[Chromoting] Retrieve process resource usage (ProcessStats) and its tests

remoting/host/process_stats_sender.h

+// Copyright 2017 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.
+
+#ifndef REMOTING_HOST_PROCESS_STATS_H_

[joedow, 2017/04/24 17:16:09]

fix the macro guard (REMOTING_HOST_PROCESS_STATS_SENDER_H_)

[Hzj_jie, 2017/04/25 00:17:54]

Done.

+#define REMOTING_HOST_PROCESS_STATS_H_
+
+#include <memory>
+#include <vector>
+
+#include "base/threading/thread_checker.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "remoting/host/process_stats_agent.h"

[joedow, 2017/04/24 17:16:09]

ProcessStatsAgent can be forward decalared

[Hzj_jie, 2017/04/25 00:17:53]

Done.

+#include "remoting/proto/process_stats.pb.h"
+#include "remoting/protocol/process_stats_stub.h"
+
+namespace remoting {
+
+// A component to report process statistic data regularly.
+class ProcessStatsSender final {
+ public:
+  // ProcessStatsSender starts immediately, and reports the statistic data to

[joedow, 2017/04/24 17:16:09]

nit: remove comma and 'the'

[Hzj_jie, 2017/04/25 00:17:53]

Done.

+  // |host_stats_stub| once per |interval_|.

[joedow, 2017/04/24 17:16:09]

s/interval_/interval

[Hzj_jie, 2017/04/25 00:17:53]

Done.

+  // ProcessStatsSender does not take the ownership of |host_stats_stub|. It
+  // must outlive the ProcessStatsSender object.
+  ProcessStatsSender(protocol::ProcessStatsStub* host_stats_stub,
+                     base::TimeDelta interval);
+
+  // ProcessStatsSender stops in destruction. The ProcessStatsSender object
+  // needs to be destructed on the same thread as constructing.

[joedow, 2017/04/24 17:16:09]

You might want to move the thread requirements into the documentation for the
class.  Then again, having a thread checker as a member typically implies that
it needs to be created/destroyed on the same thread.

[Hzj_jie, 2017/04/25 00:17:54]

Done.

+  ~ProcessStatsSender();
+
+  void AddProcessStatsAgent(std::unique_ptr<ProcessStatsAgent> agent);
+
+ private:

[joedow, 2017/04/24 17:16:09]

Do you want a private c'tor here?

[Hzj_jie, 2017/04/25 00:17:53]

Sorry, I do not follow. Why?

[joedow, 2017/04/25 15:57:28]

To prevent someone from creating a uninitialized instance (i.e. an instance w/o
a valid host_stats-stub and interval).

[Hzj_jie, 2017/04/25 22:19:19]

Ah, that seems not necessary. An explicit constructor (say, the one in line 27)
will always suppress the default constructor. See http://cpp.sh/4bb4.

+  void ReportUsage();
+
+  protocol::ProcessStatsStub* const host_stats_stub_;
+  const base::TimeDelta interval_;
+  std::vector<std::unique_ptr<ProcessStatsAgent>> agents_;
+  base::RepeatingTimer timer_;
+  base::ThreadChecker thread_checker_;
+};
+
+}  // namespace remoting
+
+#endif  // REMOTING_HOST_PROCESS_STATS_H_