548 lines
16 KiB
C
548 lines
16 KiB
C
/*
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******************************************************************************
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*
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* Copyright (C) 1997-2003, 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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*
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* File CMUTEX.C
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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 updated
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* 05/13/99 stephen Changed to umutex (from cmutex).
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* 11/22/99 aliu Make non-global mutex autoinitialize [j151]
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******************************************************************************
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*/
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/* Assume POSIX, and modify as necessary below */
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#define POSIX
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#if defined(_WIN32)
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#undef POSIX
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#endif
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#if defined(macintosh)
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#undef POSIX
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#endif
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#if defined(OS2)
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#undef POSIX
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#endif
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#include "unicode/utypes.h"
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#include "uassert.h"
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#include "ucln_cmn.h"
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#if defined(POSIX) && (ICU_USE_THREADS==1)
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# include <pthread.h> /* must be first, so that we get the multithread versions of things. */
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#endif /* POSIX && (ICU_USE_THREADS==1) */
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#ifdef WIN32
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# define WIN32_LEAN_AND_MEAN
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# define NOGDI
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# define NOUSER
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# define NOSERVICE
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# define NOIME
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# define NOMCX
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# include <windows.h>
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#endif
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#include "umutex.h"
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#include "cmemory.h"
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/*
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* A note on ICU Mutex Initialization and ICU startup:
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*
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* ICU mutexes, as used through the rest of the ICU code, are self-initializing.
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* To make this work, ICU uses the _ICU GLobal Mutex_ to synchronize the lazy init
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* of other ICU mutexes. For the global mutex itself, we need some other mechanism
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* to safely initialize it on first use. This becomes important if two or more
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* threads were more or less simultaenously the first to use ICU in a process, and
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* were racing into the mutex initialization code.
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*
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* The solution for the global mutex init is platform dependent.
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* On POSIX systems, C-style init can be used on a mutex, with the
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* macro PTHREAD_MUTEX_INITIALIZER. The mutex is then ready for use, without
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* first calling pthread_mutex_init().
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*
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* Windows has no equivalent statically initialized mutex or CRITICAL SECION.
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* InitializeCriticalSection() must be called. If the global mutex does not
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* appear to be initialized, a thread will create and initialize a new
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* CRITICAL_SECTION, then use a Windows InterlockedCompareAndExchange to
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* avoid problems with race conditions.
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*
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* If an application has overridden the ICU mutex implementation
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* by calling u_setMutexFunctions(), the user supplied init function must
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* be safe in the event that multiple threads concurrently attempt to init
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* the same mutex. The first thread should do the init, and the others should
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* have no effect.
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*
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*/
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#define MAX_MUTEXES 30
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static char gMutexesInUse[MAX_MUTEXES];
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static UBool gMutexPoolInitialized = FALSE;
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static UMTX gGlobalMutex = NULL;
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static UMTX gIncDecMutex = NULL;
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/*-------------------------------------------------------------
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*
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* WINDOWS platform variable declarations
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*
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*-------------------------------------------------------------*/
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#if defined(WIN32)
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static CRITICAL_SECTION gMutexes[MAX_MUTEXES];
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static CRITICAL_SECTION gGlobalWinMutex;
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/* Detect Recursive locking of the global mutex. For debugging only. */
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#if defined(_DEBUG) && (ICU_USE_THREADS==1)
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static int32_t gRecursionCount = 0;
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#endif
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/*-------------------------------------------------------------
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*
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* POSIX platform variable declarations
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*
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*-------------------------------------------------------------*/
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#elif defined(POSIX)
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#if (ICU_USE_THREADS == 1)
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static pthread_mutex_t gMutexes[MAX_MUTEXES] = {
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PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
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PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
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PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
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PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
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PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
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PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
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PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER
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};
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#endif
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/*-------------------------------------------------------------
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*
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* UNKNOWN platform declarations
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*
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*-------------------------------------------------------------*/
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#else
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/* Unknown platform. OK so long as ICU_USE_THREAD is not set.
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Note that user can still set mutex functions at run time,
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and that the global mutex variable is still needed in that case. */
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#if (ICU_USE_THREADS == 1)
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#error no ICU mutex implementation for this platform
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#endif
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#endif
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/*
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* User mutex implementation functions. If non-null, call back to these rather than
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* directly using the system (Posix or Windows) APIs.
