summaryrefslogtreecommitdiff
path: root/Build/source/libs/icu/icu-xetex/common/umutex.c
blob: 22396f5e1d9d942182509ace0a82df684b6c0b05 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
/*
******************************************************************************
*
*   Copyright (C) 1997-2006, International Business Machines
*   Corporation and others.  All Rights Reserved.
*
******************************************************************************
*
* File CMUTEX.C
*
* Modification History:
*
*   Date        Name        Description
*   04/02/97    aliu        Creation.
*   04/07/99    srl         updated
*   05/13/99    stephen     Changed to umutex (from cmutex).
*   11/22/99    aliu        Make non-global mutex autoinitialize [j151]
******************************************************************************
*/

#include "unicode/utypes.h"
#include "uassert.h"
#include "ucln_cmn.h"

#if defined(U_DARWIN)
#include <AvailabilityMacros.h>
#if (ICU_USE_THREADS == 1) && defined(MAC_OS_X_VERSION_10_4) && defined(MAC_OS_X_VERSION_MIN_REQUIRED) && (MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_X_VERSION_10_4)
#include <libkern/OSAtomic.h>
#define USE_MAC_OS_ATOMIC_INCREMENT 1
#endif
#endif

/* Assume POSIX, and modify as necessary below */
#define POSIX

#if defined(U_WINDOWS)
#undef POSIX
#endif
#if defined(macintosh)
#undef POSIX
#endif
#if defined(OS2)
#undef POSIX
#endif

#if defined(POSIX) && (ICU_USE_THREADS==1)
# include <pthread.h> /* must be first, so that we get the multithread versions of things. */

#endif /* POSIX && (ICU_USE_THREADS==1) */

#ifdef U_WINDOWS
# define WIN32_LEAN_AND_MEAN
# define VC_EXTRALEAN
# define NOUSER
# define NOSERVICE
# define NOIME
# define NOMCX
# include <windows.h>
#endif

#include "umutex.h"
#include "cmemory.h"

/*
 * A note on ICU Mutex Initialization and ICU startup:
 *
 *   ICU mutexes, as used through the rest of the ICU code, are self-initializing.
 *   To make this work, ICU uses the _ICU GLobal Mutex_ to synchronize the lazy init
 *   of other ICU mutexes.  For the global mutex itself, we need some other mechanism
 *   to safely initialize it on first use.  This becomes important if two or more
 *   threads were more or less simultaenously the first to use ICU in a process, and
 *   were racing into the mutex initialization code.
 *
 *   The solution for the global mutex init is platform dependent.
 *   On POSIX systems, C-style init can be used on a mutex, with the 
 *   macro PTHREAD_MUTEX_INITIALIZER.  The mutex is then ready for use, without
 *   first calling pthread_mutex_init().
 *
 *   Windows has no equivalent statically initialized mutex or CRITICAL SECION.
 *   InitializeCriticalSection() must be called.  If the global mutex does not
 *   appear to be initialized, a thread will create and initialize a new
 *   CRITICAL_SECTION, then use a Windows InterlockedCompareAndExchange to
 *   avoid problems with race conditions.
 *
 *   If an application has overridden the ICU mutex implementation
 *   by calling u_setMutexFunctions(), the user supplied init function must
 *   be safe in the event that multiple threads concurrently attempt to init
 *   the same mutex.  The first thread should do the init, and the others should
 *   have no effect.
 *
 */ 

#define  MAX_MUTEXES  30
static UMTX              gGlobalMutex          = NULL;
static UMTX              gIncDecMutex          = NULL;       
#if (ICU_USE_THREADS == 1)
static UBool             gMutexPoolInitialized = FALSE;
static char              gMutexesInUse[MAX_MUTEXES];   

#if defined(U_WINDOWS) 
/*-------------------------------------------------------------
 *
 *   WINDOWS  platform variable declarations
 *
 *-------------------------------------------------------------*/
static CRITICAL_SECTION  gMutexes[MAX_MUTEXES];
static CRITICAL_SECTION  gGlobalWinMutex;


