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bfb4a868fc
Solution: prefer CXX11 atomics if they are available to compiler intrinsics. test_hwm_pubsub fails 50% of the times on PPC64 and RISC-V with an apparent memory corruption of messages sent by the application thread to the I/O thread when using compiler intrinsics. Switching to CXX11 atomics makes the test reliable again. The standard API should be preferred anyway, if available.
308 lines
9.3 KiB
C++
308 lines
9.3 KiB
C++
/*
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Copyright (c) 2007-2016 Contributors as noted in the AUTHORS file
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This file is part of libzmq, the ZeroMQ core engine in C++.
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libzmq is free software; you can redistribute it and/or modify it under
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the terms of the GNU Lesser General Public License (LGPL) as published
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by the Free Software Foundation; either version 3 of the License, or
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(at your option) any later version.
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As a special exception, the Contributors give you permission to link
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this library with independent modules to produce an executable,
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regardless of the license terms of these independent modules, and to
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copy and distribute the resulting executable under terms of your choice,
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provided that you also meet, for each linked independent module, the
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terms and conditions of the license of that module. An independent
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module is a module which is not derived from or based on this library.
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If you modify this library, you must extend this exception to your
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version of the library.
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libzmq is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef __ZMQ_ATOMIC_PTR_HPP_INCLUDED__
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#define __ZMQ_ATOMIC_PTR_HPP_INCLUDED__
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#include "macros.hpp"
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#if defined ZMQ_FORCE_MUTEXES
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#define ZMQ_ATOMIC_PTR_MUTEX
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#elif (defined __cplusplus && __cplusplus >= 201103L) \
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|| (defined _MSC_VER && _MSC_VER >= 1900)
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#define ZMQ_ATOMIC_PTR_CXX11
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#elif defined ZMQ_HAVE_ATOMIC_INTRINSICS
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#define ZMQ_ATOMIC_PTR_INTRINSIC
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#elif (defined __i386__ || defined __x86_64__) && defined __GNUC__
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#define ZMQ_ATOMIC_PTR_X86
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#elif defined __ARM_ARCH_7A__ && defined __GNUC__
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#define ZMQ_ATOMIC_PTR_ARM
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#elif defined __tile__
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#define ZMQ_ATOMIC_PTR_TILE
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#elif defined ZMQ_HAVE_WINDOWS
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#define ZMQ_ATOMIC_PTR_WINDOWS
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#elif (defined ZMQ_HAVE_SOLARIS || defined ZMQ_HAVE_NETBSD \
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|| defined ZMQ_HAVE_GNU)
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#define ZMQ_ATOMIC_PTR_ATOMIC_H
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#else
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#define ZMQ_ATOMIC_PTR_MUTEX
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#endif
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#if defined ZMQ_ATOMIC_PTR_MUTEX
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#include "mutex.hpp"
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#elif defined ZMQ_ATOMIC_PTR_CXX11
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#include <atomic>
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#elif defined ZMQ_ATOMIC_PTR_WINDOWS
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#include "windows.hpp"
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#elif defined ZMQ_ATOMIC_PTR_ATOMIC_H
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#include <atomic.h>
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#elif defined ZMQ_ATOMIC_PTR_TILE
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#include <arch/atomic.h>
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#endif
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namespace zmq
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{
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#if !defined ZMQ_ATOMIC_PTR_CXX11
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inline void *atomic_xchg_ptr (void **ptr_,
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void *const val_
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#if defined ZMQ_ATOMIC_PTR_MUTEX
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,
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mutex_t &_sync
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#endif
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) ZMQ_NOEXCEPT
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{
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#if defined ZMQ_ATOMIC_PTR_WINDOWS
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return InterlockedExchangePointer ((PVOID *) ptr_, val_);
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#elif defined ZMQ_ATOMIC_PTR_INTRINSIC
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return __atomic_exchange_n (ptr_, val_, __ATOMIC_ACQ_REL);
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#elif defined ZMQ_ATOMIC_PTR_ATOMIC_H
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return atomic_swap_ptr (ptr_, val_);
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#elif defined ZMQ_ATOMIC_PTR_TILE
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return arch_atomic_exchange (ptr_, val_);
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#elif defined ZMQ_ATOMIC_PTR_X86
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void *old;
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__asm__ volatile("lock; xchg %0, %2"
