CSE2410 Fall 2014 Bounce

// 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

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// (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_