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 namespace base {
  32 class Pickle;
  33 class PickleIterator;
  34 }
  35
  36 namespace disk_cache {
  37
  38 class SimpleIndexDelegate;
  39 class SimpleIndexFile;
  40 struct SimpleIndexLoadResult;
  41
  42 class NET_EXPORT_PRIVATE EntryMetadata {
  43  public:
  44   EntryMetadata();
  45   EntryMetadata(base::Time last_used_time, uint64 entry_size);
  46
  47   base::Time GetLastUsedTime() const;
  48   void SetLastUsedTime(const base::Time& last_used_time);
  49
  50   uint64 GetEntrySize() const;
  51   void SetEntrySize(uint64 entry_size);
  52
  53   // Serialize the data into the provided pickle.
  54   void Serialize(base::Pickle* pickle) const;
  55   bool Deserialize(base::PickleIterator* it);
  56
  57   static base::TimeDelta GetLowerEpsilonForTimeComparisons() {
  58     return base::TimeDelta::FromSeconds(1);
  59   }
  60   static base::TimeDelta GetUpperEpsilonForTimeComparisons() {
  61     return base::TimeDelta();
  62   }
  63
  64  private:
  65   friend class SimpleIndexFileTest;
  66
  67   // There are tens of thousands of instances of EntryMetadata in memory, so the
  68   // size of each entry matters.  Even when the values used to set these members
  69   // are originally calculated as >32-bit types, the actual necessary size for
  70   // each shouldn't exceed 32 bits, so we use 32-bit types here.
  71   uint32 last_used_time_seconds_since_epoch_;
  72   int32 entry_size_;  // Storage size in bytes.
  73 };
  74 static_assert(sizeof(EntryMetadata) == 8, "incorrect metadata size");
  75
  76 // This class is not Thread-safe.
  77 class NET_EXPORT_PRIVATE SimpleIndex
  78     : public base::SupportsWeakPtr<SimpleIndex> {
  79  public:
  80   typedef std::vector<uint64> HashList;
  81
  82   SimpleIndex(const scoped_refptr<base::SingleThreadTaskRunner>& io_thread,
  83               SimpleIndexDelegate* delegate,
  84               net::CacheType cache_type,
  85               scoped_ptr<SimpleIndexFile> simple_index_file);
  86
  87   virtual ~SimpleIndex();
  88
  89   void Initialize(base::Time cache_mtime);
  90
  91   void SetMaxSize(uint64 max_bytes);
  92   uint64 max_size() const { return max_size_; }
  93
  94   void Insert(uint64 entry_hash);
  95   void Remove(uint64 entry_hash);
  96
  97   // Check whether the index has the entry given the hash of its key.
  98   bool Has(uint64 entry_hash) const;
  99
 100   // Update the last used time of the entry with the given key and return true
 101   // iff the entry exist in the index.
 102   bool UseIfExists(uint64 entry_hash);
 103
 104   void WriteToDisk();
 105
 106   // Update the size (in bytes) of an entry, in the metadata stored in the
 107   // index. This should be the total disk-file size including all streams of the
 108   // entry.
 109   bool UpdateEntrySize(uint64 entry_hash, int64 entry_size);
 110
 111   typedef base::hash_map<uint64, EntryMetadata> EntrySet;
 112
 113   static void InsertInEntrySet(uint64 entry_hash,
 114                                const EntryMetadata& entry_metadata,
 115                                EntrySet* entry_set);
 116
 117   // Executes the |callback| when the index is ready. Allows multiple callbacks.
 118   int ExecuteWhenReady(const net::CompletionCallback& callback);
 119
 120   // Returns entries from the index that have last accessed time matching the
 121   // range between |initial_time| and |end_time| where open intervals are
 122   // possible according to the definition given in |DoomEntriesBetween()| in the
 123   // disk cache backend interface.
 124   scoped_ptr<HashList> GetEntriesBetween(const base::Time initial_time,
 125                                          const base::Time end_time);
 126
 127   // Returns the list of all entries key hash.
 128   scoped_ptr<HashList> GetAllHashes();
 129
 130   // Returns number of indexed entries.
 131   int32 GetEntryCount() const;
 132
 133   // Returns whether the index has been initialized yet.
 134   bool initialized() const { return initialized_; }
 135
 136  private:
 137   friend class SimpleIndexTest;
 138   FRIEND_TEST_ALL_PREFIXES(SimpleIndexTest, IndexSizeCorrectOnMerge);
 139   FRIEND_TEST_ALL_PREFIXES(SimpleIndexTest, DiskWriteQueued);
 140   FRIEND_TEST_ALL_PREFIXES(SimpleIndexTest, DiskWriteExecuted);
 141   FRIEND_TEST_ALL_PREFIXES(SimpleIndexTest, DiskWritePostponed);
 142
 143   void StartEvictionIfNeeded();
 144   void EvictionDone(int result);
 145
 146   void PostponeWritingToDisk();
 147
 148   void UpdateEntryIteratorSize(EntrySet::iterator* it, int64 entry_size);
 149
 150   // Must run on IO Thread.
 151   void MergeInitializingSet(scoped_ptr<SimpleIndexLoadResult> load_result);
 152
 153 #if defined(OS_ANDROID)
 154   void OnApplicationStateChange(base::android::ApplicationState state);
 155
 156   scoped_ptr<base::android::ApplicationStatusListener> app_status_listener_;
 157 #endif
 158
 159   // The owner of |this| must ensure the |delegate_| outlives |this|.
 160   SimpleIndexDelegate* delegate_;
 161
 162   EntrySet entries_set_;
 163
 164   const net::CacheType cache_type_;
 165   uint64 cache_size_;  // Total cache storage size in bytes.
 166   uint64 max_size_;
 167   uint64 high_watermark_;
 168   uint64 low_watermark_;
 169   bool eviction_in_progress_;
 170   base::TimeTicks eviction_start_time_;
 171
 172   // This stores all the entry_hash of entries that are removed during
 173   // initialization.
 174   base::hash_set<uint64> removed_entries_;
 175   bool initialized_;
 176
 177   scoped_ptr<SimpleIndexFile> index_file_;
 178
 179   scoped_refptr<base::SingleThreadTaskRunner> io_thread_;
 180
 181   // All nonstatic SimpleEntryImpl methods should always be called on the IO
 182   // thread, in all cases. |io_thread_checker_| documents and enforces this.
 183   base::ThreadChecker io_thread_checker_;
 184
 185   // Timestamp of the last time we wrote the index to disk.
 186   // PostponeWritingToDisk() may give up postponing and allow the write if it
 187   // has been a while since last time we wrote.
 188   base::TimeTicks last_write_to_disk_;
 189
 190   base::OneShotTimer<SimpleIndex> write_to_disk_timer_;
 191   base::Closure write_to_disk_cb_;
 192
 193   typedef std::list<net::CompletionCallback> CallbackList;
 194   CallbackList to_run_when_initialized_;
 195
 196   // Set to true when the app is on the background. When the app is in the
 197   // background we can write the index much more frequently, to insure fresh
 198   // index on next startup.
 199   bool app_on_background_;
 200 };
 201
 202 }  // namespace disk_cache
 203
 204 #endif  // NET_DISK_CACHE_SIMPLE_SIMPLE_INDEX_H_