Adds a modified copy of talk/base to webrtc/base. It is the first step in migrating talk/base to webrtc/base.

BUG=N/A
R=andrew@webrtc.org, wu@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/12199004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@6107 4adac7df-926f-26a2-2b94-8c16560cd09d

webrtc/base/profiler.cc

@@ -0,0 +1,186 @@
+/*
+ *  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 "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 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_ = _min(minimum_, elapsed);
+      maximum_ = _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::Instance() {
+  LIBJINGLE_DEFINE_STATIC_LOCAL(Profiler, instance, ());
+  return &instance;
+}
+
+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 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