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Improve TCP by adding a real timeout to in flight packets.

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Note that the timeout should depend on the smoothed RTT, but for now is hard coded to 1000 ms.

This solves issues where a full cwnd gets lost.

R=pbos@webrtc.org

Review URL: https://webrtc-codereview.appspot.com/51739004

Cr-Commit-Position: refs/heads/master@{#9051}
This commit is contained in:
Stefan Holmer 2015-04-22 13:11:42 +02:00
parent 8e4b9e8804
commit ac69016b0f
2 changed files with 34 additions and 5 deletions
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17
webrtc/modules/remote_bitrate_estimator/test/packet_sender.cc
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@ -276,16 +276,25 @@ void TcpSender::RunFor(int64_t time_ms, Packets* in_out) {
UpdateCongestionControl(fb);
SendPackets(in_out);
}
for (auto it = in_flight_.begin(); it != in_flight_.end();) {
if (it->time_ms < now_ms_ - 1000)
in_flight_.erase(it++);
else
++it;
}
SendPackets(in_out);
now_ms_ += time_ms;
}
void TcpSender::SendPackets(Packets* in_out) {
int cwnd = ceil(cwnd_);
int packets_to_send = std::max(cwnd - in_flight_, 0);
int packets_to_send = std::max(cwnd - static_cast<int>(in_flight_.size()), 0);
if (packets_to_send > 0) {
Packets generated = GeneratePackets(packets_to_send);
in_flight_ += static_cast<int>(generated.size());
for (Packet* packet : generated)
in_flight_.insert(InFlight(*static_cast<MediaPacket*>(packet)));
in_out->merge(generated, DereferencingComparator<Packet>);
}
}
@ -296,10 +305,12 @@ void TcpSender::UpdateCongestionControl(const FeedbackPacket* fb) {
ack_received_ = true;
uint16_t expected = tcp_fb->acked_packets().back() - last_acked_seq_num_;
in_flight_ -= expected;
uint16_t missing =
expected - static_cast<uint16_t>(tcp_fb->acked_packets().size());
for (uint16_t ack_seq_num : tcp_fb->acked_packets())
in_flight_.erase(InFlight(ack_seq_num, now_ms_));
if (missing > 0) {
cwnd_ /= 2.0f;
in_slow_start_ = false;

22
webrtc/modules/remote_bitrate_estimator/test/packet_sender.h
View File

@ -109,7 +109,6 @@ class TcpSender : public PacketSender {
now_ms_(0),
in_slow_start_(false),
cwnd_(10),
in_flight_(0),
ack_received_(false),
last_acked_seq_num_(0),
next_sequence_number_(0) {}
@ -120,6 +119,25 @@ class TcpSender : public PacketSender {
int GetFeedbackIntervalMs() const override { return 10; }
private:
struct InFlight {
public:
InFlight(const MediaPacket& packet)
: sequence_number(packet.header().sequenceNumber),
time_ms(packet.send_time_us() / 1000) {}
InFlight(uint16_t seq_num, int64_t now_ms)
: sequence_number(seq_num), time_ms(now_ms) {}
bool operator<(const InFlight& rhs) const {
return sequence_number < rhs.sequence_number;
}
uint16_t sequence_number; // Sequence number of a packet in flight, or a
// packet which has just been acked.
int64_t time_ms; // Time of when the packet left the sender, or when the
// ack was received.
};
void SendPackets(Packets* in_out);
void UpdateCongestionControl(const FeedbackPacket* fb);
Packets GeneratePackets(size_t num_packets);
@ -127,7 +145,7 @@ class TcpSender : public PacketSender {
int64_t now_ms_;
bool in_slow_start_;
float cwnd_;
int in_flight_;
std::set<InFlight> in_flight_;
bool ack_received_;
uint16_t last_acked_seq_num_;
uint16_t next_sequence_number_;