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117 lines
2.9 KiB
C++
117 lines
2.9 KiB
C++
/* Copyright (C) 2014 InfiniDB, Inc.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; version 2 of
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the License.
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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 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 Street, Fifth Floor, Boston,
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MA 02110-1301, USA. */
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/** @file */
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#pragma once
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#include <unistd.h>
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#include <stdint.h>
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#include <sched.h>
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#include <atomic>
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/*
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This is an attempt to wrap the differneces between Windows and Linux around atomic ops.
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Boost has something in interprocess::ipcdetail, but it doesn't have 64-bit API's.
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*/
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namespace atomicops
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{
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// Atomic operations for atomic<int64_t> references
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inline int64_t atomicAddRef(std::atomic<int64_t>& ref, int64_t val)
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{
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return ref.fetch_add(val, std::memory_order_relaxed);
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}
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inline int64_t atomicSubRef(std::atomic<int64_t>& ref, int64_t val)
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{
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return ref.fetch_sub(val, std::memory_order_relaxed);
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}
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inline void atomicStoreRef(std::atomic<int64_t>& ref, int64_t val)
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{
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ref.store(val, std::memory_order_relaxed);
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}
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inline int64_t atomicLoadRef(const std::atomic<int64_t>& ref)
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{
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return ref.load(std::memory_order_relaxed);
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}
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// Returns the resulting, incremented value
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template <typename T>
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inline T atomicInc(volatile T* mem)
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{
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return __sync_add_and_fetch(mem, 1);
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}
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// decrements, but returns the pre-decrement value
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template <typename T>
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inline T atomicDec(volatile T* mem)
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{
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return __sync_fetch_and_add(mem, -1);
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}
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// Returns the resulting value (but doesn't need to yet)
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template <typename T>
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inline T atomicAdd(volatile T* mem, T val)
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{
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return __sync_add_and_fetch(mem, val);
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}
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// Returns the resulting value
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template <typename T>
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inline T atomicSub(volatile T* mem, T val)
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{
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return __sync_sub_and_fetch(mem, val);
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}
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// Implements a memory barrier
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inline void atomicMb()
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{
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__sync_synchronize();
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}
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// Returns true iff the CAS took place, that is
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// if (*mem == comp) {
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// *mem = swap;
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// return true;
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// } else {
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// return false;
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// }
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template <typename T>
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inline bool atomicCAS(volatile T* mem, T comp, T swap)
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{
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// If the current value of *mem is comp, then write swap into *comp. Return true if the comparison is
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// successful and swap was written.
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return __sync_bool_compare_and_swap(mem, comp, swap);
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}
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// implements a zero out of a variable
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template <typename T>
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inline void atomicZero(volatile T* mem)
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{
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__sync_xor_and_fetch(mem, *mem);
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}
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// Implements a scheduler yield
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inline void atomicYield()
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{
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sched_yield();
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}
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} // namespace atomicops
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