michael@0: /*
michael@0: ******************************************************************************
michael@0: *
michael@0: *   Copyright (C) 1997-2013, International Business Machines
michael@0: *   Corporation and others.  All Rights Reserved.
michael@0: *
michael@0: ******************************************************************************
michael@0: *
michael@0: * File umutex.cpp
michael@0: *
michael@0: * Modification History:
michael@0: *
michael@0: *   Date        Name        Description
michael@0: *   04/02/97    aliu        Creation.
michael@0: *   04/07/99    srl         updated
michael@0: *   05/13/99    stephen     Changed to umutex (from cmutex).
michael@0: *   11/22/99    aliu        Make non-global mutex autoinitialize [j151]
michael@0: ******************************************************************************
michael@0: */
michael@0: 
michael@0: #include "umutex.h"
michael@0: 
michael@0: #include "unicode/utypes.h"
michael@0: #include "uassert.h"
michael@0: #include "cmemory.h"
michael@0: #include "ucln_cmn.h"
michael@0: 
michael@0: 
michael@0: // The ICU global mutex. Used when ICU implementation code passes NULL for the mutex pointer.
michael@0: static UMutex   globalMutex = U_MUTEX_INITIALIZER;
michael@0: 
michael@0: /*
michael@0:  * ICU Mutex wrappers.  Wrap operating system mutexes, giving the rest of ICU a
michael@0:  * platform independent set of mutex operations.  For internal ICU use only.
michael@0:  */
michael@0: 
michael@0: #if defined(U_USER_MUTEX_CPP)
michael@0: // Build time user mutex hook: #include "U_USER_MUTEX_CPP"
michael@0: #include U_MUTEX_XSTR(U_USER_MUTEX_CPP)
michael@0: 
michael@0: #elif U_PLATFORM_HAS_WIN32_API
michael@0: 
michael@0: //-------------------------------------------------------------------------------------------
michael@0: //
michael@0: //    Windows Specific Definitions
michael@0: //
michael@0: //        Note: Cygwin (and possibly others) have both WIN32 and POSIX.
michael@0: //              Prefer Win32 in these cases.  (Win32 comes ahead in the #if chain)
michael@0: //
michael@0: //-------------------------------------------------------------------------------------------
michael@0: 
michael@0: #if defined U_NO_PLATFORM_ATOMICS
michael@0: #error ICU on Win32 requires support for low level atomic operations.
michael@0: // Visual Studio, gcc, clang are OK. Shouldn't get here.
michael@0: #endif
michael@0: 
michael@0: 
michael@0: // This function is called when a test of a UInitOnce::fState reveals that
michael@0: //   initialization has not completed, that we either need to call the
michael@0: //   function on this thread, or wait for some other thread to complete.
michael@0: //
michael@0: // The actual call to the init function is made inline by template code
michael@0: //   that knows the C++ types involved. This function returns TRUE if
michael@0: //   the caller needs to call the Init function.
michael@0: //
michael@0: 
michael@0: U_NAMESPACE_BEGIN
michael@0: 
michael@0: U_COMMON_API UBool U_EXPORT2 umtx_initImplPreInit(UInitOnce &uio) {
michael@0:     for (;;) {
michael@0:         int32_t previousState = InterlockedCompareExchange(
michael@0: #if (U_PLATFORM == U_PF_MINGW) || (U_PLATFORM == U_PF_CYGWIN)
michael@0:            (LONG volatile *) // this is the type given in the API doc for this function.
michael@0: #endif
michael@0:             &uio.fState,  //  Destination
michael@0:             1,            //  Exchange Value
michael@0:             0);           //  Compare value
michael@0: 
michael@0:         if (previousState == 0) {
michael@0:             return true;   // Caller will next call the init function.
michael@0:                            // Current state == 1.
michael@0:         } else if (previousState == 2) {
michael@0:             // Another thread already completed the initialization.
michael@0:             //   We can simply return FALSE, indicating no
michael@0:             //   further action is needed by the caller.
michael@0:             return FALSE;
michael@0:         } else {
michael@0:             // Another thread is currently running the initialization.
michael@0:             // Wait until it completes.
michael@0:             do {
michael@0:                 Sleep(1);
michael@0:                 previousState = umtx_loadAcquire(uio.fState);
michael@0:             } while (previousState == 1);
michael@0:         }
michael@0:     }
michael@0: }
michael@0: 
michael@0: // This function is called by the thread that ran an initialization function,
michael@0: // just after completing the function.
michael@0: //
michael@0: //   success: True:  the inialization succeeded. No further calls to the init
michael@0: //                   function will be made.
