From e2e000059d1a0a1ceaf787544c833e4945d112aa Mon Sep 17 00:00:00 2001
From: Christoffer Rodbro <crodbro@webrtc.org>
Date: Thu, 20 Dec 2018 15:46:03 +0100
Subject: [PATCH] Make pacing buffer send interval configurable.

Bug: webrtc:10153
Change-Id: I2f71b5fc902e24b87f0b6cba474d988b8c27aefa
Reviewed-on: https://webrtc-review.googlesource.com/c/115301
Commit-Queue: Christoffer Rodbro <crodbro@webrtc.org>
Reviewed-by: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#26076}
---
 modules/pacing/BUILD.gn        |  1 +
 modules/pacing/paced_sender.cc | 12 ++++++++----
 modules/pacing/paced_sender.h  |  2 ++
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/modules/pacing/BUILD.gn b/modules/pacing/BUILD.gn
index 25284980cd..1b3716866b 100644
--- a/modules/pacing/BUILD.gn
+++ b/modules/pacing/BUILD.gn
@@ -36,6 +36,7 @@ rtc_static_library("pacing") {
     "../../rtc_base:checks",
     "../../rtc_base:rtc_base_approved",
     "../../rtc_base/experiments:alr_experiment",
+    "../../rtc_base/experiments:field_trial_parser",
     "../../system_wrappers",
     "../../system_wrappers:field_trial",
     "../congestion_controller/goog_cc:alr_detector",
diff --git a/modules/pacing/paced_sender.cc b/modules/pacing/paced_sender.cc
index 050fbb651a..f512938557 100644
--- a/modules/pacing/paced_sender.cc
+++ b/modules/pacing/paced_sender.cc
@@ -26,7 +26,7 @@
 
 namespace {
 // Time limit in milliseconds between packet bursts.
-const int64_t kMinPacketLimitMs = 5;
+const int64_t kDefaultMinPacketLimitMs = 5;
 const int64_t kCongestedPacketIntervalMs = 500;
 const int64_t kPausedProcessIntervalMs = kCongestedPacketIntervalMs;
 const int64_t kMaxElapsedTimeMs = 2000;
@@ -52,6 +52,7 @@ PacedSender::PacedSender(const Clock* clock,
       send_padding_if_silent_(
           field_trial::IsEnabled("WebRTC-Pacer-PadInSilence")),
       video_blocks_audio_(!field_trial::IsDisabled("WebRTC-Pacer-BlockAudio")),
+      min_packet_limit_ms_("", kDefaultMinPacketLimitMs),
       last_timestamp_ms_(clock_->TimeInMilliseconds()),
       paused_(false),
       media_budget_(0),
@@ -70,10 +71,13 @@ PacedSender::PacedSender(const Clock* clock,
       pacing_factor_(kDefaultPaceMultiplier),
       queue_time_limit(kMaxQueueLengthMs),
       account_for_audio_(false) {
-  if (!drain_large_queues_)
+  if (!drain_large_queues_) {
     RTC_LOG(LS_WARNING) << "Pacer queues will not be drained,"
                            "pushback experiment must be enabled.";
-  UpdateBudgetWithElapsedTime(kMinPacketLimitMs);
+  }
+  ParseFieldTrial({&min_packet_limit_ms_},
+                  field_trial::FindFullName("WebRTC-Pacer-MinPacketLimitMs"));
+  UpdateBudgetWithElapsedTime(min_packet_limit_ms_);
 }
 
 PacedSender::~PacedSender() {}
@@ -258,7 +262,7 @@ int64_t PacedSender::TimeUntilNextProcess() {
     if (ret > 0 || (ret == 0 && !probing_send_failure_))
       return ret;
   }
-  return std::max<int64_t>(kMinPacketLimitMs - elapsed_time_ms, 0);
+  return std::max<int64_t>(min_packet_limit_ms_ - elapsed_time_ms, 0);
 }
 
 int64_t PacedSender::UpdateTimeAndGetElapsedMs(int64_t now_us) {
diff --git a/modules/pacing/paced_sender.h b/modules/pacing/paced_sender.h
index 6c88159e53..7b8ecc1c6a 100644
--- a/modules/pacing/paced_sender.h
+++ b/modules/pacing/paced_sender.h
@@ -24,6 +24,7 @@
 #include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 #include "modules/utility/include/process_thread.h"
 #include "rtc_base/criticalsection.h"
+#include "rtc_base/experiments/field_trial_parser.h"
 #include "rtc_base/thread_annotations.h"
 
 namespace webrtc {
@@ -172,6 +173,7 @@ class PacedSender : public Pacer {
   const bool drain_large_queues_;
   const bool send_padding_if_silent_;
   const bool video_blocks_audio_;
+  FieldTrialParameter<int> min_packet_limit_ms_;
 
   rtc::CriticalSection critsect_;
   // TODO(webrtc:9716): Remove this when we are certain clocks are monotonic.