net/disk_cache/blockfile/backend_impl_v3.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // See net/disk_cache/disk_cache.h for the public interface of the cache.
   6
   7 #ifndef NET_DISK_CACHE_BLOCKFILE_BACKEND_IMPL_V3_H_
   8 #define NET_DISK_CACHE_BLOCKFILE_BACKEND_IMPL_V3_H_
   9
  10 #include "base/containers/hash_tables.h"
  11 #include "base/files/file_path.h"
  12 #include "base/memory/ref_counted.h"
  13 #include "base/timer/timer.h"
  14 #include "net/disk_cache/blockfile/block_bitmaps_v3.h"
  15 #include "net/disk_cache/blockfile/block_files.h"
  16 #include "net/disk_cache/blockfile/eviction_v3.h"
  17 #include "net/disk_cache/blockfile/index_table_v3.h"
  18 #include "net/disk_cache/blockfile/stats.h"
  19 #include "net/disk_cache/blockfile/stress_support.h"
  20 #include "net/disk_cache/blockfile/trace.h"
  21 #include "net/disk_cache/disk_cache.h"
  22
  23 namespace base {
  24 class SingleThreadTaskRunner;
  25 }  // namespace base
  26
  27 namespace net {
  28 class NetLog;
  29 }  // namespace net
  30
  31 namespace disk_cache {
  32
  33 class EntryImplV3;
  34
  35 // This class implements the Backend interface. An object of this
  36 // class handles the operations of the cache for a particular profile.
  37 class NET_EXPORT_PRIVATE BackendImplV3 : public Backend {
  38  public:
  39   enum BackendFlags {
  40     MAX_SIZE = 1 << 1,            // A maximum size was provided.
  41     UNIT_TEST_MODE = 1 << 2,      // We are modifying the behavior for testing.
  42     UPGRADE_MODE = 1 << 3,        // This is the upgrade tool (dump).
  43     EVICTION_V2 = 1 << 4,         // Use of new eviction was specified.
  44     BASIC_UNIT_TEST = 1 << 5,     // Identifies almost all unit tests.
  45     NO_LOAD_PROTECTION = 1 << 6,  // Don't act conservatively under load.
  46     NO_BUFFERING = 1 << 7,        // Disable extended IO buffering.
  47     NO_CLEAN_ON_EXIT = 1 << 8     // Avoid saving data at exit time.
  48   };
  49
  50   BackendImplV3(const base::FilePath& path,
  51                 const scoped_refptr<base::SingleThreadTaskRunner>& cache_thread,
  52                 net::NetLog* net_log);
  53   ~BackendImplV3() override;
  54
  55   // Performs general initialization for this current instance of the cache.
  56   int Init(const CompletionCallback& callback);
  57
  58   // Sets the maximum size for the total amount of data stored by this instance.
  59   bool SetMaxSize(int max_bytes);
  60
  61   // Sets the cache type for this backend.
  62   void SetType(net::CacheType type);
  63
  64   // Creates a new storage block of size block_count.
  65   bool CreateBlock(FileType block_type, int block_count,
  66                    Addr* block_address);
  67
  68   // Updates the ranking information for an entry.
  69   void UpdateRank(EntryImplV3* entry, bool modified);
  70
  71   // Permanently deletes an entry, but still keeps track of it.
  72   void InternalDoomEntry(EntryImplV3* entry);
  73
  74   // This method must be called when an entry is released for the last time, so
  75   // the entry should not be used anymore. |address| is the cache address of the
  76   // entry.
  77   void OnEntryDestroyBegin(Addr address);
  78
  79   // This method must be called after all resources for an entry have been
  80   // released.
  81   void OnEntryDestroyEnd();
  82
  83   // If the |address| corresponds to an open entry, returns a pointer to that
  84   // entry, otherwise returns NULL. Note that this method does not increase the
  85   // ref counter for the entry.
  86   EntryImplV3* GetOpenEntry(Addr address) const;
  87
  88   // Returns the id being used on this run of the cache.
