Check in the pristine copy of ICU 4.6...

icu46/source/common/umutex.c

+/*
+******************************************************************************
+*
+*   Copyright (C) 1997-2009, 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.
+ */
+
+#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)
+#if defined(__STRICT_ANSI__)
+#define UPRV_REMAP_INLINE
+#define inline
+#endif
+#include <libkern/OSAtomic.h>
+#define USE_MAC_OS_ATOMIC_INCREMENT 1
+#if defined(UPRV_REMAP_INLINE)
+#undef inline
+#undef UPRV_REMAP_INLINE
+#endif
+#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 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;
+}
+
+