include/proxy/http3/Http3FrameDispatcher.h

/** @file
 *
 *  A brief file description
 *
 *  @section license License
 *
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

#pragma once

#include "iocore/net/quic/QUICApplication.h"
#include "proxy/http3/Http3Frame.h"
#include "proxy/http3/Http3FrameHandler.h"
#include <array>
#include <cstdint>

class QUICStreamVCAdapter;

class Http3FrameDispatcher
{
public:
  Http3ErrorUPtr on_read_ready(QUICStreamId stream_id, Http3StreamType stream_type, IOBufferReader &reader, uint64_t &nread);

  void add_handler(Http3FrameHandler *handler);

private:
  // At most a handful of handlers ever register interest in the same frame type (currently
  // up to 3: the frame counter, the protocol enforcer, and one of the header/data handlers).
  // Inline storage avoids a heap allocation per handler registration, which otherwise runs
  // once per HTTP/3 request since this dispatcher is a per-transaction object.
  static constexpr size_t MAX_HANDLERS_PER_TYPE = 4;

  enum READING_STATE {
    READING_TYPE_LEN,
    READING_LENGTH_LEN,
    READING_PAYLOAD_LEN,
    READING_PAYLOAD,
  } _reading_state = READING_TYPE_LEN;
  int64_t                     _reading_frame_type_len;
  int64_t                     _reading_frame_length_len;
  uint64_t                    _reading_frame_payload_len;
  uint64_t                    _bytes_to_skip;
  Http3FrameFactory           _frame_factory;
  std::shared_ptr<Http3Frame> _current_frame = nullptr;

  std::array<Http3FrameHandler *, MAX_HANDLERS_PER_TYPE> _handlers[256]      = {};
  uint8_t                                                _handler_count[256] = {};
};