Cleanup Semaphore class.

src/platform/semaphore.h

+// 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() V8_WARN_UNUSED_RESULT {
+    return native_handle_;
+  }
+  const NativeHandle& native_handle() const V8_WARN_UNUSED_RESULT {
+    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_