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
23namespace base {
24class SingleThreadTaskRunner;
25}  // namespace base
26
27namespace net {
28class NetLog;
29}  // namespace net
30
31namespace disk_cache {
32
33class 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.
37class 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  virtual ~BackendImplV3();
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  virtual net::CacheType GetCacheType() const OVERRIDE;
176  virtual int32 GetEntryCount() const OVERRIDE;
177  virtual int OpenEntry(const std::string& key, Entry** entry,
178                        const CompletionCallback& callback) OVERRIDE;
179  virtual int CreateEntry(const std::string& key, Entry** entry,
180                          const CompletionCallback& callback) OVERRIDE;
181  virtual int DoomEntry(const std::string& key,
182                        const CompletionCallback& callback) OVERRIDE;
183  virtual int DoomAllEntries(const CompletionCallback& callback) OVERRIDE;
184  virtual int DoomEntriesBetween(base::Time initial_time,
185                                 base::Time end_time,
186                                 const CompletionCallback& callback) OVERRIDE;
187  virtual int DoomEntriesSince(base::Time initial_time,
188                               const CompletionCallback& callback) OVERRIDE;
189  virtual scoped_ptr<Iterator> CreateIterator() OVERRIDE;
190  virtual void GetStats(StatsItems* stats) OVERRIDE;
191  virtual void OnExternalCacheHit(const std::string& key) OVERRIDE;
192
193 private:
194  friend class EvictionV3;
195  typedef base::hash_map<CacheAddr, EntryImplV3*> EntriesMap;
196  class IteratorImpl;
197  class NotImplementedIterator;
198  class Worker;
199
200  void AdjustMaxCacheSize();
201  bool InitStats(void* stats_data);
202  void StoreStats();
203
204  // Deletes the cache and starts again.
205  void RestartCache(bool failure);
206  void PrepareForRestart();
207
208  // Performs final cleanup.
209  void CleanupCache();
210
211  // Creates a new entry object. Returns zero on success, or a disk_cache error
212  // on failure.
213  int NewEntry(Addr address, EntryImplV3** entry);
214
215  // Handles the used storage count.
216  void AddStorageSize(int32 bytes);
217  void SubstractStorageSize(int32 bytes);
218
219  // Update the number of referenced cache entries.
220  void IncreaseNumRefs();
221  void DecreaseNumRefs();
222  void IncreaseNumEntries();
223  void DecreaseNumEntries();
224
225  // Dumps current cache statistics to the log.
226  void LogStats();
227
228  // Send UMA stats.
229  void ReportStats();
230
231  // Reports an uncommon, recoverable error.
232  void ReportError(int error);
233
234  // Performs basic checks on the index file. Returns false on failure.
235  bool CheckIndex();
236
237  // Part of the self test. Returns the number or dirty entries, or an error.
238  int CheckAllEntries();
239
240  // Part of the self test. Returns false if the entry is corrupt.
241  bool CheckEntry(EntryImplV3* cache_entry);
242
243  // Returns the maximum total memory for the memory buffers.
244  int MaxBuffersSize();
245
246  IndexTable index_;
247  base::FilePath path_;  // Path to the folder used as backing storage.
248  BlockBitmaps block_files_;
249  int32 max_size_;  // Maximum data size for this instance.
250  EvictionV3 eviction_;  // Handler of the eviction algorithm.
251  EntriesMap open_entries_;
252  int num_refs_;  // Number of referenced cache entries.
253  int max_refs_;  // Max number of referenced cache entries.
254  int entry_count_;  // Number of entries accessed lately.
255  int byte_count_;  // Number of bytes read/written lately.
256  int buffer_bytes_;  // Total size of the temporary entries' buffers.
257  int up_ticks_;  // The number of timer ticks received (OnTimerTick).
258  net::CacheType cache_type_;
259  int uma_report_;  // Controls transmission of UMA data.
260  uint32 user_flags_;  // Flags set by the user.
261  bool init_;  // controls the initialization of the system.
262  bool restarted_;
263  bool read_only_;  // Prevents updates of the rankings data (used by tools).
264  bool disabled_;
265  bool lru_eviction_;  // What eviction algorithm should be used.
266  bool first_timer_;  // True if the timer has not been called.
267  bool user_load_;  // True if we see a high load coming from the caller.
268
269  net::NetLog* net_log_;
270
271  Stats stats_;  // Usage statistics.
272  scoped_ptr<base::RepeatingTimer<BackendImplV3> > timer_;  // Usage timer.
273  scoped_refptr<TraceObject> trace_object_;  // Initializes internal tracing.
274  base::WeakPtrFactory<BackendImplV3> ptr_factory_;
275
276  DISALLOW_COPY_AND_ASSIGN(BackendImplV3);
277};
278
279}  // namespace disk_cache
280
281#endif  // NET_DISK_CACHE_BLOCKFILE_BACKEND_IMPL_V3_H_
282