From 0133d46847430bd9cc93cd99c6da36f0ed49a2a1 Mon Sep 17 00:00:00 2001
From: Ying Wang <yinwa@webrtc.org>
Date: Mon, 5 Mar 2018 13:15:56 +0100
Subject: [PATCH] Use a smaller size of sequence number set, to improve
 performance

Bug: webrtc:8857
Change-Id: I78b4e6d191b1b7eb96f5109323ef48b24b99c7c2
Reviewed-on: https://webrtc-review.googlesource.com/49361
Reviewed-by: Stefan Holmer <stefan@webrtc.org>
Commit-Queue: Ying Wang <yinwa@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22286}
---
 video/video_send_stream.cc | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/video/video_send_stream.cc b/video/video_send_stream.cc
index 42a613cad4..946eed2899 100644
--- a/video/video_send_stream.cc
+++ b/video/video_send_stream.cc
@@ -11,9 +11,9 @@
 
 #include <algorithm>
 #include <cmath>
-#include <set>
 #include <sstream>
 #include <string>
+#include <unordered_set>
 #include <utility>
 #include <vector>
 
@@ -41,7 +41,11 @@
 namespace webrtc {
 
 static const int kMinSendSidePacketHistorySize = 600;
-static const int kSendSideSeqNumSetMaxSize = 15000;
+
+// Assume an average video stream has around 3 packets per frame (1 mbps / 30
+// fps / 1400B) A sequence number set with size 5500 will be able to store
+// packet sequence number for at least last 60 seconds.
+static const int kSendSideSeqNumSetMaxSize = 5500;
 
 namespace {
 
@@ -414,7 +418,7 @@ class VideoSendStreamImpl : public webrtc::BitrateAllocatorObserver,
       RTC_GUARDED_BY(overhead_bytes_per_packet_crit_);
   size_t transport_overhead_bytes_per_packet_;
 
-  std::set<uint16_t> feedback_packet_seq_num_set_;
+  std::unordered_set<uint16_t> feedback_packet_seq_num_set_;
   std::vector<bool> loss_mask_vector_;
 };