Disk cache v3 ref2

net/disk_cache/v3/backend_impl_v3.h

 // Copyright (c) 2012 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_
+#ifndef NET_DISK_CACHE_V3_BACKEND_IMPL_V3_H_
+#define NET_DISK_CACHE_V3_BACKEND_IMPL_V3_H_
 
 #include "base/containers/hash_tables.h"
 #include "base/files/file_path.h"
+#include "base/synchronization/waitable_event.h"
 #include "base/timer/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/stress_support.h"
 #include "net/disk_cache/trace.h"
+#include "net/disk_cache/v3/block_bitmaps.h"
+#include "net/disk_cache/v3/eviction_v3.h"
+#include "net/disk_cache/v3/index_table.h"
 
 namespace net {
 class NetLog;
 }  // namespace net
 
 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.
-  kNoBuffering = 1 << 7         // Disable extended IO buffering.
-};
+class EntryImplV3;
 
 // This class implements the Backend interface. An object of this
 // class handles the operations of the cache for a particular profile.
-class NET_EXPORT_PRIVATE BackendImpl : public Backend {
-  friend class Eviction;
+class NET_EXPORT_PRIVATE BackendImplV3
+    : public Backend,
+      public IndexTableBackend {
+  friend class EvictionV3;
  public:
-  BackendImpl(const base::FilePath& path, base::MessageLoopProxy* cache_thread,
+  enum BackendFlags {
+    MAX_SIZE = 1 << 1,            // A maximum size was provided.
+    UNIT_TEST_MODE = 1 << 2,      // We are modifying the behavior for testing.
+    UPGRADE_MODE = 1 << 3,        // This is the upgrade tool (dump).
+    EVICTION_V2 = 1 << 4,         // Use of new eviction was specified.
+    BASIC_UNIT_TEST = 1 << 5,     // Identifies almost all unit tests.
+    NO_LOAD_PROTECTION = 1 << 6,  // Don't act conservatively under load.
+    NO_BUFFERING = 1 << 7,        // Disable extended IO buffering.
+    NO_CLEAN_ON_EXIT              // Avoid saving data at exit time.
+  };
+
+  BackendImplV3(const base::FilePath& path, base::MessageLoopProxy* cache_thread,
               net::NetLog* net_log);
-  // mask can be used to limit the usable size of the hash table, for testing.
-  BackendImpl(const base::FilePath& path, uint32 mask,
-              base::MessageLoopProxy* cache_thread, net::NetLog* net_log);
-  virtual ~BackendImpl();
+  virtual ~BackendImplV3();
 
   // Performs general initialization for this current instance of the cache.
   int Init(const CompletionCallback& callback);
 
   // Same behavior as OpenNextEntry but walks the list from back to front.
   int OpenPrevEntry(void** iter, Entry** prev_entry,
                     const CompletionCallback& callback);
 
   // 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);
 
   // Creates a new storage block of size block_count.
   bool CreateBlock(FileType block_type, int block_count,
                    Addr* block_address);
 
   // Updates the ranking information for an entry.
-  void UpdateRank(EntryImpl* entry, bool modified);
+  void UpdateRank(EntryImplV3* entry, bool modified);
 
   // Permanently deletes an entry, but still keeps track of it.
-  void InternalDoomEntry(EntryImpl* entry);
+  void InternalDoomEntry(EntryImplV3* entry);
+
+  // Returns true is te entry should be deleted at this time. Otherwise, the
+  // entry will receive another Close() in later on.
+  bool ShouldDeleteNow(EntryImplV3* entry);
+
+  // Called when an entry is about to destroyed, after the data has been saved.
+  // The backend may extend the lifetime of the entry waiting for a call to
+  // OpenEntry().
+  void OnEntryCleanup(EntryImplV3* 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.
   void OnEntryDestroyBegin(Addr address);
 
   // This method must be called after all resources for an entry have been
   // released.
   void OnEntryDestroyEnd();
 
-  // If the data stored by the provided |rankings| points to an open entry,
-  // returns a pointer to that entry, otherwise returns NULL. Note that this
-  // method does NOT increase the ref counter for the entry.
-  EntryImpl* GetOpenEntry(CacheRankingsBlock* rankings) const;
+  // Callen when an entry is modified for the first time.
+  void OnEntryModified(EntryImplV3* entry);
 
