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// Copyright 2015 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 CC_BASE_HISTOGRAMS_H_
#define CC_BASE_HISTOGRAMS_H_
#include "base/compiler_specific.h"
#include "base/macros.h"
#include "base/metrics/histogram_base.h"
#include "base/metrics/histogram_macros.h"
#include "base/numerics/safe_math.h"
#include "base/strings/stringprintf.h"
#include "base/time/time.h"
#include "base/timer/elapsed_timer.h"
#include "cc/base/cc_export.h"
namespace cc {
// Supplies a client name to be inserted into histogram names.
// These are known so far: Renderer, Browser
//
// We currently assume that there is only one distinct client per process.
// Not thread-safe. If called multiple times, warns and skips metrics.
CC_EXPORT void SetClientNameForMetrics(const char* client_name);
// Returns the client name, for use by applicable cc metrics code.
// May return null, in which case no clients, or at least two clients, set the
// client name, and these metrics should be omitted.
//
// This method guarantees that it will never return two distinct non-null
// values over the lifetime of the process.
const char* GetClientNameForMetrics();
// Emits UMA histogram trackers for time spent as well as area (in pixels)
// processed per unit time. Time is measured in microseconds, and work in
// pixels per millisecond. Histogram name should include a %s to grab the client
// name.
//
// Usage:
// // Outside of a method, perhaps in a namespace.
// DEFINE_SCOPED_UMA_HISTOGRAM_AREA_TIMER(
// ScopedReticulateSplinesTimer,
// "Compositing.%s.ReticulateSplinesUs",
// "Compositing.%s.ReticulateSplinesPixelsPerMs");
//
// // Inside a method.
// ScopedReticulateSplinesTimer timer;
// timer.AddArea(some_rect.size().GetArea());
//
#define DEFINE_SCOPED_UMA_HISTOGRAM_AREA_TIMER(class_name, time_histogram, \
area_histogram) \
class class_name : public ScopedUMAHistogramAreaTimerBase { \
public: \
~class_name(); \
}; \
class_name::~class_name() { \
Sample time_sample; \
Sample area_sample; \
const char* client_name = GetClientNameForMetrics(); \
if (client_name && GetHistogramValues(&time_sample, &area_sample)) { \
/* GetClientNameForMetrics only returns one non-null value over */ \
/* the lifetime of the process, so these histogram names are */ \
/* runtime constant. */ \
UMA_HISTOGRAM_COUNTS(base::StringPrintf(time_histogram, client_name), \
time_sample); \
UMA_HISTOGRAM_COUNTS(base::StringPrintf(area_histogram, client_name), \
area_sample); \
} \
}
// Version of the above macro for cases which only care about time, not area.
#define DEFINE_SCOPED_UMA_HISTOGRAM_TIMER(class_name, time_histogram) \
class class_name : public ScopedUMAHistogramAreaTimerBase { \
public: \
~class_name(); \
}; \
class_name::~class_name() { \
Sample time_sample; \
Sample area_sample; \
const char* client_name = GetClientNameForMetrics(); \
if (client_name && GetHistogramValues(&time_sample, &area_sample)) { \
DCHECK_EQ(0, area_sample); \
/* GetClientNameForMetrics only returns one non-null value over */ \
/* the lifetime of the process, so these histogram names are */ \
/* runtime constant. */ \
UMA_HISTOGRAM_COUNTS(base::StringPrintf(time_histogram, client_name), \
time_sample); \
} \
}
class CC_EXPORT ScopedUMAHistogramAreaTimerBase {
public:
void AddArea(const base::CheckedNumeric<int>& area) { area_ += area; }
void SetArea(const base::CheckedNumeric<int>& area) { area_ = area; }
protected:
using Sample = base::HistogramBase::Sample;
ScopedUMAHistogramAreaTimerBase();
~ScopedUMAHistogramAreaTimerBase();
// Returns true if histograms should be recorded (i.e. values are valid).
bool GetHistogramValues(Sample* time_microseconds,
Sample* pixels_per_ms) const;
private:
static bool GetHistogramValues(base::TimeDelta elapsed,
int area,
Sample* time_microseconds,
Sample* pixels_per_ms);
base::ElapsedTimer timer_;
base::CheckedNumeric<int> area_;
friend class ScopedUMAHistogramAreaTimerBaseTest;
DISALLOW_COPY_AND_ASSIGN(ScopedUMAHistogramAreaTimerBase);
};
} // namespace cc
#endif // CC_BASE_HISTOGRAMS_H_