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// Copyright 2013 the V8 project authors. All rights reserved.
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following
// disclaimer in the documentation and/or other materials provided
// with the distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived
// from this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
#ifndef V8_PLATFORM_SEMAPHORE_H_
#define V8_PLATFORM_SEMAPHORE_H_
#include "lazy-instance.h"
#if V8_OS_WIN
#include "win32-headers.h"
#endif
#if V8_OS_MACOSX
#include <mach/semaphore.h> // NOLINT
#elif V8_OS_POSIX
#include <semaphore.h> // NOLINT
#endif
namespace v8 {
namespace internal {
// Forward declarations.
class TimeDelta;
// ----------------------------------------------------------------------------
// Semaphore
//
// A semaphore object is a synchronization object that maintains a count. The
// count is decremented each time a thread completes a wait for the semaphore
// object and incremented each time a thread signals the semaphore. When the
// count reaches zero, threads waiting for the semaphore blocks until the
// count becomes non-zero.
class Semaphore V8_FINAL {
public:
explicit Semaphore(int count);
~Semaphore();
// Increments the semaphore counter.
void Signal();
// Suspends the calling thread until the semaphore counter is non zero
// and then decrements the semaphore counter.
void Wait();
// Suspends the calling thread until the counter is non zero or the timeout
// time has passed. If timeout happens the return value is false and the
// counter is unchanged. Otherwise the semaphore counter is decremented and
// true is returned.
bool WaitFor(const TimeDelta& rel_time) V8_WARN_UNUSED_RESULT;
#if V8_OS_MACOSX
typedef semaphore_t NativeHandle;
#elif V8_OS_POSIX
typedef sem_t NativeHandle;
#elif V8_OS_WIN
typedef HANDLE NativeHandle;
#endif
NativeHandle& native_handle() {
return native_handle_;
}
const NativeHandle& native_handle() const {
return native_handle_;
}
private:
NativeHandle native_handle_;
DISALLOW_COPY_AND_ASSIGN(Semaphore);
};
// POD Semaphore initialized lazily (i.e. the first time Pointer() is called).
// Usage:
// // The following semaphore starts at 0.
// static LazySemaphore<0>::type my_semaphore = LAZY_SEMAPHORE_INITIALIZER;
//
// void my_function() {
// // Do something with my_semaphore.Pointer().
// }
//
template <int N>
struct CreateSemaphoreTrait {
static Semaphore* Create() {
return new Semaphore(N);
}
};
template <int N>
struct LazySemaphore {
typedef typename LazyDynamicInstance<
Semaphore,
CreateSemaphoreTrait<N>,
ThreadSafeInitOnceTrait>::type type;
};
#define LAZY_SEMAPHORE_INITIALIZER LAZY_DYNAMIC_INSTANCE_INITIALIZER
} } // namespace v8::internal
#endif // V8_PLATFORM_SEMAPHORE_H_
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