/*
******************************************************************************
*
* Copyright (C) 1997-2011, International Business Machines
* Corporation and others. All Rights Reserved.
*
******************************************************************************
*
* File umutex.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"
/*
* ICU Mutex wrappers. Wrap operating system mutexes, giving the rest of ICU a
* platform independent set of mutex operations. For internal ICU use only.
*/
/* 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 when two or more
* threads are more or less simultaenously the first to use ICU in a process, and
* are racing into the mutex initialization code.
*
*
* The solution for the global mutex init is platform dependent.
* On POSIX systems, plain C-style initialization 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
* swap it in as the global mutex while avoid problems with race conditions.
*/
/* On WIN32 mutexes are reentrant. On POSIX platforms they are not, and a deadlock
* will occur if a thread attempts to acquire a mutex it already has locked.
* ICU mutexes (in debug builds) include checking code that will cause an assertion
* failure if a mutex is reentered. If you are having deadlock problems
* on a POSIX machine, debugging may be easier on Windows.
*/
#if (ICU_USE_THREADS == 0)
#define MUTEX_TYPE void *
#define PLATFORM_MUTEX_INIT(m)
#define PLATFORM_MUTEX_LOCK(m)
#define PLATFORM_MUTEX_UNLOCK(m)
#define PLATFORM_MUTEX_DESTROY(m)
#define PLATFORM_MUTEX_INITIALIZER NULL
#define SYNC_COMPARE_AND_SWAP(dest, oldval, newval) \
mutexed_compare_and_swap(dest, newval, oldval)
#elif defined(U_WINDOWS)
#define MUTEX_TYPE CRITICAL_SECTION
#define PLATFORM_MUTEX_INIT(m) InitializeCriticalSection(m)
#define PLATFORM_MUTEX_LOCK(m) EnterCriticalSection(m)
#define PLATFORM_MUTEX_UNLOCK(m) LeaveCriticalSection(m)
#define PLATFORM_MUTEX_DESTROY(m) DeleteCriticalSection(m)
#define SYNC_COMPARE_AND_SWAP(dest, oldval, newval) \
InterlockedCompareExchangePointer(dest, newval, oldval)
#elif defined(POSIX)
#define MUTEX_TYPE pthread_mutex_t
#define PLATFORM_MUTEX_INIT(m) pthread_mutex_init(m, NULL)
#define PLATFORM_MUTEX_LOCK(m) pthread_mutex_lock(m)
#define PLATFORM_MUTEX_UNLOCK(m) pthread_mutex_unlock(m)
#define PLATFORM_MUTEX_DESTROY(m) pthread_mutex_destroy(m)
#define PLATFORM_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
#if (U_HAVE_GCC_ATOMICS == 1)
#define SYNC_COMPARE_AND_SWAP(dest, oldval, newval) \
__sync_val_compare_and_swap(dest, oldval, newval)
#else
#define SYNC_COMPARE_AND_SWAP(dest, oldval, newval) \
mutexed_compare_and_swap(dest, newval, oldval)
#endif
#else
/* Unknown platform. Note that user can still set mutex functions at run time. */
#define MUTEX_TYPE void *
#define PLATFORM_MUTEX_INIT(m)
#define PLATFORM_MUTEX_LOCK(m)
#define PLATFORM_MUTEX_UNLOCK(m)
#define PLATFORM_MUTEX_DESTROY(m)
#define SYNC_COMPARE_AND_SWAP(dest, oldval, newval) \
mutexed_compare_and_swap(dest, newval, oldval)
#endif
/* Forward declarations */
static void *mutexed_compare_and_swap(void **dest, void *newval, void *oldval);
typedef struct ICUMutex ICUMutex;
/*
* ICUMutex One of these is set up for each UMTX that is used by other ICU code.
* The opaque UMTX points to the corresponding ICUMutex struct.
*
* Because the total number of ICU mutexes is quite small, no effort has
* been made to squeeze every byte out of this struct.
*/
struct ICUMutex {
UMTX *owner; /* Points back to the UMTX corrsponding to this */
/* ICUMutex object. */
UBool heapAllocated; /* Set if this ICUMutex is heap allocated, and */
/* will need to be deleted. The global mutex */
/* is static on POSIX platforms; all others */
/* will be heap allocated. */
ICUMutex *next; /* All ICUMutexes are chained into a list so that */
/* they can be found and deleted by u_cleanup(). */
int32_t recursionCount; /* For debugging, detect recursive mutex locks. */
MUTEX_TYPE platformMutex; /* The underlying OS mutex being wrapped. */
UMTX userMutex; /* For use with u_setMutexFunctions operations, */
/* corresponds to platformMutex. */
};
/* The global ICU mutex.