-  // Returns the id being used on this run of the cache.
-  int32 GetCurrentEntryId() const;
+  // Methods that perform file IO. Each method result in a task posted to the
+  // cache thread, with the |callback| invoked when the operation completes.
+  // Any error would result in the |entry| being automatically deleted. Note
+  // that these methods do not operate directly on entries, but rather on the
+  // |address| provided. For example, Delete() deletes the data pointed by
+  // |address|, it doesn't delete |entry|.
+  void ReadData(EntryImplV3* entry, Addr address, int offset,
+                net::IOBuffer* buffer, int buffer_len,
+                const CompletionCallback& callback);
+  void WriteData(EntryImplV3* entry, Addr address, int offset,
+                 net::IOBuffer* buffer, int buffer_len,
+                 const CompletionCallback& callback);
+  void MoveData(EntryImplV3* entry, Addr source, Addr destination, int len,
+                const CompletionCallback& callback);
+  void Truncate(EntryImplV3* entry, Addr address, int offset);
+  void Delete(EntryImplV3* entry, Addr address);
+  void Close(EntryImplV3* entry, Addr address);
+
+  // Evicts the entry located at |address|, with the given |hash|. Returns true
+  // if the entry can be evicted and the caller should expect a completion
+  // notification, false otherwise.
+  // This method is used by the eviction module, and OnEvictEntryComplete() will
+  // be called to notify the end of the operation.
+  bool EvictEntry(uint32 hash, Addr address);
+
+  // If the |address| corresponds to an open entry, returns a pointer to that
+  // entry, otherwise returns NULL. Note that this method increases the ref
+  // counter for the entry.
+  EntryImplV3* GetOpenEntry(Addr address) const;
 
   // Returns the maximum size for a file to reside on the cache.
   int MaxFileSize() const;
 
   // A user data block is being created, extended or truncated.
   void ModifyStorageSize(int32 old_size, int32 new_size);
 
   // Logs requests that are denied due to being too big.
   void TooMuchStorageRequested(int32 size);
 
   // Returns true if a temporary buffer is allowed to be extended.
-  bool IsAllocAllowed(int current_size, int new_size);
+  bool IsAllocAllowed(int current_size, int new_size, bool force);
 
   // Tracks the release of |size| bytes by an entry buffer.
   void BufferDeleted(int size);
 
   // Only intended for testing the two previous methods.
   int GetTotalBuffersSize() const {
     return buffer_bytes_;
   }
 
   // Returns true if this instance seems to be under heavy load.
   bool IsLoaded() const;
 
+  // Returns the current time. For tests to run properly, use this method
+  // instead of calling base::Time::Now() directly.
+  base::Time GetCurrentTime() const;
+
   // Returns the full histogram name, for the given base |name| and experiment,
   // and the current cache type. The name will be "DiskCache.t.name_e" where n
   // is the cache type and e the provided |experiment|.
   std::string HistogramName(const char* name, int experiment) const;
 
   net::CacheType cache_type() const {
     return cache_type_;
   }
 
   bool read_only() const {
     return read_only_;
   }
 
   // Returns a weak pointer to this object.
-  base::WeakPtr<BackendImpl> GetWeakPtr();
+  base::WeakPtr<BackendImplV3> GetWeakPtr();
 
   // Returns true if we should send histograms for this user again. The caller
   // must call this function only once per run (because it returns always the
   // same thing on a given run).
   bool ShouldReportAgain();
 
   // Reports some data when we filled up the cache.
   void FirstEviction();
 
   // Called when an interesting event should be logged (counted).
   void OnEvent(Stats::Counters an_event);
 
   // Keeps track of payload access (doesn't include metadata).
   void OnRead(int bytes);
   void OnWrite(int bytes);
 
-  // Timer callback to calculate usage statistics.
-  void OnStatsTimer();
+  // Increases the size of the block files.
+  void GrowBlockFiles();
+
+  // Timer callback to calculate usage statistics and perform backups.
+  void OnTimerTick();
 
   // Sets internal parameters to enable unit testing mode.
   void SetUnitTestMode();
 
   // Sets internal parameters to enable upgrade mode (for internal tools).
   void SetUpgradeMode();
 
   // Sets the eviction algorithm to version 2.
   void SetNewEviction();
 
   // Sets an explicit set of BackendFlags.
   void SetFlags(uint32 flags);
 
   // Sends a dummy operation through the operation queue, for unit tests.
   int FlushQueueForTest(const CompletionCallback& callback);
 
