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/*
* 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.
*/
#include "net/dcsctp/tx/rr_send_queue.h"
#include <cstdint>
#include <deque>
#include <limits>
#include <map>
#include <set>
#include <utility>
#include <vector>
#include "absl/algorithm/container.h"
#include "absl/types/optional.h"
#include "api/array_view.h"
#include "net/dcsctp/common/internal_types.h"
#include "net/dcsctp/packet/data.h"
#include "net/dcsctp/public/dcsctp_message.h"
#include "net/dcsctp/public/dcsctp_socket.h"
#include "net/dcsctp/public/types.h"
#include "net/dcsctp/tx/send_queue.h"
#include "rtc_base/logging.h"
#include "rtc_base/strings/str_join.h"
namespace dcsctp {
using ::webrtc::TimeDelta;
using ::webrtc::Timestamp;
RRSendQueue::RRSendQueue(absl::string_view log_prefix,
DcSctpSocketCallbacks* callbacks,
size_t buffer_size,
size_t mtu,
StreamPriority default_priority,
size_t total_buffered_amount_low_threshold)
: log_prefix_(log_prefix),
callbacks_(*callbacks),
buffer_size_(buffer_size),
default_priority_(default_priority),
scheduler_(log_prefix_, mtu),
total_buffered_amount_(
[this]() { callbacks_.OnTotalBufferedAmountLow(); }) {
total_buffered_amount_.SetLowThreshold(total_buffered_amount_low_threshold);
}
size_t RRSendQueue::OutgoingStream::bytes_to_send_in_next_message() const {
if (pause_state_ == PauseState::kPaused ||
pause_state_ == PauseState::kResetting) {
// The stream has paused (and there is no partially sent message).
return 0;
}
if (items_.empty()) {
return 0;
}
return items_.front().remaining_size;
}
void RRSendQueue::OutgoingStream::AddHandoverState(
DcSctpSocketHandoverState::OutgoingStream& state) const {
state.next_ssn = next_ssn_.value();
state.next_ordered_mid = next_ordered_mid_.value();
state.next_unordered_mid = next_unordered_mid_.value();
state.priority = *scheduler_stream_->priority();
}
bool RRSendQueue::IsConsistent() const {
std::set<StreamID> expected_active_streams;
std::set<StreamID> actual_active_streams =
scheduler_.ActiveStreamsForTesting();
size_t total_buffered_amount = 0;
for (const auto& [stream_id, stream] : streams_) {
total_buffered_amount += stream.buffered_amount().value();
if (stream.bytes_to_send_in_next_message() > 0) {
expected_active_streams.emplace(stream_id);
}
}
if (expected_active_streams != actual_active_streams) {
auto fn = [&](rtc::StringBuilder& sb, const auto& p) { sb << *p; };
RTC_DLOG(LS_ERROR) << "Active streams mismatch, is=["
<< StrJoin(actual_active_streams, ",", fn)
<< "], expected=["
<< StrJoin(expected_active_streams, ",", fn) << "]";
return false;
}
return total_buffered_amount == total_buffered_amount_.value();
}
bool RRSendQueue::OutgoingStream::IsConsistent() const {
size_t bytes = 0;
for (const auto& item : items_) {
bytes += item.remaining_size;
}
return bytes == buffered_amount_.value();
}
void RRSendQueue::ThresholdWatcher::Decrease(size_t bytes) {
RTC_DCHECK(bytes <= value_);
size_t old_value = value_;
value_ -= bytes;
if (old_value > low_threshold_ && value_ <= low_threshold_) {
on_threshold_reached_();
}
}
void RRSendQueue::ThresholdWatcher::SetLowThreshold(size_t low_threshold) {
// Betting on https://github.com/w3c/webrtc-pc/issues/2654 being accepted.
if (low_threshold_ < value_ && low_threshold >= value_) {
on_threshold_reached_();
}
low_threshold_ = low_threshold;
}
void RRSendQueue::OutgoingStream::Add(DcSctpMessage message,
MessageAttributes attributes) {
bool was_active = bytes_to_send_in_next_message() > 0;
buffered_amount_.Increase(message.payload().size());
parent_.total_buffered_amount_.Increase(message.payload().size());
OutgoingMessageId message_id = parent_.current_message_id;
parent_.current_message_id =
OutgoingMessageId(*parent_.current_message_id + 1);
items_.emplace_back(message_id, std::move(message), std::move(attributes));
if (!was_active) {
scheduler_stream_->MaybeMakeActive();
}
RTC_DCHECK(IsConsistent());
}
absl::optional<SendQueue::DataToSend> RRSendQueue::OutgoingStream::Produce(
Timestamp now,
size_t max_size) {
RTC_DCHECK(pause_state_ != PauseState::kPaused &&
pause_state_ != PauseState::kResetting);
while (!items_.empty()) {
Item& item = items_.front();
DcSctpMessage& message = item.message;
// Allocate Message ID and SSN when the first fragment is sent.
