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107 lines
3.2 KiB
C++
107 lines
3.2 KiB
C++
// atomic_int.h
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// atomic wrapper for unsigned
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/* Copyright 2009 10gen Inc.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#if defined(_WIN32)
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# include <windows.h>
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#endif
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namespace mongo {
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struct AtomicUInt {
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AtomicUInt() : x(0) {}
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AtomicUInt(unsigned z) : x(z) { }
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operator unsigned() const { return x; }
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unsigned get() const { return x; }
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inline AtomicUInt operator++(); // ++prefix
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inline AtomicUInt operator++(int);// postfix++
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inline AtomicUInt operator--(); // --prefix
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inline AtomicUInt operator--(int); // postfix--
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inline void zero();
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volatile unsigned x;
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};
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#if defined(_WIN32)
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void AtomicUInt::zero() {
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InterlockedExchange((volatile long*)&x, 0);
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}
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AtomicUInt AtomicUInt::operator++() {
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return InterlockedIncrement((volatile long*)&x);
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}
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AtomicUInt AtomicUInt::operator++(int) {
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return InterlockedIncrement((volatile long*)&x)-1;
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}
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AtomicUInt AtomicUInt::operator--() {
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return InterlockedDecrement((volatile long*)&x);
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}
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AtomicUInt AtomicUInt::operator--(int) {
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return InterlockedDecrement((volatile long*)&x)+1;
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}
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#elif defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)
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// this is in GCC >= 4.1
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inline void AtomicUInt::zero() { x = 0; } // TODO: this isn't thread safe - maybe
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AtomicUInt AtomicUInt::operator++() {
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return __sync_add_and_fetch(&x, 1);
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}
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AtomicUInt AtomicUInt::operator++(int) {
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return __sync_fetch_and_add(&x, 1);
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}
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AtomicUInt AtomicUInt::operator--() {
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return __sync_add_and_fetch(&x, -1);
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}
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AtomicUInt AtomicUInt::operator--(int) {
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return __sync_fetch_and_add(&x, -1);
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}
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#elif defined(__GNUC__) && (defined(__i386__) || defined(__x86_64__))
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inline void AtomicUInt::zero() { x = 0; } // TODO: this isn't thread safe
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// from boost 1.39 interprocess/detail/atomic.hpp
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inline unsigned atomic_int_helper(volatile unsigned *x, int val) {
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int r;
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asm volatile
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(
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"lock\n\t"
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"xadd %1, %0":
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"+m"( *x ), "=r"( r ): // outputs (%0, %1)
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"1"( val ): // inputs (%2 == %1)
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"memory", "cc" // clobbers
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);
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return r;
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}
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AtomicUInt AtomicUInt::operator++() {
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return atomic_int_helper(&x, 1)+1;
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}
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AtomicUInt AtomicUInt::operator++(int) {
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return atomic_int_helper(&x, 1);
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}
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AtomicUInt AtomicUInt::operator--() {
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return atomic_int_helper(&x, -1)-1;
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}
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AtomicUInt AtomicUInt::operator--(int) {
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return atomic_int_helper(&x, -1);
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}
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#else
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# error "unsupported compiler or platform"
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#endif
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} // namespace mongo
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