Disk Cache: Don't depend on the backend being enabled to

be able to return the key of an open entry.

Whenever a critical corruption is detected by the disk cache,
the backend disables itself and starts failing all requests
until it's able to re-create the backing store.

Key's longer than 928 bytes are not stored inside the entry
itself, so a file object is required to access them. The backend
will reject any request for a file object after it is disabled,
so a user's request for the key of an open entry will also
fail.

Now we keep a pointer to the related file object (if needed) so
that we don't have to ask the backend for it when the user
requests the current key.

BUG=9952
TEST=unittest


Review URL: http://codereview.chromium.org/165030

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@22637 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 4 insertions, 2 deletions

diff --git a/net/disk_cache/entry_impl.h b/net/disk_cache/entry_impl.h
index da82396..4bb4d04 100644
--- a/net/disk_cache/entry_impl.h
+++ b/net/disk_cache/entry_impl.h
@@ -176,8 +176,10 @@ class EntryImpl : public Entry, public base::RefCounted<EntryImpl> {
   CacheRankingsBlock node_;   // Rankings related information for this entry.
   BackendImpl* backend_;      // Back pointer to the cache.
   scoped_array<char> user_buffers_[kNumStreams];  // Store user data.
-  scoped_refptr<File> files_[kNumStreams + 1];    // Files to store external
-                                                  // user data and key.
+  // Files to store external user data and key.
+  scoped_refptr<File> files_[kNumStreams + 1];
+  // Copy of the file used to store the key. We don't own this object.
+  mutable File* key_file_;
   int unreported_size_[kNumStreams];  // Bytes not reported yet to the backend.
   bool doomed_;               // True if this entry was removed from the cache.
   scoped_ptr<SparseControl> sparse_;  // Support for sparse entries.