michael@0: //            False: the initializtion failed. The next call to umtx_initOnce()
michael@0: //                   will retry the initialization.
michael@0: 
michael@0: U_COMMON_API void U_EXPORT2 umtx_initImplPostInit(UInitOnce &uio) {
michael@0:     umtx_storeRelease(uio.fState, 2);
michael@0: }
michael@0: 
michael@0: U_NAMESPACE_END
michael@0: 
michael@0: static void winMutexInit(CRITICAL_SECTION *cs) {
michael@0:     InitializeCriticalSection(cs);
michael@0:     return;
michael@0: }
michael@0: 
michael@0: U_CAPI void  U_EXPORT2
michael@0: umtx_lock(UMutex *mutex) {
michael@0:     if (mutex == NULL) {
michael@0:         mutex = &globalMutex;
michael@0:     }
michael@0:     CRITICAL_SECTION *cs = &mutex->fCS;
michael@0:     umtx_initOnce(mutex->fInitOnce, winMutexInit, cs);
michael@0:     EnterCriticalSection(cs);
michael@0: }
michael@0: 
michael@0: U_CAPI void  U_EXPORT2
michael@0: umtx_unlock(UMutex* mutex)
michael@0: {
michael@0:     if (mutex == NULL) {
michael@0:         mutex = &globalMutex;
michael@0:     }
michael@0:     LeaveCriticalSection(&mutex->fCS);
michael@0: }
michael@0: 
michael@0: #elif U_PLATFORM_IMPLEMENTS_POSIX
michael@0: 
michael@0: //-------------------------------------------------------------------------------------------
michael@0: //
michael@0: //  POSIX specific definitions
michael@0: //
michael@0: //-------------------------------------------------------------------------------------------
michael@0: 
michael@0: # include <pthread.h>
michael@0: 
michael@0: // Each UMutex consists of a pthread_mutex_t.
michael@0: // All are statically initialized and ready for use.
michael@0: // There is no runtime mutex initialization code needed.
michael@0: 
michael@0: U_CAPI void  U_EXPORT2
michael@0: umtx_lock(UMutex *mutex) {
michael@0:     if (mutex == NULL) {
michael@0:         mutex = &globalMutex;
michael@0:     }
michael@0:     int sysErr = pthread_mutex_lock(&mutex->fMutex);
michael@0:     (void)sysErr;   // Suppress unused variable warnings.
michael@0:     U_ASSERT(sysErr == 0);
michael@0: }
michael@0: 
michael@0: 
michael@0: U_CAPI void  U_EXPORT2
michael@0: umtx_unlock(UMutex* mutex)
michael@0: {
michael@0:     if (mutex == NULL) {
michael@0:         mutex = &globalMutex;
michael@0:     }
michael@0:     int sysErr = pthread_mutex_unlock(&mutex->fMutex);
michael@0:     (void)sysErr;   // Suppress unused variable warnings.
michael@0:     U_ASSERT(sysErr == 0);
michael@0: }
michael@0: 
michael@0: U_NAMESPACE_BEGIN
michael@0: 
michael@0: static pthread_mutex_t initMutex = PTHREAD_MUTEX_INITIALIZER;
michael@0: static pthread_cond_t initCondition = PTHREAD_COND_INITIALIZER;
michael@0: 
michael@0: 
michael@0: // This function is called when a test of a UInitOnce::fState reveals that
michael@0: //   initialization has not completed, that we either need to call the
michael@0: //   function on this thread, or wait for some other thread to complete.
michael@0: //
michael@0: // The actual call to the init function is made inline by template code
michael@0: //   that knows the C++ types involved. This function returns TRUE if
michael@0: //   the caller needs to call the Init function.
michael@0: //
michael@0: U_COMMON_API UBool U_EXPORT2
michael@0: umtx_initImplPreInit(UInitOnce &uio) {
michael@0:     pthread_mutex_lock(&initMutex);
michael@0:     int32_t state = uio.fState;
michael@0:     if (state == 0) {
michael@0:         umtx_storeRelease(uio.fState, 1);
michael@0:         pthread_mutex_unlock(&initMutex);
michael@0:         return TRUE;   // Caller will next call the init function.
michael@0:     } else {
michael@0:         while (uio.fState == 1) {
michael@0:             // Another thread is currently running the initialization.
michael@0:             // Wait until it completes.
michael@0:             pthread_cond_wait(&initCondition, &initMutex);
michael@0:         }
michael@0:         pthread_mutex_unlock(&initMutex);
michael@0:         U_ASSERT(uio.fState == 2);
michael@0:         return FALSE;
michael@0:     }
michael@0: }
michael@0: 
michael@0: 
michael@0: 
michael@0: // This function is called by the thread that ran an initialization function,
michael@0: // just after completing the function.
