Add systemInfo.cpu.onUpdated event implementation.

chrome/browser/extensions/api/system_info_cpu/cpu_info_provider.cc

 // Copyright (c) 2012 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 "chrome/browser/extensions/api/system_info_cpu/cpu_info_provider.h"
 
 #include "base/sys_info.h"
+#include "chrome/common/chrome_notification_types.h"
+#include "content/public/browser/browser_thread.h"
+#include "content/public/browser/notification_details.h"
+#include "content/public/browser/notification_service.h"
+#include "content/public/browser/notification_source.h"
+#include "content/public/browser/notification_types.h"
 
 namespace extensions {
 
 using api::experimental_system_info_cpu::CpuInfo;
+using api::experimental_system_info_cpu::CpuUpdateInfo;
+using content::BrowserThread;
+
+// Default sampling interval is 1000ms.
+const unsigned int kDefaultSamplingIntervalMs = 1000;
+
+CpuInfoProvider::CpuInfoProvider()
+  : is_sampling_started_(false),
+    sampling_timer_(NULL),
+    sampling_interval_(kDefaultSamplingIntervalMs) {
+  registrar_.Add(this, chrome::NOTIFICATION_APP_TERMINATING,
+                 content::NotificationService::AllSources());
+}
+
+CpuInfoProvider::~CpuInfoProvider() {
+  DCHECK(sampling_timer_ == NULL);
+  registrar_.RemoveAll();
+}
 
 bool CpuInfoProvider::QueryInfo(CpuInfo* info) {
   if (info == NULL)
     return false;
 
   info->num_of_processors = base::SysInfo::NumberOfProcessors();
   info->arch_name = base::SysInfo::CPUArchitecture();
   info->model_name = base::SysInfo::CPUModelName();
   return true;
 }
 
-bool CpuInfoProvider::StartSampling(const QueryCpuTimeCallback& callback) {
-  // TODO(hongbo): Implement sampling functionality for event router.
-  return false;
+void CpuInfoProvider::StartSampling(const SamplingCallback& callback) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  BrowserThread::PostTask(
+      BrowserThread::FILE,
+      FROM_HERE,
+      base::Bind(&CpuInfoProvider::StartSamplingOnFileThread,
+                 base::Unretained(this), callback));
 }
 
-bool CpuInfoProvider::StopSampling() {
-  // TODO(hongbo): Implement sampling functionality for event router.
-  return false;
+void CpuInfoProvider::StopSampling() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  BrowserThread::PostTask(
+      BrowserThread::FILE,
+      FROM_HERE,
+      base::Bind(&CpuInfoProvider::StopSamplingOnFileThread,
+                 base::Unretained(this)));
 }
 
 // static
 CpuInfoProvider* CpuInfoProvider::Get() {
   return CpuInfoProvider::GetInstance<CpuInfoProvider>();
 }
 
+void CpuInfoProvider::Observe(int type,
+                       const content::NotificationSource& source,

[benwells, 2012/10/04 06:58:59]

Nit: fix indenting here. If you have room line up the types inside the bracket:

foo bar(int type,
        const content::.....

otherwise move down a line and indent 4 spaces:

foo bar(
    int type,
    const content::.....

[Hongbo Min, 2012/10/05 02:40:56]

Done.

+                       const content::NotificationDetails& details) {
+  switch (type) {
+    case chrome::NOTIFICATION_APP_TERMINATING:
+      StopSampling();
+      break;
+    default:
+      NOTREACHED();
+      break;
+  }
+}
+
+void CpuInfoProvider::StartSamplingOnFileThread(
+    const SamplingCallback& callback) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+  if (is_sampling_started_)
+    return;
+
+  if (!QueryCpuTimePerProcessor(&baseline_cpu_time_))
+    return;
+
+  is_sampling_started_ = true;
+  callback_ = callback;
+  DCHECK(!sampling_timer_) << "The sampling timer is leaked. Did you forgot "

[benwells, 2012/10/04 06:58:59]

Nit: The sampling timer has leaked. Did you forget to call...

[Hongbo Min, 2012/10/05 02:40:56]

Done.

+                              "calling StopSampling?";
+  // Should be deleted on FILE thread.
+  sampling_timer_ = new base::RepeatingTimer<CpuInfoProvider>();
+  sampling_timer_->Start(FROM_HERE,
+      base::TimeDelta::FromMilliseconds(sampling_interval_),
+      this, &CpuInfoProvider::DoSample);
+}
+
+void CpuInfoProvider::StopSamplingOnFileThread() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+  if (!is_sampling_started_) return;
+  delete sampling_timer_;
+  sampling_timer_ = NULL;
+  baseline_cpu_time_.clear();
+  is_sampling_started_ = false;
+}
+
+void CpuInfoProvider::DoSample() {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::FILE));
+
+  std::vector<CpuTime> next_cpu_time;
+  if (!QueryCpuTimePerProcessor(&next_cpu_time))
+    return;
+
+  // Calculate the CPU usage information from the next_cpu_time and
+  // |baseline_cpu_time_|.
+  double total_usage = 0;
+  scoped_ptr<CpuUpdateInfo> info(new CpuUpdateInfo());
+  for (size_t i = 0; i < next_cpu_time.size(); ++i) {
+    double total_time =
+        (next_cpu_time[i].user - baseline_cpu_time_[i].user) +
+        (next_cpu_time[i].kernel - baseline_cpu_time_[i].kernel) +
+        (next_cpu_time[i].idle - baseline_cpu_time_[i].idle);
+    double idle_time = next_cpu_time[i].idle - baseline_cpu_time_[i].idle;
+
+    double usage = 0;
+    if (total_time != 0)
+      usage = (100 - idle_time * 100 / total_time);
+    info->usage_per_processor.push_back(usage);
+    total_usage += usage;
+  }
+
+  info->average_usage = total_usage / next_cpu_time.size();
+  if (!callback_.is_null())
+    callback_.Run(info.Pass());
+  // Use next_cpu_time as baseline_cpu_time_ for the next sampling cycle.
+  baseline_cpu_time_.swap(next_cpu_time);
+}
+
 }  // namespace extensions