Expose packet loss counts from QUIC to NetworkQualityEstimator

net/base/socket_performance_watcher.h

 // Copyright 2015 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 NET_BASE_SOCKET_PERFORMANCE_WATCHER_H_
 #define NET_BASE_SOCKET_PERFORMANCE_WATCHER_H_
 
+#include <stddef.h>
+#include <stdint.h>
+
 #include "base/macros.h"
 #include "net/base/net_export.h"
 #include "net/base/socket_performance_watcher_factory.h"
 
 namespace base {
 class TimeDelta;
 }  // namespace base
 
 namespace net {
 
 // SocketPerformanceWatcher is the base class for recording and aggregating
 // socket statistics.
 class NET_EXPORT_PRIVATE SocketPerformanceWatcher {
  public:
   // |socket_performance_watcher_factory| is the factory that constructed
   // |this| watcher.
   SocketPerformanceWatcher(
       const SocketPerformanceWatcherFactory::Protocol protocol,
       SocketPerformanceWatcherFactory* socket_performance_watcher_factory);
 
   virtual ~SocketPerformanceWatcher();
 
   // Called when updated transport layer RTT information is available. This
   // must be the transport layer RTT from this device to the remote transport
   // layer endpoint. This method is called immediately after the observation is
   // made, hence no timestamp.
   void OnUpdatedRTTAvailable(const base::TimeDelta& rtt) const;
 
+  // Called when an updated packet count at the transport layer is available.
+  // All the counts are since the last call to the
+  // OnUpdatedPacketCountAvailable. This method is called immediately after the
+  // observation is made, hence no timestamp.
+
+  // An example:
+  // Last observation after packet #1. Packets #5 and #6 are received:
+  //   missing = 3, in_order = 2, out_of_order = 0.
+
+  // Last observation after packet #6. Packet #3 received:
+  //   missing = 0, in_order = 0, out_of_order = 1.
+  void OnUpdatedPacketCountAvailable(

[Ryan Hamilton, 2016/03/07 20:02:10]

Perhaps s/Updated/Incremental/?

[tbansal1, 2016/03/08 02:59:58]

Done.

+      size_t packets_missing,

[Ryan Hamilton, 2016/03/07 20:02:10]

I was hoping to see a comment here about how out_of_order and missing interact
to determine the packet loss rate. Can you add one?

[tbansal1, 2016/03/08 02:59:58]

There are  2 use cases for this: (1) Report the raw incremental packet count
numbers to the observers (One app based on Cronet is waiting for this CL. They
plan to run their own logic on the raw data).
(2) Compute the packet loss rate for use within Chromium. This would require
figuring out how the 3 counts interact with each other. I added some more
comments in nqe.cc::OnIncrementalPacketCountAvailable() on how this can be done.
I have removed the code for this from this CL since at this point, it is not
clear if it is really needed.

+      size_t packets_received_in_order,
+      size_t packets_received_out_of_order) const;
+
  private:
   // Transport layer protocol used by the socket that |this| is watching.
   const SocketPerformanceWatcherFactory::Protocol protocol_;
 
   // |socket_performance_watcher_factory_| is the factory that created
   // |this| watcher.
   SocketPerformanceWatcherFactory* socket_performance_watcher_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SocketPerformanceWatcher);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_SOCKET_PERFORMANCE_WATCHER_H_