epoll.h

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/*
 * Copyright (C) 2022 The Android Open Source Project
 *
 * 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 <sys/epoll.h>
 
#include <memory>
#include <optional>
#include <set>
#include <shared_mutex>
 
#include "cuttlefish/common/libs/fs/shared_fd.h"
#include "cuttlefish/common/libs/utils/result.h"
 
namespace cuttlefish {
 
struct EpollEvent {
  SharedFD fd;
  uint32_t events;
};
 
class Epoll {
 public:
  static Result<Epoll> Create();
  Epoll(); // Invalid instance
  Epoll(Epoll&&);
  Epoll& operator=(Epoll&&);
 
  Result<void> Add(SharedFD fd, uint32_t events);
  Result<void> Modify(SharedFD fd, uint32_t events);
  Result<void> AddOrModify(SharedFD fd, uint32_t events);
  Result<void> Delete(SharedFD fd);
  Result<std::optional<EpollEvent>> Wait();
 
 private:
  Epoll(SharedFD);
 
  std::shared_mutex epoll_mutex_;
  SharedFD epoll_fd_;
  std::shared_mutex watched_mutex_;
  std::set<SharedFD> watched_;
};
 
}  // namespace cuttlefish