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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 <map>
#include <utility>
#include <vector>
#include "absl/algorithm/container.h"
#include "absl/types/optional.h"
#include "api/array_view.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"
namespace dcsctp {
bool RRSendQueue::OutgoingStream::HasDataToSend(TimeMs now) {
while (!items_.empty()) {
RRSendQueue::OutgoingStream::Item& item = items_.front();
if (item.message_id.has_value()) {
// Already partially sent messages can always continue to be sent.
return true;
}
// Message has expired. Remove it and inspect the next one.
if (item.expires_at.has_value() && *item.expires_at <= now) {
buffered_amount_.Decrease(item.remaining_size);
total_buffered_amount_.Decrease(item.remaining_size);
items_.pop_front();
RTC_DCHECK(IsConsistent());
continue;
}
if (is_paused_) {
// The stream has paused (and there is no partially sent message).
return false;
}
return true;
}
return false;
}
bool RRSendQueue::IsConsistent() const {
size_t total_buffered_amount = 0;
for (const auto& stream_entry : streams_) {
total_buffered_amount += stream_entry.second.buffered_amount().value();
}
if (previous_message_has_ended_) {
auto it = streams_.find(current_stream_id_);
if (it != streams_.end() && it->second.has_partially_sent_message()) {
RTC_DLOG(LS_ERROR)
<< "Previous message has ended, but still partial message in stream";
return false;
}
} else {
auto it = streams_.find(current_stream_id_);
if (it == streams_.end() || !it->second.has_partially_sent_message()) {
RTC_DLOG(LS_ERROR)
<< "Previous message has NOT ended, but there is no partial message";
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,
absl::optional<TimeMs> expires_at,
const SendOptions& send_options) {
buffered_amount_.Increase(message.payload().size());
total_buffered_amount_.Increase(message.payload().size());
items_.emplace_back(std::move(message), expires_at, send_options);
RTC_DCHECK(IsConsistent());
}
absl::optional<SendQueue::DataToSend> RRSendQueue::OutgoingStream::Produce(
TimeMs now,
size_t max_size) {
RTC_DCHECK(!items_.empty());
Item* item = &items_.front();
DcSctpMessage& message = item->message;
if (item->remaining_size > max_size && max_size < kMinimumFragmentedPayload) {
RTC_DCHECK(IsConsistent());
return absl::nullopt;
}
// Allocate Message ID and SSN when the first fragment is sent.
if (!item->message_id.has_value()) {
MID& mid =
item->send_options.unordered ? next_unordered_mid_ : next_ordered_mid_;
item->message_id = mid;
mid = MID(*mid + 1);
}
if (!item->send_options.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());
total_buffered_amount_.Decrease(payload.size());
SendQueue::DataToSend chunk(Data(stream_id, item->ssn.value_or(SSN(0)),
item->message_id.value(), fsn, ppid,
std::move(payload), is_beginning, is_end,
item->send_options.unordered));
chunk.max_retransmissions = item->send_options.max_retransmissions;
chunk.expires_at = item->expires_at;
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();
} 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;
}
bool RRSendQueue::OutgoingStream::Discard(IsUnordered unordered,
MID message_id) {
bool result = false;
if (!items_.empty()) {
Item& item = items_.front();
if (item.send_options.unordered == unordered &&
item.message_id.has_value() && *item.message_id == message_id) {
buffered_amount_.Decrease(item.remaining_size);
total_buffered_amount_.Decrease(item.remaining_size);
items_.pop_front();
// As the item still existed, it had unsent data.
result = true;
}
}
RTC_DCHECK(IsConsistent());
return result;
}
void RRSendQueue::OutgoingStream::Pause() {
is_paused_ = true;
// A stream is paused when it's about to be reset. In this implementation,
// it will throw away all non-partially send messages. 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) {
buffered_amount_.Decrease(it->remaining_size);
total_buffered_amount_.Decrease(it->remaining_size);
it = items_.erase(it);
} else {
++it;
}
}
RTC_DCHECK(IsConsistent());
}
void RRSendQueue::OutgoingStream::Reset() {
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);
total_buffered_amount_.Increase(item.message.payload().size() -
item.remaining_size);
item.remaining_offset = 0;
item.remaining_size = item.message.payload().size();
item.message_id = absl::nullopt;
item.ssn = absl::nullopt;
item.current_fsn = FSN(0);
}
is_paused_ = false;
next_ordered_mid_ = MID(0);
next_unordered_mid_ = MID(0);
next_ssn_ = SSN(0);
RTC_DCHECK(IsConsistent());
}
bool RRSendQueue::OutgoingStream::has_partially_sent_message() const {
if (items_.empty()) {
return false;
}
return items_.front().message_id.has_value();
}
void RRSendQueue::Add(TimeMs 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.
