Implement video frame acknowledgements in the chromoting protocol.

remoting/protocol/host_video_dispatcher.cc

Index: remoting/protocol/host_video_dispatcher.cc
diff --git a/remoting/protocol/host_video_dispatcher.cc b/remoting/protocol/host_video_dispatcher.cc
index b9a12c0294f28ac8e95d65ca52c8e6c000e8334f..95778e13eeb90cc8537d80cd7641db6b62c14edd 100644
--- a/remoting/protocol/host_video_dispatcher.cc
+++ b/remoting/protocol/host_video_dispatcher.cc
@@ -5,24 +5,84 @@
 #include "remoting/protocol/host_video_dispatcher.h"
 
 #include "base/bind.h"
+#include "base/callback_helpers.h"
 #include "net/socket/stream_socket.h"
 #include "remoting/base/constants.h"
-#include "remoting/proto/video.pb.h"
+#include "remoting/protocol/errors.h"
 #include "remoting/protocol/message_serialization.h"
 
 namespace remoting {
 namespace protocol {
 
+HostVideoDispatcher::PendingFrame::PendingFrame(
+    int frame_id,
+    const ProgressCallback& progress_callback)
+    : frame_id(frame_id), progress_callback(progress_callback) {
+}
+
 HostVideoDispatcher::HostVideoDispatcher()
-    : ChannelDispatcherBase(kVideoChannelName) {
+    : ChannelDispatcherBase(kVideoChannelName),
+      frame_id_(0),
+      parser_(
+          base::Bind(&HostVideoDispatcher::OnVideoAck, base::Unretained(this)),
+          reader()) {
 }
 
 HostVideoDispatcher::~HostVideoDispatcher() {
 }
 
-void HostVideoDispatcher::ProcessVideoPacket(scoped_ptr<VideoPacket> packet,
-                                             const base::Closure& done) {
-  writer()->Write(SerializeAndFrameMessage(*packet), done);
+void HostVideoDispatcher::ProcessVideoPacket(
+    scoped_ptr<VideoPacket> packet,
+    const ProgressCallback& progress_callback) {
+  if (SupportsAcks()) {
+    packet->set_frame_id(frame_id_);
+    pending_frames_.push_back(PendingFrame(frame_id_, progress_callback));
+    frame_id_++;
+  }
+
+  writer()->Write(
+      SerializeAndFrameMessage(*packet),
+      base::Bind(&HostVideoDispatcher::OnPacketSent, base::Unretained(this),
+                 progress_callback));
+}
+
+bool HostVideoDispatcher::SupportsAcks() {
+  return channel_config().version > kVideoStreamVersionNoAck;
+}
+
+void HostVideoDispatcher::OnPacketSent(
+    const ProgressCallback& progress_callback) {
+  progress_callback.Run(PacketProgress::SENT);
+
+  // For older clients that don't send explicit video Ack message call notify
+  // DONE state as soon as the frame is pushed to the channel.
+  if (!SupportsAcks())
+    progress_callback.Run(PacketProgress::DONE);
+}
+
+void HostVideoDispatcher::OnVideoAck(scoped_ptr<VideoAck> ack,
+                                     const base::Closure& done) {
+  base::ScopedClosureRunner done_runner(done);
+
+  if (!SupportsAcks()) {
+    LOG(ERROR) << "Unexpected VideoAck message received.";
+    return;
+  }
+
+  if (pending_frames_.empty() ||
+      pending_frames_.front().frame_id != ack->frame_id()) {
+    NotifyError(INCOMPATIBLE_PROTOCOL);
+    return;
+  }
+
+  // TODO(sergeyu): Currently the latency information in |ack| is ignored.
+  // Expose it from this class so that CaptureScheduler can utilize it somehow.
+  // See crbug.com/453177 .
+
+  ProgressCallback progress_callback =
+      pending_frames_.front().progress_callback;
+  pending_frames_.pop_front();
+  progress_callback.Run(PacketProgress::DONE);
 }
 
 }  // namespace protocol