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+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_CrossProcessSemaphore_h
+#define mozilla_CrossProcessSemaphore_h
+
+#include "base/process.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/Maybe.h"
+
+#if defined(OS_WIN)
+# include "mozilla/UniquePtrExtensions.h"
+#endif
+#if !defined(OS_WIN) && !defined(OS_MACOSX)
+# include <pthread.h>
+# include <semaphore.h>
+# include "mozilla/ipc/SharedMemoryBasic.h"
+# include "mozilla/Atomics.h"
+#endif
+
+namespace IPC {
+template <typename T>
+struct ParamTraits;
+} // namespace IPC
+
+//
+// Provides:
+//
+// - CrossProcessSemaphore, a semaphore that can be shared across processes
+namespace mozilla {
+
+template <typename T>
+inline bool IsHandleValid(const T& handle) {
+ return bool(handle);
+}
+
+#if defined(OS_WIN)
+typedef mozilla::UniqueFileHandle CrossProcessSemaphoreHandle;
+#elif !defined(OS_MACOSX)
+typedef mozilla::ipc::SharedMemoryBasic::Handle CrossProcessSemaphoreHandle;
+
+template <>
+inline bool IsHandleValid<CrossProcessSemaphoreHandle>(
+ const CrossProcessSemaphoreHandle& handle) {
+ return !(handle == mozilla::ipc::SharedMemoryBasic::NULLHandle());
+}
+#else
+// Stub for other platforms. We can't use uintptr_t here since different
+// processes could disagree on its size.
+typedef uintptr_t CrossProcessSemaphoreHandle;
+#endif
+
+class CrossProcessSemaphore {
+ public:
+ /**
+ * CrossProcessSemaphore
+ * @param name A name which can reference this lock (currently unused)
+ **/
+ static CrossProcessSemaphore* Create(const char* aName,
+ uint32_t aInitialValue);
+
+ /**
+ * CrossProcessSemaphore
+ * @param handle A handle of an existing cross process semaphore that can be
+ * opened.
+ */
+ static CrossProcessSemaphore* Create(CrossProcessSemaphoreHandle aHandle);
+
+ ~CrossProcessSemaphore();
+
+ /**
+ * Decrements the current value of the semaphore. This will block if the
+ * current value of the semaphore is 0, up to a maximum of aWaitTime (if
+ * specified).
+ * Returns true if the semaphore was succesfully decremented, false otherwise.
+ **/
+ bool Wait(const Maybe<TimeDuration>& aWaitTime = Nothing());
+
+ /**
+ * Increments the current value of the semaphore.
+ **/
+ void Signal();
+
+ /**
+ * CloneHandle
+ * This function is called to generate a serializable structure that can
+ * be sent to the specified process and opened on the other side.
+ *
+ * @returns A handle that can be shared to another process
+ */
+ CrossProcessSemaphoreHandle CloneHandle();
+
+ void CloseHandle();
+
+ private:
+ friend struct IPC::ParamTraits<CrossProcessSemaphore>;
+
+ CrossProcessSemaphore();
+ CrossProcessSemaphore(const CrossProcessSemaphore&);
+ CrossProcessSemaphore& operator=(const CrossProcessSemaphore&);
+
+#if defined(OS_WIN)
+ explicit CrossProcessSemaphore(HANDLE aSemaphore);
+
+ HANDLE mSemaphore;
+#elif !defined(OS_MACOSX)
+ RefPtr<mozilla::ipc::SharedMemoryBasic> mSharedBuffer;
+ sem_t* mSemaphore;
+ mozilla::Atomic<int32_t>* mRefCount;
+#endif
+};
+
+} // namespace mozilla
+
+#endif