read the page to erase from the erase entry.
|
||||
let mut page = match self.parse_entry(&mut erase.clone())? {
|
||||
ParsedEntry::Internal(InternalEntry::Erase { page }) => page,
|
||||
_ => return Err(StoreError::InvalidStorage),
|
||||
};
|
||||
// Erase the page.
|
||||
self.storage_erase_page(page)?;
|
||||
let head = self.head()?;
|
||||
// Update the head.
|
||||
page = (page + 1) % self.format.num_pages();
|
||||
let init = match self.parse_init(page)? {
|
||||
WordState::Valid(x) => x,
|
||||
_ => return Err(StoreError::InvalidStorage),
|
||||
};
|
||||
let head = self.format.page_head(init, page);
|
||||
if let Some(entries) = &mut self.entries {
|
||||
let head_offset = u16::try_from(head - self.head?).ok()?;
|
||||
for entry in entries {
|
||||
*entry = entry.checked_sub(head_offset)?;
|
||||
}
|
||||
}
|
||||
self.head = Some(head);
|
||||
// Wipe the overlapping entry from the erased page.
|
||||
let pos = head.page_begin(&self.format);
|
||||
self.wipe_span(pos, head - pos)?;
|
||||
// Mark the erase entry as done.
|
||||
self.set_padding(erase)?;
|
||||
Ok(())
|
||||
}
|
||||
@@ -704,13 +791,13 @@ impl<S: Storage> Store<S> {
|
||||
fn transaction_apply(&mut self, sorted_keys: &[Nat], marker: Position) -> StoreResult<()> {
|
||||
self.delete_keys(&sorted_keys, marker)?;
|
||||
self.set_padding(marker)?;
|
||||
let end = self.head()? + self.format.virt_size();
|
||||
let end = self.head? + self.format.virt_size();
|
||||
let mut pos = marker + 1;
|
||||
while pos < end {
|
||||
let entry_pos = pos;
|
||||
match self.parse_entry(&mut pos)? {
|
||||
ParsedEntry::Tail => break,
|
||||
ParsedEntry::User(_) => (),
|
||||
ParsedEntry::User(_) => self.push_entry(entry_pos)?,
|
||||
ParsedEntry::Internal(InternalEntry::Remove { .. }) => {
|
||||
self.set_padding(entry_pos)?
|
||||
}
|
||||
@@ -727,37 +814,38 @@ impl<S: Storage> Store<S> {
|
||||
ParsedEntry::Internal(InternalEntry::Clear { min_key }) => min_key,
|
||||
_ => return Err(StoreError::InvalidStorage),
|
||||
};
|
||||
let mut pos = self.head()?;
|
||||
let end = pos + self.format.virt_size();
|
||||
while pos < end {
|
||||
let entry_pos = pos;
|
||||
match self.parse_entry(&mut pos)? {
|
||||
ParsedEntry::Internal(InternalEntry::Clear { .. }) if entry_pos == clear => break,
|
||||
ParsedEntry::User(header) if header.key >= min_key => {
|
||||
self.delete_pos(entry_pos, pos - entry_pos - 1)?;
|
||||
}
|
||||
ParsedEntry::Padding | ParsedEntry::User(_) => (),
|
||||
_ => return Err(StoreError::InvalidStorage),
|
||||
}
|
||||
}
|
||||
self.delete_if(clear, |key| key >= min_key)?;
|
||||
self.set_padding(clear)?;
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Deletes a set of entries up to a certain position.
|
||||
fn delete_keys(&mut self, sorted_keys: &[Nat], end: Position) -> StoreResult<()> {
|
||||
let mut pos = self.head()?;
|
||||
while pos < end {
|
||||
let entry_pos = pos;
|
||||
match self.parse_entry(&mut pos)? {
|
||||
ParsedEntry::Tail => break,
|
||||
ParsedEntry::User(header) if sorted_keys.binary_search(&header.key).is_ok() => {
|
||||
self.delete_pos(entry_pos, pos - entry_pos - 1)?;
|
||||
}
|
||||
ParsedEntry::Padding | ParsedEntry::User(_) => (),
|
||||
self.delete_if(end, |key| sorted_keys.binary_search(&key).is_ok())
|
||||
}
|
||||
|
||||
/// Deletes entries matching a predicate up to a certain position.
