backend_impl_v3.h revision a1401311d1ab56c4ed0a474bd38c108f75cb0cd9
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/timer/timer.h" 13#include "net/disk_cache/blockfile/block_bitmaps_v3.h" 14#include "net/disk_cache/blockfile/block_files.h" 15#include "net/disk_cache/blockfile/eviction_v3.h" 16#include "net/disk_cache/blockfile/index_table_v3.h" 17#include "net/disk_cache/blockfile/stats.h" 18#include "net/disk_cache/blockfile/stress_support.h" 19#include "net/disk_cache/blockfile/trace.h" 20#include "net/disk_cache/disk_cache.h" 21 22namespace net { 23class NetLog; 24} // namespace net 25 26namespace disk_cache { 27 28class EntryImplV3; 29 30// This class implements the Backend interface. An object of this 31// class handles the operations of the cache for a particular profile. 32class NET_EXPORT_PRIVATE BackendImplV3 : public Backend { 33 public: 34 enum BackendFlags { 35 MAX_SIZE = 1 << 1, // A maximum size was provided. 36 UNIT_TEST_MODE = 1 << 2, // We are modifying the behavior for testing. 37 UPGRADE_MODE = 1 << 3, // This is the upgrade tool (dump). 38 EVICTION_V2 = 1 << 4, // Use of new eviction was specified. 39 BASIC_UNIT_TEST = 1 << 5, // Identifies almost all unit tests. 40 NO_LOAD_PROTECTION = 1 << 6, // Don't act conservatively under load. 41 NO_BUFFERING = 1 << 7, // Disable extended IO buffering. 42 NO_CLEAN_ON_EXIT = 1 << 8 // Avoid saving data at exit time. 43 }; 44 45 BackendImplV3(const base::FilePath& path, 46 base::MessageLoopProxy* cache_thread, 47 net::NetLog* net_log); 48 virtual ~BackendImplV3(); 49 50 // Performs general initialization for this current instance of the cache. 51 int Init(const CompletionCallback& callback); 52 53 // Same behavior as OpenNextEntry but walks the list from back to front. 54 int OpenPrevEntry(void** iter, Entry** prev_entry, 55 const CompletionCallback& callback); 56 57 // Sets the maximum size for the total amount of data stored by this instance. 58 bool SetMaxSize(int max_bytes); 59 60 // Sets the cache type for this backend. 61 void SetType(net::CacheType type); 62 63 // Creates a new storage block of size block_count. 64 bool CreateBlock(FileType block_type, int block_count, 65 Addr* block_address); 66 67 // Updates the ranking information for an entry. 68 void UpdateRank(EntryImplV3* entry, bool modified); 69 70 // Permanently deletes an entry, but still keeps track of it. 71 void InternalDoomEntry(EntryImplV3* entry); 72 73 // This method must be called when an entry is released for the last time, so 74 // the entry should not be used anymore. |address| is the cache address of the 75 // entry. 76 void OnEntryDestroyBegin(Addr address); 77 78 // This method must be called after all resources for an entry have been 79 // released. 80 void OnEntryDestroyEnd(); 81 82 // If the |address| corresponds to an open entry, returns a pointer to that 83 // entry, otherwise returns NULL. Note that this method does not increase the 84 // ref counter for the entry. 85 EntryImplV3* GetOpenEntry(Addr address) const; 86 87 // Returns the id being used on this run of the cache. 88 int32 GetCurrentEntryId() const; 89 90 // Returns the maximum size for a file to reside on the cache. 91 int MaxFileSize() const; 92 93 // A user data block is being created, extended or truncated. 94 void ModifyStorageSize(int32 old_size, int32 new_size); 95 96 // Logs requests that are denied due to being too big. 97 void TooMuchStorageRequested(int32 size); 98 99 // Returns true if a temporary buffer is allowed to be extended. 100 bool IsAllocAllowed(int current_size, int new_size); 101 102 // Tracks the release of |size| bytes by an entry buffer. 103 void BufferDeleted(int size); 104 105 // Only intended for testing the two previous methods. 106 int GetTotalBuffersSize() const { 107 return buffer_bytes_; 108 } 109 110 // Returns true if this instance seems to be under heavy load. 111 bool IsLoaded() const; 112 113 // Returns the full histogram name, for the given base |name| and the current 114 // cache type. The name will be "DiskCache3.name_type". 