1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
#ifndef QPID_SYS_ATOMICVALUE_GCC_H
#define QPID_SYS_ATOMICVALUE_GCC_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
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) { return __sync_add_and_fetch(&value, n); }
inline T operator-=(T n) { return __sync_sub_and_fetch(&value, n); }
inline T operator++() { return *this += 1; }
inline T operator--() { return *this -= 1; }
// Update and return old value.
inline T fetchAndAdd(T n) { return __sync_fetch_and_add(&value, n); }
inline T fetchAndSub(T n) { return __sync_fetch_and_sub(&value, n); }
inline T operator++(int) { return fetchAndAdd(1); }
inline T operator--(int) { return fetchAndSub(1); }
/** If current value == testval then set to newval. Returns the old value. */
T valueCompareAndSwap(T testval, T newval) { return __sync_val_compare_and_swap(&value, testval, newval); }
/** If current value == testval then set to newval. Returns true if the swap was performed. */
bool boolCompareAndSwap(T testval, T newval) { return __sync_bool_compare_and_swap(&value, testval, newval); }
T get() const { return const_cast<AtomicValue<T>*>(this)->fetchAndAdd(static_cast<T>(0)); }
private:
T value;
};
}} // namespace qpid::sys
#endif /*!QPID_SYS_ATOMICVALUE_GCC_H*/
|