  89   int32 GetCurrentEntryId() const;
  90
  91   // Returns the maximum size for a file to reside on the cache.
  92   int MaxFileSize() const;
  93
  94   // A user data block is being created, extended or truncated.
  95   void ModifyStorageSize(int32 old_size, int32 new_size);
  96
  97   // Logs requests that are denied due to being too big.
  98   void TooMuchStorageRequested(int32 size);
  99
 100   // Returns true if a temporary buffer is allowed to be extended.
 101   bool IsAllocAllowed(int current_size, int new_size);
 102
 103   // Tracks the release of |size| bytes by an entry buffer.
 104   void BufferDeleted(int size);
 105
 106   // Only intended for testing the two previous methods.
 107   int GetTotalBuffersSize() const {
 108     return buffer_bytes_;
 109   }
 110
 111   // Returns true if this instance seems to be under heavy load.
 112   bool IsLoaded() const;
 113
 114   // Returns the full histogram name, for the given base |name| and the current
 115   // cache type. The name will be "DiskCache3.name_type".
 116   std::string HistogramName(const char* name) const;
 117
 118   net::CacheType cache_type() const {
 119     return cache_type_;
 120   }
 121
 122   bool read_only() const {
 123     return read_only_;
 124   }
 125
 126   // Returns a weak pointer to this object.
 127   base::WeakPtr<BackendImplV3> GetWeakPtr();
 128
 129   // Returns true if we should send histograms for this user again. The caller
 130   // must call this function only once per run (because it returns always the
 131   // same thing on a given run).
 132   bool ShouldReportAgain();
 133
 134   // Reports some data when we filled up the cache.
 135   void FirstEviction();
 136
 137   // Called when an interesting event should be logged (counted).
 138   void OnEvent(Stats::Counters an_event);
 139
 140   // Keeps track of payload access (doesn't include metadata).
 141   void OnRead(int bytes);
 142   void OnWrite(int bytes);
 143
 144   // Timer callback to calculate usage statistics and perform backups.
 145   void OnTimerTick();
 146
 147   // Sets internal parameters to enable unit testing mode.
 148   void SetUnitTestMode();
 149
 150   // Sets internal parameters to enable upgrade mode (for internal tools).
 151   void SetUpgradeMode();
 152
 153   // Sets the eviction algorithm to version 2.
 154   void SetNewEviction();
 155
 156   // Sets an explicit set of BackendFlags.
 157   void SetFlags(uint32 flags);
 158
 159   // Sends a dummy operation through the operation queue, for unit tests.
 160   int FlushQueueForTest(const CompletionCallback& callback);
 161
 162   // Trims an entry (all if |empty| is true) from the list of deleted
 163   // entries. This method should be called directly on the cache thread.
 164   void TrimForTest(bool empty);
 165
 166   // Trims an entry (all if |empty| is true) from the list of deleted
 167   // entries. This method should be called directly on the cache thread.
 168   void TrimDeletedListForTest(bool empty);
 169
 170   // Performs a simple self-check, and returns the number of dirty items
 171   // or an error code (negative value).
 172   int SelfCheck();
 173
 174   // Backend implementation.
 175   net::CacheType GetCacheType() const override;
 176   int32 GetEntryCount() const override;
 177   int OpenEntry(const std::string& key,
 178                 Entry** entry,
 179                 const CompletionCallback& callback) override;
 180   int CreateEntry(const std::string& key,
 181                   Entry** entry,
 182                   const CompletionCallback& callback) override;
 183   int DoomEntry(const std::string& key,
 184                 const CompletionCallback& callback) override;
 185   int DoomAllEntries(const CompletionCallback& callback) override;
 186   int DoomEntriesBetween(base::Time initial_time,
 187                          base::Time end_time,
 188                          const CompletionCallback& callback) override;
 189   int DoomEntriesSince(base::Time initial_time,
 190                        const CompletionCallback& callback) override;
 191   scoped_ptr<Iterator> CreateIterator() override;
 192   void GetStats(StatsItems* stats) override;
 193   void OnExternalCacheHit(const std::string& key) override;
 194
 195  private:
 196   friend class EvictionV3;
 197   typedef base::hash_map<CacheAddr, EntryImplV3*> EntriesMap;
 198   class IteratorImpl;
 199   class NotImplementedIterator;
 200   class Worker;
 201
 202   void AdjustMaxCacheSize();
 203   bool InitStats(void* stats_data);
 204   void StoreStats();
 205
 206   // Deletes the cache and starts again.
