net/disk_cache/histogram_macros.h

// 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.

// This file contains macros to simplify histogram reporting from the disk
// cache. The main issue is that we want to have separate histograms for each
// type of cache (regular vs. media, etc), without adding the complexity of
// keeping track of a potentially large number of histogram objects that have to
// survive the backend object that created them.

#ifndef NET_DISK_CACHE_HISTOGRAM_MACROS_H_
#define NET_DISK_CACHE_HISTOGRAM_MACROS_H_
#pragma once

// -----------------------------------------------------------------------------

// These histograms follow the definition of UMA_HISTOGRAMN_XXX except that
// whenever the name changes (the experiment group changes), the histrogram
// object is re-created.
// Note: These macros are only run on one thread, so the declarations of
// |counter| was made static (i.e., there will be no race for reinitialization).

#define CACHE_HISTOGRAM_CUSTOM_COUNTS(name, sample, min, max, bucket_count) \
    do { \
      static base::Histogram* counter(NULL); \
      if (!counter || name != counter->histogram_name()) \
        counter = base::Histogram::FactoryGet( \
            name, min, max, bucket_count, \
            base::Histogram::kUmaTargetedHistogramFlag); \
      counter->Add(sample); \
    } while (0)

#define CACHE_HISTOGRAM_COUNTS(name, sample) CACHE_HISTOGRAM_CUSTOM_COUNTS( \
    name, sample, 1, 1000000, 50)

#define CACHE_HISTOGRAM_COUNTS_10000(name, sample) \
    CACHE_HISTOGRAM_CUSTOM_COUNTS(name, sample, 1, 10000, 50)

#define CACHE_HISTOGRAM_COUNTS_50000(name, sample) \
    CACHE_HISTOGRAM_CUSTOM_COUNTS(name, sample, 1, 50000000, 50)

#define CACHE_HISTOGRAM_CUSTOM_TIMES(name, sample, min, max, bucket_count) \
    do { \
      static base::Histogram* counter(NULL); \
      if (!counter || name != counter->histogram_name()) \
        counter = base::Histogram::FactoryTimeGet( \
            name, min, max, bucket_count, \
            base::Histogram::kUmaTargetedHistogramFlag); \
      counter->AddTime(sample); \
    } while (0)

#define CACHE_HISTOGRAM_TIMES(name, sample) CACHE_HISTOGRAM_CUSTOM_TIMES( \
    name, sample, base::TimeDelta::FromMilliseconds(1), \
    base::TimeDelta::FromSeconds(10), 50)

#define CACHE_HISTOGRAM_ENUMERATION(name, sample, boundary_value) do { \
    static base::Histogram* counter(NULL); \
    if (!counter || name != counter->histogram_name()) \
      counter = base::LinearHistogram::FactoryGet( \
                    name, 1, boundary_value, boundary_value + 1, \
                    base::Histogram::kUmaTargetedHistogramFlag); \
    counter->Add(sample); \
  } while (0)

#define CACHE_HISTOGRAM_PERCENTAGE(name, under_one_hundred) \
    CACHE_HISTOGRAM_ENUMERATION(name, under_one_hundred, 101)

// -----------------------------------------------------------------------------

// HISTOGRAM_HOURS will collect time related data with a granularity of hours
// and normal values of a few months.
#define CACHE_HISTOGRAM_HOURS CACHE_HISTOGRAM_COUNTS_10000

// HISTOGRAM_AGE will collect time elapsed since |initial_time|, with a
// granularity of hours and normal values of a few months.
#define CACHE_HISTOGRAM_AGE(name, initial_time) \
    CACHE_HISTOGRAM_COUNTS_10000(name, \
                                 (base::Time::Now() - initial_time).InHours())

// HISTOGRAM_AGE_MS will collect time elapsed since |initial_time|, with the
// normal resolution of the UMA_HISTOGRAM_TIMES.
#define CACHE_HISTOGRAM_AGE_MS(name, initial_time)\
    CACHE_HISTOGRAM_TIMES(name, base::TimeTicks::Now() - initial_time)

#define CACHE_HISTOGRAM_CACHE_ERROR(name, sample) \
    CACHE_HISTOGRAM_ENUMERATION(name, sample, 50)

#ifdef NET_DISK_CACHE_BACKEND_IMPL_CC_
#define BACKEND_OBJ this
#else
#define BACKEND_OBJ backend_
#endif

// Generates a UMA histogram of the given type, generating the proper name for
// it (asking backend_->HistogramName), and adding the provided sample.
// For example, to generate a regualar UMA_HISTOGRAM_COUNTS, this macro would
// be used as:
//  CACHE_UMA(COUNTS, "MyName", 0, 20);
//  CACHE_UMA(COUNTS, "MyExperiment", 530, 55);
// which roughly translates to:
//  UMA_HISTOGRAM_COUNTS("DiskCache.2.MyName", 20);  // "2" is the CacheType.
//  UMA_HISTOGRAM_COUNTS("DiskCache.2.MyExperiment_530", 55);
//
#define CACHE_UMA(type, name, experiment, sample) {\
    const std::string my_name = BACKEND_OBJ->HistogramName(name, experiment);\
    switch (BACKEND_OBJ->cache_type()) {\
      case net::DISK_CACHE:\
        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
        break;\
      case net::MEDIA_CACHE:\
        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
        break;\
      case net::APP_CACHE:\
        CACHE_HISTOGRAM_##type(my_name.data(), sample);\
        break;\
      default:\
        NOTREACHED();\
        break;\
    }\
  }

#endif  // NET_DISK_CACHE_HISTOGRAM_MACROS_H_