third_party/WebKit/Source/platform/WaitableEvent.h

/*
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 * modification, are permitted provided that the following conditions are
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#ifndef WaitableEvent_h
#define WaitableEvent_h

#include "platform/PlatformExport.h"
#include "wtf/OwnPtr.h"
#include "wtf/Vector.h"

namespace base {
class WaitableEvent;
}; // namespace base

namespace blink {

// Provides a thread synchronization that can be used to allow one thread to
// wait until another thread to finish some work.
class PLATFORM_EXPORT WaitableEvent {
public:
    // If ResetPolicy::Manual is specified on creation, to set the event state
    // to non-signaled, a consumer must call reset().  Otherwise, the system
    // automatically resets the event state to non-signaled after a single
    // waiting thread has been released.
    enum class ResetPolicy { Auto, Manual };

    // Specify the initial state on creation.
    enum class InitialState { NonSignaled, Signaled };

    explicit WaitableEvent(ResetPolicy = ResetPolicy::Auto, InitialState = InitialState::NonSignaled);

    ~WaitableEvent();

    // Puts the event in the un-signaled state.
    void reset();

    // Waits indefinitely for the event to be signaled.
    void wait();

    // Puts the event in the signaled state. Causing any thread blocked on Wait
    // to be woken up. The event state is reset to non-signaled after
    // a waiting thread has been released.
    void signal();

    // Waits on multiple events and returns the index of the object that
    // has been signaled. Any event objects given to this method must
    // not deleted while this wait is happening.
    static size_t waitMultiple(const WTF::Vector<WaitableEvent*>& events);

private:
    WaitableEvent(const WaitableEvent&) = delete;
    void operator=(const WaitableEvent&) = delete;

    OwnPtr<base::WaitableEvent> m_impl;
};

} // namespace blink

#endif // WaitableEvent_h