Disk cache: Add base files for implementation of file format version 3.

net/disk_cache/v3/backend_impl_v3.h

Index: net/disk_cache/v3/backend_impl_v3.h
===================================================================
--- net/disk_cache/v3/backend_impl_v3.h	(revision 0)
+++ net/disk_cache/v3/backend_impl_v3.h	(working copy)
@@ -52,83 +52,26 @@
   // Performs general initialization for this current instance of the cache.
   int Init(const CompletionCallback& callback);
 
-  // Performs the actual initialization and final cleanup on destruction.
-  int SyncInit();
-  void CleanupCache();
-
   // Same behavior as OpenNextEntry but walks the list from back to front.
   int OpenPrevEntry(void** iter, Entry** prev_entry,
                     const CompletionCallback& callback);
 
-  // Synchronous implementation of the asynchronous interface.
-  int SyncOpenEntry(const std::string& key, Entry** entry);
-  int SyncCreateEntry(const std::string& key, Entry** entry);
-  int SyncDoomEntry(const std::string& key);
-  int SyncDoomAllEntries();
-  int SyncDoomEntriesBetween(base::Time initial_time,
-                             base::Time end_time);
-  int SyncDoomEntriesSince(base::Time initial_time);
-  int SyncOpenNextEntry(void** iter, Entry** next_entry);
-  int SyncOpenPrevEntry(void** iter, Entry** prev_entry);
-  void SyncEndEnumeration(void* iter);
-  void SyncOnExternalCacheHit(const std::string& key);
-
-  // Open or create an entry for the given |key| or |iter|.
-  EntryImpl* OpenEntryImpl(const std::string& key);
-  EntryImpl* CreateEntryImpl(const std::string& key);
-  EntryImpl* OpenNextEntryImpl(void** iter);
-  EntryImpl* OpenPrevEntryImpl(void** iter);
-
   // Sets the maximum size for the total amount of data stored by this instance.
   bool SetMaxSize(int max_bytes);
 
   // Sets the cache type for this backend.
   void SetType(net::CacheType type);
 
-  // Returns the full name for an external storage file.
-  base::FilePath GetFileName(Addr address) const;
-
-  // Returns the actual file used to store a given (non-external) address.
-  MappedFile* File(Addr address);
-
-  // Returns a weak pointer to the background queue.
-  base::WeakPtr<InFlightBackendIO> GetBackgroundQueue();
-
-  // Creates an external storage file.
-  bool CreateExternalFile(Addr* address);
-
   // Creates a new storage block of size block_count.
   bool CreateBlock(FileType block_type, int block_count,
                    Addr* block_address);
 
-  // Deletes a given storage block. deep set to true can be used to zero-fill
-  // the related storage in addition of releasing the related block.
-  void DeleteBlock(Addr block_address, bool deep);
-
-  // Retrieves a pointer to the LRU-related data.
-  LruData* GetLruData();
-
   // Updates the ranking information for an entry.
   void UpdateRank(EntryImpl* entry, bool modified);
 
-  // A node was recovered from a crash, it may not be on the index, so this
-  // method checks it and takes the appropriate action.
-  void RecoveredEntry(CacheRankingsBlock* rankings);
-
   // Permanently deletes an entry, but still keeps track of it.
   void InternalDoomEntry(EntryImpl* entry);
 
-#if defined(NET_BUILD_STRESS_CACHE)
-  // Returns the address of the entry linked to the entry at a given |address|.
-  CacheAddr GetNextAddr(Addr address);
-
-  // Verifies that |entry| is not currently reachable through the index.
-  void NotLinked(EntryImpl* entry);
-#endif
-
-  // Removes all references to this entry.
-  void RemoveEntry(EntryImpl* entry);
-
   // This method must be called when an entry is released for the last time, so
   // the entry should not be used anymore. |address| is the cache address of the
   // entry.
@@ -193,12 +136,6 @@
   // Reports some data when we filled up the cache.
   void FirstEviction();
 
-  // Reports a critical error (and disables the cache).
-  void CriticalError(int error);
-
-  // Reports an uncommon, recoverable error.
-  void ReportError(int error);
-
   // Called when an interesting event should be logged (counted).
   void OnEvent(Stats::Counters an_event);
 
@@ -209,10 +146,6 @@
   // Timer callback to calculate usage statistics.
   void OnStatsTimer();
 
