EventHandler.h

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/*
 * Copyright 2014-present Facebook, Inc.
 *
 * Licensed 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 <cstddef>

#include <boost/noncopyable.hpp>
#include <glog/logging.h>

#include <folly/io/async/EventUtil.h>
#include <folly/net/NetworkSocket.h>
#include <folly/portability/Event.h>

namespace folly {

class EventBase;

class EventHandler : private boost::noncopyable {
 public:
  enum EventFlags {
    NONE = 0,
    READ = EV_READ,
    WRITE = EV_WRITE,
    READ_WRITE = (READ | WRITE),
    PERSIST = EV_PERSIST,
// Temporary flag until EPOLLPRI is upstream on libevent.
#ifdef EV_PRI
    PRI = EV_PRI,
#endif
  };

  explicit EventHandler(EventBase* eventBase, int fd)
      : EventHandler(eventBase, NetworkSocket::fromFd(fd)) {}
  explicit EventHandler(
      EventBase* eventBase = nullptr,
      NetworkSocket fd = NetworkSocket());

  virtual ~EventHandler();

  virtual void handlerReady(uint16_t events) noexcept = 0;

  bool registerHandler(uint16_t events) {
    return registerImpl(events, false);
  }

  void unregisterHandler();

  bool isHandlerRegistered() const {
    return EventUtil::isEventRegistered(&event_);
  }

  void attachEventBase(EventBase* eventBase);

  void detachEventBase();

  void changeHandlerFD(int fd) {
    changeHandlerFD(NetworkSocket::fromFd(fd));
  }

  void changeHandlerFD(NetworkSocket fd);

  void initHandler(EventBase* eventBase, int fd) {
    initHandler(eventBase, NetworkSocket::fromFd(fd));
  }

  void initHandler(EventBase* eventBase, NetworkSocket fd);

  uint16_t getRegisteredEvents() const {
    return (isHandlerRegistered()) ? uint16_t(event_.ev_events) : 0u;
  }

  bool registerInternalHandler(uint16_t events) {
    return registerImpl(events, true);
  }

  bool isPending() const;

 private:
  bool registerImpl(uint16_t events, bool internal);
  void ensureNotRegistered(const char* fn);

  void setEventBase(EventBase* eventBase);

  static void libeventCallback(libevent_fd_t fd, short events, void* arg);

  struct event event_;
  EventBase* eventBase_;
};

} // namespace folly