/* On WIN32 mutexes are reentrant.  This makes it difficult to debug
 * deadlocking problems that show up on POSIXy platforms, where
 * mutexes deadlock upon reentry.  ICU contains checking code for
 * the global mutex as well as for other mutexes in the pool.
 *
 * This is for debugging purposes.
 *
 * This has no effect on non-WIN32 platforms, non-DEBUG builds, and
 * non-ICU_USE_THREADS builds.
 *
 * Note: The CRITICAL_SECTION structure already has a RecursionCount
 * member that can be used for this purpose, but portability to
 * Win98/NT/2K needs to be tested before use.  Works fine on XP.
 * After portability is confirmed, the built-in RecursionCount can be
 * used, and the gRecursionCountPool can be removed.
 *
 * Note: Non-global mutex checking only happens if there is no custom
 * pMutexLockFn defined.  Use one function, not two (don't use
 * pMutexLockFn and pMutexUnlockFn) so the increment and decrement of
 * the recursion count don't get out of sync.  Users might set just
 * one function, e.g., to perform a custom action, followed by a
 * standard call to EnterCriticalSection.
 */
#if defined(U_DEBUG) && (ICU_USE_THREADS==1)
static int32_t gRecursionCount = 0; /* detect global mutex locking */      
static int32_t gRecursionCountPool[MAX_MUTEXES]; /* ditto for non-global */
#endif


#elif defined(POSIX) 
/*-------------------------------------------------------------
 *
 *   POSIX   platform variable declarations
 *
 *-------------------------------------------------------------*/
static pthread_mutex_t   gMutexes[MAX_MUTEXES] = {
    PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
    PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
    PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
    PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
    PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
    PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER,
    PTHREAD_MUTEX_INITIALIZER, PTHREAD_MUTEX_INITIALIZER
};

#else 
/*-------------------------------------------------------------
 *
 *   UNKNOWN   platform  declarations
 *
 *-------------------------------------------------------------*/
static void *gMutexes[MAX_MUTEXES] = {
    NULL, NULL, NULL,
    NULL, NULL, NULL,
    NULL, NULL, NULL,
    NULL, NULL, NULL,
    NULL, NULL, NULL,
    NULL, NULL, NULL,
    NULL, NULL };

/* Unknown platform.  OK so long as ICU_USE_THREAD is not set.  
                      Note that user can still set mutex functions at run time,
                      and that the global mutex variable is still needed in that case. */
#if (ICU_USE_THREADS == 1)
#error no ICU mutex implementation for this platform
#endif
#endif
#endif /* ICU_USE_THREADS==1 */




/*
 *  User mutex implementation functions.  If non-null, call back to these rather than
 *  directly using the system (Posix or Windows) APIs.
 *    (declarations are in uclean.h)
 */
static UMtxInitFn    *pMutexInitFn    = NULL;
static UMtxFn        *pMutexDestroyFn = NULL;
static UMtxFn        *pMutexLockFn    = NULL;
static UMtxFn        *pMutexUnlockFn  = NULL;
static const void    *gMutexContext   = NULL;



/*
 *   umtx_lock
 */
U_CAPI void  U_EXPORT2
umtx_lock(UMTX *mutex)
{
    if (mutex == NULL) {
        mutex = &gGlobalMutex;
    }

    if (*mutex == NULL) {
        /* Lock of an uninitialized mutex.  Initialize it before proceeding.   */
        umtx_init(mutex);    
    }

    if (pMutexLockFn != NULL) {
        (*pMutexLockFn)(gMutexContext, mutex);
    } else {

#if (ICU_USE_THREADS == 1)
#if defined(U_WINDOWS)
        EnterCriticalSection((CRITICAL_SECTION*) *mutex);
#elif defined(POSIX)
        pthread_mutex_lock((pthread_mutex_t*) *mutex);
#endif   /* cascade of platforms */
#endif /* ICU_USE_THREADS==1 */
    }

#if defined(U_WINDOWS) && defined(U_DEBUG) && (ICU_USE_THREADS==1)
    if (mutex == &gGlobalMutex) {         /* Detect Reentrant locking of the global mutex.      */
        gRecursionCount++;                /* Recursion causes deadlocks on Unixes.              */
        U_ASSERT(gRecursionCount == 1);   /* Detection works on Windows.  Debug problems there. */
    }
    /* This handles gGlobalMutex too, but only if there is no pMutexLockFn */
    else if (pMutexLockFn == NULL) { /* see comments above */
        size_t i = ((CRITICAL_SECTION*)*mutex) - &gMutexes[0];
        U_ASSERT(i >= 0 && i < MAX_MUTEXES);
        ++gRecursionCountPool[i];

