Allow packets to be reordered in the fake network pipe.

webrtc/test/fake_network_pipe.h

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_TEST_FAKE_NETWORK_PIPE_H_
 #define WEBRTC_TEST_FAKE_NETWORK_PIPE_H_
 
+#include <set>
+#include <string.h>
 #include <queue>
 
 #include "webrtc/base/constructormagic.h"
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/base/scoped_ptr.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 
 class Clock;
 class CriticalSectionWrapper;
-class NetworkPacket;
 class PacketReceiver;
 
+class NetworkPacket {
+ public:
+  NetworkPacket(const uint8_t* data, size_t length, int64_t send_time,
+      int64_t arrival_time)
+      : data_(new uint8_t[length]),
+        data_length_(length),
+        send_time_(send_time),
+        arrival_time_(arrival_time) {
+    memcpy(data_.get(), data, length);
+  }
+
+  uint8_t* data() const { return data_.get(); }
+  size_t data_length() const { return data_length_; }
+  int64_t send_time() const { return send_time_; }
+  int64_t arrival_time() const { return arrival_time_; }
+  void IncrementArrivalTime(int64_t extra_delay) {
+    arrival_time_+= extra_delay;
+  }
+
+ private:
+  // The packet data.
+  rtc::scoped_ptr<uint8_t> data_;
+  // Length of data_.
+  size_t data_length_;
+  // The time the packet was sent out on the network.
+  const int64_t send_time_;
+  // The time the packet should arrive at the reciver.

[stefan-webrtc, 2016/01/25 13:16:57]

s/reciver/receiver

[philipel, 2016/01/26 10:50:47]

Done.

+  int64_t arrival_time_;
+};
+
 // Class faking a network link. This is a simple and naive solution just faking
 // capacity and adding an extra transport delay in addition to the capacity
 // introduced delay.
 
 // TODO(mflodman) Add random and bursty packet loss.
 class FakeNetworkPipe {
  public:
   struct Config {
     Config() {}
     // Queue length in number of packets.
     size_t queue_length_packets = 0;
     // Delay in addition to capacity induced delay.
     int queue_delay_ms = 0;
     // Standard deviation of the extra delay.
     int delay_standard_deviation_ms = 0;
     // Link capacity in kbps.
     int link_capacity_kbps = 0;
     // Random packet loss.
     int loss_percent = 0;
+    // If packets are allowed to be reordered.
+    bool allow_reordering = false;
   };
 
   FakeNetworkPipe(Clock* clock, const FakeNetworkPipe::Config& config);
   ~FakeNetworkPipe();
 
   // Must not be called in parallel with SendPacket or Process.
   void SetReceiver(PacketReceiver* receiver);
 
   // Sets a new configuration. This won't affect packets already in the pipe.
   void SetConfig(const FakeNetworkPipe::Config& config);
@@ skipping 10 matching lines @@
   float PercentageLoss();
   int AverageDelay();
   size_t dropped_packets() { return dropped_packets_; }
   size_t sent_packets() { return sent_packets_; }
 
  private:
   Clock* const clock_;
   mutable rtc::CriticalSection lock_;
   PacketReceiver* packet_receiver_;
   std::queue<NetworkPacket*> capacity_link_;
-  std::queue<NetworkPacket*> delay_link_;
+
+  // Since we need to access both the packet with the earliest and latest
+  // arrival time we need to use a multiset to keep all packets sorted,
+  // hence, we cannot use a priority queue.

[stefan-webrtc, 2016/01/25 13:16:57]

I guess it's also a way to make sure that the packets are delivered in arrival
time order, which may not be the case now that we introduced reordering?

[philipel, 2016/01/26 10:50:47]

The packets are always delivered in arrival time order, only now we allow the
arrival time to be modified in such a way that reordering occurs.

[stefan-webrtc, 2016/01/26 11:50:46]

Yes, and that's one of the reasons why you need a sorted data structure, since
otherwise the modified arrival time would be out of order. You may want to add
that to the comment, but I can live without it.

+  struct PacketArrivalTimeComparator {
+    bool operator()(const NetworkPacket* p1, const NetworkPacket* p2) {
+      return p1->arrival_time() < p2->arrival_time();
+    }
+  };
+  std::multiset<NetworkPacket*, PacketArrivalTimeComparator> delay_link_;
 
   // Link configuration.
   Config config_;
 
   // Statistics.
   size_t dropped_packets_;
   size_t sent_packets_;
   int total_packet_delay_;
 
   int64_t next_process_time_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(FakeNetworkPipe);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_TEST_FAKE_NETWORK_PIPE_H_