379 lines
11 KiB
C++
379 lines
11 KiB
C++
// © 2016 and later: Unicode, Inc. and others.
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// License & terms of use: http://www.unicode.org/copyright.html
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/*
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******************************************************************************
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*
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* Copyright (C) 1997-2016, International Business Machines
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* Corporation and others. All Rights Reserved.
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*
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******************************************************************************
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*
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* File umutex.cpp
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*
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* Modification History:
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*
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* Date Name Description
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* 04/02/97 aliu Creation.
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* 04/07/99 srl updated
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* 05/13/99 stephen Changed to umutex (from cmutex).
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* 11/22/99 aliu Make non-global mutex autoinitialize [j151]
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******************************************************************************
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*/
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#include "umutex.h"
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#include "unicode/utypes.h"
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#include "uassert.h"
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#include "cmemory.h"
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// The ICU global mutex. Used when ICU implementation code passes NULL for the mutex pointer.
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static UMutex globalMutex = U_MUTEX_INITIALIZER;
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/*
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* ICU Mutex wrappers. Wrap operating system mutexes, giving the rest of ICU a
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* platform independent set of mutex operations. For internal ICU use only.
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*/
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#if defined(U_USER_MUTEX_CPP)
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// Build time user mutex hook: #include "U_USER_MUTEX_CPP"
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#include U_MUTEX_XSTR(U_USER_MUTEX_CPP)
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#elif U_PLATFORM_USES_ONLY_WIN32_API
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#if defined U_NO_PLATFORM_ATOMICS
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#error ICU on Win32 requires support for low level atomic operations.
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// Visual Studio, gcc, clang are OK. Shouldn't get here.
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#endif
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// This function is called when a test of a UInitOnce::fState reveals that
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// initialization has not completed, that we either need to call the
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// function on this thread, or wait for some other thread to complete.
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//
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// The actual call to the init function is made inline by template code
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// that knows the C++ types involved. This function returns TRUE if
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// the caller needs to call the Init function.
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//
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U_NAMESPACE_BEGIN
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U_COMMON_API UBool U_EXPORT2 umtx_initImplPreInit(UInitOnce &uio) {
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for (;;) {
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int32_t previousState = InterlockedCompareExchange(
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(LONG volatile *) // this is the type given in the API doc for this function.
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&uio.fState, // Destination
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1, // Exchange Value
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0); // Compare value
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if (previousState == 0) {
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return true; // Caller will next call the init function.
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// Current state == 1.
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} else if (previousState == 2) {
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// Another thread already completed the initialization.
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// We can simply return FALSE, indicating no
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// further action is needed by the caller.
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return FALSE;
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} else {
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// Another thread is currently running the initialization.
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// Wait until it completes.
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do {
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Sleep(1);
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previousState = umtx_loadAcquire(uio.fState);
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} while (previousState == 1);
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}
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}
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}
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// This function is called by the thread that ran an initialization function,
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// just after completing the function.
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U_COMMON_API void U_EXPORT2 umtx_initImplPostInit(UInitOnce &uio) {
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umtx_storeRelease(uio.fState, 2);
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}
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U_NAMESPACE_END
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static void winMutexInit(CRITICAL_SECTION *cs) {
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InitializeCriticalSection(cs);
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return;
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}
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U_CAPI void U_EXPORT2
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umtx_lock(UMutex *mutex) {
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if (mutex == NULL) {
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mutex = &globalMutex;
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}
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CRITICAL_SECTION *cs = &mutex->fCS;
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umtx_initOnce(mutex->fInitOnce, winMutexInit, cs);
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EnterCriticalSection(cs);
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}
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U_CAPI void U_EXPORT2
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umtx_unlock(UMutex* mutex)
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{
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if (mutex == NULL) {
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mutex = &globalMutex;
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}
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LeaveCriticalSection(&mutex->fCS);
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}
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U_CAPI void U_EXPORT2
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umtx_condBroadcast(UConditionVar *condition) {
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// We require that the associated mutex be held by the caller,
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// so access to fWaitCount is protected and safe. No other thread can
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// call condWait() while we are here.