|
||||
fn delete_if(&mut self, end: Position, delete: impl Fn(Nat) -> bool) -> StoreResult<()> {
|
||||
let head = self.head?;
|
||||
let mut entries = self.entries.take()?;
|
||||
let mut i = 0;
|
||||
while i < entries.len() {
|
||||
let pos = head + entries[i] as Nat;
|
||||
if pos >= end {
|
||||
break;
|
||||
}
|
||||
let header = match self.parse_entry(&mut pos.clone())? {
|
||||
ParsedEntry::User(x) => x,
|
||||
_ => return Err(StoreError::InvalidStorage),
|
||||
};
|
||||
if delete(header.key) {
|
||||
self.delete_pos(pos, self.format.bytes_to_words(header.length))?;
|
||||
entries.swap_remove(i);
|
||||
} else {
|
||||
i += 1;
|
||||
}
|
||||
}
|
||||
self.entries = Some(entries);
|
||||
Ok(())
|
||||
}
|
||||
|
||||
@@ -792,7 +880,7 @@ impl<S: Storage> Store<S> {
|
||||
let init_info = self.format.build_init(InitInfo {
|
||||
cycle: new_first.cycle(&self.format),
|
||||
prefix: new_first.word(&self.format),
|
||||
});
|
||||
})?;
|
||||
self.storage_write_slice(index, &init_info)?;
|
||||
Ok(())
|
||||
}
|
||||
@@ -800,7 +888,7 @@ impl<S: Storage> Store<S> {
|
||||
/// Sets the padding bit of a user header.
|
||||
fn set_padding(&mut self, pos: Position) -> StoreResult<()> {
|
||||
let mut word = Word::from_slice(self.read_word(pos));
|
||||
self.format.set_padding(&mut word);
|
||||
self.format.set_padding(&mut word)?;
|
||||
self.write_slice(pos, &word.as_slice())?;
|
||||
Ok(())
|
||||
}
|
||||
@@ -836,19 +924,20 @@ impl<S: Storage> Store<S> {
|
||||
}
|
||||
}
|
||||
// There is always at least one initialized page.
|
||||
best.ok_or(StoreError::InvalidStorage)
|
||||
Ok(best?)
|
||||
}
|
||||
|
||||
/// Returns the number of words that can be written without compaction.
|
||||
fn immediate_capacity(&self) -> StoreResult<Nat> {
|
||||
let tail = self.tail()?;
|
||||
let end = self.head()? + self.format.virt_size();
|
||||
let end = self.head? + self.format.virt_size();
|
||||
Ok(end.get().saturating_sub(tail.get()))
|
||||
}
|
||||
|
||||
/// Returns the position of the first word in the store.
|
||||
#[cfg(feature = "std")]
|
||||
pub(crate) fn head(&self) -> StoreResult<Position> {
|
||||
self.get_extremum_page_head(Ordering::Less)
|
||||
Ok(self.head?)
|
||||
}
|
||||
|
||||
/// Returns one past the position of the last word in the store.
|
||||
@@ -863,6 +952,30 @@ impl<S: Storage> Store<S> {
|
||||
Ok(pos)
|
||||
}
|
||||
|
||||
fn push_entry(&mut self, pos: Position) -> StoreResult<()> {
|
||||
let entries = match &mut self.entries {
|
||||
None => return Ok(()),
|
||||
Some(x) => x,
|
||||
};
|
||||
let head = self.head?;
|
||||
let offset = u16::try_from(pos - head).ok()?;
|
||||
debug_assert!(!entries.contains(&offset));
|
||||
entries.push(offset);
|
||||
Ok(())
|
||||
}
|
||||
|
||||
fn remove_entry(&mut self, pos: Position) -> StoreResult<()> {
|
||||
let entries = match &mut self.entries {
|
||||
None => return Ok(()),
|
||||
Some(x) => x,
|
||||
};
|
||||
let head = self.head?;
|
||||
let offset = u16::try_from(pos - head).ok()?;
|
||||
let i = entries.iter().position(|x| *x == offset)?;
|
||||
entries.swap_remove(i);
|
||||
Ok(())
|
||||
}
|
||||
|
||||
/// Parses the entry at a given position.
|
||||
///
|
||||
/// The position is updated to point to the next entry.
|
||||
@@ -1061,7 +1174,7 @@ impl Store<BufferStorage> {
|
||||
/// If the value has been partially compacted, only return the non-compacted part. Returns an
|
||||
/// empty value if it has been fully compacted.