115 std::string HistogramName(const char* name) const; 116 117 net::CacheType cache_type() const { 118 return cache_type_; 119 } 120 121 bool read_only() const { 122 return read_only_; 123 } 124 125 // Returns a weak pointer to this object. 126 base::WeakPtr<BackendImplV3> GetWeakPtr(); 127 128 // Returns true if we should send histograms for this user again. The caller 129 // must call this function only once per run (because it returns always the 130 // same thing on a given run). 131 bool ShouldReportAgain(); 132 133 // Reports some data when we filled up the cache. 134 void FirstEviction(); 135 136 // Called when an interesting event should be logged (counted). 137 void OnEvent(Stats::Counters an_event); 138 139 // Keeps track of payload access (doesn't include metadata). 140 void OnRead(int bytes); 141 void OnWrite(int bytes); 142 143 // Timer callback to calculate usage statistics and perform backups. 144 void OnTimerTick(); 145 146 // Sets internal parameters to enable unit testing mode. 147 void SetUnitTestMode(); 148 149 // Sets internal parameters to enable upgrade mode (for internal tools). 150 void SetUpgradeMode(); 151 152 // Sets the eviction algorithm to version 2. 153 void SetNewEviction(); 154 155 // Sets an explicit set of BackendFlags. 156 void SetFlags(uint32 flags); 157 158 // Sends a dummy operation through the operation queue, for unit tests. 159 int FlushQueueForTest(const CompletionCallback& callback); 160 161 // Trims an entry (all if |empty| is true) from the list of deleted 162 // entries. This method should be called directly on the cache thread. 163 void TrimForTest(bool empty); 164 165 // Trims an entry (all if |empty| is true) from the list of deleted 166 // entries. This method should be called directly on the cache thread. 167 void TrimDeletedListForTest(bool empty); 168 169 // Performs a simple self-check, and returns the number of dirty items 170 // or an error code (negative value). 171 int SelfCheck(); 172 173 // Backend implementation. 174 virtual net::CacheType GetCacheType() const OVERRIDE; 175 virtual int32 GetEntryCount() const OVERRIDE; 176 virtual int OpenEntry(const std::string& key, Entry** entry, 177 const CompletionCallback& callback) OVERRIDE; 178 virtual int CreateEntry(const std::string& key, Entry** entry, 179 const CompletionCallback& callback) OVERRIDE; 180 virtual int DoomEntry(const std::string& key, 181 const CompletionCallback& callback) OVERRIDE; 182 virtual int DoomAllEntries(const CompletionCallback& callback) OVERRIDE; 183 virtual int DoomEntriesBetween(base::Time initial_time, 184 base::Time end_time, 185 const CompletionCallback& callback) OVERRIDE; 186 virtual int DoomEntriesSince(base::Time initial_time, 187 const CompletionCallback& callback) OVERRIDE; 188 virtual int OpenNextEntry(void** iter, Entry** next_entry, 189 const CompletionCallback& callback) OVERRIDE; 190 virtual void EndEnumeration(void** iter) OVERRIDE; 191 virtual void GetStats(StatsItems* stats) OVERRIDE; 192 virtual void OnExternalCacheHit(const std::string& key) OVERRIDE; 193 194 private: 195 friend class EvictionV3; 196 typedef base::hash_map<CacheAddr, EntryImplV3*> EntriesMap; 197 198 void AdjustMaxCacheSize(); 199 bool InitStats(void* stats_data); 200 void StoreStats(); 201 202 // Deletes the cache and starts again. 203 void RestartCache(bool failure); 204 void PrepareForRestart(); 205 206 // Performs final cleanup. 207 void CleanupCache(); 208 209 // Creates a new entry object. Returns zero on success, or a disk_cache error 210 // on failure. 211 int NewEntry(Addr address, EntryImplV3** entry); 212 213 // Opens the next or previous entry on a cache iteration. 214 int OpenFollowingEntry(bool forward, void** iter, Entry** next_entry, 215 const CompletionCallback& callback); 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_ 284