if (!item.mid.has_value()) {
// Oops, this entire message has already expired. Try the next one.
if (item.attributes.expires_at <= now) {
HandleMessageExpired(item);
items_.pop_front();
continue;
}
MID& mid =
item.attributes.unordered ? next_unordered_mid_ : next_ordered_mid_;
item.mid = mid;
mid = MID(*mid + 1);
}
if (!item.attributes.unordered && !item.ssn.has_value()) {
item.ssn = next_ssn_;
next_ssn_ = SSN(*next_ssn_ + 1);
}
// Grab the next `max_size` fragment from this message and calculate flags.
rtc::ArrayView<const uint8_t> chunk_payload =
item.message.payload().subview(item.remaining_offset, max_size);
rtc::ArrayView<const uint8_t> message_payload = message.payload();
Data::IsBeginning is_beginning(chunk_payload.data() ==
message_payload.data());
Data::IsEnd is_end((chunk_payload.data() + chunk_payload.size()) ==
(message_payload.data() + message_payload.size()));
StreamID stream_id = message.stream_id();
PPID ppid = message.ppid();
// Zero-copy the payload if the message fits in a single chunk.
std::vector<uint8_t> payload =
is_beginning && is_end
? std::move(message).ReleasePayload()
: std::vector<uint8_t>(chunk_payload.begin(), chunk_payload.end());
FSN fsn(item.current_fsn);
item.current_fsn = FSN(*item.current_fsn + 1);
buffered_amount_.Decrease(payload.size());
parent_.total_buffered_amount_.Decrease(payload.size());
SendQueue::DataToSend chunk(
item.message_id, Data(stream_id, item.ssn.value_or(SSN(0)), *item.mid,
fsn, ppid, std::move(payload), is_beginning,
is_end, item.attributes.unordered));
chunk.max_retransmissions = item.attributes.max_retransmissions;
chunk.expires_at = item.attributes.expires_at;
chunk.lifecycle_id =
is_end ? item.attributes.lifecycle_id : LifecycleId::NotSet();
if (is_end) {
// The entire message has been sent, and its last data copied to `chunk`,
// so it can safely be discarded.
items_.pop_front();
if (pause_state_ == PauseState::kPending) {
RTC_DLOG(LS_VERBOSE) << "Pause state on " << *stream_id
<< " is moving from pending to paused";
pause_state_ = PauseState::kPaused;
}
} else {
item.remaining_offset += chunk_payload.size();
item.remaining_size -= chunk_payload.size();
RTC_DCHECK(item.remaining_offset + item.remaining_size ==
item.message.payload().size());
RTC_DCHECK(item.remaining_size > 0);
}
RTC_DCHECK(IsConsistent());
return chunk;
}
RTC_DCHECK(IsConsistent());
return absl::nullopt;
}
void RRSendQueue::OutgoingStream::HandleMessageExpired(
OutgoingStream::Item& item) {
buffered_amount_.Decrease(item.remaining_size);
parent_.total_buffered_amount_.Decrease(item.remaining_size);
if (item.attributes.lifecycle_id.IsSet()) {
RTC_DLOG(LS_VERBOSE) << "Triggering OnLifecycleMessageExpired("
<< item.attributes.lifecycle_id.value() << ", false)";
parent_.callbacks_.OnLifecycleMessageExpired(item.attributes.lifecycle_id,
/*maybe_delivered=*/false);
parent_.callbacks_.OnLifecycleEnd(item.attributes.lifecycle_id);
}
}
bool RRSendQueue::OutgoingStream::Discard(OutgoingMessageId message_id) {
bool result = false;
if (!items_.empty()) {
Item& item = items_.front();
if (item.message_id == message_id) {
HandleMessageExpired(item);
items_.pop_front();
// Only partially sent messages are discarded, so if a message was
// discarded, then it was the currently sent message.
scheduler_stream_->ForceReschedule();
if (pause_state_ == PauseState::kPending) {
pause_state_ = PauseState::kPaused;
scheduler_stream_->MakeInactive();
} else if (bytes_to_send_in_next_message() == 0) {
scheduler_stream_->MakeInactive();
}
// As the item still existed, it had unsent data.
result = true;
}
}
RTC_DCHECK(IsConsistent());
return result;
}
void RRSendQueue::OutgoingStream::Pause() {
if (pause_state_ != PauseState::kNotPaused) {
// Already in progress.
return;
}
bool had_pending_items = !items_.empty();
// https://datatracker.ietf.org/doc/html/rfc8831#section-6.7
// "Closing of a data channel MUST be signaled by resetting the corresponding
// outgoing streams [RFC6525]. This means that if one side decides to close
// the data channel, it resets the corresponding outgoing stream."
