Temporary commit to evaluate perf impact of prototype CPU profiler

base/profiler/cpu_profiler.cc

Index: base/profiler/cpu_profiler.cc
diff --git a/base/profiler/cpu_profiler.cc b/base/profiler/cpu_profiler.cc
new file mode 100644
index 0000000000000000000000000000000000000000..48014ce4195043911fee1d32425bbd7b2c8e0acb
--- /dev/null
+++ b/base/profiler/cpu_profiler.cc
@@ -0,0 +1,174 @@
+// 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.
+
+#include "base/profiler/cpu_profiler.h"
+
+#include <stddef.h>
+
+#include "base/debug/stack_trace.h"
+#include "base/metrics/field_trial.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/threading/thread_id_name_manager.h"
+#include "base/time/time.h"
+#include "base/timer/elapsed_timer.h"
+
+namespace base {
+
+namespace {
+
+const char kMode[] = "Mode";
+const char kInitialDelay[] = "InitialDelay";
+const char kNumberOfBursts[] = "NumberOfBursts";
+const char kBurstIdleTime[] = "IdleTime";
+const char kNumberOfSamples[] = "NumberOfSamples";
+const char kSamplingSleepTime[] = "SamplingSleepTime";
+
+}  // namespace
+
+class CpuProfiler::SamplingThread : public PlatformThread::Delegate {
+ public:
+  SamplingThread(CpuProfiler* cpu_profiler);
+  ~SamplingThread() override;
+
+  // Implementation of PlatformThread::Delegate:
+  void ThreadMain() override;
+
+  void Stop();
+
+  void GetSamples();
+
+ private:
+  CpuProfiler* cpu_profiler_;
+
+  bool thread_running_;
+
+  base::WaitableEvent waitable_event_;
+
+  DISALLOW_COPY_AND_ASSIGN(SamplingThread);
+};
+
+CpuProfiler::SamplingThread::SamplingThread(CpuProfiler* cpu_profiler)
+    : cpu_profiler_(cpu_profiler),
+      thread_running_(false),
+      waitable_event_(false, false) {
+}
+
+CpuProfiler::SamplingThread::~SamplingThread() {}
+
+void CpuProfiler::SamplingThread::ThreadMain() {
+  PlatformThread::SetName("Chrome_CPUProfilerThread");
+  thread_running_ = true;
+
+  if (cpu_profiler_->GetStringParam(kMode) == "bursts") {
+    int64 initial_delay = cpu_profiler_->GetInt64Param(kInitialDelay);
+    int number_of_bursts = cpu_profiler_->GetIntParam(kNumberOfBursts);
+    int64 burst_idle_time = cpu_profiler_->GetInt64Param(kBurstIdleTime);
+    int number_of_samples = cpu_profiler_->GetIntParam(kNumberOfSamples);
+    int64 sampling_sleep_time =
+        cpu_profiler_->GetInt64Param(kSamplingSleepTime);
+
+    if (waitable_event_.TimedWait(TimeDelta::FromMicroseconds(initial_delay)))
+      return;
+    for (int i = 0; i < number_of_bursts; ++i) {
+      int64 delta = 0;
+      for (int j = 0; ; ++j) {
+        base::ElapsedTimer time;
+        GetSamples();
+        delta = time.Elapsed().InMicroseconds();
+        if (j == (number_of_samples - 1))
+          break;
+        if (delta < sampling_sleep_time) {
+          if (waitable_event_.TimedWait(
+              TimeDelta::FromMicroseconds(sampling_sleep_time - delta)))
+            return;
+        } else {
+          if (waitable_event_.TimedWait(
+              TimeDelta::FromMicroseconds(sampling_sleep_time)))
+            return;
+        }
+      }
+      if (waitable_event_.TimedWait(
+          TimeDelta::FromMicroseconds(burst_idle_time - delta)))
+        return;
+    }
+  }
+}
+
+void CpuProfiler::SamplingThread::Stop() {
+  waitable_event_.Signal();
+}
+
+void CpuProfiler::SamplingThread::GetSamples() {
+  cpu_profiler_->OnTimer();
+}
+
+void CpuProfiler::SamplingThreadDeleter::operator()(
+    SamplingThread* thread) const {
+  delete thread;
+}
+
+void CpuProfiler::Initialize(const std::map<std::string, std::string>* params) {
+  if (!CpuProfiler::IsPlatformSupported())
+    return;
+
+  std::map<std::string, std::string> default_params;
+  default_params[kMode] = "bursts";
+  default_params[kInitialDelay] = "0"; // 0 sec
+  default_params[kNumberOfBursts] = "1";
+  default_params[kBurstIdleTime] = "10000000"; // 10 sec
+  default_params[kNumberOfSamples] = "300";
+  default_params[kSamplingSleepTime] = "100000"; // 100 ms
+
+  if (!params)
+    SetParams(default_params);
+  else
+    SetParams(*params);
+
+  sampling_thread_.reset(new SamplingThread(this));
+  if (!PlatformThread::Create(0, sampling_thread_.get(),
+                              &sampling_thread_handle_)) {
+    LOG(ERROR) << "failed to create thread";
+  }
+}
+
+void CpuProfiler::Stop() {
+  if (sampling_thread_)
+    sampling_thread_->Stop();
+}
+
+
+std::string CpuProfiler::GetStringParam(const std::string& key) const{
+  const auto entry = params_.find(key);
+  if (entry != params_.end()) {
+    return entry->second;
+  }
+  return "";
+}
+
+int CpuProfiler::GetIntParam(const std::string& key) const {
+  const auto entry = params_.find(key);
+  if (entry != params_.end()) {
+    int output;
+    if (base::StringToInt(entry->second, &output))
+      return output;
+  }
+  return 0;
+}
+
+int64 CpuProfiler::GetInt64Param(const std::string& key) const {
+  const auto entry = params_.find(key);
+  if (entry != params_.end()) {
+    int64 output;
+    if (base::StringToInt64(entry->second, &output))
+      return output;
+  }
+  return 0;
+}
+
+void CpuProfiler::SetParams(
+    const std::map<std::string, std::string>& params) {
+  params_ = params;
+}
+
+}  // namespace base