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+/*
+**********************************************************************
+* Copyright (C) 1997-2011, International Business Machines
+* Corporation and others. All Rights Reserved.
+**********************************************************************
+*
+* File UMUTEX.H
+*
+* Modification History:
+*
+* Date Name Description
+* 04/02/97 aliu Creation.
+* 04/07/99 srl rewrite - C interface, multiple mutices
+* 05/13/99 stephen Changed to umutex (from cmutex)
+******************************************************************************
+*/
+
+#ifndef UMUTEX_H
+#define UMUTEX_H
+
+#include "unicode/utypes.h"
+#include "unicode/uclean.h"
+#include "putilimp.h"
+
+#if defined(_MSC_VER) && _MSC_VER >= 1500
+# include <intrin.h>
+#endif
+
+#if U_PLATFORM_IS_DARWIN_BASED
+#if defined(__STRICT_ANSI__)
+#define UPRV_REMAP_INLINE
+#define inline
+#endif
+#include <libkern/OSAtomic.h>
+#define USE_MAC_OS_ATOMIC_INCREMENT 1
+#if defined(UPRV_REMAP_INLINE)
+#undef inline
+#undef UPRV_REMAP_INLINE
+#endif
+#endif
+
+/*
+ * If we do not compile with dynamic_annotations.h then define
+ * empty annotation macros.
+ * See http://code.google.com/p/data-race-test/wiki/DynamicAnnotations
+ */
+#ifndef ANNOTATE_HAPPENS_BEFORE
+# define ANNOTATE_HAPPENS_BEFORE(obj)
+# define ANNOTATE_HAPPENS_AFTER(obj)
+# define ANNOTATE_UNPROTECTED_READ(x) (x)
+#endif
+
+#ifndef UMTX_FULL_BARRIER
+# if !ICU_USE_THREADS
+# define UMTX_FULL_BARRIER
+# elif U_HAVE_GCC_ATOMICS
+# define UMTX_FULL_BARRIER __sync_synchronize();
+# elif defined(_MSC_VER) && _MSC_VER >= 1500
+ /* From MSVC intrin.h. Use _ReadWriteBarrier() only on MSVC 9 and higher. */
+# define UMTX_FULL_BARRIER _ReadWriteBarrier();
+# elif U_PLATFORM_IS_DARWIN_BASED
+# define UMTX_FULL_BARRIER OSMemoryBarrier();
+# else
+# define UMTX_FULL_BARRIER \
+ { \
+ umtx_lock(NULL); \
+ umtx_unlock(NULL); \
+ }
+# endif
+#endif
+
+#ifndef UMTX_ACQUIRE_BARRIER
+# define UMTX_ACQUIRE_BARRIER UMTX_FULL_BARRIER
+#endif
+
+#ifndef UMTX_RELEASE_BARRIER
+# define UMTX_RELEASE_BARRIER UMTX_FULL_BARRIER
+#endif
+
+/**
+ * \def UMTX_CHECK
+ * Encapsulates a safe check of an expression
+ * for use with double-checked lazy inititialization.
+ * Either memory barriers or mutexes are required, to prevent both the hardware
+ * and the compiler from reordering operations across the check.
+ * The expression must involve only a _single_ variable, typically
+ * a possibly null pointer or a boolean that indicates whether some service
+ * is initialized or not.
+ * The setting of the variable involved in the test must be the last step of
+ * the initialization process.
+ *
+ * @internal
+ */
+#define UMTX_CHECK(pMutex, expression, result) \
+ { \
+ (result)=(expression); \
+ UMTX_ACQUIRE_BARRIER; \
+ }
+/*
+ * TODO: Replace all uses of UMTX_CHECK and surrounding code
+ * with SimpleSingleton or TriStateSingleton, and remove UMTX_CHECK.
+ */
+
+/*
+ * Code within ICU that accesses shared static or global data should
+ * instantiate a Mutex object while doing so. The unnamed global mutex
+ * is used throughout ICU, so keep locking short and sweet.
+ *
+ * For example:
+ *
+ * void Function(int arg1, int arg2)
+ * {
+ * static Object* foo; // Shared read-write object
+ * umtx_lock(NULL); // Lock the ICU global mutex
+ * foo->Method();
+ * umtx_unlock(NULL);
+ * }
+ *
+ * an alternative C++ mutex API is defined in the file common/mutex.h
+ */
+
+/* Lock a mutex.
+ * @param mutex The given mutex to be locked. Pass NULL to specify
+ * the global ICU mutex. Recursive locks are an error
+ * and may cause a deadlock on some platforms.
+ */
+U_CAPI void U_EXPORT2 umtx_lock ( UMTX* mutex );
+
+/* Unlock a mutex. Pass in NULL if you want the single global
+ mutex.
+ * @param mutex The given mutex to be unlocked. Pass NULL to specify
+ * the global ICU mutex.
+ */
+U_CAPI void U_EXPORT2 umtx_unlock ( UMTX* mutex );
+
+/* Initialize a mutex. Use it this way:
+ umtx_init( &aMutex );
+ * ICU Mutexes do not need explicit initialization before use. Use of this
+ * function is not necessary.
+ * Initialization of an already initialized mutex has no effect, and is safe to do.
+ * Initialization of mutexes is thread safe. Two threads can concurrently
+ * initialize the same mutex without causing problems.
+ * @param mutex The given mutex to be initialized
+ */
+U_CAPI void U_EXPORT2 umtx_init ( UMTX* mutex );
+
+/* Destroy a mutex. This will free the resources of a mutex.
+ * Use it this way:
+ * umtx_destroy( &aMutex );
+ * Destroying an already destroyed mutex has no effect, and causes no problems.
+ * This function is not thread safe. Two threads must not attempt to concurrently
+ * destroy the same mutex.
+ * @param mutex The given mutex to be destroyed.
+ */
+U_CAPI void U_EXPORT2 umtx_destroy( UMTX *mutex );
+
+/*
+ * Atomic Increment and Decrement of an int32_t value.
+ *
+ * Return Values:
+ * If the result of the operation is zero, the return zero.
+ * If the result of the operation is not zero, the sign of returned value
+ * is the same as the sign of the result, but the returned value itself may
+ * be different from the result of the operation.
+ */
+U_CAPI int32_t U_EXPORT2 umtx_atomic_inc(int32_t *);
+U_CAPI int32_t U_EXPORT2 umtx_atomic_dec(int32_t *);
+
+#endif /*_CMUTEX*/
+/*eof*/