// ... "[RFC6525] also guarantees that all the messages are delivered (or
// abandoned) before the stream is reset."
// A stream is paused when it's about to be reset. In this implementation,
// it will throw away all non-partially send messages - they will be abandoned
// as noted above. This is subject to change. It will however not discard any
// partially sent messages - only whole messages. Partially delivered messages
// (at the time of receiving a Stream Reset command) will always deliver all
// the fragments before actually resetting the stream.
for (auto it = items_.begin(); it != items_.end();) {
if (it->remaining_offset == 0) {
HandleMessageExpired(*it);
it = items_.erase(it);
} else {
++it;
}
}
pause_state_ = (items_.empty() || items_.front().remaining_offset == 0)
? PauseState::kPaused
: PauseState::kPending;
if (had_pending_items && pause_state_ == PauseState::kPaused) {
RTC_DLOG(LS_VERBOSE) << "Stream " << *stream_id()
<< " was previously active, but is now paused.";
scheduler_stream_->MakeInactive();
}
RTC_DCHECK(IsConsistent());
}
void RRSendQueue::OutgoingStream::Resume() {
RTC_DCHECK(pause_state_ == PauseState::kResetting);
pause_state_ = PauseState::kNotPaused;
scheduler_stream_->MaybeMakeActive();
RTC_DCHECK(IsConsistent());
}
void RRSendQueue::OutgoingStream::Reset() {
// This can be called both when an outgoing stream reset has been responded
// to, or when the entire SendQueue is reset due to detecting the peer having
// restarted. The stream may be in any state at this time.
PauseState old_pause_state = pause_state_;
pause_state_ = PauseState::kNotPaused;
next_ordered_mid_ = MID(0);
next_unordered_mid_ = MID(0);
next_ssn_ = SSN(0);
if (!items_.empty()) {
// If this message has been partially sent, reset it so that it will be
// re-sent.
auto& item = items_.front();
buffered_amount_.Increase(item.message.payload().size() -
item.remaining_size);
parent_.total_buffered_amount_.Increase(item.message.payload().size() -
item.remaining_size);
item.remaining_offset = 0;
item.remaining_size = item.message.payload().size();
item.mid = absl::nullopt;
item.ssn = absl::nullopt;
item.current_fsn = FSN(0);
if (old_pause_state == PauseState::kPaused ||
old_pause_state == PauseState::kResetting) {
scheduler_stream_->MaybeMakeActive();
}
}
RTC_DCHECK(IsConsistent());
}
bool RRSendQueue::OutgoingStream::has_partially_sent_message() const {
if (items_.empty()) {
return false;
}
return items_.front().mid.has_value();
}
void RRSendQueue::Add(Timestamp now,
DcSctpMessage message,
const SendOptions& send_options) {
RTC_DCHECK(!message.payload().empty());
// Any limited lifetime should start counting from now - when the message
// has been added to the queue.
// `expires_at` is the time when it expires. Which is slightly larger than the
// message's lifetime, as the message is alive during its entire lifetime
// (which may be zero).
