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Diffstat (limited to 'qpid/cpp/src/qpid/sys/AtomicValue_mutex.h')
-rw-r--r-- | qpid/cpp/src/qpid/sys/AtomicValue_mutex.h | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/qpid/cpp/src/qpid/sys/AtomicValue_mutex.h b/qpid/cpp/src/qpid/sys/AtomicValue_mutex.h new file mode 100644 index 0000000000..e4d433e7f5 --- /dev/null +++ b/qpid/cpp/src/qpid/sys/AtomicValue_mutex.h @@ -0,0 +1,83 @@ +#ifndef QPID_SYS_ATOMICVALUE_MUTEX_H +#define QPID_SYS_ATOMICVALUE_MUTEX_H + +/* + * + * Licensed to the Apache Software Foundation (ASF) under one + * or more contributor license agreements. See the NOTICE file + * distributed with this work for additional information + * regarding copyright ownership. The ASF licenses this file + * to you under the Apache License, Version 2.0 (the + * "License"); you may not use this file except in compliance + * with the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, + * software distributed under the License is distributed on an + * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY + * KIND, either express or implied. See the License for the + * specific language governing permissions and limitations + * under the License. + * + */ + +#if !defined(QPID_SYS_ATOMICVALUE_H) +#error "This file should only be included via AtomicValue.h." +#endif + +#include "qpid/sys/Mutex.h" + +namespace qpid { +namespace sys { + +/** + * Atomic value of type T. T must be an integral type of size 1,2,4 or 8 bytes. + * All operations are atomic and preform a full memory barrier unless otherwise noted. + */ +template <class T> +class AtomicValue +{ + public: + AtomicValue(T init=0) : value(init) {} + + // Update and return new value. + inline T operator+=(T n) { Lock l(lock); return value += n; } + inline T operator-=(T n) { Lock l(lock); return value -= n; } + inline T operator++() { return *this += 1; } + inline T operator--() { return *this -= 1; } + + // Update and return old value. + inline T fetchAndAdd(T n) { Lock l(lock); T old=value; value += n; return old; } + inline T fetchAndSub(T n) { Lock l(lock); T old=value; value -= n; return old; } + inline T operator++(int) { return fetchAndAdd(1); } + inline T operator--(int) { return fetchAndSub(1); } + + AtomicValue& operator=(T newval) { Lock l(lock); value = newval; return *this; } + + /** If current value == testval then set to newval. Returns the old value. */ + T valueCompareAndSwap(T testval, T newval) { + Lock l(lock); + T old=value; + if (value == testval) value = newval; + return old; + } + + /** If current value == testval then set to newval. Returns true if the swap was performed. */ + bool boolCompareAndSwap(T testval, T newval) { + Lock l(lock); + if (value == testval) { value = newval; return true; } + return false; + } + + T get() const { Lock l(lock); return value; } + + private: + typedef Mutex::ScopedLock Lock; + T value; + mutable Mutex lock; +}; + +}} // namespace qpid::sys + +#endif /*!QPID_SYS_ATOMICVALUE_MUTEX_H*/ |