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: "=r"(old), "=m"(*ptr_)
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: "m"(*ptr_), "0"(val_));
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return old;
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#elif defined ZMQ_ATOMIC_PTR_ARM
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void *old;
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unsigned int flag;
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__asm__ volatile(" dmb sy\n\t"
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"1: ldrex %1, [%3]\n\t"
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" strex %0, %4, [%3]\n\t"
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" teq %0, #0\n\t"
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" bne 1b\n\t"
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" dmb sy\n\t"
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: "=&r"(flag), "=&r"(old), "+Qo"(*ptr_)
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: "r"(ptr_), "r"(val_)
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: "cc");
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return old;
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#elif defined ZMQ_ATOMIC_PTR_MUTEX
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_sync.lock ();
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void *old = *ptr_;
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*ptr_ = val_;
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_sync.unlock ();
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return old;
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#else
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#error atomic_ptr is not implemented for this platform
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#endif
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}
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inline void *atomic_cas (void *volatile *ptr_,
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void *cmp_,
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void *val_
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#if defined ZMQ_ATOMIC_PTR_MUTEX
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,
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mutex_t &_sync
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#endif
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) ZMQ_NOEXCEPT
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{
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#if defined ZMQ_ATOMIC_PTR_WINDOWS
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return InterlockedCompareExchangePointer ((volatile PVOID *) ptr_, val_,
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cmp_);
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#elif defined ZMQ_ATOMIC_PTR_INTRINSIC
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void *old = cmp_;
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__atomic_compare_exchange_n (ptr_, &old, val_, false, __ATOMIC_RELEASE,
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__ATOMIC_ACQUIRE);
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return old;
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#elif defined ZMQ_ATOMIC_PTR_ATOMIC_H
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return atomic_cas_ptr (ptr_, cmp_, val_);
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#elif defined ZMQ_ATOMIC_PTR_TILE
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return arch_atomic_val_compare_and_exchange (ptr_, cmp_, val_);
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#elif defined ZMQ_ATOMIC_PTR_X86
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void *old;
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__asm__ volatile("lock; cmpxchg %2, %3"
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: "=a"(old), "=m"(*ptr_)
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: "r"(val_), "m"(*ptr_), "0"(cmp_)
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: "cc");
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return old;
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#elif defined ZMQ_ATOMIC_PTR_ARM
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void *old;
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unsigned int flag;
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__asm__ volatile(" dmb sy\n\t"
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"1: ldrex %1, [%3]\n\t"
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" mov %0, #0\n\t"
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" teq %1, %4\n\t"
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" it eq\n\t"
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" strexeq %0, %5, [%3]\n\t"
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" teq %0, #0\n\t"
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" bne 1b\n\t"
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" dmb sy\n\t"
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: "=&r"(flag), "=&r"(old), "+Qo"(*ptr_)
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: "r"(ptr_), "r"(cmp_), "r"(val_)
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: "cc");
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return old;
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#elif defined ZMQ_ATOMIC_PTR_MUTEX
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_sync.lock ();
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void *old = *ptr_;
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if (*ptr_ == cmp_)
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*ptr_ = val_;
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_sync.unlock ();
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return old;
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#else
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#error atomic_ptr is not implemented for this platform
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#endif
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}
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#endif
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// This class encapsulates several atomic operations on pointers.
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template <typename T> class atomic_ptr_t
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{
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public:
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// Initialise atomic pointer
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inline atomic_ptr_t () ZMQ_NOEXCEPT { _ptr = NULL; }
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// Set value of atomic pointer in a non-threadsafe way
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// Use this function only when you are sure that at most one
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// thread is accessing the pointer at the moment.
