Implement the NackModule as part of the new jitter buffer.

webrtc/modules/video_coding/nack_module_unittest.cc

Index: webrtc/modules/video_coding/nack_module_unittest.cc
diff --git a/webrtc/modules/video_coding/nack_module_unittest.cc b/webrtc/modules/video_coding/nack_module_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..bc5e0b87c739ab8df4e2ff722ec26fb54306a425
--- /dev/null
+++ b/webrtc/modules/video_coding/nack_module_unittest.cc
@@ -0,0 +1,154 @@
+/*
+ *  Copyright (c) 2016 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.
+ */
+
+#include <cstring>
+#include "testing/gtest/include/gtest/gtest.h"
+#include "webrtc/modules/video_coding/include/video_coding_defines.h"
+#include "webrtc/modules/video_coding/nack_module.h"
+#include "webrtc/system_wrappers/include/clock.h"
+
+namespace webrtc {
+class TestNackModule : public ::testing::Test,
+                       public VCMNackSender,
+                       public VCMKeyFrameRequestSender {
+ protected:
+  TestNackModule()
+      : clock_(new SimulatedClock(0)),
+        nack_module_(CriticalSectionWrapper::CreateCriticalSection(),
+                     clock_.get(),
+                     this,
+                     this),
+        keyframes_requested_(0) {}
+
+  int32_t SendNack(const uint16_t* sequence_numbers, uint16_t length) override {
+    for (int s = 0; s < length; ++s) {
+      sent_nacks_.push_back(sequence_numbers[s]);
+    }
+    return 0;
+  }
+
+  int32_t RequestKeyFrame() override {
+    ++keyframes_requested_;
+    return 0;
+  }
+
+  rtc::scoped_ptr<SimulatedClock> clock_;
+  NackModule nack_module_;
+  std::vector<uint16_t> sent_nacks_;
+  int keyframes_requested_;
+};
+
+TEST_F(TestNackModule, NackOnePacket) {
+  VCMPacket packet;
+  packet.seqNum = 1;
+  nack_module_.Notify(packet);
+  packet.seqNum = 3;
+  nack_module_.Notify(packet);
+  EXPECT_EQ(1u, sent_nacks_.size());
+  EXPECT_EQ(2, sent_nacks_[0]);
+}
+
+TEST_F(TestNackModule, ResendNack) {
+  VCMPacket packet;
+  packet.seqNum = 1;
+  nack_module_.Notify(packet);
+  packet.seqNum = 3;
+  nack_module_.Notify(packet);
+  EXPECT_EQ(1u, sent_nacks_.size());
+  EXPECT_EQ(2, sent_nacks_[0]);
+
+  // Default RTT is 100
+  clock_->AdvanceTimeMilliseconds(99);
+  nack_module_.Process();
+  EXPECT_EQ(1u, sent_nacks_.size());
+
+  clock_->AdvanceTimeMilliseconds(1);
+  nack_module_.Process();
+  EXPECT_EQ(2u, sent_nacks_.size());
+
+  nack_module_.UpdateRtt(50);
+  clock_->AdvanceTimeMilliseconds(100);
+  nack_module_.Process();
+  EXPECT_EQ(3u, sent_nacks_.size());
+
+  clock_->AdvanceTimeMilliseconds(50);
+  nack_module_.Process();
+  EXPECT_EQ(4u, sent_nacks_.size());
+
+  packet.seqNum = 2;
+  nack_module_.Notify(packet);
+  clock_->AdvanceTimeMilliseconds(50);
+  nack_module_.Process();
+  EXPECT_EQ(4u, sent_nacks_.size());
+}
+
+TEST_F(TestNackModule, ResendPacketMaxRetries) {
+  VCMPacket packet;
+  packet.seqNum = 1;
+  nack_module_.Notify(packet);
+  packet.seqNum = 3;
+  nack_module_.Notify(packet);
+  EXPECT_EQ(1u, sent_nacks_.size());
+  EXPECT_EQ(2, sent_nacks_[0]);
+
+  for (size_t retries = 1; retries < 10; ++retries) {
+    clock_->AdvanceTimeMilliseconds(100);
+    nack_module_.Process();
+    EXPECT_EQ(retries+1, sent_nacks_.size());
+  }
+
+  clock_->AdvanceTimeMilliseconds(100);
+  nack_module_.Process();
+  EXPECT_EQ(10u, sent_nacks_.size());
+}
+
+TEST_F(TestNackModule, TooLargeNackList) {
+  VCMPacket packet;
+  packet.seqNum = 0;
+  nack_module_.Notify(packet);
+  packet.seqNum = 1000;
+  nack_module_.Notify(packet);
+  EXPECT_EQ(999u, sent_nacks_.size());
+  EXPECT_EQ(0, keyframes_requested_);
+  packet.seqNum = 1002;
+  nack_module_.Notify(packet);
+  EXPECT_EQ(999u, sent_nacks_.size());
+  EXPECT_EQ(1, keyframes_requested_);
+  packet.seqNum = 1003;
+  nack_module_.Notify(packet);
+  EXPECT_EQ(999u, sent_nacks_.size());
+  EXPECT_EQ(1, keyframes_requested_);
+}
+
+TEST_F(TestNackModule, TooLargeNackListWithKeyFrame) {
+  VCMPacket packet;
+  packet.seqNum = 0;
+  nack_module_.Notify(packet);
+  packet.seqNum = 1;
+  packet.isFirstPacket = true;
+  packet.frameType = kVideoFrameKey;
+  nack_module_.Notify(packet);
+  packet.seqNum = 1000;
+  packet.isFirstPacket = false;
+  packet.frameType = kVideoFrameKey;
+  nack_module_.Notify(packet);
+  EXPECT_EQ(998u, sent_nacks_.size());
+  EXPECT_EQ(0, keyframes_requested_);
+  packet.seqNum = 1002;
+  nack_module_.Notify(packet);
+  EXPECT_EQ(999u, sent_nacks_.size());
+  EXPECT_EQ(0, keyframes_requested_);
+  packet.seqNum = 1004;
+  nack_module_.Notify(packet);
+  EXPECT_EQ(999u, sent_nacks_.size());
+  EXPECT_EQ(1, keyframes_requested_);
+}
+

[stefan-webrtc, 2016/02/23 12:29:02]

I think it would be good to add more tests where we have sequence number
overflows and reordering. For instance the case when we've had a sequence number
overflow after the last received key frame and the nack list becomes too large.

+}  // namespace webrtc