net/disk_cache/simple/simple_index.h

   1 // Copyright (c) 2013 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 #ifndef NET_DISK_CACHE_SIMPLE_SIMPLE_INDEX_H_
   6 #define NET_DISK_CACHE_SIMPLE_SIMPLE_INDEX_H_
   7
   8 #include <list>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/callback.h"
  13 #include "base/containers/hash_tables.h"
  14 #include "base/files/file_path.h"
  15 #include "base/gtest_prod_util.h"
  16 #include "base/memory/ref_counted.h"
  17 #include "base/memory/scoped_ptr.h"
  18 #include "base/memory/weak_ptr.h"
  19 #include "base/single_thread_task_runner.h"
  20 #include "base/threading/thread_checker.h"
  21 #include "base/time/time.h"
  22 #include "base/timer/timer.h"
  23 #include "net/base/cache_type.h"
  24 #include "net/base/completion_callback.h"
  25 #include "net/base/net_export.h"
  26
  27 #if defined(OS_ANDROID)
  28 #include "base/android/application_status_listener.h"
  29 #endif
  30
  31 class Pickle;
  32 class PickleIterator;
  33
  34 namespace disk_cache {
  35
  36 class SimpleIndexDelegate;
  37 class SimpleIndexFile;
  38 struct SimpleIndexLoadResult;
  39
  40 class NET_EXPORT_PRIVATE EntryMetadata {
  41  public:
  42   EntryMetadata();
  43   EntryMetadata(base::Time last_used_time, uint64 entry_size);
  44
  45   base::Time GetLastUsedTime() const;
  46   void SetLastUsedTime(const base::Time& last_used_time);
  47
  48   uint64 GetEntrySize() const;
  49   void SetEntrySize(uint64 entry_size);
  50
  51   // Serialize the data into the provided pickle.
  52   void Serialize(Pickle* pickle) const;
  53   bool Deserialize(PickleIterator* it);
  54
  55   static base::TimeDelta GetLowerEpsilonForTimeComparisons() {
  56     return base::TimeDelta::FromSeconds(1);
  57   }
  58   static base::TimeDelta GetUpperEpsilonForTimeComparisons() {
  59     return base::TimeDelta();
  60   }
  61
  62  private:
  63   friend class SimpleIndexFileTest;
  64
  65   // There are tens of thousands of instances of EntryMetadata in memory, so the
  66   // size of each entry matters.  Even when the values used to set these members
  67   // are originally calculated as >32-bit types, the actual necessary size for
  68   // each shouldn't exceed 32 bits, so we use 32-bit types here.
  69   uint32 last_used_time_seconds_since_epoch_;
  70   int32 entry_size_;  // Storage size in bytes.
  71 };
  72 static_assert(sizeof(EntryMetadata) == 8, "incorrect metadata size");
  73
  74 // This class is not Thread-safe.
  75 class NET_EXPORT_PRIVATE SimpleIndex
  76     : public base::SupportsWeakPtr<SimpleIndex> {
  77  public:
  78   typedef std::vector<uint64> HashList;
  79
  80   SimpleIndex(const scoped_refptr<base::SingleThreadTaskRunner>& io_thread,
  81               SimpleIndexDelegate* delegate,
  82               net::CacheType cache_type,
  83               scoped_ptr<SimpleIndexFile> simple_index_file);
  84
  85   virtual ~SimpleIndex();
  86
  87   void Initialize(base::Time cache_mtime);
  88
  89   void SetMaxSize(uint64 max_bytes);
  90   uint64 max_size() const { return max_size_; }
  91
  92   void Insert(uint64 entry_hash);
  93   void Remove(uint64 entry_hash);
  94
  95   // Check whether the index has the entry given the hash of its key.
  96   bool Has(uint64 entry_hash) const;
  97
  98   // Update the last used time of the entry with the given key and return true
  99   // iff the entry exist in the index.
 100   bool UseIfExists(uint64 entry_hash);
 101
 102   void WriteToDisk();
 103
 104   // Update the size (in bytes) of an entry, in the metadata stored in the
 105   // index. This should be the total disk-file size including all streams of the
 106   // entry.