        U_ASSERT(gRecursionCountPool[i] == 1); /* !Detect Deadlock! */

        /* This works and is fast, but needs testing on Win98/NT/2K.
           See comments above. [alan]
          U_ASSERT((CRITICAL_SECTION*)*mutex >= &gMutexes[0] &&
                   (CRITICAL_SECTION*)*mutex <= &gMutexes[MAX_MUTEXES]);
          U_ASSERT(((CRITICAL_SECTION*)*mutex)->RecursionCount == 1);
        */
    }
#endif /*U_DEBUG*/
}



/*
 * umtx_unlock
 */
U_CAPI void  U_EXPORT2
umtx_unlock(UMTX* mutex)
{
    if(mutex == NULL) {
        mutex = &gGlobalMutex;
    }

    if(*mutex == NULL)    {
#if (ICU_USE_THREADS == 1)
        U_ASSERT(FALSE);  /* This mutex is not initialized.     */
#endif
        return; 
    }

#if defined (U_WINDOWS) && defined (U_DEBUG) && (ICU_USE_THREADS==1)
    if (mutex == &gGlobalMutex) {
        gRecursionCount--;
        U_ASSERT(gRecursionCount == 0);  /* Detect unlock of an already unlocked mutex */
    }
    /* This handles gGlobalMutex too, but only if there is no pMutexLockFn */
    else if (pMutexLockFn == NULL) { /* see comments above */
        size_t i = ((CRITICAL_SECTION*)*mutex) - &gMutexes[0];
        U_ASSERT(i >= 0 && i < MAX_MUTEXES);
        --gRecursionCountPool[i];

        U_ASSERT(gRecursionCountPool[i] == 0); /* !Detect Deadlock! */

        /* This works and is fast, but needs testing on Win98/NT/2K.
           Note that RecursionCount will be 1, not 0, since we haven't
           left the CRITICAL_SECTION yet.  See comments above. [alan]
          U_ASSERT((CRITICAL_SECTION*)*mutex >= &gMutexes[0] &&
                   (CRITICAL_SECTION*)*mutex <= &gMutexes[MAX_MUTEXES]);
          U_ASSERT(((CRITICAL_SECTION*)*mutex)->RecursionCount == 1);
        */
    }
#endif

    if (pMutexUnlockFn) {
        (*pMutexUnlockFn)(gMutexContext, mutex);
    } else {
#if (ICU_USE_THREADS==1)
#if defined (U_WINDOWS)
        LeaveCriticalSection((CRITICAL_SECTION*)*mutex);
#elif defined (POSIX)
        pthread_mutex_unlock((pthread_mutex_t*)*mutex);
#endif  /* cascade of platforms */
#endif /* ICU_USE_THREADS == 1 */
    }
}




/*
 *   initGlobalMutex    Do the platform specific initialization of the ICU global mutex.
 *                      Separated out from the other mutexes because it is different:
 *                      Mutex storage is static for POSIX, init must be thread safe 
 *                      without the use of another mutex.
 */
static void initGlobalMutex() {
    /*
     * If User Supplied mutex functions are in use
     *    init the icu global mutex using them.  
     */
    if (pMutexInitFn != NULL) {
        if (gGlobalMutex==NULL) {
            UErrorCode status = U_ZERO_ERROR;
            (*pMutexInitFn)(gMutexContext, &gGlobalMutex, &status);
            if (U_FAILURE(status)) {
                /* TODO:  how should errors here be handled? */
                return;
            }
        }
        return;
    }

    /* No user override of mutex functions.
     *   Use default ICU mutex implementations.
     */
#if (ICU_USE_THREADS == 1)
    /*
     *  for Windows, init the pool of critical sections that we
     *    will use as needed for ICU mutexes.
     */
#if defined (U_WINDOWS)
    if (gMutexPoolInitialized == FALSE) {
        int i;
        for (i=0; i<MAX_MUTEXES; i++) {
            InitializeCriticalSection(&gMutexes[i]);
#if defined (U_DEBUG)
            gRecursionCountPool[i] = 0; /* see comments above */
#endif
        }
        gMutexPoolInitialized = TRUE;
    }
#elif defined (POSIX)
    /*  TODO:  experimental code.  Shouldn't need to explicitly init the mutexes. */
    if (gMutexPoolInitialized == FALSE) {
        int i;
        for (i=0; i<MAX_MUTEXES; i++) {
            pthread_mutex_init(&gMutexes[i], NULL);
        }
        gMutexPoolInitialized = TRUE;
    }
#endif 