* For POSIX platforms, it gets a C style initialization, and is ready to use
* at program startup.
* For Windows, it will be lazily instantiated on first use.
*/
#if defined(POSIX)
static UMTX globalUMTX;
static ICUMutex globalMutex = {&globalUMTX, FALSE, NULL, 0, PLATFORM_MUTEX_INITIALIZER, NULL};
static UMTX globalUMTX = &globalMutex;
#else
static UMTX globalUMTX = NULL;
#endif
/* Head of the list of all ICU mutexes.
* Linked list is through ICUMutex::next
* Modifications to the list are synchronized with the global mutex.
* The list is used by u_cleanup(), which needs to dispose of all of the ICU mutexes.
*
* The statically initialized global mutex on POSIX platforms does not get added to this
* mutex list, but that's not a problem - the global mutex gets special handling
* during u_cleanup().
*/
static ICUMutex *mutexListHead;
/*
* User mutex implementation functions. If non-null, call back to these rather than
* directly using the system (Posix or Windows) APIs. See u_setMutexFunctions().
* (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)
{
ICUMutex *m;
if (mutex == NULL) {
mutex = &globalUMTX;
}
m = (ICUMutex *)*mutex;
if (m == NULL) {
/* See note on lazy initialization, above. We can get away with it here, with mutexes,
* where we couldn't with normal user level data.
*/
umtx_init(mutex);
m = (ICUMutex *)*mutex;
}
U_ASSERT(m->owner == mutex);
if (pMutexLockFn != NULL) {
(*pMutexLockFn)(gMutexContext, &m->userMutex);
} else {
PLATFORM_MUTEX_LOCK(&m->platformMutex);
}
#if defined(U_DEBUG)
m->recursionCount++; /* Recursion causes deadlock on Unixes. */
U_ASSERT(m->recursionCount == 1); /* Recursion detection works on Windows. */
/* Assertion failure on non-Windows indicates a */
/* problem with the mutex implementation itself. */
#endif
}
/*
* umtx_unlock
*/
U_CAPI void U_EXPORT2
umtx_unlock(UMTX* mutex)
{
ICUMutex *m;
if(mutex == NULL) {
mutex = &globalUMTX;
}
m = (ICUMutex *)*mutex;
if (m == NULL) {
U_ASSERT(FALSE); /* This mutex is not initialized. */
return;
}
U_ASSERT(m->owner == mutex);
#if defined (U_DEBUG)
m->recursionCount--;
U_ASSERT(m->recursionCount == 0); /* Detect unlock of an already unlocked mutex */
#endif
if (pMutexUnlockFn) {
(*pMutexUnlockFn)(gMutexContext, &m->userMutex);
} else {
PLATFORM_MUTEX_UNLOCK(&m->platformMutex);
}
}
/* umtx_ct Allocate and initialize a new ICUMutex.
* If a non-null pointer is supplied, initialize an existing ICU Mutex.
*/
static ICUMutex *umtx_ct(ICUMutex *m) {
if (m == NULL) {
m = (ICUMutex *)uprv_malloc(sizeof(ICUMutex));
m->heapAllocated = TRUE;
}
m->next = NULL; /* List of mutexes is maintained at a higher level. */
m->recursionCount = 0;
m->userMutex = NULL;
if (pMutexInitFn != NULL) {
UErrorCode status = U_ZERO_ERROR;
(*pMutexInitFn)(gMutexContext, &m->userMutex, &status);
U_ASSERT(U_SUCCESS(status));
} else {
PLATFORM_MUTEX_INIT(&m->platformMutex);
}
return m;
}
/* umtx_dt Delete a ICUMutex. Destroy the underlying OS Platform mutex.
* Does not touch the linked list of ICU Mutexes.
*/
static void umtx_dt(ICUMutex *m) {
if (pMutexDestroyFn != NULL) {
(*pMutexDestroyFn)(gMutexContext, &m->userMutex);
m->userMutex = NULL;
} else {
PLATFORM_MUTEX_DESTROY(&m->platformMutex);
}
if (m->heapAllocated) {
uprv_free(m);
}
}
U_CAPI void U_EXPORT2
umtx_init(UMTX *mutex) {
ICUMutex *m = NULL;
void *originalValue;
if (*mutex != NULL) {
/* Mutex is already initialized.
* Multiple umtx_init()s of a UMTX by other ICU code are explicitly permitted.