 107   bool UpdateEntrySize(uint64 entry_hash, int64 entry_size);
 108
 109   typedef base::hash_map<uint64, EntryMetadata> EntrySet;
 110
 111   static void InsertInEntrySet(uint64 entry_hash,
 112                                const EntryMetadata& entry_metadata,
 113                                EntrySet* entry_set);
 114
 115   // Executes the |callback| when the index is ready. Allows multiple callbacks.
 116   int ExecuteWhenReady(const net::CompletionCallback& callback);
 117
 118   // Returns entries from the index that have last accessed time matching the
 119   // range between |initial_time| and |end_time| where open intervals are
 120   // possible according to the definition given in |DoomEntriesBetween()| in the
 121   // disk cache backend interface.
 122   scoped_ptr<HashList> GetEntriesBetween(const base::Time initial_time,
 123                                          const base::Time end_time);
 124
 125   // Returns the list of all entries key hash.
 126   scoped_ptr<HashList> GetAllHashes();
 127
 128   // Returns number of indexed entries.
 129   int32 GetEntryCount() const;
 130
 131   // Returns whether the index has been initialized yet.
 132   bool initialized() const { return initialized_; }
 133
 134  private:
 135   friend class SimpleIndexTest;
 136   FRIEND_TEST_ALL_PREFIXES(SimpleIndexTest, IndexSizeCorrectOnMerge);
 137   FRIEND_TEST_ALL_PREFIXES(SimpleIndexTest, DiskWriteQueued);
 138   FRIEND_TEST_ALL_PREFIXES(SimpleIndexTest, DiskWriteExecuted);
 139   FRIEND_TEST_ALL_PREFIXES(SimpleIndexTest, DiskWritePostponed);
 140
 141   void StartEvictionIfNeeded();
 142   void EvictionDone(int result);
 143
 144   void PostponeWritingToDisk();
 145
 146   void UpdateEntryIteratorSize(EntrySet::iterator* it, int64 entry_size);
 147
 148   // Must run on IO Thread.
 149   void MergeInitializingSet(scoped_ptr<SimpleIndexLoadResult> load_result);
 150
 151 #if defined(OS_ANDROID)
 152   void OnApplicationStateChange(base::android::ApplicationState state);
 153
 154   scoped_ptr<base::android::ApplicationStatusListener> app_status_listener_;
 155 #endif
 156
 157   // The owner of |this| must ensure the |delegate_| outlives |this|.
 158   SimpleIndexDelegate* delegate_;
 159
 160   EntrySet entries_set_;
 161
 162   const net::CacheType cache_type_;
 163   uint64 cache_size_;  // Total cache storage size in bytes.
 164   uint64 max_size_;
 165   uint64 high_watermark_;
 166   uint64 low_watermark_;
 167   bool eviction_in_progress_;
 168   base::TimeTicks eviction_start_time_;
 169
 170   // This stores all the entry_hash of entries that are removed during
 171   // initialization.
 172   base::hash_set<uint64> removed_entries_;
 173   bool initialized_;
 174
 175   scoped_ptr<SimpleIndexFile> index_file_;
 176
 177   scoped_refptr<base::SingleThreadTaskRunner> io_thread_;
 178
 179   // All nonstatic SimpleEntryImpl methods should always be called on the IO
 180   // thread, in all cases. |io_thread_checker_| documents and enforces this.
 181   base::ThreadChecker io_thread_checker_;
 182
 183   // Timestamp of the last time we wrote the index to disk.
 184   // PostponeWritingToDisk() may give up postponing and allow the write if it
 185   // has been a while since last time we wrote.
 186   base::TimeTicks last_write_to_disk_;
 187
 188   base::OneShotTimer<SimpleIndex> write_to_disk_timer_;
 189   base::Closure write_to_disk_cb_;
 190
 191   typedef std::list<net::CompletionCallback> CallbackList;
 192   CallbackList to_run_when_initialized_;
 193
 194   // Set to true when the app is on the background. When the app is in the
 195   // background we can write the index much more frequently, to insure fresh
 196   // index on next startup.
 197   bool app_on_background_;
 198 };
 199
 200 }  // namespace disk_cache
 201
 202 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_INDEX_H_