Add multi_process_lock to chrome/common

base/shared_mutex.h

Index: base/shared_mutex.h
diff --git a/base/shared_mutex.h b/base/shared_mutex.h
new file mode 100644
index 0000000000000000000000000000000000000000..6c01b5841105af053bdf133cff683fb582121205
--- /dev/null
+++ b/base/shared_mutex.h
@@ -0,0 +1,51 @@
+// Copyright (c) 2010 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef BASE_SHARED_MUTEX_H_
+#define BASE_SHARED_MUTEX_H_
+#pragma once
+
+#include "base/basictypes.h"
+#include <string>

[Mark Mentovai, 2010/11/09 17:43:14]

System <headers> before project "headers."

[dmac, 2010/11/11 21:47:59]

Done.

+
+#if OS_MACOSX

[Mark Mentovai, 2010/11/09 17:43:14]

Nope - #if defined(OS_MACOSX).

[dmac, 2010/11/11 21:47:59]

Done.

+#include <CoreFoundation/CoreFoundation.h>
+#elif OS_WIN

[Mark Mentovai, 2010/11/09 17:43:14]

Same.

[dmac, 2010/11/11 21:47:59]

Done.

+#include <windows.h>
+#endif
+
+namespace base {
+
+// Platform abstraction for a shared mutex between processes. The process
+// that owns the mutex lock will release it on exit even if exit is due
+// to a crash.
+// On Windows it is implemented as an event.
+// On Mac it is implemented using a CFMessagePort name.
+// On Linux it is implement using an abstract name port socket.
+class SharedMutex {
+ public:
+  SharedMutex(const std::string& name);

[Mark Mentovai, 2010/11/09 17:43:14]

explicit.

[dmac, 2010/11/11 21:47:59]

Done.

+  ~SharedMutex() { Unlock(); }
+
+  // Try to grab ownership of the mutex.
+  bool TryLock();
+
+  // Release ownership of the mutex.
+  void Unlock();
+
+ private:
+#if OS_WIN

[Mark Mentovai, 2010/11/09 17:43:14]

#if defined(…) again.

[dmac, 2010/11/11 21:47:59]

Done.

+  HANDLE event_;

[sanjeevr, 2010/11/09 06:21:05]

We should use a ScopedHandle.

[dmac, 2010/11/11 21:47:59]

Done.

+#elif OS_LINUX
+  int fd_;
+#elif OS_MACOSX
+  CFMessagePortRef port_;

[TVL, 2010/11/09 13:19:01]

base::mac::ScopedCFTypeRef?

[dmac, 2010/11/11 21:47:59]

Done.

+#endif
+  std::string name_;
+  DISALLOW_COPY_AND_ASSIGN(SharedMutex);
+};
+
+}  // namespace base
+
+#endif  // BASE_SHARED_MUTEX_H_