mirror of
https://github.com/facebookincubator/mvfst.git
synced 2025-11-09 10:00:57 +03:00
04baa15a04
Summary: Make a custom variant type for PacketHeader. By not relying on boost::variant this reduces the code size of the implementation. This uses a combination of a union type as well as a enum type to emulate a variant Reviewed By: yangchi Differential Revision: D17187589 fbshipit-source-id: 00c2b9b8dd3f3e73af766d84888b13b9d867165a
69 lines
2.2 KiB
C++
69 lines
2.2 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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*/
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#include <quic/codec/QuicPacketRebuilder.h>
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#include <quic/state/QuicStateFunctions.h>
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#include <folly/lang/Assume.h>
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namespace quic {
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template <typename ClockType>
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inline folly::Optional<PacketNum> AckScheduler::writeNextAcks(
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PacketBuilderInterface& builder,
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AckMode mode) {
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switch (mode) {
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case AckMode::Immediate: {
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return writeAcksImpl<ClockType>(builder);
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}
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case AckMode::Pending: {
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return writeAcksIfPending<ClockType>(builder);
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}
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}
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folly::assume_unreachable();
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}
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template <typename ClockType>
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inline folly::Optional<PacketNum> AckScheduler::writeAcksIfPending(
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PacketBuilderInterface& builder) {
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if (ackState_.needsToSendAckImmediately) {
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return writeAcksImpl<ClockType>(builder);
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}
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return folly::none;
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}
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template <typename ClockType>
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folly::Optional<PacketNum> AckScheduler::writeAcksImpl(
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PacketBuilderInterface& builder) {
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// Use default ack delay for long headers. Usually long headers are sent
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// before crypto negotiation, so the peer might not know about the ack delay
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// exponent yet, so we use the default.
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uint8_t ackDelayExponentToUse =
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builder.getPacketHeader().getHeaderForm() == HeaderForm::Long
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? kDefaultAckDelayExponent
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: conn_.transportSettings.ackDelayExponent;
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auto largestAckedPacketNum = *largestAckToSend(ackState_);
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auto ackingTime = ClockType::now();
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DCHECK(ackState_.largestRecvdPacketTime.hasValue())
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<< "Missing received time for the largest acked packet";
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// assuming that we're going to ack the largest received with hightest pri
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auto receivedTime = *ackState_.largestRecvdPacketTime;
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std::chrono::microseconds ackDelay =
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(ackingTime > receivedTime
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? std::chrono::duration_cast<std::chrono::microseconds>(
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ackingTime - receivedTime)
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: 0us);
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AckFrameMetaData meta(ackState_.acks, ackDelay, ackDelayExponentToUse);
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auto ackWriteResult = writeAckFrame(meta, builder);
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if (!ackWriteResult) {
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return folly::none;
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}
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return largestAckedPacketNum;
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}
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} // namespace quic
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