Disk cache: Switch the disk cache to use the cache_thread....

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_
 
 #include "base/file_path.h"
 #include "base/hash_tables.h"
 #include "base/timer.h"
 #include "net/disk_cache/block_files.h"
 #include "net/disk_cache/disk_cache.h"
 #include "net/disk_cache/eviction.h"
+#include "net/disk_cache/in_flight_backend_io.h"
 #include "net/disk_cache/rankings.h"
 #include "net/disk_cache/stats.h"
 #include "net/disk_cache/trace.h"
 
 namespace disk_cache {
 
 enum BackendFlags {
   kNone = 0,
   kMask = 1,                    // A mask (for the index table) was specified.
   kMaxSize = 1 << 1,            // A maximum size was provided.
   kUnitTestMode = 1 << 2,       // We are modifying the behavior for testing.
   kUpgradeMode = 1 << 3,        // This is the upgrade tool (dump).
   kNewEviction = 1 << 4,        // Use of new eviction was specified.
   kNoRandom = 1 << 5,           // Don't add randomness to the behavior.
   kNoLoadProtection = 1 << 6    // Don't act conservatively under load.
 };
 
 // This class implements the Backend interface. An object of this
 // class handles the operations of the cache for a particular profile.
 class BackendImpl : public Backend {
   friend class Eviction;
  public:
   BackendImpl(const FilePath& path, base::MessageLoopProxy* cache_thread)
-      : path_(path), block_files_(path), mask_(0), max_size_(0),
+      : ALLOW_THIS_IN_INITIALIZER_LIST(background_queue_(this, cache_thread)),
+        path_(path), block_files_(path), mask_(0), max_size_(0),
         cache_type_(net::DISK_CACHE), uma_report_(0), user_flags_(0),
         init_(false), restarted_(false), unit_test_(false), read_only_(false),
-        new_eviction_(false), first_timer_(true),
+        new_eviction_(false), first_timer_(true), done_(true, false),
         ALLOW_THIS_IN_INITIALIZER_LIST(factory_(this)) {}
   // mask can be used to limit the usable size of the hash table, for testing.
   BackendImpl(const FilePath& path, uint32 mask,
               base::MessageLoopProxy* cache_thread)
-      : path_(path), block_files_(path), mask_(mask), max_size_(0),
+      : ALLOW_THIS_IN_INITIALIZER_LIST(background_queue_(this, cache_thread)),
+        path_(path), block_files_(path), mask_(mask), max_size_(0),
         cache_type_(net::DISK_CACHE), uma_report_(0), user_flags_(kMask),
         init_(false), restarted_(false), unit_test_(false), read_only_(false),
-        new_eviction_(false), first_timer_(true),
+        new_eviction_(false), first_timer_(true), done_(true, false),
         ALLOW_THIS_IN_INITIALIZER_LIST(factory_(this)) {}
   ~BackendImpl();
 
   // Returns a new backend with the desired flags. See the declaration of
   // CreateCacheBackend().
   static int CreateBackend(const FilePath& full_path, bool force,
                            int max_bytes, net::CacheType type,
                            uint32 flags, base::MessageLoopProxy* thread,
                            Backend** backend, CompletionCallback* callback);
 
   // Performs general initialization for this current instance of the cache.
-  bool Init();
+  bool Init();  // Deprecated.
+  int Init(CompletionCallback* callback);
+  int SyncInit();
+
+  // Performs final cleanup on destruction.
+  void CleanupCache();
 
   // 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);
   virtual int DoomEntry(const std::string& key, CompletionCallback* callback);
   virtual int DoomAllEntries(CompletionCallback* callback);
   virtual int DoomEntriesBetween(const base::Time initial_time,
                                  const base::Time end_time,
                                  CompletionCallback* callback);
   virtual int DoomEntriesSince(const base::Time initial_time,
                                CompletionCallback* callback);
   virtual int OpenNextEntry(void** iter, Entry** next_entry,
                             CompletionCallback* callback);
   virtual void EndEnumeration(void** iter);
   virtual void GetStats(StatsItems* stats);
 
+  // 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(const base::Time initial_time,
+                             const base::Time end_time);
+  int SyncDoomEntriesSince(const base::Time initial_time);
+  int SyncOpenNextEntry(void** iter, Entry** next_entry);
+  void SyncEndEnumeration(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.
   FilePath GetFileName(Addr address) const;
 
   // Returns the actual file used to store a given (non-external) address.
   MappedFile* File(Addr address);
 
+  InFlightBackendIO* background_queue() {
+    return &background_queue_;
+  }
+
   // 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);
@@ skipping 82 matching lines @@
 
   // Sets the eviction algorithm to version 2.
   void SetNewEviction();
 
   // 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(CompletionCallback* callback);
+
   // Peforms a simple self-check, and returns the number of dirty items
   // or an error code (negative value).
   int SelfCheck();
 
   // Same bahavior as OpenNextEntry but walks the list from back to front.
-  bool OpenPrevEntry(void** iter, Entry** prev_entry);
+  int OpenPrevEntry(void** iter, Entry** prev_entry,
+                    CompletionCallback* callback);
+  int SyncOpenPrevEntry(void** iter, Entry** prev_entry);
 
   // Old Backend interface.
   bool OpenEntry(const std::string& key, Entry** entry);
   bool CreateEntry(const std::string& key, Entry** entry);
   bool DoomEntry(const std::string& key);
   bool DoomAllEntries();
   bool DoomEntriesBetween(const base::Time initial_time,
                           const base::Time end_time);
   bool DoomEntriesSince(const base::Time initial_time);
-  bool OpenNextEntry(void** iter, Entry** next_entry);
 
-  // Open or create an entry for the given |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);
 
  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);
 
   // Deletes the cache and starts again.
   void RestartCache();
   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);
 
   // Opens the next or previous entry on a cache iteration.
-  bool OpenFollowingEntry(bool forward, void** iter, Entry** next_entry);
+  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.
@@ skipping 26 matching lines @@
 
   // Performs basic checks on the index file. Returns false on failure.
   bool CheckIndex();
 
   // Part of the selt test. Returns the number or dirty entries, or an error.
   int CheckAllEntries();
 
   // Part of the self test. Returns false if the entry is corrupt.
   bool CheckEntry(EntryImpl* cache_entry);
 
+  InFlightBackendIO background_queue_;  // The controller of pending operations.
   scoped_refptr<MappedFile> index_;  // The main cache index.
   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.
   net::CacheType cache_type_;
   int uma_report_;  // Controls transmision of UMA data.
   uint32 user_flags_;  // Flags set by the user.
   bool init_;  // controls the initialization of the system.
   bool restarted_;
   bool unit_test_;
   bool read_only_;  // Prevents updates of the rankings data (used by tools).
   bool disabled_;
   bool new_eviction_;  // What eviction algorithm should be used.
   bool first_timer_;  // True if the timer has not been called.
 
   Stats stats_;  // Usage statistcs.
   base::RepeatingTimer<BackendImpl> timer_;  // Usage timer.
+  base::WaitableEvent done_;  // Signals the end of background work.
   scoped_refptr<TraceObject> trace_object_;  // Inits internal tracing.
   ScopedRunnableMethodFactory<BackendImpl> factory_;
 
   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_