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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <cstdint>
#include "mongo/platform/atomic_word.h"
namespace mongo {
/**
* A 64bit (atomic) counter.
*
* The constructor allows setting the start value, and increment([int]) is used to change it.
*
* The value can be returned using get() or the (long long) function operator.
*/
class Counter64 {
public:
/** Atomically increment. */
void increment(uint64_t n = 1) {
_counter.addAndFetch(n);
}
/** Atomically decrement. */
void decrement(uint64_t n = 1) {
_counter.subtractAndFetch(n);
}
/** Return the current value */
long long get() const {
return _counter.load();
}
operator long long() const {
return get();
}
private:
AtomicWord<long long> _counter;
};
} // namespace mongo
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