net/disk_cache/stats.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 #ifndef NET_DISK_CACHE_STATS_H_
   6 #define NET_DISK_CACHE_STATS_H_
   7
   8 #include <string>
   9 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "net/disk_cache/stats_histogram.h"
  13
  14 namespace base {
  15 class HistogramSamples;
  16 }  // namespace base
  17
  18 namespace disk_cache {
  19
  20 class BackendImpl;
  21
  22 typedef std::vector<std::pair<std::string, std::string> > StatsItems;
  23
  24 // This class stores cache-specific usage information, for tunning purposes.
  25 class Stats {
  26  public:
  27   static const int kDataSizesLength = 28;
  28   enum Counters {
  29     MIN_COUNTER = 0,
  30     OPEN_MISS = MIN_COUNTER,
  31     OPEN_HIT,
  32     CREATE_MISS,
  33     CREATE_HIT,
  34     RESURRECT_HIT,
  35     CREATE_ERROR,
  36     TRIM_ENTRY,
  37     DOOM_ENTRY,
  38     DOOM_CACHE,
  39     INVALID_ENTRY,
  40     OPEN_ENTRIES,  // Average number of open entries.
  41     MAX_ENTRIES,  // Maximum number of open entries.
  42     TIMER,
  43     READ_DATA,
  44     WRITE_DATA,
  45     OPEN_RANKINGS,  // An entry has to be read just to modify rankings.
  46     GET_RANKINGS,  // We got the ranking info without reading the whole entry.
  47     FATAL_ERROR,
  48     LAST_REPORT,  // Time of the last time we sent a report.
  49     LAST_REPORT_TIMER,  // Timer count of the last time we sent a report.
  50     DOOM_RECENT,  // The cache was partially cleared.
  51     GAJS_EVICTED,  // ga.js was evicted from the cache.
  52     MAX_COUNTER
  53   };
  54
  55   Stats();
  56   ~Stats();
  57
  58   bool Init(BackendImpl* backend, uint32* storage_addr);
  59
  60   // Tracks changes to the stoage space used by an entry.
  61   void ModifyStorageStats(int32 old_size, int32 new_size);
  62
  63   // Tracks general events.
  64   void OnEvent(Counters an_event);
  65   void SetCounter(Counters counter, int64 value);
  66   int64 GetCounter(Counters counter) const;
  67
  68   void GetItems(StatsItems* items);
  69   int GetHitRatio() const;
  70   int GetResurrectRatio() const;
  71   void ResetRatios();
  72
  73   // Returns the lower bound of the space used by entries bigger than 512 KB.
  74   int GetLargeEntriesSize();
  75
  76   // Saves the stats to disk.
  77   void Store();
  78
  79   // Support for StatsHistograms. Together, these methods allow StatsHistograms
  80   // to take a snapshot of the data_sizes_ as the histogram data.
  81   int GetBucketRange(size_t i) const;
  82   void Snapshot(base::HistogramSamples* samples) const;
  83
  84  private:
  85   int GetStatsBucket(int32 size);
  86   int GetRatio(Counters hit, Counters miss) const;
  87
  88   BackendImpl* backend_;
  89   uint32 storage_addr_;
  90   int data_sizes_[kDataSizesLength];
  91   int64 counters_[MAX_COUNTER];
  92   StatsHistogram* size_histogram_;
  93
  94   DISALLOW_COPY_AND_ASSIGN(Stats);
  95 };
  96
  97 }  // namespace disk_cache
  98
  99 #endif  // NET_DISK_CACHE_STATS_H_