    /*
     * for both Windows & POSIX, the first mutex in the array is used
     *   for the ICU global mutex.
     */
    gGlobalMutex = &gMutexes[0];
    gMutexesInUse[0] = 1;

#else  /* ICU_USE_THREADS */
    gGlobalMutex = &gGlobalMutex;  /* With no threads, we must still set the mutex to
                                    * some non-null value to make the rest of the
                                    *   (not ifdefed) mutex code think that it is initialized.
                                    */
#endif /* ICU_USE_THREADS */
}





U_CAPI void  U_EXPORT2
umtx_init(UMTX *mutex)
{
    if (mutex == NULL || mutex == &gGlobalMutex) {
        initGlobalMutex();
    } else {
        umtx_lock(NULL);
        if (*mutex != NULL) {
            /* Another thread initialized this mutex first. */
            umtx_unlock(NULL);
            return;
        }

        if (pMutexInitFn != NULL) {
            UErrorCode status = U_ZERO_ERROR;
            (*pMutexInitFn)(gMutexContext, mutex, &status);
            /* TODO:  how to report failure on init? */
            umtx_unlock(NULL);
            return;
        }
        else {
#if (ICU_USE_THREADS == 1)
            /*  Search through our pool of pre-allocated mutexes for one that is not
            *  already in use.    */
            int i;
            for (i=0; i<MAX_MUTEXES; i++) {
                if (gMutexesInUse[i] == 0) {
                    gMutexesInUse[i] = 1;
                    *mutex = &gMutexes[i];
                    break;
                }
            }
#endif
        }
        umtx_unlock(NULL);

#if (ICU_USE_THREADS == 1)
        /* No more mutexes were available from our pre-allocated pool.  */
        /*   TODO:  how best to deal with this?                    */
        U_ASSERT(*mutex != NULL);
#endif
    }
}


/*
 *  umtx_destroy.    Un-initialize a mutex, releasing any underlying resources
 *                   that it may be holding.  Destroying an already destroyed
 *                   mutex has no effect.  Unlike umtx_init(), this function
 *                   is not thread safe;  two threads must not concurrently try to
 *                   destroy the same mutex.
 */                  
U_CAPI void  U_EXPORT2
umtx_destroy(UMTX *mutex) {
    if (mutex == NULL) {  /* destroy the global mutex */
        mutex = &gGlobalMutex;
    }
    
    if (*mutex == NULL) {  /* someone already did it. */
        return;
    }

    /*  The life of the inc/dec mutex is tied to that of the global mutex.  */
    if (mutex == &gGlobalMutex) {
        umtx_destroy(&gIncDecMutex);
    }

    if (pMutexDestroyFn != NULL) {
        /* Mutexes are being managed by the app.  Call back to it for the destroy. */
        (*pMutexDestroyFn)(gMutexContext, mutex);
    }
    else {
#if (ICU_USE_THREADS == 1)
        /* Return this mutex to the pool of available mutexes, if it came from the
         *  pool in the first place.
         */
        /* TODO use pointer math here, instead of iterating! */
        int i;
        for (i=0; i<MAX_MUTEXES; i++)  {
            if (*mutex == &gMutexes[i]) {
                gMutexesInUse[i] = 0;
                break;
            }
        }
#endif
    }

    *mutex = NULL;
}



U_CAPI void U_EXPORT2 
u_setMutexFunctions(const void *context, UMtxInitFn *i, UMtxFn *d, UMtxFn *l, UMtxFn *u,
                    UErrorCode *status) {
    if (U_FAILURE(*status)) {
        return;
    }

    /* Can not set a mutex function to a NULL value  */
    if (i==NULL || d==NULL || l==NULL || u==NULL) {
        *status = U_ILLEGAL_ARGUMENT_ERROR;
        return;
    }

    /* If ICU is not in an initial state, disallow this operation. */
    if (cmemory_inUse()) {
        *status = U_INVALID_STATE_ERROR;
        return;
    }

    /* Swap in the mutex function pointers.  */
    pMutexInitFn    = i;
    pMutexDestroyFn = d;
    pMutexLockFn    = l;
    pMutexUnlockFn  = u;
    gMutexContext   = context;
    gGlobalMutex    = NULL;         /* For POSIX, the global mutex will be pre-initialized */
                                    /*   Undo that, force re-initialization when u_init()  */
                                    /*   happens.                                          */
}