|
||||
pub fn inspect_value(&self, handle: &StoreHandle) -> Vec<u8> {
|
||||
let head = self.head().unwrap();
|
||||
let head = self.head.unwrap();
|
||||
let length = self.format.bytes_to_words(handle.len);
|
||||
if head <= handle.pos {
|
||||
// The value has not been compacted.
|
||||
@@ -1087,20 +1200,21 @@ impl Store<BufferStorage> {
|
||||
store
|
||||
.iter()
|
||||
.unwrap()
|
||||
.map(|x| x.unwrap())
|
||||
.filter(|x| delete_key(x.key as usize))
|
||||
.collect::<Vec<_>>()
|
||||
.filter(|x| x.is_err() || delete_key(x.as_ref().unwrap().key as usize))
|
||||
.collect::<Result<Vec<_>, _>>()
|
||||
};
|
||||
match *operation {
|
||||
StoreOperation::Transaction { ref updates } => {
|
||||
let keys: HashSet<usize> = updates.iter().map(|x| x.key()).collect();
|
||||
let deleted = deleted(self, &|key| keys.contains(&key));
|
||||
(deleted, self.transaction(updates))
|
||||
}
|
||||
StoreOperation::Clear { min_key } => {
|
||||
let deleted = deleted(self, &|key| key >= min_key);
|
||||
(deleted, self.clear(min_key))
|
||||
match deleted(self, &|key| keys.contains(&key)) {
|
||||
Ok(deleted) => (deleted, self.transaction(updates)),
|
||||
Err(error) => (Vec::new(), Err(error)),
|
||||
}
|
||||
}
|
||||
StoreOperation::Clear { min_key } => match deleted(self, &|key| key >= min_key) {
|
||||
Ok(deleted) => (deleted, self.clear(min_key)),
|
||||
Err(error) => (Vec::new(), Err(error)),
|
||||
},
|
||||
StoreOperation::Prepare { length } => (Vec::new(), self.prepare(length)),
|
||||
}
|
||||
}
|
||||
@@ -1110,10 +1224,12 @@ impl Store<BufferStorage> {
|
||||
let format = Format::new(storage).unwrap();
|
||||
// Write the init info of the first page.
|
||||
let mut index = format.index_init(0);
|
||||
let init_info = format.build_init(InitInfo {
|
||||
cycle: usize_to_nat(cycle),
|
||||
prefix: 0,
|
||||
});
|
||||
let init_info = format
|
||||
.build_init(InitInfo {
|
||||
cycle: usize_to_nat(cycle),
|
||||
prefix: 0,
|
||||
})
|
||||
.unwrap();
|
||||
storage.write_slice(index, &init_info).unwrap();
|
||||
// Pad the first word of the page. This makes the store looks used, otherwise we may confuse
|
||||
// it with a partially initialized store.
|
||||
@@ -1165,61 +1281,6 @@ enum ParsedEntry {
|
||||
Tail,
|
||||
}
|
||||
|
||||
/// Iterates over the entries of a store.
|
||||
pub struct StoreIter<'a, S: Storage> {
|
||||
/// The store being iterated.
|
||||
store: &'a Store<S>,
|
||||
|
||||
/// The position of the next entry.
|
||||
pos: Position,
|
||||
|
||||
/// Iteration stops when reaching this position.
|
||||
end: Position,
|
||||
}
|
||||
|
||||
impl<'a, S: Storage> StoreIter<'a, S> {
|
||||
/// Creates an iterator over the entries of a store.
|
||||
fn new(store: &'a Store<S>) -> StoreResult<StoreIter<'a, S>> {
|
||||
let pos = store.head()?;
|
||||
let end = pos + store.format.virt_size();
|
||||
Ok(StoreIter { store, pos, end })
|
||||
}
|
||||
}
|
||||
|
||||
impl<'a, S: Storage> StoreIter<'a, S> {
|
||||
/// Returns the next entry and advances the iterator.
