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Diffstat (limited to 'intl/icu/source/common/umutex.cpp')
| -rw-r--r-- | intl/icu/source/common/umutex.cpp | 378 |
1 files changed, 378 insertions, 0 deletions
diff --git a/intl/icu/source/common/umutex.cpp b/intl/icu/source/common/umutex.cpp new file mode 100644 index 000000000..0532838ca --- /dev/null +++ b/intl/icu/source/common/umutex.cpp @@ -0,0 +1,378 @@ +// Copyright (C) 2016 and later: Unicode, Inc. and others. +// License & terms of use: http://www.unicode.org/copyright.html +/* +****************************************************************************** +* +* Copyright (C) 1997-2016, International Business Machines +* Corporation and others. All Rights Reserved. +* +****************************************************************************** +* +* File umutex.cpp +* +* 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 "umutex.h" + +#include "unicode/utypes.h" +#include "uassert.h" +#include "cmemory.h" + + +// The ICU global mutex. Used when ICU implementation code passes NULL for the mutex pointer. +static UMutex globalMutex = U_MUTEX_INITIALIZER; + +/* + * 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_USER_MUTEX_CPP) +// Build time user mutex hook: #include "U_USER_MUTEX_CPP" +#include U_MUTEX_XSTR(U_USER_MUTEX_CPP) + +#elif U_PLATFORM_USES_ONLY_WIN32_API + +#if defined U_NO_PLATFORM_ATOMICS +#error ICU on Win32 requires support for low level atomic operations. +// Visual Studio, gcc, clang are OK. Shouldn't get here. +#endif + + +// This function is called when a test of a UInitOnce::fState reveals that +// initialization has not completed, that we either need to call the +// function on this thread, or wait for some other thread to complete. +// +// The actual call to the init function is made inline by template code +// that knows the C++ types involved. This function returns TRUE if +// the caller needs to call the Init function. +// + +U_NAMESPACE_BEGIN + +U_COMMON_API UBool U_EXPORT2 umtx_initImplPreInit(UInitOnce &uio) { + for (;;) { + int32_t previousState = InterlockedCompareExchange( + (LONG volatile *) // this is the type given in the API doc for this function. + &uio.fState, // Destination + 1, // Exchange Value + 0); // Compare value + + if (previousState == 0) { + return true; // Caller will next call the init function. + // Current state == 1. + } else if (previousState == 2) { + // Another thread already completed the initialization. + // We can simply return FALSE, indicating no + // further action is needed by the caller. + return FALSE; + } else { + // Another thread is currently running the initialization. + // Wait until it completes. + do { + Sleep(1); + previousState = umtx_loadAcquire(uio.fState); + } while (previousState == 1); + } + } +} + +// This function is called by the thread that ran an initialization function, +// just after completing the function. + +U_COMMON_API void U_EXPORT2 umtx_initImplPostInit(UInitOnce &uio) { + umtx_storeRelease(uio.fState, 2); +} + +U_NAMESPACE_END + +static void winMutexInit(CRITICAL_SECTION *cs) { + InitializeCriticalSection(cs); + return; +} + +U_CAPI void U_EXPORT2 +umtx_lock(UMutex *mutex) { + if (mutex == NULL) { + mutex = &globalMutex; + } + CRITICAL_SECTION *cs = &mutex->fCS; + umtx_initOnce(mutex->fInitOnce, winMutexInit, cs); + EnterCriticalSection(cs); +} + +U_CAPI void U_EXPORT2 +umtx_unlock(UMutex* mutex) +{ + if (mutex == NULL) { + mutex = &globalMutex; + } + LeaveCriticalSection(&mutex->fCS); +} + + +U_CAPI void U_EXPORT2 +umtx_condBroadcast(UConditionVar *condition) { + // We require that the associated mutex be held by the caller, + // so access to fWaitCount is protected and safe. No other thread can + // call condWait() while we are here. + if (condition->fWaitCount == 0) { + return; + } + ResetEvent(condition->fExitGate); + SetEvent(condition->fEntryGate); +} + +U_CAPI void U_EXPORT2 +umtx_condSignal(UConditionVar *condition) { + // Function not implemented. There is no immediate requirement from ICU to have it. + // Once ICU drops support for Windows XP and Server 2003, ICU Condition Variables will be + // changed to be thin wrappers on native Windows CONDITION_VARIABLEs, and this function + // becomes trivial to provide. + U_ASSERT(FALSE); +} + +U_CAPI void U_EXPORT2 +umtx_condWait(UConditionVar *condition, UMutex *mutex) { + if (condition->fEntryGate == NULL) { + // Note: because the associated mutex must be locked when calling + // wait, we know that there can not be multiple threads + // running here with the same condition variable. + // Meaning that lazy initialization is safe. + U_ASSERT(condition->fExitGate == NULL); + condition->fEntryGate = CreateEvent(NULL, // Security Attributes + TRUE, // Manual Reset + FALSE, // Initially reset + NULL); // Name. + U_ASSERT(condition->fEntryGate != NULL); + condition->fExitGate = CreateEvent(NULL, TRUE, TRUE, NULL); + U_ASSERT(condition->fExitGate != NULL); + } + + condition->fWaitCount++; + umtx_unlock(mutex); + WaitForSingleObject(condition->fEntryGate, INFINITE); + umtx_lock(mutex); + condition->fWaitCount--; + if (condition->fWaitCount == 0) { + // All threads that were waiting at the entry gate have woken up + // and moved through. Shut the entry gate and open the exit gate. + ResetEvent(condition->fEntryGate); + SetEvent(condition->fExitGate); + } else { + umtx_unlock(mutex); + WaitForSingleObject(condition->fExitGate, INFINITE); + umtx_lock(mutex); + } +} + + +#elif U_PLATFORM_IMPLEMENTS_POSIX + +//------------------------------------------------------------------------------------------- +// +// POSIX specific definitions +// +//------------------------------------------------------------------------------------------- + +# include <pthread.h> + +// Each UMutex consists of a pthread_mutex_t. +// All are statically initialized and ready for use. +// There is no runtime mutex initialization code needed. + +U_CAPI void U_EXPORT2 +umtx_lock(UMutex *mutex) { + if (mutex == NULL) { + mutex = &globalMutex; + } + int sysErr = pthread_mutex_lock(&mutex->fMutex); + (void)sysErr; // Suppress unused variable warnings. + U_ASSERT(sysErr == 0); +} + + +U_CAPI void U_EXPORT2 +umtx_unlock(UMutex* mutex) +{ + if (mutex == NULL) { + mutex = &globalMutex; + } + int sysErr = pthread_mutex_unlock(&mutex->fMutex); + (void)sysErr; // Suppress unused variable warnings. + U_ASSERT(sysErr == 0); +} + + +U_CAPI void U_EXPORT2 +umtx_condWait(UConditionVar *cond, UMutex *mutex) { + if (mutex == NULL) { + mutex = &globalMutex; + } + int sysErr = pthread_cond_wait(&cond->fCondition, &mutex->fMutex); + (void)sysErr; + U_ASSERT(sysErr == 0); +} + +U_CAPI void U_EXPORT2 +umtx_condBroadcast(UConditionVar *cond) { + int sysErr = pthread_cond_broadcast(&cond->fCondition); + (void)sysErr; + U_ASSERT(sysErr == 0); +} + +U_CAPI void U_EXPORT2 +umtx_condSignal(UConditionVar *cond) { + int sysErr = pthread_cond_signal(&cond->fCondition); + (void)sysErr; + U_ASSERT(sysErr == 0); +} + + + +U_NAMESPACE_BEGIN + +static pthread_mutex_t initMutex = PTHREAD_MUTEX_INITIALIZER; +static pthread_cond_t initCondition = PTHREAD_COND_INITIALIZER; + + +// This function is