Log audio network adapter decisions in event log.

webrtc/modules/audio_coding/audio_network_adaptor/event_log_writer.cc

Index: webrtc/modules/audio_coding/audio_network_adaptor/event_log_writer.cc
diff --git a/webrtc/modules/audio_coding/audio_network_adaptor/event_log_writer.cc b/webrtc/modules/audio_coding/audio_network_adaptor/event_log_writer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..6e9173019b650138a30f76fd8e3309c89e5dde8e
--- /dev/null
+++ b/webrtc/modules/audio_coding/audio_network_adaptor/event_log_writer.cc
@@ -0,0 +1,79 @@
+/*
+ *  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 <cmath>
+
+#include "webrtc/modules/audio_coding/audio_network_adaptor/event_log_writer.h"
+#include "webrtc/logging/rtc_event_log/rtc_event_log.h"
+
+namespace webrtc {
+
+namespace {
+constexpr int kMinBitreateChangeBps = 5000;
+constexpr float kMinPacketLossChangeFraction = 0.5;
+}
+
+EventLogWriter::EventLogWriter(RtcEventLog* event_log)
+    : EventLogWriter(event_log,
+                     kMinBitreateChangeBps,
+                     kMinPacketLossChangeFraction) {}
+
+EventLogWriter::EventLogWriter(RtcEventLog* event_log,
+                               int min_bitreate_change_bps,
+                               float min_packet_loss_change_fraction)
+    : event_log_(event_log),
+      min_bitreate_change_bps_(min_bitreate_change_bps),
+      min_packet_loss_change_fraction_(min_packet_loss_change_fraction) {
+  RTC_CHECK(event_log_);
+}
+
+EventLogWriter::~EventLogWriter() = default;
+
+void EventLogWriter::MayLogEncoderRuntimeConfig(
+    const AudioNetworkAdaptor::EncoderRuntimeConfig& config) {
+  if (last_runtime_config_) {

[the sun, 2016/12/13 16:31:18]

I don't understand the mechanics here. It looks like you're checking deltas and
logging only if there is a change. But you do that up to three times. So there
may be three events in the proto containing *exactly* the same data? And to
boot, all the fields in the events are optional so they may be set, or not.

I'm sorry, but that seems both inefficient and highly ambiguous.

[michaelt, 2016/12/14 14:41:37]

This is partly a bug and party a feature. 
It should just be logged once => this is the bug.
Added a unit-test and a fix.

The feature is that all data is logged. This is done to be sure which ANA
controller are active.
All active controllers have to set the Encoder config field.

+    if (last_runtime_config_->num_channels != config.num_channels ||
+        last_runtime_config_->enable_dtx != config.enable_dtx ||
+        last_runtime_config_->enable_fec != config.enable_fec ||
+        last_runtime_config_->frame_length_ms != config.frame_length_ms)
+      event_log_->LogAnaDecisionEvent(
+          config.bitrate_bps, config.frame_length_ms,
+          config.uplink_packet_loss_fraction, config.enable_fec,
+          config.enable_dtx, config.num_channels);
+
+    if (last_runtime_config_->bitrate_bps && config.bitrate_bps &&
+        std::abs(*last_runtime_config_->bitrate_bps - *config.bitrate_bps) >=
+            min_bitreate_change_bps_)
+      event_log_->LogAnaDecisionEvent(
+          config.bitrate_bps, config.frame_length_ms,
+          config.uplink_packet_loss_fraction, config.enable_fec,
+          config.enable_dtx, config.num_channels);
+
+    if (last_runtime_config_->uplink_packet_loss_fraction &&
+        config.uplink_packet_loss_fraction &&
+        std::abs(*last_runtime_config_->uplink_packet_loss_fraction -
+                 *config.uplink_packet_loss_fraction) >=
+            min_packet_loss_change_fraction_ *
+                *last_runtime_config_->uplink_packet_loss_fraction)
+      event_log_->LogAnaDecisionEvent(
+          config.bitrate_bps, config.frame_length_ms,
+          config.uplink_packet_loss_fraction, config.enable_fec,
+          config.enable_dtx, config.num_channels);
+
+  } else {
+    event_log_->LogAnaDecisionEvent(config.bitrate_bps, config.frame_length_ms,
+                                    config.uplink_packet_loss_fraction,
+                                    config.enable_fec, config.enable_dtx,
+                                    config.num_channels);
+  }
+  last_runtime_config_ =
+      rtc::Optional<AudioNetworkAdaptor::EncoderRuntimeConfig>(config);
+}
+}  // namespace webrtc