michael@0: //   Some threads may be waiting on the condition, requiring the broadcast wakeup.
michael@0: //   Some threads may be racing to test the fState variable outside of the mutex,
michael@0: //   requiring the use of store/release when changing its value.
michael@0: 
michael@0: U_COMMON_API void U_EXPORT2
michael@0: umtx_initImplPostInit(UInitOnce &uio) {
michael@0:     pthread_mutex_lock(&initMutex);
michael@0:     umtx_storeRelease(uio.fState, 2);
michael@0:     pthread_cond_broadcast(&initCondition);
michael@0:     pthread_mutex_unlock(&initMutex);
michael@0: }
michael@0: 
michael@0: U_NAMESPACE_END
michael@0: 
michael@0: // End of POSIX specific umutex implementation.
michael@0: 
michael@0: #else  // Platform #define chain.
michael@0: 
michael@0: #error Unknown Platform
michael@0: 
michael@0: #endif  // Platform #define chain.
michael@0: 
michael@0: 
michael@0: //-------------------------------------------------------------------------------
michael@0: //
michael@0: //   Atomic Operations, out-of-line versions.
michael@0: //                      These are conditional, only defined if better versions
michael@0: //                      were not available for the platform.
michael@0: //
michael@0: //                      These versions are platform neutral.
michael@0: //
michael@0: //--------------------------------------------------------------------------------
michael@0: 
michael@0: #if defined U_NO_PLATFORM_ATOMICS
michael@0: static UMutex   gIncDecMutex = U_MUTEX_INITIALIZER;
michael@0: 
michael@0: U_NAMESPACE_BEGIN
michael@0: 
michael@0: U_COMMON_API int32_t U_EXPORT2
michael@0: umtx_atomic_inc(u_atomic_int32_t *p)  {
michael@0:     int32_t retVal;
michael@0:     umtx_lock(&gIncDecMutex);
michael@0:     retVal = ++(*p);
michael@0:     umtx_unlock(&gIncDecMutex);
michael@0:     return retVal;
michael@0: }
michael@0: 
michael@0: 
michael@0: U_COMMON_API int32_t U_EXPORT2
michael@0: umtx_atomic_dec(u_atomic_int32_t *p) {
michael@0:     int32_t retVal;
michael@0:     umtx_lock(&gIncDecMutex);
michael@0:     retVal = --(*p);
michael@0:     umtx_unlock(&gIncDecMutex);
michael@0:     return retVal;
michael@0: }
michael@0: 
michael@0: U_COMMON_API int32_t U_EXPORT2
michael@0: umtx_loadAcquire(u_atomic_int32_t &var) {
michael@0:     int32_t val = var;
michael@0:     umtx_lock(&gIncDecMutex);
michael@0:     umtx_unlock(&gIncDecMutex);
michael@0:     return val;
michael@0: }
michael@0: 
michael@0: U_COMMON_API void U_EXPORT2
michael@0: umtx_storeRelease(u_atomic_int32_t &var, int32_t val) {
michael@0:     umtx_lock(&gIncDecMutex);
michael@0:     umtx_unlock(&gIncDecMutex);
michael@0:     var = val;
michael@0: }
michael@0: 
michael@0: U_NAMESPACE_END
michael@0: #endif
michael@0: 
michael@0: //--------------------------------------------------------------------------
michael@0: //
michael@0: //  Deprecated functions for setting user mutexes.
michael@0: //
michael@0: //--------------------------------------------------------------------------
michael@0: 
michael@0: U_DEPRECATED void U_EXPORT2
michael@0: u_setMutexFunctions(const void * /*context */, UMtxInitFn *, UMtxFn *,
michael@0:                     UMtxFn *,  UMtxFn *, UErrorCode *status) {
michael@0:     if (U_SUCCESS(*status)) {
michael@0:         *status = U_UNSUPPORTED_ERROR;
michael@0:     }
michael@0:     return;
michael@0: }
michael@0: 
michael@0: 
michael@0: 
michael@0: U_DEPRECATED void U_EXPORT2
michael@0: u_setAtomicIncDecFunctions(const void * /*context */, UMtxAtomicFn *, UMtxAtomicFn *,
michael@0:                            UErrorCode *status) {
michael@0:     if (U_SUCCESS(*status)) {
michael@0:         *status = U_UNSUPPORTED_ERROR;
michael@0:     }
michael@0:     return;
michael@0: }