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* (declarations are in uclean.h)
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*/
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static UMtxInitFn *pMutexInitFn = NULL;
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static UMtxFn *pMutexDestroyFn = NULL;
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static UMtxFn *pMutexLockFn = NULL;
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static UMtxFn *pMutexUnlockFn = NULL;
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static const void *gMutexContext = NULL;
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/*
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* umtx_lock
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*/
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U_CAPI void U_EXPORT2
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umtx_lock(UMTX *mutex)
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{
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if (mutex == NULL) {
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mutex = &gGlobalMutex;
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}
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if (*mutex == NULL) {
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/* Lock of an uninitialized mutex. Initialize it before proceeding. */
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umtx_init(mutex);
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}
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if (pMutexLockFn != NULL) {
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(*pMutexLockFn)(gMutexContext, mutex);
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} else {
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#if (ICU_USE_THREADS == 1)
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#if defined(WIN32)
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EnterCriticalSection((CRITICAL_SECTION*) *mutex);
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#elif defined(POSIX)
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pthread_mutex_lock((pthread_mutex_t*) *mutex);
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#endif /* cascade of platforms */
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#endif /* ICU_USE_THREADS==1 */
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}
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#if defined(WIN32) && defined(_DEBUG) && (ICU_USE_THREADS==1)
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if (mutex == &gGlobalMutex) { /* Detect Reentrant locking of the global mutex. */
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gRecursionCount++; /* Recursion causes deadlocks on Unixes. */
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U_ASSERT(gRecursionCount == 1); /* Detection works on Windows. Debug problems there. */
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}
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#endif /*_DEBUG*/
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}
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/*
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* umtx_unlock
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*/
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U_CAPI void U_EXPORT2
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umtx_unlock(UMTX* mutex)
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{
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if(mutex == NULL) {
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mutex = &gGlobalMutex;
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}
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if(*mutex == NULL) {
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U_ASSERT(FALSE); /* This mutex is not initialized. */
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return;
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}
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#if defined (WIN32) && defined (_DEBUG) && (ICU_USE_THREADS==1)
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if (mutex == &gGlobalMutex) {
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gRecursionCount--;
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U_ASSERT(gRecursionCount == 0); /* Detect unlock of an already unlocked mutex */
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}
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#endif
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if (pMutexUnlockFn) {
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(*pMutexUnlockFn)(gMutexContext, mutex);
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} else {
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#if (ICU_USE_THREADS==1)
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#if defined (WIN32)
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LeaveCriticalSection((CRITICAL_SECTION*)*mutex);
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#elif defined (POSIX)
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pthread_mutex_unlock((pthread_mutex_t*)*mutex);
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#endif /* cascade of platforms */
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#endif /* ICU_USE_THREADS == 1 */
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}
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}
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/*
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* initGlobalMutex Do the platform specific initialization of the ICU global mutex.
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* Separated out from the other mutexes because it is different:
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* Mutex storage is static for POSIX, init must be thread safe
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* without the use of another mutex.
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*/
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static void initGlobalMutex() {
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int i;
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/*
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* If User Supplied mutex functions are in use
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* init the icu global mutex using them.
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*/
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if (pMutexInitFn != NULL) {
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if (gGlobalMutex==NULL) {
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UErrorCode status = U_ZERO_ERROR;
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(*pMutexInitFn)(gMutexContext, &gGlobalMutex, &status);
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if (U_FAILURE(status)) {
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/* TODO: how should errors here be handled? */
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return;
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}
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}
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return;
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}
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/* No user override of mutex functions.
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* Use default ICU mutex implementations.
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*/
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#if (ICU_USE_THREADS == 1)
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/*
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* for Windows, init the pool of critical sections that we
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* will use as needed for ICU mutexes.
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*/
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#if defined (WIN32)
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if (gMutexPoolInitialized == FALSE) {
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for (i=0; i<MAX_MUTEXES; i++) {
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InitializeCriticalSection(&gMutexes[i]);
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}
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}
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gMutexPoolInitialized = TRUE;
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#elif defined (POSIX)
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/* TODO: experimental code. Shouldn't need to explicitly init the mutexes. */
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if (gMutexPoolInitialized == FALSE) {
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for (i=0; i<MAX_MUTEXES; i++) {
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pthread_mutex_init(&gMutexes[i], NULL);
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}
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}
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gMutexPoolInitialized = TRUE;
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#endif
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/*
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* for both Windows & POSIX, the first mutex in the array is used
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* for the ICU global mutex.
