ref-count.hpp
Go to the documentation of this file.00001 /* -*- mode: C++; c-basic-offset: 2; indent-tabs-mode: nil -*- */ 00002 /* 00003 * Main authors: 00004 * Christian Schulte <schulte@gecode.org> 00005 * 00006 * Copyright: 00007 * Christian Schulte, 2017 00008 * 00009 * This file is part of Gecode, the generic constraint 00010 * development environment: 00011 * http://www.gecode.org 00012 * 00013 * Permission is hereby granted, free of charge, to any person obtaining 00014 * a copy of this software and associated documentation files (the 00015 * "Software"), to deal in the Software without restriction, including 00016 * without limitation the rights to use, copy, modify, merge, publish, 00017 * distribute, sublicense, and/or sell copies of the Software, and to 00018 * permit persons to whom the Software is furnished to do so, subject to 00019 * the following conditions: 00020 * 00021 * The above copyright notice and this permission notice shall be 00022 * included in all copies or substantial portions of the Software. 00023 * 00024 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 00025 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 00026 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 00027 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 00028 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 00029 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 00030 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 00031 * 00032 */ 00033 00034 #include <atomic> 00035 00036 namespace Gecode { namespace Support { 00037 00039 class RefCount { 00040 protected: 00042 std::atomic_ulong n; 00043 public: 00045 RefCount(unsigned long int n); 00047 void inc(void); 00049 bool dec(void); 00051 operator bool(void) const; 00052 }; 00053 00054 forceinline 00055 RefCount::RefCount(unsigned long int n0) { 00056 n.store(n0,std::memory_order_release); 00057 } 00058 forceinline void 00059 RefCount::inc(void) { 00060 (void) n.fetch_add(1U,std::memory_order_relaxed); 00061 } 00062 forceinline bool 00063 RefCount::dec(void) { 00064 return n.fetch_sub(1U,std::memory_order_acq_rel) == 1U; 00065 } 00066 forceinline 00067 RefCount::operator bool(void) const { 00068 return n.load(std::memory_order_acquire) > 0U; 00069 } 00070 00071 }} 00072 00073 // STATISTICS: support-any