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// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef NET_DISK_CACHE_STATS_H_
#define NET_DISK_CACHE_STATS_H_
#pragma once
#include <string>
#include <vector>
#include "base/basictypes.h"
#include "base/memory/scoped_ptr.h"
#include "net/disk_cache/stats_histogram.h"
namespace disk_cache {
class BackendImpl;
typedef std::vector<std::pair<std::string, std::string> > StatsItems;
// This class stores cache-specific usage information, for tunning purposes.
class Stats {
public:
static const int kDataSizesLength = 28;
enum Counters {
MIN_COUNTER = 0,
OPEN_MISS = MIN_COUNTER,
OPEN_HIT,
CREATE_MISS,
CREATE_HIT,
RESURRECT_HIT,
CREATE_ERROR,
TRIM_ENTRY,
DOOM_ENTRY,
DOOM_CACHE,
INVALID_ENTRY,
OPEN_ENTRIES, // Average number of open entries.
MAX_ENTRIES, // Maximum number of open entries.
TIMER,
READ_DATA,
WRITE_DATA,
OPEN_RANKINGS, // An entry has to be read just to modify rankings.
GET_RANKINGS, // We got the ranking info without reading the whole entry.
FATAL_ERROR,
LAST_REPORT, // Time of the last time we sent a report.
LAST_REPORT_TIMER, // Timer count of the last time we sent a report.
DOOM_RECENT, // The cache was partially cleared.
MAX_COUNTER
};
Stats();
~Stats();
bool Init(BackendImpl* backend, uint32* storage_addr);
// Tracks changes to the stoage space used by an entry.
void ModifyStorageStats(int32 old_size, int32 new_size);
// Tracks general events.
void OnEvent(Counters an_event);
void SetCounter(Counters counter, int64 value);
int64 GetCounter(Counters counter) const;
void GetItems(StatsItems* items);
int GetHitRatio() const;
int GetResurrectRatio() const;
void ResetRatios();
// Returns the lower bound of the space used by entries bigger than 512 KB.
int GetLargeEntriesSize();
// Saves the stats to disk.
void Store();
// Support for StatsHistograms. Together, these methods allow StatsHistograms
// to take a snapshot of the data_sizes_ as the histogram data.
int GetBucketRange(size_t i) const;
void Snapshot(StatsHistogram::StatsSamples* samples) const;
private:
int GetStatsBucket(int32 size);
int GetRatio(Counters hit, Counters miss) const;
BackendImpl* backend_;
uint32 storage_addr_;
int data_sizes_[kDataSizesLength];
int64 counters_[MAX_COUNTER];
StatsHistogram* size_histogram_;
DISALLOW_COPY_AND_ASSIGN(Stats);
};
} // namespace disk_cache
#endif // NET_DISK_CACHE_STATS_H_
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