called when a test of a UInitOnce::fState reveals that +// initialization has not completed, that we either need to call the +// function on this thread, or wait for some other thread to complete. +// +// The actual call to the init function is made inline by template code +// that knows the C++ types involved. This function returns TRUE if +// the caller needs to call the Init function. +// +U_COMMON_API UBool U_EXPORT2 +umtx_initImplPreInit(UInitOnce &uio) { + pthread_mutex_lock(&initMutex); + int32_t state = uio.fState; + if (state == 0) { + umtx_storeRelease(uio.fState, 1); + pthread_mutex_unlock(&initMutex); + return TRUE; // Caller will next call the init function. + } else { + while (uio.fState == 1) { + // Another thread is currently running the initialization. + // Wait until it completes. + pthread_cond_wait(&initCondition, &initMutex); + } + pthread_mutex_unlock(&initMutex); + U_ASSERT(uio.fState == 2); + return FALSE; + } +} + + + +// This function is called by the thread that ran an initialization function, +// just after completing the function. +// Some threads may be waiting on the condition, requiring the broadcast wakeup. +// Some threads may be racing to test the fState variable outside of the mutex, +// requiring the use of store/release when changing its value. + +U_COMMON_API void U_EXPORT2 +umtx_initImplPostInit(UInitOnce &uio) { + pthread_mutex_lock(&initMutex); + umtx_storeRelease(uio.fState, 2); + pthread_cond_broadcast(&initCondition); + pthread_mutex_unlock(&initMutex); +} + +U_NAMESPACE_END + +// End of POSIX specific umutex implementation. + +#else // Platform #define chain. + +#error Unknown Platform + +#endif // Platform #define chain. + + +//------------------------------------------------------------------------------- +// +// Atomic Operations, out-of-line versions. +// These are conditional, only defined if better versions +// were not available for the platform. +// +// These versions are platform neutral. +// +//-------------------------------------------------------------------------------- + +#if defined U_NO_PLATFORM_ATOMICS +static UMutex gIncDecMutex = U_MUTEX_INITIALIZER; + +U_NAMESPACE_BEGIN + +U_COMMON_API int32_t U_EXPORT2 +umtx_atomic_inc(u_atomic_int32_t *p) { + int32_t retVal; + umtx_lock(&gIncDecMutex); + retVal = ++(*p); + umtx_unlock(&gIncDecMutex); + return retVal; +} + + +U_COMMON_API int32_t U_EXPORT2 +umtx_atomic_dec(u_atomic_int32_t *p) { + int32_t retVal; + umtx_lock(&gIncDecMutex); + retVal = --(*p); + umtx_unlock(&gIncDecMutex); + return retVal; +} + +U_COMMON_API int32_t U_EXPORT2 +umtx_loadAcquire(u_atomic_int32_t &var) { + umtx_lock(&gIncDecMutex); + int32_t val = var; + umtx_unlock(&gIncDecMutex); + return val; +} + +U_COMMON_API void U_EXPORT2 +umtx_storeRelease(u_atomic_int32_t &var, int32_t val) { + umtx_lock(&gIncDecMutex); + var = val; + umtx_unlock(&gIncDecMutex); +} + +U_NAMESPACE_END +#endif + +//-------------------------------------------------------------------------- +// +// Deprecated functions for setting user mutexes. +// +//-------------------------------------------------------------------------- + +U_DEPRECATED void U_EXPORT2 +u_setMutexFunctions(const void * /*context */, UMtxInitFn *, UMtxFn *, + UMtxFn *, UMtxFn *, UErrorCode *status) { + if (U_SUCCESS(*status)) { + *status = U_UNSUPPORTED_ERROR; + } + return; +} + + + +U_DEPRECATED void U_EXPORT2 +u_setAtomicIncDecFunctions(const void * /*context */, UMtxAtomicFn *, UMtxAtomicFn *, + UErrorCode *status) { + if (U_SUCCESS(*status)) { + *status = U_UNSUPPORTED_ERROR; + } + return; +} |