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*/
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gGlobalMutex = &gMutexes[0];
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gMutexesInUse[0] = 1;
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#else /* ICU_USE_THREADS */
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gGlobalMutex = &gGlobalMutex; /* With no threads, we must still set the mutex to
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* some non-null value to make the rest of the
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* (not ifdefed) mutex code think that it is initialized.
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*/
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#endif /* ICU_USE_THREADS */
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}
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U_CAPI void U_EXPORT2
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umtx_init(UMTX *mutex)
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{
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if (mutex == NULL || mutex == &gGlobalMutex) {
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initGlobalMutex();
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} else {
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int i;
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umtx_lock(NULL);
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if (*mutex != NULL) {
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/* Another thread initialized this mutex first. */
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umtx_unlock(NULL);
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return;
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}
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if (pMutexInitFn != NULL) {
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UErrorCode status = U_ZERO_ERROR;
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(*pMutexInitFn)(gMutexContext, mutex, &status);
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/* TODO: how to report failure on init? */
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umtx_unlock(NULL);
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return;
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}
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/* Search through our pool of pre-allocated mutexes for one that is not
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* already in use. */
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for (i=0; i<MAX_MUTEXES; i++) {
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if (gMutexesInUse[i] == 0) {
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gMutexesInUse[i] = 1;
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*mutex = &gMutexes[i];
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break;
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}
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}
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umtx_unlock(NULL);
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/* No more mutexes were available from our pre-allocated pool. */
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/* TODO: how best to deal with this? */
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U_ASSERT(*mutex != NULL);
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}
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}
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/*
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* umtx_destroy. Un-initialize a mutex, releasing any underlying resources
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* that it may be holding. Destroying an already destroyed
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* mutex has no effect. Unlike umtx_init(), this function
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* is not thread safe; two threads must not concurrently try to
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* destroy the same mutex.
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*/
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U_CAPI void U_EXPORT2
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umtx_destroy(UMTX *mutex) {
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if (mutex == NULL) { /* destroy the global mutex */
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mutex = &gGlobalMutex;
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}
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if (*mutex == NULL) { /* someone already did it. */
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return;
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}
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/* The life of the inc/dec mutex is tied to that of the global mutex. */
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if (mutex == &gGlobalMutex) {
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umtx_destroy(&gIncDecMutex);
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}
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if (pMutexDestroyFn != NULL) {
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/* Mutexes are being managed by the app. Call back to it for the destroy. */
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(*pMutexDestroyFn)(gMutexContext, mutex);
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} else {
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/* Return this mutex to the pool of available mutexes, if it came from the
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* pool in the first place.
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*/
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int i;
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for (i=0; i<MAX_MUTEXES; i++) {
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if (*mutex == &gMutexes[i]) {
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gMutexesInUse[i] = 0;
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break;
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}
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}
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}
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*mutex = NULL;
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}
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U_CAPI void U_EXPORT2
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u_setMutexFunctions(const void *context, UMtxInitFn *i, UMtxFn *d, UMtxFn *l, UMtxFn *u,
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UErrorCode *status) {
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if (U_FAILURE(*status)) {
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return;
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}
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/* Can not set a mutex function to a NULL value */
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if (i==NULL || d==NULL || l==NULL || u==NULL) {
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*status = U_ILLEGAL_ARGUMENT_ERROR;
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return;
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}
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/* If ICU is not in an initial state, disallow this operation. */
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if (cmemory_inUse()) {
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*status = U_INVALID_STATE_ERROR;
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return;
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}
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/* Swap in the mutex function pointers. */
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pMutexInitFn = i;
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pMutexDestroyFn = d;
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pMutexLockFn = l;
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pMutexUnlockFn = u;
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gMutexContext = context;
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gGlobalMutex = NULL; /* For POSIX, the global mutex will be pre-initialized */
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/* Undo that, force re-initialization when u_init() */
