From 0f368f0b48b6830451948bcf5d991cb37e0fd7a7 Mon Sep 17 00:00:00 2001
From: Julien Cretin <cretin@google.com>
Date: Fri, 3 Jun 2022 17:03:06 +0200
Subject: [PATCH] Add justification for Cow usage

---
 libraries/persistent_store/src/storage.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libraries/persistent_store/src/storage.rs b/libraries/persistent_store/src/storage.rs
index adc3c53..696c258 100644
--- a/libraries/persistent_store/src/storage.rs
+++ b/libraries/persistent_store/src/storage.rs
@@ -62,6 +62,9 @@ pub trait Storage {
     /// Reads a byte slice from the storage.
     ///
     /// The `index` must designate `length` bytes in the storage.
+    ///
+    /// Note that we use `Cow` just because it derefs to `[u8]`. We don't really need the fact that
+    /// one can convert it to a `Vec`. In particular we don't do it in the store implementation.
     fn read_slice(&self, index: StorageIndex, length: usize) -> StorageResult<Cow<[u8]>>;
 
     /// Writes a word slice to the storage.