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inline void set (T *ptr_) ZMQ_NOEXCEPT { _ptr = ptr_; }
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// Perform atomic 'exchange pointers' operation. Pointer is set
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// to the 'val_' value. Old value is returned.
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inline T *xchg (T *val_) ZMQ_NOEXCEPT
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{
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#if defined ZMQ_ATOMIC_PTR_CXX11
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return _ptr.exchange (val_, std::memory_order_acq_rel);
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#else
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return (T *) atomic_xchg_ptr ((void **) &_ptr, val_
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#if defined ZMQ_ATOMIC_PTR_MUTEX
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,
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_sync
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#endif
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);
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#endif
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}
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// Perform atomic 'compare and swap' operation on the pointer.
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// The pointer is compared to 'cmp' argument and if they are
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// equal, its value is set to 'val_'. Old value of the pointer
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// is returned.
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inline T *cas (T *cmp_, T *val_) ZMQ_NOEXCEPT
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{
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#if defined ZMQ_ATOMIC_PTR_CXX11
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_ptr.compare_exchange_strong (cmp_, val_, std::memory_order_acq_rel);
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return cmp_;
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#else
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return (T *) atomic_cas ((void **) &_ptr, cmp_, val_
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#if defined ZMQ_ATOMIC_PTR_MUTEX
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,
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_sync
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#endif
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);
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#endif
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}
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private:
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#if defined ZMQ_ATOMIC_PTR_CXX11
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std::atomic<T *> _ptr;
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#else
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volatile T *_ptr;
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#endif
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#if defined ZMQ_ATOMIC_PTR_MUTEX
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mutex_t _sync;
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#endif
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#if !defined ZMQ_ATOMIC_PTR_CXX11
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atomic_ptr_t (const atomic_ptr_t &);
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const atomic_ptr_t &operator= (const atomic_ptr_t &);
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#endif
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};
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struct atomic_value_t
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{
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atomic_value_t (const int value_) ZMQ_NOEXCEPT : _value (value_) {}
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atomic_value_t (const atomic_value_t &src_) ZMQ_NOEXCEPT
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: _value (src_.load ())
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{
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}
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void store (const int value_) ZMQ_NOEXCEPT
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{
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#if defined ZMQ_ATOMIC_PTR_CXX11
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_value.store (value_, std::memory_order_release);
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#else
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atomic_xchg_ptr ((void **) &_value, (void *) (ptrdiff_t) value_
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#if defined ZMQ_ATOMIC_PTR_MUTEX
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,
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_sync
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#endif
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);
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#endif
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}
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int load () const ZMQ_NOEXCEPT
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{
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#if defined ZMQ_ATOMIC_PTR_CXX11
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return _value.load (std::memory_order_acquire);
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#else
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return (int) (ptrdiff_t) atomic_cas ((void **) &_value, 0, 0
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#if defined ZMQ_ATOMIC_PTR_MUTEX
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,
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#if defined __SUNPRO_CC
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const_cast<mutex_t &> (_sync)
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#else
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_sync
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#endif
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#endif
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);
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#endif
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}
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private:
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#if defined ZMQ_ATOMIC_PTR_CXX11
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std::atomic<int> _value;
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#else
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volatile ptrdiff_t _value;
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#endif
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#if defined ZMQ_ATOMIC_PTR_MUTEX
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mutable mutex_t _sync;
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#endif
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private:
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atomic_value_t &operator= (const atomic_value_t &src_);
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};
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}
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// Remove macros local to this file.
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#undef ZMQ_ATOMIC_PTR_MUTEX
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#undef ZMQ_ATOMIC_PTR_INTRINSIC
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#undef ZMQ_ATOMIC_PTR_CXX11
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#undef ZMQ_ATOMIC_PTR_X86
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#undef ZMQ_ATOMIC_PTR_ARM
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#undef ZMQ_ATOMIC_PTR_TILE
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#undef ZMQ_ATOMIC_PTR_WINDOWS
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#undef ZMQ_ATOMIC_PTR_ATOMIC_H
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#endif
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