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DependentExtensions/cat/threads/WaitableFlag.hpp

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+/*
+	Copyright (c) 2009-2010 Christopher A. Taylor.  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 LibCat 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 HOLDER 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 CAT_WAITABLE_FLAG_HPP
+#define CAT_WAITABLE_FLAG_HPP
+
+#include <cat/Platform.hpp>
+
+#if defined(CAT_OS_WINDOWS)
+# include <cat/port/WindowsInclude.hpp>
+#else // use POSIX thread library otherwise
+# include <pthread.h>
+#endif
+
+namespace cat {
+
+
+/*
+	class WaitableFlag
+
+	Can be set, reset or waited upon.
+
+	Initially unset.
+	Flag is edge-triggered.
+	Successful waiting will reset the flag.
+	Only one thread can wait at a time.
+
+	Designed to synchronize threads:
+		One thread can wait for this flag to be raised by another thread before continuing.
+*/
+class WaitableFlag
+{
+#if defined(CAT_OS_WINDOWS)
+	HANDLE _event;
+#else
+	bool _valid, _valid_cond, _valid_mutex;
+	volatile u32 _flag;
+	pthread_cond_t _cond;
+	pthread_mutex_t _mutex;
+#endif
+
+	void Cleanup();
+
+public:
+	WaitableFlag();
+	CAT_INLINE virtual ~WaitableFlag()
+	{
+		Cleanup();
+	}
+
+	CAT_INLINE bool Valid()
+	{
+#if defined(CAT_OS_WINDOWS)
+		return _event != 0;
+#else
+		return _valid;
+#endif
+	}
+
+	bool Set();
+	bool Wait(int milliseconds = -1); // < 0 = wait forever
+};
+
+
+} // namespace cat
+
+#endif // CAT_WAITABLE_FLAG_HPP