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Remove time constraint on first retransmit of a packet.

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We don't allow more than one retransmission within one RTT, but the RTT
estimate might be off. Reasonably, the remote end will not send a NACK
until the packet after has been received - so always resend on first
request.

Review URL: https://codereview.webrtc.org/1414563003

Cr-Commit-Position: refs/heads/master@{#10362}
This commit is contained in:
sprang
2015-10-21 13:46:33 -07:00
committed by Commit bot
parent c96df779b0
commit affa39cb39
3 changed files with 62 additions and 19 deletions
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24
webrtc/modules/rtp_rtcp/source/rtp_packet_history.cc
View File

@ -16,6 +16,7 @@
#include <limits>
#include <set>
#include "webrtc/base/checks.h"
#include "webrtc/modules/rtp_rtcp/source/rtp_utility.h"
#include "webrtc/system_wrappers/interface/critical_section_wrapper.h"
#include "webrtc/system_wrappers/interface/logging.h"
@ -118,6 +119,7 @@ int32_t RTPPacketHistory::PutRTPPacket(const uint8_t* packet,
(capture_time_ms > 0) ? capture_time_ms : clock_->TimeInMilliseconds();
stored_packets_[prev_index_].send_time = 0; // Packet not sent.
stored_packets_[prev_index_].storage_type = type;
stored_packets_[prev_index_].has_been_retransmitted = false;
++prev_index_;
if (prev_index_ >= stored_packets_.size()) {
@ -173,10 +175,9 @@ bool RTPPacketHistory::GetPacketAndSetSendTime(uint16_t sequence_number,
size_t* packet_length,
int64_t* stored_time_ms) {
CriticalSectionScoped cs(critsect_.get());
assert(*packet_length >= IP_PACKET_SIZE);
if (!store_) {
RTC_CHECK_GE(*packet_length, static_cast<size_t>(IP_PACKET_SIZE));
if (!store_)
return false;
}
int32_t index = 0;
bool found = FindSeqNum(sequence_number, &index);
@ -193,17 +194,22 @@ bool RTPPacketHistory::GetPacketAndSetSendTime(uint16_t sequence_number,
return false;
}
// Verify elapsed time since last retrieve.
// Verify elapsed time since last retrieve, but only for retransmissions and
// always send packet upon first retransmission request.
int64_t now = clock_->TimeInMilliseconds();
if (min_elapsed_time_ms > 0 &&
if (min_elapsed_time_ms > 0 && retransmit &&
stored_packets_[index].has_been_retransmitted &&
((now - stored_packets_[index].send_time) < min_elapsed_time_ms)) {
return false;
}
if (retransmit && stored_packets_[index].storage_type == kDontRetransmit) {
// No bytes copied since this packet shouldn't be retransmitted or is
// of zero size.
return false;
if (retransmit) {
if (stored_packets_[index].storage_type == kDontRetransmit) {
// No bytes copied since this packet shouldn't be retransmitted or is
// of zero size.
return false;
}
stored_packets_[index].has_been_retransmitted = true;
}
stored_packets_[index].send_time = clock_->TimeInMilliseconds();
GetPacket(index, packet, packet_length, stored_time_ms);

6
webrtc/modules/rtp_rtcp/source/rtp_packet_history.h
View File

@ -46,13 +46,12 @@ class RTPPacketHistory {
// The packet is copied to the buffer pointed to by ptr_rtp_packet.
// The rtp_packet_length should show the available buffer size.
// Returns true if packet is found.
// rtp_packet_length: returns the copied packet length on success.
// packet_length: returns the copied packet length on success.
// min_elapsed_time_ms: the minimum time that must have elapsed since the last
// time the packet was resent (parameter is ignored if set to zero).
// If the packet is found but the minimum time has not elaped, no bytes are
// If the packet is found but the minimum time has not elapsed, no bytes are
// copied.
// stored_time_ms: returns the time when the packet was stored.
// type: returns the storage type set in PutRTPPacket.
bool GetPacketAndSetSendTime(uint16_t sequence_number,
int64_t min_elapsed_time_ms,
bool retransmit,
@ -94,6 +93,7 @@ class RTPPacketHistory {
int64_t time_ms = 0;
int64_t send_time = 0;
StorageType storage_type = kDontRetransmit;
bool has_been_retransmitted = false;
uint8_t data[IP_PACKET_SIZE];
size_t length = 0;

