74 lines
2.3 KiB
C++
74 lines
2.3 KiB
C++
/* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */
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/*
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* Main authors:
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* Christian Schulte <schulte@gecode.org>
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*
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* Copyright:
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* Christian Schulte, 2017
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*
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* This file is part of Gecode, the generic constraint
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* development environment:
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* http://www.gecode.org
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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* LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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* OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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* WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*
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*/
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#include <atomic>
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namespace Gecode { namespace Support {
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/// A class for thread-safe reference counting
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class RefCount {
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protected:
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/// The reference count
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std::atomic_ulong n;
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public:
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/// Initialize
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RefCount(unsigned long int n);
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/// Increment counter
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void inc(void);
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/// Decrement counter and return true if it hits zero
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bool dec(void);
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/// Test whether reference count is non-zero
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operator bool(void) const;
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};
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forceinline
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RefCount::RefCount(unsigned long int n0) {
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n.store(n0,std::memory_order_release);
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}
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forceinline void
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RefCount::inc(void) {
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(void) n.fetch_add(1U,std::memory_order_relaxed);
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}
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forceinline bool
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RefCount::dec(void) {
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return n.fetch_sub(1U,std::memory_order_acq_rel) == 1U;
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}
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forceinline
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RefCount::operator bool(void) const {
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return n.load(std::memory_order_acquire) > 0U;
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}
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}}
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// STATISTICS: support-any
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