diff options
Diffstat (limited to 'third_party/libwebrtc/net/dcsctp/tx/retransmission_queue.h')
| -rw-r--r-- | third_party/libwebrtc/net/dcsctp/tx/retransmission_queue.h | 257 |
1 files changed, 257 insertions, 0 deletions
diff --git a/third_party/libwebrtc/net/dcsctp/tx/retransmission_queue.h b/third_party/libwebrtc/net/dcsctp/tx/retransmission_queue.h new file mode 100644 index 0000000000..830c0b346d --- /dev/null +++ b/third_party/libwebrtc/net/dcsctp/tx/retransmission_queue.h @@ -0,0 +1,257 @@ +/* + * Copyright (c) 2021 The WebRTC project authors. All Rights Reserved. + * + * Use of this source code is governed by a BSD-style license + * that can be found in the LICENSE file in the root of the source + * tree. An additional intellectual property rights grant can be found + * in the file PATENTS. All contributing project authors may + * be found in the AUTHORS file in the root of the source tree. + */ +#ifndef NET_DCSCTP_TX_RETRANSMISSION_QUEUE_H_ +#define NET_DCSCTP_TX_RETRANSMISSION_QUEUE_H_ + +#include <cstdint> +#include <functional> +#include <map> +#include <set> +#include <string> +#include <utility> +#include <vector> + +#include "absl/strings/string_view.h" +#include "absl/types/optional.h" +#include "api/array_view.h" +#include "net/dcsctp/common/sequence_numbers.h" +#include "net/dcsctp/packet/chunk/forward_tsn_chunk.h" +#include "net/dcsctp/packet/chunk/iforward_tsn_chunk.h" +#include "net/dcsctp/packet/chunk/sack_chunk.h" +#include "net/dcsctp/packet/data.h" +#include "net/dcsctp/public/dcsctp_handover_state.h" +#include "net/dcsctp/public/dcsctp_options.h" +#include "net/dcsctp/public/dcsctp_socket.h" +#include "net/dcsctp/timer/timer.h" +#include "net/dcsctp/tx/outstanding_data.h" +#include "net/dcsctp/tx/retransmission_timeout.h" +#include "net/dcsctp/tx/send_queue.h" + +namespace dcsctp { + +// The RetransmissionQueue manages all DATA/I-DATA chunks that are in-flight and +// schedules them to be retransmitted if necessary. Chunks are retransmitted +// when they have been lost for a number of consecutive SACKs, or when the +// retransmission timer, `t3_rtx` expires. +// +// As congestion control is tightly connected with the state of transmitted +// packets, that's also managed here to limit the amount of data that is +// in-flight (sent, but not yet acknowledged). +class RetransmissionQueue { + public: + static constexpr size_t kMinimumFragmentedPayload = 10; + using State = OutstandingData::State; + // Creates a RetransmissionQueue which will send data using `my_initial_tsn` + // (or a value from `DcSctpSocketHandoverState` if given) as the first TSN + // to use for sent fragments. It will poll data from `send_queue`. When SACKs + // are received, it will estimate the RTT, and call `on_new_rtt`. When an + // outstanding chunk has been ACKed, it will call + // `on_clear_retransmission_counter` and will also use `t3_rtx`, which is the + // SCTP retransmission timer to manage retransmissions. + RetransmissionQueue(absl::string_view log_prefix, + DcSctpSocketCallbacks* callbacks, + TSN my_initial_tsn, + size_t a_rwnd, + SendQueue& send_queue, + std::function<void(DurationMs rtt)> on_new_rtt, + std::function<void()> on_clear_retransmission_counter, + Timer& t3_rtx, + const DcSctpOptions& options, + bool supports_partial_reliability = true, + bool use_message_interleaving = false); + + // Handles a received SACK. Returns true if the `sack` was processed and + // false if it was discarded due to received out-of-order and not relevant. + bool HandleSack(TimeMs now, const SackChunk& sack); + + // Handles an expired retransmission timer. + void HandleT3RtxTimerExpiry(); + + bool has_data_to_be_fast_retransmitted() const { + return outstanding_data_.has_data_to_be_fast_retransmitted(); + } + + // Returns a list of chunks to "fast retransmit" that would fit in one SCTP + // packet with `bytes_in_packet` bytes available. The current value + // of `cwnd` is ignored. + std::vector<std::pair<TSN, Data>> GetChunksForFastRetransmit( + size_t bytes_in_packet); + + // Returns a list of chunks to send that would fit in one SCTP packet with + // `bytes_remaining_in_packet` bytes available. This may be further limited by + // the congestion control windows. Note that `ShouldSendForwardTSN` must be + // called prior to this method, to abandon expired chunks, as this method will + // not expire any chunks. + std::vector<std::pair<TSN, Data>> GetChunksToSend( + TimeMs now, + size_t bytes_remaining_in_packet); + + // Returns the internal state of all queued chunks. This is only used in + // unit-tests. + std::vector<std::pair<TSN, OutstandingData::State>> GetChunkStatesForTesting() + const { + return outstanding_data_.GetChunkStatesForTesting(); + } + + // Returns the next TSN that will be allocated for sent DATA chunks. + TSN next_tsn() const { return outstanding_data_.next_tsn().Wrap(); } + + // Returns the size of the congestion window, in bytes. This is the number of + // bytes that may be in-flight. + size_t cwnd() const { return cwnd_; } + + // Overrides the current congestion window size. + void set_cwnd(size_t cwnd) { cwnd_ = cwnd; } + + // Returns the current receiver window size. + size_t rwnd() const { return rwnd_; } + + // Returns the number of bytes of packets that are in-flight. + size_t outstanding_bytes() const { + return outstanding_data_.outstanding_bytes(); + } + + // Returns the number of DATA chunks that are in-flight. + size_t outstanding_items() const { + return outstanding_data_.outstanding_items(); + } + + // Indicates if the congestion control algorithm allows data to be sent. + bool can_send_data() const; + + // Given the current time `now`, it will evaluate if there are chunks that + // have expired and that need to be discarded. It returns true if a + // FORWARD-TSN should be sent. + bool ShouldSendForwardTsn(TimeMs now); + + // Creates a FORWARD-TSN chunk. + ForwardTsnChunk CreateForwardTsn() const { + return outstanding_data_.CreateForwardTsn(); + } + + // Creates an I-FORWARD-TSN chunk. + IForwardTsnChunk CreateIForwardTsn() const { + return outstanding_data_.CreateIForwardTsn(); + } + + // See the SendQueue for a longer description of these methods related + // to stream resetting. + void PrepareResetStream(StreamID stream_id); + bool HasStreamsReadyToBeReset() const; + std::vector<StreamID> GetStreamsReadyToBeReset() const { + return send_queue_.GetStreamsReadyToBeReset(); + } + void CommitResetStreams(); + void RollbackResetStreams(); + + HandoverReadinessStatus GetHandoverReadiness() const; + + void AddHandoverState(DcSctpSocketHandoverState& state); + void RestoreFromState(const DcSctpSocketHandoverState& state); + + private: + enum class CongestionAlgorithmPhase { + kSlowStart, + kCongestionAvoidance, + }; + + bool IsConsistent() const; + + // Returns how large a chunk will be, serialized, carrying the data + size_t GetSerializedChunkSize(const Data& data) const; + + // Indicates if the congestion control algorithm is in "fast recovery". + bool is_in_fast_recovery() const { + return fast_recovery_exit_tsn_.has_value(); + } + + // Indicates if the provided SACK is valid given what has previously been + // received. If it returns false, the SACK is most likely a duplicate of + // something already seen, so this returning false doesn't necessarily mean + // that the SACK is illegal. + bool IsSackValid(const SackChunk& sack) const; + + // When a SACK chunk is received, this method will be called which _may_ call + // into the `RetransmissionTimeout` to update the RTO. + void UpdateRTT(TimeMs now, UnwrappedTSN cumulative_tsn_ack); + + // If the congestion control is in "fast recovery mode", this may be exited + // now. + void MaybeExitFastRecovery(UnwrappedTSN cumulative_tsn_ack); + + // If chunks have been ACKed, stop the retransmission timer. + void StopT3RtxTimerOnIncreasedCumulativeTsnAck( + UnwrappedTSN cumulative_tsn_ack); + + // Update the congestion control algorithm given as the cumulative ack TSN + // value has increased, as reported in an incoming SACK chunk. + void HandleIncreasedCumulativeTsnAck(size_t outstanding_bytes, + size_t total_bytes_acked); + // Update the congestion control algorithm, given as packet loss has been + // detected, as reported in an incoming SACK chunk. + void HandlePacketLoss(UnwrappedTSN highest_tsn_acked); + // Update the view of the receiver window size. + void UpdateReceiverWindow(uint32_t a_rwnd); + // If there is data sent and not ACKED, ensure that the retransmission timer + // is running. + void StartT3RtxTimerIfOutstandingData(); + + // Returns the current congestion control algorithm phase. + CongestionAlgorithmPhase phase() const { + return (cwnd_ <= ssthresh_) + ? CongestionAlgorithmPhase::kSlowStart + : CongestionAlgorithmPhase::kCongestionAvoidance; + } + + // Returns the number of bytes that may be sent in a single packet according + // to the congestion control algorithm. + size_t max_bytes_to_send() const; + + DcSctpSocketCallbacks& callbacks_; + const DcSctpOptions options_; + // The minimum bytes required to be available in the congestion window to + // allow packets to be sent - to avoid sending too small packets. + const size_t min_bytes_required_to_send_; + // If the peer supports RFC3758 - SCTP Partial Reliability Extension. + const bool partial_reliability_; + const std::string log_prefix_; + // The size of the data chunk (DATA/I-DATA) header that is used. + const size_t data_chunk_header_size_; + // Called when a new RTT measurement has been done + const std::function<void(DurationMs rtt)> on_new_rtt_; + // Called when a SACK has been seen that cleared the retransmission counter. + const std::function<void()> on_clear_retransmission_counter_; + // The retransmission counter. + Timer& t3_rtx_; + // Unwraps TSNs + UnwrappedTSN::Unwrapper tsn_unwrapper_; + + // Congestion Window. Number of bytes that may be in-flight (sent, not acked). + size_t cwnd_; + // Receive Window. Number of bytes available in the receiver's RX buffer. + size_t rwnd_; + // Slow Start Threshold. See RFC4960. + size_t ssthresh_; + // Partial Bytes Acked. See RFC4960. + size_t partial_bytes_acked_; + // If set, fast recovery is enabled until this TSN has been cumulative + // acked. + absl::optional<UnwrappedTSN> fast_recovery_exit_tsn_ = absl::nullopt; + + // The send queue. + SendQueue& send_queue_; + // All the outstanding data chunks that are in-flight and that have not been + // cumulative acked. Note that it also contains chunks that have been acked in + // gap ack blocks. + OutstandingData outstanding_data_; +}; +} // namespace dcsctp + +#endif // NET_DCSCTP_TX_RETRANSMISSION_QUEUE_H_ |