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/*
* Copyright (C) 2018 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.
*/
#ifndef INCLUDE_PERFETTO_EXT_BASE_EVENT_FD_H_
#define INCLUDE_PERFETTO_EXT_BASE_EVENT_FD_H_
#include "perfetto/base/build_config.h"
#include "perfetto/ext/base/scoped_file.h"
#if PERFETTO_BUILDFLAG(PERFETTO_OS_LINUX) || \
PERFETTO_BUILDFLAG(PERFETTO_OS_ANDROID)
#define PERFETTO_USE_EVENTFD() 1
#else
#define PERFETTO_USE_EVENTFD() 0
#endif
namespace perfetto {
namespace base {
// A waitable event that can be used with poll/select.
// This is really a wrapper around eventfd_create with a pipe-based fallback
// for other platforms where eventfd is not supported.
class EventFd {
public:
EventFd();
~EventFd();
EventFd(EventFd&&) noexcept = default;
EventFd& operator=(EventFd&&) = default;
// The non-blocking file descriptor that can be polled to wait for the event.
int fd() const { return fd_.get(); }
// Can be called from any thread.
void Notify();
// Can be called from any thread. If more Notify() are queued a Clear() call
// can clear all of them (up to 16 per call).
void Clear();
private:
// The eventfd, when eventfd is supported, otherwise this is the read end of
// the pipe for fallback mode.
ScopedFile fd_;
#if !PERFETTO_USE_EVENTFD()
// The write end of the wakeup pipe.
ScopedFile write_fd_;
#endif
};
} // namespace base
} // namespace perfetto
#endif // INCLUDE_PERFETTO_EXT_BASE_EVENT_FD_H_
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