chromium/net/third_party/quiche/src/quiche/quic/core/quic_mtu_discovery.h

// Copyright (c) 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef QUICHE_QUIC_CORE_QUIC_MTU_DISCOVERY_H_
#define QUICHE_QUIC_CORE_QUIC_MTU_DISCOVERY_H_

#include <iostream>

#include "quiche/quic/core/quic_constants.h"
#include "quiche/quic/core/quic_types.h"

namespace quic {

// The initial number of packets between MTU probes.  After each attempt the
// number is doubled.
inline constexpr QuicPacketCount kPacketsBetweenMtuProbesBase = …;

// The number of MTU probes that get sent before giving up.
inline constexpr size_t kMtuDiscoveryAttempts = …;

// Ensure that exponential back-off does not result in an integer overflow.
// The number of packets can be potentially capped, but that is not useful at
// current kMtuDiscoveryAttempts value, and hence is not implemented at present.
static_assert …;
static_assert …;

// The increased packet size targeted when doing path MTU discovery.
inline constexpr QuicByteCount kMtuDiscoveryTargetPacketSizeHigh = …;
inline constexpr QuicByteCount kMtuDiscoveryTargetPacketSizeLow = …;

static_assert …;
static_assert …;

static_assert …;
static_assert …;

// QuicConnectionMtuDiscoverer is a MTU discovery controller, it answers two
// questions:
// 1) Probe scheduling: Whether a connection should send a MTU probe packet
//    right now.
// 2) MTU search stradegy: When it is time to send, what should be the size of
//    the probing packet.
// Note the discoverer does not actually send or process probing packets.
//
// Unit tests are in QuicConnectionTest.MtuDiscovery*.
class QUICHE_EXPORT QuicConnectionMtuDiscoverer { … };

}  // namespace quic

#endif  // QUICHE_QUIC_CORE_QUIC_MTU_DISCOVERY_H_