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if (condition->fWaitCount == 0) {
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return;
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}
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ResetEvent(condition->fExitGate);
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SetEvent(condition->fEntryGate);
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}
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U_CAPI void U_EXPORT2
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umtx_condSignal(UConditionVar * /* condition */) {
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// Function not implemented. There is no immediate requirement from ICU to have it.
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// Once ICU drops support for Windows XP and Server 2003, ICU Condition Variables will be
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// changed to be thin wrappers on native Windows CONDITION_VARIABLEs, and this function
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// becomes trivial to provide.
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U_ASSERT(FALSE);
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}
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U_CAPI void U_EXPORT2
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umtx_condWait(UConditionVar *condition, UMutex *mutex) {
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if (condition->fEntryGate == NULL) {
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// Note: because the associated mutex must be locked when calling
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// wait, we know that there can not be multiple threads
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// running here with the same condition variable.
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// Meaning that lazy initialization is safe.
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U_ASSERT(condition->fExitGate == NULL);
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condition->fEntryGate = CreateEvent(NULL, // Security Attributes
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TRUE, // Manual Reset
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FALSE, // Initially reset
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NULL); // Name.
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U_ASSERT(condition->fEntryGate != NULL);
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condition->fExitGate = CreateEvent(NULL, TRUE, TRUE, NULL);
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U_ASSERT(condition->fExitGate != NULL);
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}
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condition->fWaitCount++;
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umtx_unlock(mutex);
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WaitForSingleObject(condition->fEntryGate, INFINITE);
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umtx_lock(mutex);
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condition->fWaitCount--;
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if (condition->fWaitCount == 0) {
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// All threads that were waiting at the entry gate have woken up
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// and moved through. Shut the entry gate and open the exit gate.
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ResetEvent(condition->fEntryGate);
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SetEvent(condition->fExitGate);
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} else {
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umtx_unlock(mutex);
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WaitForSingleObject(condition->fExitGate, INFINITE);
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umtx_lock(mutex);
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}
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}
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#elif U_PLATFORM_IMPLEMENTS_POSIX
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//-------------------------------------------------------------------------------------------
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//
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// POSIX specific definitions
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//
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//-------------------------------------------------------------------------------------------
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# include <pthread.h>
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// Each UMutex consists of a pthread_mutex_t.
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// All are statically initialized and ready for use.
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// There is no runtime mutex initialization code needed.
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U_CAPI void U_EXPORT2
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umtx_lock(UMutex *mutex) {
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if (mutex == NULL) {
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mutex = &globalMutex;
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}
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int sysErr = pthread_mutex_lock(&mutex->fMutex);
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(void)sysErr; // Suppress unused variable warnings.
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U_ASSERT(sysErr == 0);
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}
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U_CAPI void U_EXPORT2
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umtx_unlock(UMutex* mutex)
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{
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if (mutex == NULL) {
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mutex = &globalMutex;
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}
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int sysErr = pthread_mutex_unlock(&mutex->fMutex);
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(void)sysErr; // Suppress unused variable warnings.
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U_ASSERT(sysErr == 0);
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}
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U_CAPI void U_EXPORT2
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umtx_condWait(UConditionVar *cond, UMutex *mutex) {
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if (mutex == NULL) {
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mutex = &globalMutex;
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}
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int sysErr = pthread_cond_wait(&cond->fCondition, &mutex->fMutex);
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(void)sysErr;
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U_ASSERT(sysErr == 0);
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}
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U_CAPI void U_EXPORT2
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umtx_condBroadcast(UConditionVar *cond) {
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int sysErr = pthread_cond_broadcast(&cond->fCondition);
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(void)sysErr;
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U_ASSERT(sysErr == 0);
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}
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U_CAPI void U_EXPORT2
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umtx_condSignal(UConditionVar *cond) {
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int sysErr = pthread_cond_signal(&cond->fCondition);
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(void)sysErr;
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U_ASSERT(sysErr == 0);
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}
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U_NAMESPACE_BEGIN
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static pthread_mutex_t initMutex = PTHREAD_MUTEX_INITIALIZER;
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static pthread_cond_t initCondition = PTHREAD_COND_INITIALIZER;
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// This function is called when a test of a UInitOnce::fState reveals that
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// initialization has not completed, that we either need to call the
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// function on this thread, or wait for some other thread to complete.