-  // Handles the pending asynchronous IO count.
-  void IncrementIoCount();
-  void DecrementIoCount();
-
   // Sets internal parameters to enable unit testing mode.
   void SetUnitTestMode();
 
@@ -225,17 +158,9 @@
   // Sets an explicit set of BackendFlags.
   void SetFlags(uint32 flags);
 
-  // Clears the counter of references to test handling of corruptions.
-  void ClearRefCountForTest();
-
   // Sends a dummy operation through the operation queue, for unit tests.
   int FlushQueueForTest(const CompletionCallback& callback);
 
-  // Runs the provided task on the cache thread. The task will be automatically
-  // deleted after it runs.
-  int RunTaskForTest(const base::Closure& task,
-                     const CompletionCallback& callback);
-
   // 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);
@@ -248,9 +173,6 @@
   // or an error code (negative value).
   int SelfCheck();
 
-  // Ensures the index is flushed to disk (a no-op on platforms with mmap).
-  void FlushIndex();
-
   // Backend implementation.
   virtual net::CacheType GetCacheType() const OVERRIDE;
   virtual int32 GetEntryCount() const OVERRIDE;
@@ -275,9 +197,6 @@
  private:
   typedef base::hash_map<CacheAddr, EntryImpl*> EntriesMap;
 
-  // Creates a new backing file for the cache index.
-  bool CreateBackingStore(disk_cache::File* file);
-  bool InitBackingStore(bool* file_created);
   void AdjustMaxCacheSize(int table_len);
 
   bool InitStats();
@@ -287,38 +206,15 @@
   void RestartCache(bool failure);
   void PrepareForRestart();
 
+  void CleanupCache();
+
   // Creates a new entry object. Returns zero on success, or a disk_cache error
   // on failure.
   int NewEntry(Addr address, EntryImpl** entry);
 
-  // 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). 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 successful,
-  // |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|, from the given |list|.
-  EntryImpl* GetEnumeratedEntry(CacheRankingsBlock* next, Rankings::List list);
-
-  // Re-opens an entry that was previously deleted.
-  EntryImpl* ResurrectEntry(EntryImpl* deleted_entry);
-
-  void DestroyInvalidEntry(EntryImpl* entry);
-
   // Handles the used storage count.
   void AddStorageSize(int32 bytes);
   void SubstractStorageSize(int32 bytes);
@@ -335,8 +231,8 @@
   // Send UMA stats.
   void ReportStats();
 
-  // Upgrades the index file to version 2.1.
-  void UpgradeTo2_1();
+  // Reports an uncommon, recoverable error.
+  void ReportError(int error);
 
   // Performs basic checks on the index file. Returns false on failure.
   bool CheckIndex();
@@ -350,19 +246,14 @@
   // Returns the maximum total memory for the memory buffers.
   int MaxBuffersSize();
 
-  InFlightBackendIO background_queue_;  // The controller of pending operations.
   scoped_refptr<MappedFile> index_;  // The main cache index.
   base::FilePath path_;  // Path to the folder used as backing storage.
-  Index* data_;  // Pointer to the index data.
   BlockFiles block_files_;  // Set of files used to store all data.
-  Rankings rankings_;  // Rankings to be able to trim the cache.
-  uint32 mask_;  // Binary mask to map a hash to the hash table.
   int32 max_size_;  // Maximum data size for this instance.
   Eviction eviction_;  // Handler of the eviction algorithm.
   EntriesMap open_entries_;  // Map of open entries.
   int num_refs_;  // Number of referenced cache entries.
   int max_refs_;  // Max number of referenced cache entries.
-  int num_pending_io_;  // Number of pending IO operations.
   int entry_count_;  // Number of entries accessed lately.
   int byte_count_;  // Number of bytes read/written lately.
   int buffer_bytes_;  // Total size of the temporary entries' buffers.
@@ -383,7 +274,6 @@
 
   Stats stats_;  // Usage statistics.
   scoped_ptr<base::RepeatingTimer<BackendImpl> > timer_;  // Usage timer.
-  base::WaitableEvent done_;  // Signals the end of background work.
   scoped_refptr<TraceObject> trace_object_;  // Initializes internal tracing.
   base::WeakPtrFactory<BackendImpl> ptr_factory_;