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/* happens. */
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}
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/*-----------------------------------------------------------------
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*
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* Atomic Increment and Decrement
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* umtx_atomic_inc
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* umtx_atomic_dec
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*
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*----------------------------------------------------------------*/
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/* Pointers to user-supplied inc/dec functions. Null if no funcs have been set. */
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static UMtxAtomicFn *pIncFn = NULL;
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static UMtxAtomicFn *pDecFn = NULL;
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static void *gIncDecContext = NULL;
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U_CAPI int32_t U_EXPORT2
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umtx_atomic_inc(int32_t *p) {
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int32_t retVal;
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if (pIncFn) {
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retVal = (*pIncFn)(gIncDecContext, p);
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} else {
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#if defined (WIN32) && ICU_USE_THREADS == 1
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retVal = InterlockedIncrement(p);
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#elif defined (POSIX) && ICU_USE_THREADS == 1
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umtx_lock(&gIncDecMutex);
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retVal = ++(*p);
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umtx_unlock(&gIncDecMutex);
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#else
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/* Unknown Platform, or ICU thread support compiled out. */
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retVal = ++(*p);
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#endif
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}
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return retVal;
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}
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U_CAPI int32_t U_EXPORT2
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umtx_atomic_dec(int32_t *p) {
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int32_t retVal;
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if (pDecFn) {
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retVal = (*pDecFn)(gIncDecContext, p);
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} else {
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#if defined (WIN32) && ICU_USE_THREADS == 1
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retVal = InterlockedDecrement(p);
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#elif defined (POSIX) && ICU_USE_THREADS == 1
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umtx_lock(&gIncDecMutex);
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retVal = --(*p);
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umtx_unlock(&gIncDecMutex);
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#else
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/* Unknown Platform, or ICU thread support compiled out. */
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retVal = --(*p);
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#endif
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}
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return retVal;
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}
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/* TODO: Some POSIXy platforms have atomic inc/dec functions available. Use them. */
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U_CAPI void U_EXPORT2
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u_setAtomicIncDecFunctions(const void *context, UMtxAtomicFn *ip, UMtxAtomicFn *dp,
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UErrorCode *status) {
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int32_t testInt;
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if (U_FAILURE(*status)) {
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return;
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}
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/* Can not set a mutex function to a NULL value */
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if (ip==NULL || dp==NULL) {
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*status = U_ILLEGAL_ARGUMENT_ERROR;
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return;
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}
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/* If ICU is not in an initial state, disallow this operation. */
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if (cmemory_inUse()) {
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*status = U_INVALID_STATE_ERROR;
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return;
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}
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pIncFn = ip;
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pDecFn = dp;
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testInt = 0;
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U_ASSERT(umtx_atomic_inc(&testInt) == 1); /* Sanity Check. Do the functions work at all? */
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U_ASSERT(testInt == 1);
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U_ASSERT(umtx_atomic_dec(&testInt) == 0);
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U_ASSERT(testInt == 0);
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}
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/*
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* Mutex Cleanup Function
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*
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* Destroy the global mutex(es), and reset the mutex function callback pointers.
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*/
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U_CFUNC UBool umtx_cleanup(void) {
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int i;
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umtx_destroy(NULL);
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pMutexInitFn = NULL;
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pMutexDestroyFn = NULL;
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pMutexLockFn = NULL;
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pMutexUnlockFn = NULL;
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gMutexContext = NULL;
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gGlobalMutex = NULL;
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pIncFn = NULL;
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pDecFn = NULL;
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gIncDecMutex = NULL;
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#if defined (WIN32)
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if (gMutexPoolInitialized) {
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for (i=0; i<MAX_MUTEXES; i++) {
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DeleteCriticalSection(&gMutexes[i]);
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gMutexesInUse[i] = 0;
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}
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}
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gMutexPoolInitialized = FALSE;
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#elif defined (POSIX)
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gIncDecMutex = NULL;
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for (i=0; i<MAX_MUTEXES; i++) {
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pthread_mutex_destroy(&gMutexes[i]);
|
|
gMutexesInUse[i] = 0;
|
|
}
|
|
gMutexPoolInitialized = FALSE;
|
|
#endif
|
|
|
|
return TRUE;
|
|
}
|
|
|
|
|