import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

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;
+}