Implement a dummy host to do capturing and analysis only.

remoting/test/counter_stubs.cc

+// Copyright 2016 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 "remoting/test/counter_stubs.h"
+
+#include "base/atomicops.h"
+#include "base/callback.h"
+#include "base/macros.h"
+#include "base/time/time.h"
+#include "remoting/proto/audio.pb.h"
+#include "remoting/proto/control.pb.h"
+#include "remoting/proto/video.pb.h"
+
+#ifndef ARCH_CPU_64_BITS
+#include "base/synchronization/lock.h"
+#endif
+
+namespace remoting {
+namespace test {
+namespace {
+
+template <typename T>
+class NoBarrierAtomic {
+ public:
+  T operator++() {
+    return base::subtle::NoBarrier_AtomicIncrement(&i_, 1) - 1;
+  }
+
+  T operator++(int) {
+    return base::subtle::NoBarrier_AtomicIncrement(&i_, 1);
+  }
+
+  T operator--() {
+    return base::subtle::NoBarrier_AtomicIncrement(&i_, -1) - 1;
+  }
+
+  T operator--(int) {
+    return base::subtle::NoBarrier_AtomicIncrement(&i_, -1);
+  }
+
+  T operator+=(T other) {
+    return base::subtle::NoBarrier_AtomicIncrement(&i_, other);
+  }
+
+  T operator-=(T other) {
+    return base::subtle::NoBarrier_AtomicIncrement(&i_, -other);
+  }
+
+  T operator*() const {
+    return base::subtle::NoBarrier_Load(&i_);
+  }
+
+ private:
+  volatile T i_;
+};
+
+class NoBarrierAtomicInt32 : public NoBarrierAtomic<base::subtle::Atomic32> {};
+#ifdef ARCH_CPU_64_BITS
+class NoBarrierAtomicInt64 : public NoBarrierAtomic<base::subtle::Atomic64> {};
+#else  // ifdef ARCH_CPU_64_BITS
+
+using base::AutoLock;
+
+// A barriered, lock based implementation
+class NoBarrierAtomicInt64 {
+ public:
+
+  int64_t operator++() {
+    AutoLock l(lock_);
+    return i_++;
+  }
+
+  int64_t operator++(int) {
+    AutoLock l(lock_);
+    return ++i_;
+  }
+
+  int64_t operator--() {
+    AutoLock l(lock_);
+    return i_--;
+  }
+
+  int64_t operator--(int) {
+    AutoLock l(lock_);
+    return --i_;
+  }
+
+  int64_t operator+=(int64_t other) {
+    AutoLock l(lock_);
+    return (i_ += other);
+  }
+
+  int64_t operator-=(int64_t other) {
+    AutoLock l(lock_);
+    return (i_ -= other);
+  }
+
+  int64_t operator*() const {
+    AutoLock l(lock_);
+    return i_;
+  }
+
+ private:
+  volatile int64_t i_;
+  mutable base::Lock lock_;  // field is used in operator*() const
+};
+
+#endif  // ifdef ARCH_CPU_64_BITS
+
+class MessageCounter {
+ public:
+  MessageCounter()
+      : count_(),
+        size_(),
+        last_size_(),

[joedow, 2016/05/04 16:40:44]

Why are these members in the init list?  They should have their default c'tor
called automatically.

[Hzj_jie, 2016/05/04 19:18:03]

I prefer to keep count_ and size_ initialized in the list, since they may not
always be basic types.

+        start_time_(base::Time::Now()) {}
+
+  int message_count() const {
+    return *count_;
+  }
+
+  int64_t message_size() const {
+    return *size_;
+  }
+
+  int last_message_size() const {
+    return last_size_;
+  }
+
+  double DurationSeconds() const {
+    return (base::Time::Now() - start_time_).InSecondsF();
+  }
+
+  double MessagesPerSecond() const {
+    return static_cast<double>(message_count()) / DurationSeconds();
+  }
+  double SizePerSecond() const {
+    return static_cast<double>(message_size()) / DurationSeconds();
+  }
+
+  double AverageMessageSize() const {
+    return static_cast<double>(message_size()) / message_count();
+  }
+
+  void LogMessage(const ::google::protobuf::MessageLite& message) {
+    count_++;
+    last_size_ = message.ByteSize();
+    size_ += message.ByteSize();
+  }
+
+ private:
+  NoBarrierAtomicInt32 count_;
+  NoBarrierAtomicInt64 size_;
+  int last_size_;

[joedow, 2016/05/04 16:40:44]

Init basic types inline, not in the initializer list.

[Hzj_jie, 2016/05/04 19:18:03]

Done.

+  base::Time start_time_;
+
+  DISALLOW_COPY_AND_ASSIGN(MessageCounter);
+};
+
+void OutputCounter(std::ostream& os,

[joedow, 2016/05/04 16:40:44]

DisplayStatistics?

Why isn't this part of the MessageCounter class? Each class knows it's type and
counter member.

[Hzj_jie, 2016/05/04 19:18:04]

Done.