|
||||
fn transposed_next(&mut self) -> StoreResult<Option<StoreHandle>> {
|
||||
if self.pos >= self.end {
|
||||
return Ok(None);
|
||||
}
|
||||
while self.pos < self.end {
|
||||
let entry_pos = self.pos;
|
||||
match self.store.parse_entry(&mut self.pos)? {
|
||||
ParsedEntry::Tail => break,
|
||||
ParsedEntry::Padding => (),
|
||||
ParsedEntry::User(header) => {
|
||||
return Ok(Some(StoreHandle {
|
||||
key: header.key,
|
||||
pos: entry_pos,
|
||||
len: header.length,
|
||||
}))
|
||||
}
|
||||
_ => return Err(StoreError::InvalidStorage),
|
||||
}
|
||||
}
|
||||
self.pos = self.end;
|
||||
Ok(None)
|
||||
}
|
||||
}
|
||||
|
||||
impl<'a, S: Storage> Iterator for StoreIter<'a, S> {
|
||||
type Item = StoreResult<StoreHandle>;
|
||||
|
||||
fn next(&mut self) -> Option<StoreResult<StoreHandle>> {
|
||||
self.transposed_next().transpose()
|
||||
}
|
||||
}
|
||||
|
||||
/// Returns whether 2 slices are different.
|
||||
///
|
||||
/// Returns an error if `target` has a bit set to one for which `source` is set to zero.
|
||||
@@ -1239,71 +1300,15 @@ fn is_write_needed(source: &[u8], target: &[u8]) -> StoreResult<bool> {
|
||||
#[cfg(test)]
|
||||
mod tests {
|
||||
use super::*;
|
||||
use crate::BufferOptions;
|
||||
|
||||
#[derive(Clone)]
|
||||
struct Config {
|
||||
word_size: usize,
|
||||
page_size: usize,
|
||||
num_pages: usize,
|
||||
max_word_writes: usize,
|
||||
max_page_erases: usize,
|
||||
}
|
||||
|
||||
impl Config {
|
||||
fn new_driver(&self) -> StoreDriverOff {
|
||||
let options = BufferOptions {
|
||||
word_size: self.word_size,
|
||||
page_size: self.page_size,
|
||||
max_word_writes: self.max_word_writes,
|
||||
max_page_erases: self.max_page_erases,
|
||||
strict_write: true,
|
||||
};
|
||||
StoreDriverOff::new(options, self.num_pages)
|
||||
}
|
||||
}
|
||||
|
||||
const MINIMAL: Config = Config {
|
||||
word_size: 4,
|
||||
page_size: 64,
|
||||
num_pages: 5,
|
||||
max_word_writes: 2,
|
||||
max_page_erases: 9,
|
||||
};
|
||||
|
||||
const NORDIC: Config = Config {
|
||||
word_size: 4,
|
||||
page_size: 0x1000,
|
||||
num_pages: 20,
|
||||
max_word_writes: 2,
|
||||
max_page_erases: 10000,
|
||||
};
|
||||
|
||||
const TITAN: Config = Config {
|
||||
word_size: 4,
|
||||
page_size: 0x800,
|
||||
num_pages: 10,
|
||||
max_word_writes: 2,
|
||||
max_page_erases: 10000,
|
||||
};
|
||||
use crate::test::MINIMAL;
|
||||
|
||||
#[test]
|
||||
fn nordic_capacity() {
|
||||
let driver = NORDIC.new_driver().power_on().unwrap();
|
||||
assert_eq!(driver.model().capacity().total, 19123);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn titan_capacity() {
|
||||
let driver = TITAN.new_driver().power_on().unwrap();
|
||||
assert_eq!(driver.model().capacity().total, 4315);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn minimal_virt_page_size() {
|
||||
// Make sure a virtual page has 14 words. We use this property in the other tests below to
|
||||
// know whether entries are spanning, starting, and ending pages.
|
||||
assert_eq!(MINIMAL.new_driver().model().format().virt_page_size(), 14);
|
||||
fn is_write_needed_ok() {
|
||||
assert_eq!(is_write_needed(&[], &[]), Ok(false));
|
||||
assert_eq!(is_write_needed(&[0], &[0]), Ok(false));
|
||||
assert_eq!(is_write_needed(&[0], &[1]), Err(StoreError::InvalidStorage));
|
||||
assert_eq!(is_write_needed(&[1], &[0]), Ok(true));
|
||||
assert_eq!(is_write_needed(&[1], &[1]), Ok(false));
|
||||
}
|
||||
|
||||
#[test]
|
||||
@@ -1438,4 +1443,22 @@ mod tests {
|
||||
driver = driver.power_off().power_on().unwrap();
|
||||
driver.check().unwrap();
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn entries_ok() {
|
||||
let mut driver = MINIMAL.new_driver().power_on().unwrap();
|
||||
|
||||
// The store is initially empty.