+  // Performs final cleanup, for unit tests.
+  int CleanupForTest(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);
 
   // 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);
 
+  // Simulates that aditional |seconds| have elapsed, for testing purposes.
+  void AddDelayForTest(int seconds);
+
+  // Returns a net error code to inform the caller when the entry with the
+  // desired |key| is completely closed.
+  int WaitForEntryToCloseForTest(const std::string& key,
+                                 const CompletionCallback& callback);
+
   // Performs a simple self-check, and returns the number of dirty items
   // or an error code (negative value).
   int SelfCheck();
 
+  // IndexTableBackend implementation.
+  virtual void GrowIndex() OVERRIDE;
+  virtual void SaveIndex(net::IOBuffer* buffer, int buffer_len) OVERRIDE;
+  virtual void DeleteCell(EntryCell cell) OVERRIDE;
+  virtual void FixCell(EntryCell cell) OVERRIDE;
+
   // Backend implementation.
   virtual net::CacheType GetCacheType() const OVERRIDE;
   virtual int32 GetEntryCount() const OVERRIDE;
   virtual int OpenEntry(const std::string& key, Entry** entry,
                         const CompletionCallback& callback) OVERRIDE;
   virtual int CreateEntry(const std::string& key, Entry** entry,
                           const CompletionCallback& callback) OVERRIDE;
   virtual int DoomEntry(const std::string& key,
                         const CompletionCallback& callback) OVERRIDE;
   virtual int DoomAllEntries(const CompletionCallback& callback) OVERRIDE;
   virtual int DoomEntriesBetween(base::Time initial_time,
                                  base::Time end_time,
                                  const CompletionCallback& callback) OVERRIDE;
   virtual int DoomEntriesSince(base::Time initial_time,
                                const CompletionCallback& callback) OVERRIDE;
   virtual int OpenNextEntry(void** iter, Entry** next_entry,
                             const CompletionCallback& callback) OVERRIDE;
   virtual void EndEnumeration(void** iter) OVERRIDE;
   virtual void GetStats(StatsItems* stats) OVERRIDE;
   virtual void OnExternalCacheHit(const std::string& key) OVERRIDE;
 
  private:
-  typedef base::hash_map<CacheAddr, EntryImpl*> EntriesMap;
+  typedef base::hash_map<CacheAddr, EntryImplV3*> EntriesMap;
+  typedef base::hash_set<EntryImplV3*> EntriesSet;
+  class IOCallback;
+  class Worker;
+  class WorkItem;
 
-  void AdjustMaxCacheSize(int table_len);
-
-  bool InitStats();
+  void AdjustMaxCacheSize();
+  bool InitStats(void* stats_data);
   void StoreStats();
 
   // Deletes the cache and starts again.
-  void RestartCache(bool failure);
+  void RestartCache(const CompletionCallback& callback);
   void PrepareForRestart();
 
+  // Performs final cleanup.
   void CleanupCache();
 
   // Creates a new entry object. Returns zero on success, or a disk_cache error
   // on failure.
-  int NewEntry(Addr address, EntryImpl** entry);
+  int NewEntry(WorkItem* work_item, EntryImplV3** entry);
+
+  // Scans |entries| and the list of open entries looking for a match. Returns
+  // NULL if no match is fouond.
+  EntryImplV3* LookupOpenEntry(const EntrySet& entries, const std::string key);
 
   // Opens the next or previous entry on a cache iteration.
-  EntryImpl* OpenFollowingEntry(bool forward, void** iter);
+  int OpenFollowingEntry(bool forward, void** iter, Entry** next_entry,
+                         const CompletionCallback& callback);
+
+  // Continue an enumeration by getting more cells or the next entry to open.
+  bool GetMoreCells(WorkItem* work_item);
+  int OpenNext(WorkItem* work_item);
+
+  // Doom |entry| if directed by the work_item.
+  void Doom(EntryImplV3* entry, WorkItem* work_item);
+
+  // Updates the user visible iterator an tell the user about it.
+  void UpdateIterator(EntryImplV3* entry, WorkItem* work_item);
+
+  // Deletes entries that are waiting for deletion.
+  void CloseDoomedEntries();
+
+  // Releases recent_entries_. 
+  void ReleaseRecentEntries();
+
+  // Updates the cells for entries already gone.
+  void UpdateDeletedEntries();
 
