Implement UMA and internal data structure for tracking EWOULDBLOCK.

content/browser/renderer_host/p2p/socket_host_udp.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 "content/browser/renderer_host/p2p/socket_host_udp.h"
 
 #include "base/bind.h"
 #include "base/debug/trace_event.h"
 #include "base/stl_util.h"
 #include "content/browser/renderer_host/p2p/socket_host_throttler.h"
@@ skipping 57 matching lines @@
 P2PSocketHostUdp::P2PSocketHostUdp(IPC::Sender* message_sender,
                                    int socket_id,
                                    P2PMessageThrottler* throttler)
     : P2PSocketHost(message_sender, socket_id),
       socket_(
           new net::UDPServerSocket(GetContentClient()->browser()->GetNetLog(),
                                    net::NetLog::Source())),
       send_pending_(false),
       last_dscp_(net::DSCP_CS0),
       throttler_(throttler) {
+  protocol_type_ = P2PSocketHost::UDP;
 }
 
 P2PSocketHostUdp::~P2PSocketHostUdp() {
   if (state_ == STATE_OPEN) {
     DCHECK(socket_.get());
     socket_.reset();
   }
 }
 
 bool P2PSocketHostUdp::Init(const net::IPEndPoint& local_address,
@@ skipping 118 matching lines @@
 
     if (throttler_->DropNextPacket(data.size())) {
       VLOG(0) << "STUN message is dropped due to high volume.";
       // Do not reset socket.
       return;
     }
   }
 
   if (send_pending_) {
     send_queue_.push_back(PendingPacket(to, data, options, packet_id));
+    if (send_queue_.size() > send_queue_length_max_) {
+      send_queue_length_max_ = send_queue_.size();
+    }
   } else {
     // TODO(mallinath: Remove unnecessary memcpy in this case.
     PendingPacket packet(to, data, options, packet_id);
     DoSend(packet);
   }
 }
 
 void P2PSocketHostUdp::DoSend(const PendingPacket& packet) {
   TRACE_EVENT_ASYNC_STEP_INTO1("p2p", "Send", packet.id, "UdpAsyncSendTo",
                                "size", packet.size);
@@ skipping 20 matching lines @@
   int result = socket_->SendTo(
       packet.data.get(),
       packet.size,
       packet.to,
       base::Bind(&P2PSocketHostUdp::OnSend, base::Unretained(this), packet.id));
 
   // sendto() may return an error, e.g. if we've received an ICMP Destination
   // Unreachable message. When this happens try sending the same packet again,
   // and just drop it if it fails again.
   if (IsTransientError(result)) {
     result = socket_->SendTo(

[juberti2, 2014/10/23 19:38:46]

If I understand this code right, we will never return EWOULDBLOCK here, we will
always send the packet and get a notification in OnSend when the send completes.
Perhaps it would be good to understand how long that takes, i.e. record the
elapsed time in OnSend?

This also means that our timestamping code is doing the wrong thing, we need to
update timestamps whenever we pull a packet off send_queue_, since the stamp is
now incorrect.

[guoweis2, 2014/10/24 06:08:54]

The code should send synchronously most of the time and only calls OnSend when
it can't do that.

For the timestamping issue, I have filed a separate bug 426753 to track
separately.

         packet.data.get(),
         packet.size,
         packet.to,
         base::Bind(&P2PSocketHostUdp::OnSend, base::Unretained(this),
                    packet.id));
   }
 
   if (result == net::ERR_IO_PENDING) {
     send_pending_ = true;
   } else {
@@ skipping 51 matching lines @@
     case P2P_SOCKET_OPT_DSCP:
       return (net::OK == socket_->SetDiffServCodePoint(
           static_cast<net::DiffServCodePoint>(value))) ? true : false;
     default:
       NOTREACHED();
       return false;
   }
 }
 
 }  // namespace content