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