chromium/base/synchronization/waitable_event.h

// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef BASE_SYNCHRONIZATION_WAITABLE_EVENT_H_
#define BASE_SYNCHRONIZATION_WAITABLE_EVENT_H_

#include <stddef.h>

#include "base/base_export.h"
#include "base/compiler_specific.h"
#include "base/memory/raw_ptr.h"
#include "build/build_config.h"

#if BUILDFLAG(IS_WIN)
#include "base/win/scoped_handle.h"
#elif BUILDFLAG(IS_APPLE)
#include <mach/mach.h>

#include <list>
#include <memory>

#include "base/apple/scoped_mach_port.h"
#include "base/functional/callback_forward.h"
#include "base/memory/ref_counted.h"
#elif BUILDFLAG(IS_POSIX) || BUILDFLAG(IS_FUCHSIA)
#include <list>
#include <utility>

#include "base/memory/ref_counted.h"
#include "base/synchronization/lock.h"
#endif

namespace base {

class TimeDelta;

// A WaitableEvent can be a useful thread synchronization tool when you want to
// allow one thread to wait for another thread to finish some work. For
// non-Windows systems, this can only be used from within a single address
// space.
//
// Use a WaitableEvent when you would otherwise use a Lock+ConditionVariable to
// protect a simple boolean value.  However, if you find yourself using a
// WaitableEvent in conjunction with a Lock to wait for a more complex state
// change (e.g., for an item to be added to a queue), then you should probably
// be using a ConditionVariable instead of a WaitableEvent.
//
// NOTE: On Windows, this class provides a subset of the functionality afforded
// by a Windows event object.  This is intentional.  If you are writing Windows
// specific code and you need other features of a Windows event, then you might
// be better off just using an Windows event directly.
class BASE_EXPORT WaitableEvent { … };

}  // namespace base

#endif  // BASE_SYNCHRONIZATION_WAITABLE_EVENT_H_