/*-----------------------------------------------------------------
 *
 *  Atomic Increment and Decrement
 *     umtx_atomic_inc
 *     umtx_atomic_dec
 *
 *----------------------------------------------------------------*/

/* Pointers to user-supplied inc/dec functions.  Null if no funcs have been set.  */
static UMtxAtomicFn  *pIncFn = NULL;
static UMtxAtomicFn  *pDecFn = NULL;
static const void *gIncDecContext  = NULL;


U_CAPI int32_t U_EXPORT2
umtx_atomic_inc(int32_t *p)  {
    int32_t retVal;
    if (pIncFn) {
        retVal = (*pIncFn)(gIncDecContext, p);
    } else {
        #if defined (U_WINDOWS) && ICU_USE_THREADS == 1
            retVal = InterlockedIncrement((LONG*)p);
        #elif defined(USE_MAC_OS_ATOMIC_INCREMENT)
            retVal = OSAtomicIncrement32Barrier(p);
        #elif defined (POSIX) && ICU_USE_THREADS == 1
            umtx_lock(&gIncDecMutex);
            retVal = ++(*p);
            umtx_unlock(&gIncDecMutex);
        #else
            /* Unknown Platform, or ICU thread support compiled out. */
            retVal = ++(*p);
        #endif
    }
    return retVal;
}

U_CAPI int32_t U_EXPORT2
umtx_atomic_dec(int32_t *p) {
    int32_t retVal;
    if (pDecFn) {
        retVal = (*pDecFn)(gIncDecContext, p);
    } else {
        #if defined (U_WINDOWS) && ICU_USE_THREADS == 1
            retVal = InterlockedDecrement((LONG*)p);
        #elif defined(USE_MAC_OS_ATOMIC_INCREMENT)
            retVal = OSAtomicDecrement32Barrier(p);
        #elif defined (POSIX) && ICU_USE_THREADS == 1
            umtx_lock(&gIncDecMutex);
            retVal = --(*p);
            umtx_unlock(&gIncDecMutex);
        #else
            /* Unknown Platform, or ICU thread support compiled out. */
            retVal = --(*p);
        #endif
    }
    return retVal;
}

/* TODO:  Some POSIXy platforms have atomic inc/dec functions available.  Use them. */





U_CAPI void U_EXPORT2
u_setAtomicIncDecFunctions(const void *context, UMtxAtomicFn *ip, UMtxAtomicFn *dp,
                                UErrorCode *status) {
    if (U_FAILURE(*status)) {
        return;
    }
    /* Can not set a mutex function to a NULL value  */
    if (ip==NULL || dp==NULL) {
        *status = U_ILLEGAL_ARGUMENT_ERROR;
        return;
    }
    /* If ICU is not in an initial state, disallow this operation. */
    if (cmemory_inUse()) {
        *status = U_INVALID_STATE_ERROR;
        return;
    }

    pIncFn = ip;
    pDecFn = dp;
    gIncDecContext = context;

#if !U_RELEASE
    {
        int32_t   testInt = 0;
        U_ASSERT(umtx_atomic_inc(&testInt) == 1);     /* Sanity Check.    Do the functions work at all? */
        U_ASSERT(testInt == 1);
        U_ASSERT(umtx_atomic_dec(&testInt) == 0);
        U_ASSERT(testInt == 0);
    }
#endif
}



/*
 *  Mutex Cleanup Function
 *
 *      Destroy the global mutex(es), and reset the mutex function callback pointers.
 */
U_CFUNC UBool umtx_cleanup(void) {
    umtx_destroy(NULL);
    pMutexInitFn    = NULL;
    pMutexDestroyFn = NULL;
    pMutexLockFn    = NULL;
    pMutexUnlockFn  = NULL;
    gMutexContext   = NULL;
    gGlobalMutex    = NULL;
    pIncFn          = NULL;
    pDecFn          = NULL;
    gIncDecContext  = NULL;
    gIncDecMutex    = NULL;

#if (ICU_USE_THREADS == 1)
    if (gMutexPoolInitialized) {
        int i;
        for (i=0; i<MAX_MUTEXES; i++) {
            if (gMutexesInUse[i]) {
#if defined (U_WINDOWS)
                DeleteCriticalSection(&gMutexes[i]);
#elif defined (POSIX)
                pthread_mutex_destroy(&gMutexes[i]);
#endif
                gMutexesInUse[i] = 0;
            }
        }
    }
    gMutexPoolInitialized = FALSE;
#endif

    return TRUE;
}