 207   void RestartCache(bool failure);
 208   void PrepareForRestart();
 209
 210   // Performs final cleanup.
 211   void CleanupCache();
 212
 213   // Creates a new entry object. Returns zero on success, or a disk_cache error
 214   // on failure.
 215   int NewEntry(Addr address, EntryImplV3** entry);
 216
 217   // Handles the used storage count.
 218   void AddStorageSize(int32 bytes);
 219   void SubstractStorageSize(int32 bytes);
 220
 221   // Update the number of referenced cache entries.
 222   void IncreaseNumRefs();
 223   void DecreaseNumRefs();
 224   void IncreaseNumEntries();
 225   void DecreaseNumEntries();
 226
 227   // Dumps current cache statistics to the log.
 228   void LogStats();
 229
 230   // Send UMA stats.
 231   void ReportStats();
 232
 233   // Reports an uncommon, recoverable error.
 234   void ReportError(int error);
 235
 236   // Performs basic checks on the index file. Returns false on failure.
 237   bool CheckIndex();
 238
 239   // Part of the self test. Returns the number or dirty entries, or an error.
 240   int CheckAllEntries();
 241
 242   // Part of the self test. Returns false if the entry is corrupt.
 243   bool CheckEntry(EntryImplV3* cache_entry);
 244
 245   // Returns the maximum total memory for the memory buffers.
 246   int MaxBuffersSize();
 247
 248   IndexTable index_;
 249   base::FilePath path_;  // Path to the folder used as backing storage.
 250   BlockBitmaps block_files_;
 251   int32 max_size_;  // Maximum data size for this instance.
 252   EvictionV3 eviction_;  // Handler of the eviction algorithm.
 253   EntriesMap open_entries_;
 254   int num_refs_;  // Number of referenced cache entries.
 255   int max_refs_;  // Max number of referenced cache entries.
 256   int entry_count_;  // Number of entries accessed lately.
 257   int byte_count_;  // Number of bytes read/written lately.
 258   int buffer_bytes_;  // Total size of the temporary entries' buffers.
 259   int up_ticks_;  // The number of timer ticks received (OnTimerTick).
 260   net::CacheType cache_type_;
 261   int uma_report_;  // Controls transmission of UMA data.
 262   uint32 user_flags_;  // Flags set by the user.
 263   bool init_;  // controls the initialization of the system.
 264   bool restarted_;
 265   bool read_only_;  // Prevents updates of the rankings data (used by tools).
 266   bool disabled_;
 267   bool lru_eviction_;  // What eviction algorithm should be used.
 268   bool first_timer_;  // True if the timer has not been called.
 269   bool user_load_;  // True if we see a high load coming from the caller.
 270
 271   net::NetLog* net_log_;
 272
 273   Stats stats_;  // Usage statistics.
 274   scoped_ptr<base::RepeatingTimer<BackendImplV3> > timer_;  // Usage timer.
 275   scoped_refptr<TraceObject> trace_object_;  // Initializes internal tracing.
 276   base::WeakPtrFactory<BackendImplV3> ptr_factory_;
 277
 278   DISALLOW_COPY_AND_ASSIGN(BackendImplV3);
 279 };
 280
 281 }  // namespace disk_cache
 282
 283 #endif  // NET_DISK_CACHE_BLOCKFILE_BACKEND_IMPL_V3_H_