71 lines
2.2 KiB
C++
71 lines
2.2 KiB
C++
/* Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License, version 2.0,
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as published by the Free Software Foundation.
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This program is also distributed with certain software (including
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but not limited to OpenSSL) that is licensed under separate terms,
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as designated in a particular file or component or in included license
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documentation. The authors of MySQL hereby grant you an additional
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permission to link the program and your derivative works with the
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separately licensed software that they have included with MySQL.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License, version 2.0, for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA */
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#include "my_ref_counted.h"
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/** default constructor */
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my_ref_counted::my_ref_counted() : m_count(0) {}
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/** copy constructor */
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my_ref_counted::my_ref_counted(my_ref_counted &other)
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: m_count(other.m_count.load()) {}
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/* virtual destructor */
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my_ref_counted::~my_ref_counted() {}
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/**
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Increases a reference count.
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@return old value
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*/
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uint64 my_ref_counted::add_reference() { return m_count++; }
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/**
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Decreases a reference count.
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Doesn't allow to decrease below 0.
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@param [out] new_count Pointer to variable to store new count. May be NULL.
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@return Status of performed operation
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@retval false success
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@retval true Failure. Will be returned in case counter is already 0.
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*/
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bool my_ref_counted::release_reference(uint64 *new_count) {
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uint64 old_val = m_count;
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do {
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if (old_val == 0) {
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return true;
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}
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} while (!m_count.compare_exchange_weak(old_val, old_val - 1));
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if (new_count != NULL) {
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*new_count = old_val - 1;
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}
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return false;
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}
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/**
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Returns the reference counter value.
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@return current value
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*/
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uint64 my_ref_counted::get_reference_count() const { return m_count; }
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