51
webrtc/modules/rtp_rtcp/source/rtp_packet_history_unittest.cc
View File

@ -161,6 +161,8 @@ TEST_F(RtpPacketHistoryTest, DontRetransmit) {
}
TEST_F(RtpPacketHistoryTest, MinResendTime) {
static const int64_t kMinRetransmitIntervalMs = 100;
hist_->SetStorePacketsStatus(true, 10);
size_t len = 0;
int64_t capture_time_ms = fake_clock_.TimeInMilliseconds();
@ -168,22 +170,57 @@ TEST_F(RtpPacketHistoryTest, MinResendTime) {
EXPECT_EQ(0, hist_->PutRTPPacket(packet_, len, capture_time_ms,
kAllowRetransmission));
// First transmission: TimeToSendPacket() call from pacer.
int64_t time;
len = kMaxPacketLength;
EXPECT_TRUE(hist_->GetPacketAndSetSendTime(kSeqNum, 100, false, packet_, &len,
&time));
fake_clock_.AdvanceTimeMilliseconds(100);
EXPECT_TRUE(
hist_->GetPacketAndSetSendTime(kSeqNum, 0, false, packet_, &len, &time));
fake_clock_.AdvanceTimeMilliseconds(kMinRetransmitIntervalMs);
// Time has elapsed.
len = kMaxPacketLength;
EXPECT_TRUE(hist_->GetPacketAndSetSendTime(kSeqNum, 100, false, packet_, &len,
&time));
EXPECT_TRUE(hist_->GetPacketAndSetSendTime(kSeqNum, kMinRetransmitIntervalMs,
true, packet_, &len, &time));
EXPECT_GT(len, 0u);
EXPECT_EQ(capture_time_ms, time);
fake_clock_.AdvanceTimeMilliseconds(kMinRetransmitIntervalMs - 1);
// Time has not elapsed. Packet should be found, but no bytes copied.
len = kMaxPacketLength;
EXPECT_FALSE(hist_->GetPacketAndSetSendTime(kSeqNum, 101, false, packet_,
&len, &time));
EXPECT_FALSE(hist_->GetPacketAndSetSendTime(kSeqNum, kMinRetransmitIntervalMs,
true, packet_, &len, &time));
}
TEST_F(RtpPacketHistoryTest, EarlyFirstResend) {
static const int64_t kMinRetransmitIntervalMs = 100;
hist_->SetStorePacketsStatus(true, 10);
size_t len = 0;
int64_t capture_time_ms = fake_clock_.TimeInMilliseconds();
CreateRtpPacket(kSeqNum, kSsrc, kPayload, kTimestamp, packet_, &len);
EXPECT_EQ(0, hist_->PutRTPPacket(packet_, len, capture_time_ms,
kAllowRetransmission));
// First transmission: TimeToSendPacket() call from pacer.
int64_t time;
len = kMaxPacketLength;
EXPECT_TRUE(
hist_->GetPacketAndSetSendTime(kSeqNum, 0, false, packet_, &len, &time));
fake_clock_.AdvanceTimeMilliseconds(kMinRetransmitIntervalMs - 1);
// Time has not elapsed, but this is the first retransmission request so
// allow anyway.
len = kMaxPacketLength;
EXPECT_TRUE(hist_->GetPacketAndSetSendTime(kSeqNum, kMinRetransmitIntervalMs,
true, packet_, &len, &time));
EXPECT_GT(len, 0u);
EXPECT_EQ(capture_time_ms, time);
fake_clock_.AdvanceTimeMilliseconds(kMinRetransmitIntervalMs - 1);
// Time has not elapsed. Packet should be found, but no bytes copied.
len = kMaxPacketLength;
EXPECT_FALSE(hist_->GetPacketAndSetSendTime(kSeqNum, kMinRetransmitIntervalMs,
true, packet_, &len, &time));
}
TEST_F(RtpPacketHistoryTest, DynamicExpansion) {