   // Handles the used storage count.
   void AddStorageSize(int32 bytes);
   void SubstractStorageSize(int32 bytes);
 
   // Update the number of referenced cache entries.
   void IncreaseNumRefs();
   void DecreaseNumRefs();
   void IncreaseNumEntries();
   void DecreaseNumEntries();
 
+  // Methods to post and receive notifications about tasks executed on the
+  // cache thread.
+  void PostWorkItem(WorkItem* work_item);
+  void OnWorkDone(WorkItem* work_item);
+  void OnInitComplete(WorkItem* work_item);
+  void OnGrowIndexComplete(WorkItem* work_item);
+  void OnGrowFilesComplete(WorkItem* work_item);
+  void OnOperationComplete(WorkItem* work_item);
+  void OnOpenEntryComplete(WorkItem* work_item);
+  void OnOpenForResurrectComplete(WorkItem* work_item);
+  void OnEvictEntryComplete(WorkItem* work_item);
+  void OnOpenNextComplete(WorkItem* work_item);
+
+  // Last part of CreateEntry(). |short_record| may point to stored data about
+  // a previously evicted entry matching this |key|.
+  int OnCreateEntryComplete(const std::string& key, uint32 hash, 
+                            ShortEntryRecord* short_record, Entry** entry,
+                            const CompletionCallback& callback);
+
   // Dumps current cache statistics to the log.
   void LogStats();
 
   // Send UMA stats.
   void ReportStats();
 
   // Reports an uncommon, recoverable error.
   void ReportError(int error);
 
   // Performs basic checks on the index file. Returns false on failure.
   bool CheckIndex();
 
   // Part of the self 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);
+  bool CheckEntry(EntryImplV3* cache_entry);
 
   // Returns the maximum total memory for the memory buffers.
   int MaxBuffersSize();
 
-  scoped_refptr<MappedFile> index_;  // The main cache index.
+  IndexTable index_;
   base::FilePath path_;  // Path to the folder used as backing storage.
-  BlockFiles block_files_;  // Set of files used to store all data.
+  BlockBitmaps block_files_;
   int32 max_size_;  // Maximum data size for this instance.
-  Eviction eviction_;  // Handler of the eviction algorithm.
-  EntriesMap open_entries_;  // Map of open entries.
+  EvictionV3 eviction_;  // Handler of the eviction algorithm.
+  EntriesMap open_entries_;
+  EntriesMap doomed_entries_;
+  EntriesMap entries_to_delete_;
+  EntriesSet recent_entries_;  // May still be open, or recently closed.
+  CellList deleted_entries_;
   int num_refs_;  // Number of referenced cache entries.
   int max_refs_;  // Max number of referenced cache entries.
   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.
-  int up_ticks_;  // The number of timer ticks received (OnStatsTimer).
+  int up_ticks_;  // The number of timer ticks received (OnTimerTick).
+  int test_seconds_;  // The "current time" for tests.
   net::CacheType cache_type_;
   int uma_report_;  // Controls transmission 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 lru_eviction_;  // What eviction algorithm should be used.
   bool first_timer_;  // True if the timer has not been called.
   bool user_load_;  // True if we see a high load coming from the caller.
+  bool growing_index_;
+  bool growing_files_;
 
   net::NetLog* net_log_;
 
   Stats stats_;  // Usage statistics.
-  scoped_ptr<base::RepeatingTimer<BackendImpl> > timer_;  // Usage timer.
+  scoped_ptr<base::RepeatingTimer<BackendImplV3> > timer_;  // Usage timer.
   scoped_refptr<TraceObject> trace_object_;  // Initializes internal tracing.
-  base::WeakPtrFactory<BackendImpl> ptr_factory_;
+  scoped_refptr<base::MessageLoopProxy> cache_thread_;
+  scoped_refptr<Worker> worker_;
+  base::WeakPtrFactory<BackendImplV3> ptr_factory_;
 
-  DISALLOW_COPY_AND_ASSIGN(BackendImpl);
+  DISALLOW_COPY_AND_ASSIGN(BackendImplV3);
 };
 
-// Returns the preferred max cache size given the available disk space.
-NET_EXPORT_PRIVATE int PreferedCacheSize(int64 available);
-
 }  // namespace disk_cache
 
-#endif  // NET_DISK_CACHE_BACKEND_IMPL_H_
+#endif  // NET_DISK_CACHE_V3_BACKEND_IMPL_V3_H_