absl::optional<TimeMs> expires_at = absl::nullopt;
if (send_options.lifetime.has_value()) {
// `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).
expires_at = now + *send_options.lifetime + DurationMs(1);
}
GetOrCreateStreamInfo(message.stream_id())
.Add(std::move(message), expires_at, send_options);
RTC_DCHECK(IsConsistent());
}
bool RRSendQueue::IsFull() const {
return total_buffered_amount() >= buffer_size_;
}
bool RRSendQueue::IsEmpty() const {
return total_buffered_amount() == 0;
}
std::map<StreamID, RRSendQueue::OutgoingStream>::iterator
RRSendQueue::GetNextStream(TimeMs now) {
auto start_it = streams_.lower_bound(StreamID(*current_stream_id_ + 1));
for (auto it = start_it; it != streams_.end(); ++it) {
if (it->second.HasDataToSend(now)) {
current_stream_id_ = it->first;
return it;
}
}
for (auto it = streams_.begin(); it != start_it; ++it) {
if (it->second.HasDataToSend(now)) {
current_stream_id_ = it->first;
return it;
}
}
return streams_.end();
}
absl::optional<SendQueue::DataToSend> RRSendQueue::Produce(TimeMs now,
size_t max_size) {
std::map<StreamID, RRSendQueue::OutgoingStream>::iterator stream_it;
if (previous_message_has_ended_) {
// Previous message has ended. Round-robin to a different stream, if there
// even is one with data to send.
stream_it = GetNextStream(now);
if (stream_it == streams_.end()) {
RTC_DLOG(LS_VERBOSE)
<< log_prefix_
<< "There is no stream with data; Can't produce any data.";
return absl::nullopt;
}
} else {
// The previous message has not ended; Continue from the current stream.
stream_it = streams_.find(current_stream_id_);
RTC_DCHECK(stream_it != streams_.end());
}
absl::optional<DataToSend> data = stream_it->second.Produce(now, max_size);
if (data.has_value()) {
RTC_DLOG(LS_VERBOSE) << log_prefix_ << "Producing DATA, type="
<< (data->data.is_unordered ? "unordered" : "ordered")
<< "::"
<< (*data->data.is_beginning && *data->data.is_end
? "complete"
: *data->data.is_beginning
? "first"
: *data->data.is_end ? "last" : "middle")
<< ", stream_id=" << *stream_it->first
<< ", ppid=" << *data->data.ppid
<< ", length=" << data->data.payload.size();
previous_message_has_ended_ = *data->data.is_end;
}
RTC_DCHECK(IsConsistent());
return data;
}
bool RRSendQueue::Discard(IsUnordered unordered,
StreamID stream_id,
MID message_id) {
bool has_discarded =
GetOrCreateStreamInfo(stream_id).Discard(unordered, message_id);
if (has_discarded) {
// Only partially sent messages are discarded, so if a message was
// discarded, then it was the currently sent message.
previous_message_has_ended_ = true;
}
return has_discarded;
}
void RRSendQueue::PrepareResetStreams(rtc::ArrayView<const StreamID> streams) {
for (StreamID stream_id : streams) {
GetOrCreateStreamInfo(stream_id).Pause();
}
RTC_DCHECK(IsConsistent());
}
bool RRSendQueue::CanResetStreams() const {
// Streams can be reset if those streams that are paused don't have any
// messages that are partially sent.
for (auto& stream : streams_) {
if (stream.second.is_paused() &&
stream.second.has_partially_sent_message()) {
return false;
}
}
return true;
}
void RRSendQueue::CommitResetStreams() {
Reset();
RTC_DCHECK(IsConsistent());
}
void RRSendQueue::RollbackResetStreams() {
for (auto& stream_entry : streams_) {
stream_entry.second.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& stream_entry : streams_) {
OutgoingStream& stream = stream_entry.second;
stream.Reset();
}
previous_message_has_ended_ = true;
}
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(stream_id,
OutgoingStream(
[this, stream_id]() { on_buffered_amount_low_(stream_id); },
total_buffered_amount_))
.first->second;
}
} // namespace dcsctp