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

// Copyright 2013 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_PACKET_WRITER_H_
#define QUICHE_QUIC_CORE_QUIC_PACKET_WRITER_H_

#include <cstddef>
#include <optional>
#include <utility>

#include "quiche/quic/core/quic_packets.h"
#include "quiche/quic/platform/api/quic_export.h"
#include "quiche/quic/platform/api/quic_ip_address.h"
#include "quiche/quic/platform/api/quic_socket_address.h"

namespace quic {

struct WriteResult;

// This class allows a platform to pass instructions to an associated child of
// QuicWriter without intervening QUIC code understanding anything about its
// contents.
class QUICHE_EXPORT PerPacketOptions { … };

// The owner of QuicPacketWriter can pass control information via this struct.
struct QUICHE_EXPORT QuicPacketWriterParams { … };

// An interface between writers and the entity managing the
// socket (in our case the QuicDispatcher).  This allows the Dispatcher to
// control writes, and manage any writers who end up write blocked.
// A concrete writer works in one of the two modes:
// - PassThrough mode. This is the default mode. Caller calls WritePacket with
//   caller-allocated packet buffer. Unless the writer is blocked, each call to
//   WritePacket triggers a write using the underlying socket API.
//
// - Batch mode. In this mode, a call to WritePacket may not cause a packet to
//   be sent using the underlying socket API. Instead, multiple packets are
//   saved in the writer's internal buffer until they are flushed. The flush can
//   be explicit, by calling Flush, or implicit, e.g. by calling
//   WritePacket when the internal buffer is near full.
//
// Buffer management:
// In Batch mode, a writer manages an internal buffer, which is large enough to
// hold multiple packets' data. If the caller calls WritePacket with a
// caller-allocated packet buffer, the writer will memcpy the buffer into the
// internal buffer. Caller can also avoid this memcpy by:
// 1. Call GetNextWriteLocation to get a pointer P into the internal buffer.
// 2. Serialize the packet directly to P.
// 3. Call WritePacket with P as the |buffer|.
class QUICHE_EXPORT QuicPacketWriter { … };

}  // namespace quic

#endif  // QUICHE_QUIC_CORE_QUIC_PACKET_WRITER_H_