Test and fix for huge bwe drop after alr state.

webrtc/modules/congestion_controller/acknowledged_bitrate_estimator.cc

+/*
+ *  Copyright (c) 2017 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 "webrtc/modules/congestion_controller/acknowledged_bitrate_estimator.h"
+
+#include <utility>
+
+#include "webrtc/base/ptr_util.h"
+#include "webrtc/base/timeutils.h"
+#include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
+
+namespace webrtc {
+
+namespace {
+bool IsInSendTimeHistory(const PacketFeedback& packet) {
+  return packet.send_time_ms >= 0;
+}
+}  // namespace
+
+std::unique_ptr<BitrateEstimator> BitrateEstimatorCreator::Create() const {
+  return rtc::MakeUnique<BitrateEstimator>();
+}
+
+AcknowledgedBitrateEstimator::AcknowledgedBitrateEstimator(
+    std::unique_ptr<BitrateEstimatorCreator> bitrate_estimator_creator)
+    : was_in_alr_(false),
+      bitrate_estimator_creator_(
+          bitrate_estimator_creator
+              ? std::move(bitrate_estimator_creator)
+              : rtc::MakeUnique<BitrateEstimatorCreator>()),
+      bitrate_estimator_(bitrate_estimator_creator_->Create()) {}
+
+void AcknowledgedBitrateEstimator::IncomingPacketFeedbackVector(
+    const std::vector<PacketFeedback>& packet_feedback_vector,
+    bool currently_in_alr) {
+  RTC_DCHECK(std::is_sorted(packet_feedback_vector.begin(),
+                            packet_feedback_vector.end(),
+                            PacketFeedbackComparator()));
+  MaybeResetBitrateEstimator(currently_in_alr);
+  for (const auto& packet : packet_feedback_vector) {
+    if (IsInSendTimeHistory(packet) && !SentBeforeAlrEnded(packet))
+      bitrate_estimator_->Update(packet.arrival_time_ms, packet.payload_size);
+  }
+}
+
+rtc::Optional<uint32_t> AcknowledgedBitrateEstimator::bitrate_bps() const {
+  return bitrate_estimator_->bitrate_bps();
+}
+
+bool AcknowledgedBitrateEstimator::SentBeforeAlrEnded(
+    const PacketFeedback& packet) {
+  if (alr_ended_time_ms_) {
+    if (*alr_ended_time_ms_ > packet.send_time_ms) {
+      return true;
+    } else {
+      alr_ended_time_ms_.reset();

[philipel, 2017/06/14 09:34:05]

What happens if feedback messages are reordered? Why do we need to reset this at
all?

[tschumi, 2017/06/14 10:57:46]

Right, this reset is kind of senseless. 

+    }
+  }
+  return false;
+}
+
+bool AcknowledgedBitrateEstimator::AlrEnded(bool currently_in_alr) const {
+  return was_in_alr_ && !currently_in_alr;
+}
+
+void AcknowledgedBitrateEstimator::MaybeResetBitrateEstimator(
+    bool currently_in_alr) {
+  if (AlrEnded(currently_in_alr)) {
+    bitrate_estimator_ = bitrate_estimator_creator_->Create();
+    alr_ended_time_ms_ = rtc::Optional<int64_t>(rtc::TimeMillis());
+  }
+  was_in_alr_ = currently_in_alr;
+}
+
+}  // namespace webrtc