1 files changed, 118 insertions, 0 deletions
diff --git a/ipc/glue/CrossProcessSemaphore.h b/ipc/glue/CrossProcessSemaphore.h
new file mode 100644
index 0000000000..297552853c
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+++ b/ipc/glue/CrossProcessSemaphore.h
@@ -0,0 +1,118 @@
+/* -*- 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