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/*
* Copyright 2013 The WebRTC Project Authors. All rights reserved.
*
* Use of this source code is governed by a BSD-style license
* that can be found in the LICENSE file in the root of the source
* tree. An additional intellectual property rights grant can be found
* in the file PATENTS. All contributing project authors may
* be found in the AUTHORS file in the root of the source tree.
*/
#include "webrtc/base/profiler.h"
#include <math.h>
#include <algorithm>
#include "webrtc/base/timeutils.h"
namespace {
// When written to an ostream, FormattedTime chooses an appropriate scale and
// suffix for a time value given in seconds.
class FormattedTime {
public:
explicit FormattedTime(double t) : time_(t) {}
double time() const { return time_; }
private:
double time_;
};
std::ostream& operator<<(std::ostream& stream, const FormattedTime& time) {
if (time.time() < 1.0) {
stream << (time.time() * 1000.0) << "ms";
} else {
stream << time.time() << 's';
}
return stream;
}
} // namespace
namespace rtc {
ProfilerEvent::ProfilerEvent()
: total_time_(0.0),
mean_(0.0),
sum_of_squared_differences_(0.0),
start_count_(0),
event_count_(0) {
}
void ProfilerEvent::Start() {
if (start_count_ == 0) {
current_start_time_ = TimeNanos();
}
++start_count_;
}
void ProfilerEvent::Stop(uint64_t stop_time) {
--start_count_;
ASSERT(start_count_ >= 0);
if (start_count_ == 0) {
double elapsed = static_cast<double>(stop_time - current_start_time_) /
kNumNanosecsPerSec;
total_time_ += elapsed;
if (event_count_ == 0) {
minimum_ = maximum_ = elapsed;
} else {
minimum_ = std::min(minimum_, elapsed);
maximum_ = std::max(maximum_, elapsed);
}
// Online variance and mean algorithm: http://en.wikipedia.org/wiki/
// Algorithms_for_calculating_variance#Online_algorithm
++event_count_;
double delta = elapsed - mean_;
mean_ = mean_ + delta / event_count_;
sum_of_squared_differences_ += delta * (elapsed - mean_);
}
}
void ProfilerEvent::Stop() {
Stop(TimeNanos());
}
double ProfilerEvent::standard_deviation() const {
if (event_count_ <= 1) return 0.0;
return sqrt(sum_of_squared_differences_ / (event_count_ - 1.0));
}
Profiler::~Profiler() = default;
Profiler* Profiler::Instance() {
RTC_DEFINE_STATIC_LOCAL(Profiler, instance, ());
return &instance;
}
Profiler::Profiler() {
}
void Profiler::StartEvent(const std::string& event_name) {
lock_.LockShared();
EventMap::iterator it = events_.find(event_name);
bool needs_insert = (it == events_.end());
lock_.UnlockShared();
if (needs_insert) {
// Need an exclusive lock to modify the map.
ExclusiveScope scope(&lock_);
it = events_.insert(
EventMap::value_type(event_name, ProfilerEvent())).first;
}
it->second.Start();
}
void Profiler::StopEvent(const std::string& event_name) {
// Get the time ASAP, then wait for the lock.
uint64_t stop_time = TimeNanos();
SharedScope scope(&lock_);
EventMap::iterator it = events_.find(event_name);
if (it != events_.end()) {
it->second.Stop(stop_time);
}
}
void Profiler::ReportToLog(const char* file, int line,
LoggingSeverity severity_to_use,
const std::string& event_prefix) {
if (!LogMessage::Loggable(severity_to_use)) {
return;
}
SharedScope scope(&lock_);
{ // Output first line.
LogMessage msg(file, line, severity_to_use);
msg.stream() << "=== Profile report ";
if (event_prefix.empty()) {
msg.stream() << "(prefix: '" << event_prefix << "') ";
}
msg.stream() << "===";
}
for (EventMap::const_iterator it = events_.begin();
it != events_.end(); ++it) {
if (event_prefix.empty() || it->first.find(event_prefix) == 0) {
LogMessage(file, line, severity_to_use).stream()
<< it->first << " " << it->second;
}
}
LogMessage(file, line, severity_to_use).stream()
<< "=== End profile report ===";
}
void Profiler::ReportAllToLog(const char* file, int line,
LoggingSeverity severity_to_use) {
ReportToLog(file, line, severity_to_use, "");
}
const ProfilerEvent* Profiler::GetEvent(const std::string& event_name) const {
SharedScope scope(&lock_);
EventMap::const_iterator it =
events_.find(event_name);
return (it == events_.end()) ? NULL : &it->second;
}
bool Profiler::Clear() {
ExclusiveScope scope(&lock_);
bool result = true;
// Clear all events that aren't started.
EventMap::iterator it = events_.begin();
while (it != events_.end()) {
if (it->second.is_started()) {
++it; // Can't clear started events.
result = false;
} else {
events_.erase(it++);
}
}
return result;
}
std::ostream& operator<<(std::ostream& stream,
const ProfilerEvent& profiler_event) {
stream << "count=" << profiler_event.event_count()
<< " total=" << FormattedTime(profiler_event.total_time())
<< " mean=" << FormattedTime(profiler_event.mean())
<< " min=" << FormattedTime(profiler_event.minimum())
<< " max=" << FormattedTime(profiler_event.maximum())
<< " sd=" << profiler_event.standard_deviation();
return stream;
}
} // namespace rtc
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