+                   const char* name,
+                   const MessageCounter& counter) {
+  os << name
+     << ": "
+     << counter.message_size()
+     << " bytes in "
+     << counter.message_count()
+     << " packages, last package "
+     << counter.last_message_size()
+     << " bytes, "
+     << counter.AverageMessageSize()
+     << " bytes/package, "
+     << counter.MessagesPerSecond()
+     << " packages/sec, "
+     << counter.SizePerSecond()
+     << " bytes/sec"
+     << std::endl;
+}
+
+}  // namespace
+
+class CounterStubs::CounterClientStub
+    : public protocol::ClientStub, public MessageCounter {
+ public:
+  void DeliverHostMessage(const protocol::ExtensionMessage& message) override {
+    LogMessage(message);
+  }
+  void InjectClipboardEvent(const protocol::ClipboardEvent& event) override {}
+  void SetCapabilities(const protocol::Capabilities& capabilities) override {}
+  void SetCursorShape(const protocol::CursorShapeInfo& cursor_shape) override {}
+  void SetPairingResponse(const protocol::PairingResponse& response) override {}
+  void SetVideoLayout(const protocol::VideoLayout& video_layout) override {}
+};
+
+class CounterStubs::CounterHostStub
+    : public protocol::HostStub, public MessageCounter {
+ public:

[joedow, 2016/05/04 16:40:44]

Add a comment to note which methods belong to the Stub class you are deriving
from.  Same for the other class in this file.

[Hzj_jie, 2016/05/04 19:18:04]

Done.

+  void ControlAudio(const protocol::AudioControl& audio_control) override {}
+  void ControlVideo(const protocol::VideoControl& video_control) override {}
+  void DeliverClientMessage(
+      const protocol::ExtensionMessage& message) override {
+    LogMessage(message);
+  }
+  void NotifyClientResolution(
+      const protocol::ClientResolution& resolution) override {}
+  void RequestPairing(
+      const protocol::PairingRequest& pairing_request) override {}
+  void SetCapabilities(const protocol::Capabilities& capabilities) override {}
+};
+
+class CounterStubs::CounterAudioStub
+    : public protocol::AudioStub, public MessageCounter {
+ public:
+  void ProcessAudioPacket(std::unique_ptr<AudioPacket> audio_packet,
+                          const base::Closure& done) override {
+    if (audio_packet) {
+      LogMessage(*audio_packet);

[joedow, 2016/05/04 16:40:44]

Since you are using unique_ptr, I think it wuold be clearer to use the get
method instead of dereference (audio_packet.get()) instead of *audio_packet. 
This practice is what I have seen in the other parts of our codebase as well.

[Hzj_jie, 2016/05/04 19:18:03]

Then I will need to pass a pointer of MessageLite into LogMessage function, and
do another != nullptr check.

+    }
+    done.Run();
+  }
+};
+
+class CounterStubs::CounterVideoStub
+    : public protocol::VideoStub, public MessageCounter {
+ public:
+  CounterVideoStub(protocol::FakeConnectionToClient* connection)
+      : connection_(connection) {}
+
+  void ProcessVideoPacket(std::unique_ptr<VideoPacket> video_packet,
+                          const base::Closure& done) override {
+    if (video_packet && video_packet->has_capture_overhead_time_ms()) {
+      // Not a keepalive packet

[joedow, 2016/05/04 16:40:44]

comments should end with a period.

[Hzj_jie, 2016/05/04 19:18:03]

Done.

+      if (connection_ &&
+          connection_->video_feedback_stub()) {
+        std::unique_ptr<VideoAck> ack(new VideoAck());
+        ack->set_frame_id(video_packet->frame_id());
+        connection_->video_feedback_stub()->ProcessVideoAck(std::move(ack));
+      }
+      LogMessage(*video_packet);
+    }
+    done.Run();
+  }
+
+ private:
+  protocol::FakeConnectionToClient* connection_ = nullptr;
+};
+
+CounterStubs::CounterStubs(protocol::FakeConnectionToClient* connection)
+  : client_stub_(new CounterClientStub()),
+    host_stub_(new CounterHostStub()),
+    audio_stub_(new CounterAudioStub()),
+    video_stub_(new CounterVideoStub(connection)) {}
+
+CounterStubs::~CounterStubs() {}
+
+protocol::ClientStub& CounterStubs::client_stub() {
+  return *client_stub_;

[joedow, 2016/05/04 16:40:44]

client_stub_.get()...alternatively, you could return a pointer from these
methods (this is pretty common in our codebase).

[Hzj_jie, 2016/05/04 19:18:04]

Done.

+}
+
+protocol::HostStub& CounterStubs::host_stub() {
+  return *host_stub_;
+}
+
+protocol::AudioStub& CounterStubs::audio_stub() {
+  return *audio_stub_;
+}
+
+protocol::VideoStub& CounterStubs::video_stub() {
+  return *video_stub_;
+}
+
+std::ostream& operator<<(std::ostream& os, const CounterStubs& stubs) {
+  OutputCounter(os, "audio", *stubs.audio_stub_);
+  OutputCounter(os, "video", *stubs.video_stub_);
+  OutputCounter(os, "client", *stubs.client_stub_);
+  OutputCounter(os, "host", *stubs.host_stub_);
+  return os;
+}
+
+}  // namespace test
+}  // namespace remoting