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//
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// The actual call to the init function is made inline by template code
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// that knows the C++ types involved. This function returns TRUE if
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// the caller needs to call the Init function.
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//
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U_COMMON_API UBool U_EXPORT2
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umtx_initImplPreInit(UInitOnce &uio) {
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pthread_mutex_lock(&initMutex);
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int32_t state = uio.fState;
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if (state == 0) {
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umtx_storeRelease(uio.fState, 1);
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pthread_mutex_unlock(&initMutex);
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return TRUE; // Caller will next call the init function.
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} else {
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while (uio.fState == 1) {
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// Another thread is currently running the initialization.
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// Wait until it completes.
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pthread_cond_wait(&initCondition, &initMutex);
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}
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pthread_mutex_unlock(&initMutex);
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U_ASSERT(uio.fState == 2);
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return FALSE;
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}
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}
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// This function is called by the thread that ran an initialization function,
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// just after completing the function.
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// Some threads may be waiting on the condition, requiring the broadcast wakeup.
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// Some threads may be racing to test the fState variable outside of the mutex,
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// requiring the use of store/release when changing its value.
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U_COMMON_API void U_EXPORT2
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umtx_initImplPostInit(UInitOnce &uio) {
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pthread_mutex_lock(&initMutex);
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umtx_storeRelease(uio.fState, 2);
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pthread_cond_broadcast(&initCondition);
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pthread_mutex_unlock(&initMutex);
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}
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U_NAMESPACE_END
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// End of POSIX specific umutex implementation.
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#else // Platform #define chain.
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#error Unknown Platform
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#endif // Platform #define chain.
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//-------------------------------------------------------------------------------
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//
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// Atomic Operations, out-of-line versions.
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// These are conditional, only defined if better versions
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// were not available for the platform.
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//
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// These versions are platform neutral.
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//
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//--------------------------------------------------------------------------------
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#if defined U_NO_PLATFORM_ATOMICS
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static UMutex gIncDecMutex = U_MUTEX_INITIALIZER;
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U_NAMESPACE_BEGIN
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U_COMMON_API int32_t U_EXPORT2
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umtx_atomic_inc(u_atomic_int32_t *p) {
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int32_t retVal;
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umtx_lock(&gIncDecMutex);
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retVal = ++(*p);
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umtx_unlock(&gIncDecMutex);
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return retVal;
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}
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U_COMMON_API int32_t U_EXPORT2
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umtx_atomic_dec(u_atomic_int32_t *p) {
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int32_t retVal;
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umtx_lock(&gIncDecMutex);
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retVal = --(*p);
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umtx_unlock(&gIncDecMutex);
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return retVal;
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}
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U_COMMON_API int32_t U_EXPORT2
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umtx_loadAcquire(u_atomic_int32_t &var) {
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umtx_lock(&gIncDecMutex);
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int32_t val = var;
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umtx_unlock(&gIncDecMutex);
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return val;
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}
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U_COMMON_API void U_EXPORT2
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umtx_storeRelease(u_atomic_int32_t &var, int32_t val) {
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umtx_lock(&gIncDecMutex);
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var = val;
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umtx_unlock(&gIncDecMutex);
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}
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U_NAMESPACE_END
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#endif
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//--------------------------------------------------------------------------
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//
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// Deprecated functions for setting user mutexes.
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//
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//--------------------------------------------------------------------------
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U_DEPRECATED void U_EXPORT2
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u_setMutexFunctions(const void * /*context */, UMtxInitFn *, UMtxFn *,
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UMtxFn *, UMtxFn *, UErrorCode *status) {
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if (U_SUCCESS(*status)) {
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*status = U_UNSUPPORTED_ERROR;
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}
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return;
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}
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U_DEPRECATED void U_EXPORT2
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u_setAtomicIncDecFunctions(const void * /*context */, UMtxAtomicFn *, UMtxAtomicFn *,
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UErrorCode *status) {
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if (U_SUCCESS(*status)) {
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*status = U_UNSUPPORTED_ERROR;
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}
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return;
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}
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