/* ********************************************************************** * 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*/