Disk cache: Prevent obscure file corruption and deal...

net/disk_cache/backend_impl.h

 // Copyright (c) 2006-2010 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // See net/disk_cache/disk_cache.h for the public interface of the cache.
 
 #ifndef NET_DISK_CACHE_BACKEND_IMPL_H_
 #define NET_DISK_CACHE_BACKEND_IMPL_H_
 #pragma once
 
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   // Sends a dummy operation through the operation queue, for unit tests.
   int FlushQueueForTest(CompletionCallback* callback);
 
   // Runs the provided task on the cache thread. The task will be automatically
   // deleted after it runs.
   int RunTaskForTest(Task* task, CompletionCallback* callback);
 
   // Starts or stops throttling requests.
   void ThrottleRequestsForTest(bool throttle);
 
+  // Trims an entry (all if |empty| is true) from the list of deleted
+  // entries. This method should be called directly on the cache thread.
+  void TrimForTest(bool empty);
+
+  // Trims an entry (all if |empty| is true) from the list of deleted
+  // entries. This method should be called directly on the cache thread.
+  void TrimDeletedListForTest(bool empty);
+
   // Peforms a simple self-check, and returns the number of dirty items
   // or an error code (negative value).
   int SelfCheck();
 
   // Backend interface.
   virtual int32 GetEntryCount() const;
   virtual int OpenEntry(const std::string& key, Entry** entry,
                         CompletionCallback* callback);
   virtual int CreateEntry(const std::string& key, Entry** entry,
                           CompletionCallback* callback);
@@ skipping 20 matching lines @@
   // Deletes the cache and starts again.
   void RestartCache(bool failure);
   void PrepareForRestart();
 
   // Creates a new entry object and checks to see if it is dirty. Returns zero
   // on success, or a disk_cache error on failure.
   int NewEntry(Addr address, EntryImpl** entry, bool* dirty);
 
   // Returns a given entry from the cache. The entry to match is determined by
   // key and hash, and the returned entry may be the matched one or it's parent
-  // on the list of entries with the same hash (or bucket).
-  EntryImpl* MatchEntry(const std::string& key, uint32 hash, bool find_parent);
+  // on the list of entries with the same hash (or bucket). To look for a parent
+  // of a given entry, |entry_addr| should be grabbed from that entry, so that
+  // if it doesn't match the entry on the index, we know that it was replaced
+  // with a new entry; in this case |*match_error| will be set to true and the
+  // return value will be NULL.
+  EntryImpl* MatchEntry(const std::string& key, uint32 hash, bool find_parent,
+                        Addr entry_addr, bool* match_error);
 
   // Opens the next or previous entry on a cache iteration.
   EntryImpl* OpenFollowingEntry(bool forward, void** iter);
 
   // Opens the next or previous entry on a single list. If successfull,
   // |from_entry| will be updated to point to the new entry, otherwise it will
   // be set to NULL; in other words, it is used as an explicit iterator.
   bool OpenFollowingEntryFromList(bool forward, Rankings::List list,
                                   CacheRankingsBlock** from_entry,
                                   EntryImpl** next_entry);
 
-  // Returns the entry that is pointed by |next|. If we are trimming the cache,
-  // |to_evict| should be true so that we don't perform extra disk writes.
-  EntryImpl* GetEnumeratedEntry(CacheRankingsBlock* next, bool to_evict);
+  // Returns the entry that is pointed by |next|.
+  EntryImpl* GetEnumeratedEntry(CacheRankingsBlock* next);
 
   // Re-opens an entry that was previously deleted.
   EntryImpl* ResurrectEntry(EntryImpl* deleted_entry);
 
   void DestroyInvalidEntry(EntryImpl* entry);
   void DestroyInvalidEntryFromEnumeration(EntryImpl* entry);
 
   // Handles the used storage count.
   void AddStorageSize(int32 bytes);
   void SubstractStorageSize(int32 bytes);
@@ skipping 65 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(BackendImpl);
 };
 
 // Returns the prefered max cache size given the available disk space.
 int PreferedCacheSize(int64 available);
 
 }  // namespace disk_cache
 
 #endif  // NET_DISK_CACHE_BACKEND_IMPL_H_