MessageAttributes attributes = {
.unordered = send_options.unordered,
.max_retransmissions =
send_options.max_retransmissions.has_value()
? MaxRetransmits(send_options.max_retransmissions.value())
: MaxRetransmits::NoLimit(),
.expires_at = send_options.lifetime.has_value()
? now + send_options.lifetime->ToTimeDelta() +
TimeDelta::Millis(1)
: Timestamp::PlusInfinity(),
.lifecycle_id = send_options.lifecycle_id,
};
GetOrCreateStreamInfo(message.stream_id())
.Add(std::move(message), std::move(attributes));
RTC_DCHECK(IsConsistent());
}
bool RRSendQueue::IsFull() const {
return total_buffered_amount() >= buffer_size_;
}
bool RRSendQueue::IsEmpty() const {
return total_buffered_amount() == 0;
}
absl::optional<SendQueue::DataToSend> RRSendQueue::Produce(Timestamp now,
size_t max_size) {
return scheduler_.Produce(now, max_size);
}
bool RRSendQueue::Discard(StreamID stream_id, OutgoingMessageId message_id) {
bool has_discarded = GetOrCreateStreamInfo(stream_id).Discard(message_id);
RTC_DCHECK(IsConsistent());
return has_discarded;
}
void RRSendQueue::PrepareResetStream(StreamID stream_id) {
GetOrCreateStreamInfo(stream_id).Pause();
RTC_DCHECK(IsConsistent());
}
bool RRSendQueue::HasStreamsReadyToBeReset() const {
for (auto& [unused, stream] : streams_) {
if (stream.IsReadyToBeReset()) {
return true;
}
}
return false;
}
std::vector<StreamID> RRSendQueue::GetStreamsReadyToBeReset() {
RTC_DCHECK(absl::c_count_if(streams_, [](const auto& p) {
return p.second.IsResetting();
}) == 0);
std::vector<StreamID> ready;
for (auto& [stream_id, stream] : streams_) {
if (stream.IsReadyToBeReset()) {
stream.SetAsResetting();
ready.push_back(stream_id);
}
}
return ready;
}
void RRSendQueue::CommitResetStreams() {
RTC_DCHECK(absl::c_count_if(streams_, [](const auto& p) {
return p.second.IsResetting();
}) > 0);
for (auto& [unused, stream] : streams_) {
if (stream.IsResetting()) {
stream.Reset();
}
}
RTC_DCHECK(IsConsistent());
}
void RRSendQueue::RollbackResetStreams() {
RTC_DCHECK(absl::c_count_if(streams_, [](const auto& p) {
return p.second.IsResetting();
}) > 0);
for (auto& [unused, stream] : streams_) {
if (stream.IsResetting()) {
stream.Resume();
}
}
RTC_DCHECK(IsConsistent());
}
void RRSendQueue::Reset() {
// Recalculate buffered amount, as partially sent messages may have been put
// fully back in the queue.
for (auto& [unused, stream] : streams_) {
stream.Reset();
}
scheduler_.ForceReschedule();
}
size_t RRSendQueue::buffered_amount(StreamID stream_id) const {
auto it = streams_.find(stream_id);
if (it == streams_.end()) {
return 0;
}
return it->second.buffered_amount().value();
}
size_t RRSendQueue::buffered_amount_low_threshold(StreamID stream_id) const {
auto it = streams_.find(stream_id);
if (it == streams_.end()) {
return 0;
}
return it->second.buffered_amount().low_threshold();
}
void RRSendQueue::SetBufferedAmountLowThreshold(StreamID stream_id,
size_t bytes) {
GetOrCreateStreamInfo(stream_id).buffered_amount().SetLowThreshold(bytes);
}
RRSendQueue::OutgoingStream& RRSendQueue::GetOrCreateStreamInfo(
StreamID stream_id) {
auto it = streams_.find(stream_id);
if (it != streams_.end()) {
return it->second;
}
return streams_
.emplace(
std::piecewise_construct, std::forward_as_tuple(stream_id),
std::forward_as_tuple(this, &scheduler_, stream_id, default_priority_,
[this, stream_id]() {
callbacks_.OnBufferedAmountLow(stream_id);
}))
.first->second;
}
void RRSendQueue::SetStreamPriority(StreamID stream_id,
StreamPriority priority) {
OutgoingStream& stream = GetOrCreateStreamInfo(stream_id);
stream.SetPriority(priority);
RTC_DCHECK(IsConsistent());
}
StreamPriority RRSendQueue::GetStreamPriority(StreamID stream_id) const {
auto stream_it = streams_.find(stream_id);
if (stream_it == streams_.end()) {
return default_priority_;
}
return stream_it->second.priority();
}
HandoverReadinessStatus RRSendQueue::GetHandoverReadiness() const {
HandoverReadinessStatus status;
if (!IsEmpty()) {
status.Add(HandoverUnreadinessReason::kSendQueueNotEmpty);
}
return status;
}
void RRSendQueue::AddHandoverState(DcSctpSocketHandoverState& state) {
for (const auto& [stream_id, stream] : streams_) {
DcSctpSocketHandoverState::OutgoingStream state_stream;
state_stream.id = stream_id.value();
stream.AddHandoverState(state_stream);
state.tx.streams.push_back(std::move(state_stream));
}
}
void RRSendQueue::RestoreFromState(const DcSctpSocketHandoverState& state) {
for (const DcSctpSocketHandoverState::OutgoingStream& state_stream :
state.tx.streams) {
StreamID stream_id(state_stream.id);
streams_.emplace(
std::piecewise_construct, std::forward_as_tuple(stream_id),
std::forward_as_tuple(
this, &scheduler_, stream_id, StreamPriority(state_stream.priority),
[this, stream_id]() { callbacks_.OnBufferedAmountLow(stream_id); },
&state_stream));
}
}
} // namespace dcsctp