|
||||
assert!(driver.store().entries.as_ref().unwrap().is_empty());
|
||||
|
||||
// Inserted elements are added.
|
||||
const LEN: usize = 6;
|
||||
driver.insert(0, &[0x38; (LEN - 1) * 4]).unwrap();
|
||||
driver.insert(1, &[0x5c; 4]).unwrap();
|
||||
assert_eq!(driver.store().entries, Some(vec![0, LEN as u16]));
|
||||
|
||||
// Deleted elements are removed.
|
||||
driver.remove(0).unwrap();
|
||||
assert_eq!(driver.store().entries, Some(vec![LEN as u16]));
|
||||
}
|
||||
}
|
||||
|
||||
84
libraries/persistent_store/src/test.rs
Normal file
84
libraries/persistent_store/src/test.rs
Normal file
@@ -0,0 +1,84 @@
|
||||
// Copyright 2021 Google LLC
|
||||
//
|
||||
// Licensed under the Apache License, Version 2.0 (the "License");
|
||||
// you may not use this file except in compliance with the License.
|
||||
// You may obtain a copy of the License at
|
||||
//
|
||||
// http://www.apache.org/licenses/LICENSE-2.0
|
||||
//
|
||||
// Unless required by applicable law or agreed to in writing, software
|
||||
// distributed under the License is distributed on an "AS IS" BASIS,
|
||||
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
||||
// See the License for the specific language governing permissions and
|
||||
// limitations under the License.
|
||||
|
||||
use crate::{BufferOptions, BufferStorage, Store, StoreDriverOff};
|
||||
|
||||
#[derive(Clone)]
|
||||
pub struct Config {
|
||||
word_size: usize,
|
||||
page_size: usize,
|
||||
num_pages: usize,
|
||||
max_word_writes: usize,
|
||||
max_page_erases: usize,
|
||||
}
|
||||
|
||||
impl Config {
|
||||
pub fn new_driver(&self) -> StoreDriverOff {
|
||||
let options = BufferOptions {
|
||||
word_size: self.word_size,
|
||||
page_size: self.page_size,
|
||||
max_word_writes: self.max_word_writes,
|
||||
max_page_erases: self.max_page_erases,
|
||||
strict_mode: true,
|
||||
};
|
||||
StoreDriverOff::new(options, self.num_pages)
|
||||
}
|
||||
|
||||
pub fn new_store(&self) -> Store<BufferStorage> {
|
||||
self.new_driver().power_on().unwrap().extract_store()
|
||||
}
|
||||
}
|
||||
|
||||
pub const MINIMAL: Config = Config {
|
||||
word_size: 4,
|
||||
page_size: 64,
|
||||
num_pages: 5,
|
||||
max_word_writes: 2,
|
||||
max_page_erases: 9,
|
||||
};
|
||||
|
||||
const NORDIC: Config = Config {
|
||||
word_size: 4,
|
||||
page_size: 0x1000,
|
||||
num_pages: 20,
|
||||
max_word_writes: 2,
|
||||
max_page_erases: 10000,
|
||||
};
|
||||
|
||||
const TITAN: Config = Config {
|
||||
word_size: 4,
|
||||
page_size: 0x800,
|
||||
num_pages: 10,
|
||||
max_word_writes: 2,
|
||||
max_page_erases: 10000,
|
||||
};
|
||||
|
||||
#[test]
|
||||
fn nordic_capacity() {
|
||||
let driver = NORDIC.new_driver().power_on().unwrap();
|
||||
assert_eq!(driver.model().capacity().total, 19123);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn titan_capacity() {
|
||||
let driver = TITAN.new_driver().power_on().unwrap();
|
||||
assert_eq!(driver.model().capacity().total, 4315);
|
||||
}
|
||||
|
||||
#[test]
|
||||
fn minimal_virt_page_size() {
|
||||
// Make sure a virtual page has 14 words. We use this property in the other tests below to
|
||||
// know whether entries are spanning, starting, and ending pages.
|
||||
assert_eq!(MINIMAL.new_driver().model().format().virt_page_size(), 14);
|
||||
}
|
||||
Reference in New Issue
Block a user