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