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Added congestion control functionality to pacer.

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This adds the ability to the pacer to apply a congestion window by
tracking sent data. This makes it more reliable when the congestion
window is small enough to be filled at a high rate as there are less
thread context switches that might affect the timing and performance.

Outstanding data is not reduced by the pacer as it has no information
about acknowledged packet feedback. This is by design as the pacer would
also need to keep track of on which connection packets were sent or
received, requiring a larger, more complex, change to the pacer.

Bug: webrtc:8415
Change-Id: I4ecd303e835552ced042cd21186da910288a8258
Reviewed-on: https://webrtc-review.googlesource.com/51764
Reviewed-by: Philip Eliasson <philipel@webrtc.org>
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22371}
This commit is contained in:
Sebastian Jansson
2018-03-09 12:48:01 +01:00
committed by Commit Bot
parent dae6aad6e7
commit 45d9c1de9c
5 changed files with 143 additions and 31 deletions
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97
modules/pacing/paced_sender_unittest.cc
View File

@ -562,6 +562,103 @@ TEST_F(PacedSenderTest, HighPrioDoesntAffectBudget) {
EXPECT_EQ(0u, send_bucket_->QueueSizePackets());
}
TEST_F(PacedSenderTest, SendsOnlyPaddingWhenCongested) {
uint32_t ssrc = 202020;
uint16_t sequence_number = 1000;
int kPacketSize = 250;
int kCongestionWindow = kPacketSize * 10;
send_bucket_->UpdateOutstandingData(0);
send_bucket_->SetCongestionWindow(kCongestionWindow);
int sent_data = 0;
while (sent_data < kCongestionWindow) {
sent_data += kPacketSize;
SendAndExpectPacket(PacedSender::kNormalPriority, ssrc, sequence_number++,
clock_.TimeInMilliseconds(), kPacketSize, false);
clock_.AdvanceTimeMilliseconds(5);
send_bucket_->Process();
}
testing::Mock::VerifyAndClearExpectations(&callback_);
EXPECT_CALL(callback_, TimeToSendPacket(_, _, _, _, _)).Times(0);
EXPECT_CALL(callback_, TimeToSendPadding(_, _)).Times(0);
size_t blocked_packets = 0;
int64_t expected_time_until_padding = 500;
while (expected_time_until_padding > 5) {
send_bucket_->InsertPacket(PacedSender::kNormalPriority, ssrc,
sequence_number++, clock_.TimeInMilliseconds(),
kPacketSize, false);
blocked_packets++;
clock_.AdvanceTimeMilliseconds(5);
send_bucket_->Process();
expected_time_until_padding -= 5;
}
testing::Mock::VerifyAndClearExpectations(&callback_);
EXPECT_CALL(callback_, TimeToSendPadding(1, _)).Times(1);
clock_.AdvanceTimeMilliseconds(5);
send_bucket_->Process();
EXPECT_EQ(blocked_packets, send_bucket_->QueueSizePackets());
}
TEST_F(PacedSenderTest, ResumesSendingWhenCongestionEnds) {
uint32_t ssrc = 202020;
uint16_t sequence_number = 1000;
int64_t kPacketSize = 250;
int64_t kCongestionCount = 10;
int64_t kCongestionWindow = kPacketSize * kCongestionCount;
int64_t kCongestionTimeMs = 1000;
send_bucket_->UpdateOutstandingData(0);
send_bucket_->SetCongestionWindow(kCongestionWindow);
int sent_data = 0;
while (sent_data < kCongestionWindow) {
sent_data += kPacketSize;
SendAndExpectPacket(PacedSender::kNormalPriority, ssrc, sequence_number++,
clock_.TimeInMilliseconds(), kPacketSize, false);
clock_.AdvanceTimeMilliseconds(5);
send_bucket_->Process();
}
testing::Mock::VerifyAndClearExpectations(&callback_);
EXPECT_CALL(callback_, TimeToSendPacket(_, _, _, _, _)).Times(0);
int unacked_packets = 0;
for (int duration = 0; duration < kCongestionTimeMs; duration += 5) {
send_bucket_->InsertPacket(PacedSender::kNormalPriority, ssrc,
sequence_number++, clock_.TimeInMilliseconds(),
kPacketSize, false);
unacked_packets++;
clock_.AdvanceTimeMilliseconds(5);
send_bucket_->Process();
}
testing::Mock::VerifyAndClearExpectations(&callback_);
// First mark half of the congested packets as cleared and make sure that just
// as many are sent
int ack_count = kCongestionCount / 2;
EXPECT_CALL(callback_, TimeToSendPacket(ssrc, _, _, false, _))
.Times(ack_count)
.WillRepeatedly(Return(true));
send_bucket_->UpdateOutstandingData(kCongestionWindow -
kPacketSize * ack_count);
for (int duration = 0; duration < kCongestionTimeMs; duration += 5) {
clock_.AdvanceTimeMilliseconds(5);
send_bucket_->Process();
}
unacked_packets -= ack_count;
testing::Mock::VerifyAndClearExpectations(&callback_);
// Second make sure all packets are sent if sent packets are continuously
// marked as acked.
EXPECT_CALL(callback_, TimeToSendPacket(ssrc, _, _, false, _))
.Times(unacked_packets)
.WillRepeatedly(Return(true));
for (int duration = 0; duration < kCongestionTimeMs; duration += 5) {
send_bucket_->UpdateOutstandingData(0);
clock_.AdvanceTimeMilliseconds(5);
send_bucket_->Process();
}
}
TEST_F(PacedSenderTest, Pause) {
uint32_t ssrc_low_priority = 12345;
uint32_t ssrc = 12346;