chrome power profiler chrome side changes

content/browser/power_profiler/power_profiler_service.cc

+// Copyright 2014 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 "content/public/browser/power_profiler_service.h"
+
+#include "base/bind.h"
+#include "base/message_loop/message_loop.h"
+#include "base/threading/sequenced_worker_pool.h"
+#include "content/public/browser/browser_thread.h"
+
+namespace content {
+
+PowerProfilerService::PowerProfilerService()
+    : delay_(0)
+    , status_(UNINITIALIZED)
+    , data_provider_(PowerDataProviderFactory::Create()) {
+
+  if (!data_provider_->IsDummy()) {
+      status_ = INITIALIZED;
+      InitializeDelays();
+      task_runner_ = BrowserThread::GetBlockingPool()->GetSequencedTaskRunner(
+          BrowserThread::GetBlockingPool()->GetSequenceToken());
+  }
+  DCHECK(base::MessageLoop::current());

[qsr, 2014/01/22 15:30:01]

Not really useful. More useful would be to test you are on the UI thread.

+}
+
+PowerProfilerService::~PowerProfilerService() {
+  if (query_power_timer_.IsRunning())
+    query_power_timer_.Stop();

[qsr, 2014/01/22 15:30:01]

Not needed. Destroying the timer will stop it.

+}
+
+void PowerProfilerService::InitializeDelays() {
+  delays_[PowerProfilerObserver::LOW] = 4000;
+  delays_[PowerProfilerObserver::NORMAL] = 200;
+  delays_[PowerProfilerObserver::HIGH] = 50;
+}
+
+PowerProfilerService* PowerProfilerService::GetInstance() {
+  return Singleton<PowerProfilerService>::get();
+}
+
+void PowerProfilerService::AddObserver(PowerProfilerObserver* obs) {
+  if (UNINITIALIZED == status_)
+    return;
+
+  observers_.insert(obs);
+  UpdateResolution();
+  if (observers_.size() == 1)
+    Start();
+}
+
+void PowerProfilerService::RemoveObserver(PowerProfilerObserver* obs) {
+  observers_.erase(obs);
+  UpdateResolution();
+  if (observers_.empty())
+    Stop();
+}
+
+void PowerProfilerService::UpdateResolution() {
+  if (UNINITIALIZED == status_)
+    return;
+
+  PowerProfilerObserver::Resolution resolution = PowerProfilerObserver::LOW;
+  std::set<PowerProfilerObserver*>::iterator it = observers_.begin();
+  for (; it != observers_.end(); ++it)
+      if ((*it)->resolution() > resolution)
+          resolution = (*it)->resolution();
+
+  // if delay_ will be reset, reschedule the timer immediately
+  if (delay_ != delays_[resolution]) {
+      delay_ = delays_[resolution];
+
+      if (query_power_timer_.IsRunning()) {
+          query_power_timer_.Stop();

[qsr, 2014/01/22 15:30:01]

Stop is not useful, restarting it will stop the current one.

+          query_power_timer_.Start(FROM_HERE,
+              base::TimeDelta::FromMilliseconds(delay_), this,
+              &PowerProfilerService::OnTimer);
+      }
+  }
+}
+
+void PowerProfilerService::Start() {
+  DCHECK (!query_power_timer_.IsRunning() && delay_);
+  status_ = PROFILING;
+
+  // send out power events immediately.
+  task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&PowerProfilerService::ProcessData, base::Unretained(this)));
+
+  query_power_timer_.Start(FROM_HERE,
+      base::TimeDelta::FromMilliseconds(delay_), this,
+      &PowerProfilerService::OnTimer);
+}
+
+void PowerProfilerService::Stop() {
+  // stop timer, set status to INITIALIZED
+  if (PROFILING == status_) {
+    query_power_timer_.Stop();
+    status_ = INITIALIZED;
+  }
+}
+
+void PowerProfilerService::OnTimer() {
+  task_runner_->PostTask(
+      FROM_HERE,
+      base::Bind(&PowerProfilerService::ProcessData, base::Unretained(this)));
+}
+
+void PowerProfilerService::Notify(PowerEvent* event) {

[qsr, 2014/01/22 15:30:01]

You do not want to notify from your task runner, as the observer have absolutely
no reason to be thread safe. Delegate the power event back to the main thread.
Moreover, that also creates a concurrency issue accessing observers_.

+  std::set<PowerProfilerObserver*>::iterator it = observers_.begin();
+  for (; it != observers_.end(); ++it)
+    (*it)->Send(event);
+}
+
+void PowerProfilerService::ProcessData() {
+  if (PROFILING != status_)
+    return;
+
+  // Get Data and Notify
+  PowerEvent event;
+  if(data_provider_->GetData(&event))
+    Notify(&event);
+}
+
+}  // namespace content