[chromeos/about:power] Collect cpuidle and cpufreq stats

chrome/browser/chromeos/power/cpu_data_collector.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 "base/bind.h"
+#include "chrome/browser/chromeos/power/cpu_data_collector.h"
+#include "chrome/browser/chromeos/power/power_data_collector.h"
+
+namespace chromeos {
+
+namespace {
+// The CPU data is sampled every |kCpuDataSamplePeriodSec| seconds.
+const int kCpuDataSamplePeriodSec = 30
+
+// Sequence name for blocking pool sequenced tasks.
+const char kCpuDataCollectionSequenceName[] =
+    "chromeos_power_cpu_data_collector_sequence";
+}
+
+CpuDataCollector::CpuDataCollector() {
+}
+
+CpuDataCollector::~CpuDataCollector() {
+  time_.Stop();

[Daniel Erat, 2014/01/30 15:47:51]

is this supposed to be timer_? you don't need to stop it; it'll stop
automatically when it's destroyed

+}
+
+void CpuDataCollector::Start() {
+  timer_.Start(FROM_HERE,
+               base::TimeDelta::FromSeconds(kCpuDataSamplePeriodSec),
+               this,
+               &CpuDataCollector::PostCollectSample);
+}
+
+void CpuDataCollector::Lock() {
+}
+
+void CpuDataCollector::PostCollectSample() {
+  content::BrowserThread::PostBlockingPoolSequencedTask(

[Daniel Erat, 2014/01/30 15:47:51]

use PostBlockingPoolTaskAndReply() instead, like i think i recommended earlier.
you don't need sequencing semantics here, since all of your tasks are identical.
and you should use the AndReply variant so the data will be posted back to the
ui thread, eliminating the need for synchronization.

// first, add a WeakPtrFactory member

// then, do this here:
IdleSample* idle = new IdleSample;
FreqSample* freq = new FreqSample;
content::BrowserThread::PostBlockingPoolTaskAndReply(
    FROM_HERE,
    base::Bind(&CpuDataCollector::ReadDataOnBlockingPool,
               weak_factory_.GetWeakPtr(), idle, freq),
    base::Bind(&CpuDataCollector::SaveData, weak_factory_.GetWeakPtr(),
               base::Owned(idle), base::Owned(freq));

void CpuDataCollector::ReadDataOnBlockingPool(IdleSample* idle,
                                              FreqSample* freq) {
  DCHECK(!BrowserThread::CurrentlyOn(BrowserThread::UI));
  // read from sysfs and update |*idle| and |*freq|
}

void CpuDataCollector::SaveData(IdleSample* idle, FreqSample* freq) {
  DCHECK(content::BrowserThread::CurrentlyOn(BrowserThread::UI));
  cpu_idle_state_data_.push_back(*idle);
  cpu_freq_state_data_.push_back(*freq);
}

+      kCpuDataCollectionSequenceName,
+      FROM_HERE,
+      base::Bind(&CpuDataCollector::CollectSample, base::Unretained(this)));
+}
+
+void CpuDataCollector::CollectSample() {
+  // Read samples from sysfs
+
+  Lock();
+  // Add samples to cpu_idle_state_data_ and cpu_freq_state_data_
+  Unlock();
+}
+
+}  // namespace chromeos