*/
return;
}
#if defined(POSIX)
if (mutex == &globalUMTX) {
m = &globalMutex;
}
#endif
m = umtx_ct(m);
originalValue = SYNC_COMPARE_AND_SWAP(mutex, NULL, m);
if (originalValue != NULL) {
umtx_dt(m);
return;
}
m->owner = mutex;
/* Hook the new mutex into the list of all ICU mutexes, so that we can find and
* delete it for u_cleanup().
*/
umtx_lock(NULL);
m->next = mutexListHead;
mutexListHead = m;
umtx_unlock(NULL);
return;
}
/*
* 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) {
ICUMutex *m;
/* No one should be deleting the global ICU mutex.
* (u_cleanup() does delete it, but does so explicitly, not by passing NULL)
*/
U_ASSERT(mutex != NULL);
if (mutex == NULL) {
return;
}
m = (ICUMutex *)*mutex;
if (m == NULL) { /* Mutex not initialized, or already destroyed. */
return;
}
U_ASSERT(m->owner == mutex);
if (m->owner != mutex) {
return;
}
/* Remove this mutex from the linked list of mutexes. */
umtx_lock(NULL);
if (mutexListHead == m) {
mutexListHead = m->next;
} else {
ICUMutex *prev;
for (prev = mutexListHead; prev!=NULL && prev->next!=m; prev = prev->next);
/* Empty for loop body */
if (prev != NULL) {
prev->next = m->next;
}
}
umtx_unlock(NULL);
umtx_dt(m); /* Delete the internal ICUMutex */
*mutex = NULL; /* Clear the caller's UMTX */
}
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;
}
/* Kill any existing global mutex. POSIX platforms have a global mutex
* even before any other part of ICU is initialized.
*/
umtx_destroy(&globalUMTX);
/* Swap in the mutex function pointers. */
pMutexInitFn = i;
pMutexDestroyFn = d;
pMutexLockFn = l;
pMutexUnlockFn = u;
gMutexContext = context;
#if defined (POSIX)
/* POSIX platforms must have a pre-initialized global mutex
* to allow other mutexes to initialize safely. */
umtx_init(&globalUMTX);
#endif
}
/* synchronized compare and swap function, for use when OS or compiler built-in
* equivalents aren't available.
*
* This operation relies on the ICU global mutex for synchronization.
*
* There are two cases where this function can be entered when the global mutex is not
* yet initialized - at the end u_cleanup(), and at the end of u_setMutexFunctions, both
* of which re-init the global mutex. But neither function is thread-safe, so the lack of
* synchronization at these points doesn't matter.
*/
static void *mutexed_compare_and_swap(void **dest, void *newval, void *oldval) {
void *temp;
UBool needUnlock = FALSE;
if (globalUMTX != NULL) {
umtx_lock(&globalUMTX);
needUnlock = TRUE;
}
temp = *dest;
if (temp == oldval) {
*dest = newval;
}
if (needUnlock) {
umtx_unlock(&globalUMTX);
}
return temp;
}
/*-----------------------------------------------------------------
*
* 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;
static UMTX gIncDecMutex = 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 (U_HAVE_GCC_ATOMICS == 1)
retVal = __sync_add_and_fetch(p, 1);
#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 (U_HAVE_GCC_ATOMICS == 1)
retVal = __sync_sub_and_fetch(p, 1);
#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 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) {
ICUMutex *thisMutex = NULL;
ICUMutex *nextMutex = NULL;
/* Extra, do-nothing function call to suppress compiler warnings on platforms where
* mutexed_compare_and_swap is not otherwise used. */
mutexed_compare_and_swap(&globalUMTX, NULL, NULL);
/* Delete all of the ICU mutexes. Do the global mutex last because it is used during
* the umtx_destroy operation of other mutexes.
*/
for (thisMutex=mutexListHead; thisMutex!=NULL; thisMutex=nextMutex) {
UMTX *umtx = thisMutex->owner;
nextMutex = thisMutex->next;
U_ASSERT(*umtx = (void *)thisMutex);
if (umtx != &globalUMTX) {
umtx_destroy(umtx);
}
}
umtx_destroy(&globalUMTX);
pMutexInitFn = NULL;
pMutexDestroyFn = NULL;
pMutexLockFn = NULL;
pMutexUnlockFn = NULL;
gMutexContext = NULL;
pIncFn = NULL;
pDecFn = NULL;
gIncDecContext = NULL;
gIncDecMutex = NULL;
#if defined (POSIX)
/* POSIX platforms must come out of u_cleanup() with a functioning global mutex
* to permit the safe resumption of use of ICU in multi-threaded environments.
*/
umtx_init(&globalUMTX);
#endif
return TRUE;
}