/*
******************************************************************************
*
* 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;
}