D7net
Home
Console
Upload
information
Create File
Create Folder
About
Tools
:
/
usr
/
include
/
mysql
/
server
/
private
/
Filename :
my_atomic.h
back
Copy
#ifndef MY_ATOMIC_INCLUDED #define MY_ATOMIC_INCLUDED /* Copyright (c) 2006, 2010, Oracle and/or its affiliates. All rights reserved. Copyright (c) 2018, 2022, MariaDB This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; version 2 of the License. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1335 USA */ /* This header defines five atomic operations: my_atomic_add#(&var, what) my_atomic_add#_explicit(&var, what, memory_order) 'Fetch and Add' add 'what' to *var, and return the old value of *var All memory orders are valid. my_atomic_fas#(&var, what) my_atomic_fas#_explicit(&var, what, memory_order) 'Fetch And Store' store 'what' in *var, and return the old value of *var All memory orders are valid. my_atomic_cas#(&var, &old, new) my_atomic_cas#_weak_explicit(&var, &old, new, succ, fail) my_atomic_cas#_strong_explicit(&var, &old, new, succ, fail) 'Compare And Swap' if *var is equal to *old, then store 'new' in *var, and return TRUE otherwise store *var in *old, and return FALSE succ - the memory synchronization ordering for the read-modify-write operation if the comparison succeeds. All memory orders are valid. fail - the memory synchronization ordering for the load operation if the comparison fails. Cannot be MY_MEMORY_ORDER_RELEASE or MY_MEMORY_ORDER_ACQ_REL and cannot specify stronger ordering than succ. The weak form is allowed to fail spuriously, that is, act as if *var != *old even if they are equal. When a compare-and-exchange is in a loop, the weak version will yield better performance on some platforms. When a weak compare-and-exchange would require a loop and a strong one would not, the strong one is preferable. my_atomic_load#(&var) my_atomic_load#_explicit(&var, memory_order) return *var Order must be one of MY_MEMORY_ORDER_RELAXED, MY_MEMORY_ORDER_CONSUME, MY_MEMORY_ORDER_ACQUIRE, MY_MEMORY_ORDER_SEQ_CST. my_atomic_store#(&var, what) my_atomic_store#_explicit(&var, what, memory_order) store 'what' in *var Order must be one of MY_MEMORY_ORDER_RELAXED, MY_MEMORY_ORDER_RELEASE, MY_MEMORY_ORDER_SEQ_CST. '#' is substituted by a size suffix - 8, 16, 32, 64, or ptr (e.g. my_atomic_add8, my_atomic_fas32, my_atomic_casptr). The first version orders memory accesses according to MY_MEMORY_ORDER_SEQ_CST, the second version (with _explicit suffix) orders memory accesses according to given memory order. memory_order specifies how non-atomic memory accesses are to be ordered around an atomic operation: MY_MEMORY_ORDER_RELAXED - there are no constraints on reordering of memory accesses around the atomic variable. MY_MEMORY_ORDER_CONSUME - no reads in the current thread dependent on the value currently loaded can be reordered before this load. This ensures that writes to dependent variables in other threads that release the same atomic variable are visible in the current thread. On most platforms, this affects compiler optimization only. MY_MEMORY_ORDER_ACQUIRE - no reads in the current thread can be reordered before this load. This ensures that all writes in other threads that release the same atomic variable are visible in the current thread. MY_MEMORY_ORDER_RELEASE - no writes in the current thread can be reordered after this store. This ensures that all writes in the current thread are visible in other threads that acquire the same atomic variable. MY_MEMORY_ORDER_ACQ_REL - no reads in the current thread can be reordered before this load as well as no writes in the current thread can be reordered after this store. The operation is read-modify-write operation. It is ensured that all writes in another threads that release the same atomic variable are visible before the modification and the modification is visible in other threads that acquire the same atomic variable. MY_MEMORY_ORDER_SEQ_CST - The operation has the same semantics as acquire-release operation, and additionally has sequentially-consistent operation ordering. We choose implementation as follows: on Windows using Visual C++ the native implementation should be preferable. When using gcc we prefer the Solaris implementation before the gcc because of stability preference, we choose gcc builtins if available. */ #if defined(_MSC_VER) #include "atomic/generic-msvc.h" #elif defined(HAVE_SOLARIS_ATOMIC) #include "atomic/solaris.h" #elif defined(HAVE_GCC_C11_ATOMICS) #include "atomic/gcc_builtins.h" #endif #ifndef MY_MEMORY_ORDER_SEQ_CST #define MY_MEMORY_ORDER_RELAXED #define MY_MEMORY_ORDER_CONSUME #define MY_MEMORY_ORDER_ACQUIRE #define MY_MEMORY_ORDER_RELEASE #define MY_MEMORY_ORDER_ACQ_REL #define MY_MEMORY_ORDER_SEQ_CST #define my_atomic_store32_explicit(P, D, O) my_atomic_store32((P), (D)) #define my_atomic_store64_explicit(P, D, O) my_atomic_store64((P), (D)) #define my_atomic_storeptr_explicit(P, D, O) my_atomic_storeptr((P), (D)) #define my_atomic_load32_explicit(P, O) my_atomic_load32((P)) #define my_atomic_load64_explicit(P, O) my_atomic_load64((P)) #define my_atomic_loadptr_explicit(P, O) my_atomic_loadptr((P)) #define my_atomic_fas32_explicit(P, D, O) my_atomic_fas32((P), (D)) #define my_atomic_fas64_explicit(P, D, O) my_atomic_fas64((P), (D)) #define my_atomic_fasptr_explicit(P, D, O) my_atomic_fasptr((P), (D)) #define my_atomic_add32_explicit(P, A, O) my_atomic_add32((P), (A)) #define my_atomic_add64_explicit(P, A, O) my_atomic_add64((P), (A)) #define my_atomic_addptr_explicit(P, A, O) my_atomic_addptr((P), (A)) #define my_atomic_cas32_weak_explicit(P, E, D, S, F) \ my_atomic_cas32((P), (E), (D)) #define my_atomic_cas64_weak_explicit(P, E, D, S, F) \ my_atomic_cas64((P), (E), (D)) #define my_atomic_casptr_weak_explicit(P, E, D, S, F) \ my_atomic_casptr((P), (E), (D)) #define my_atomic_cas32_strong_explicit(P, E, D, S, F) \ my_atomic_cas32((P), (E), (D)) #define my_atomic_cas64_strong_explicit(P, E, D, S, F) \ my_atomic_cas64((P), (E), (D)) #define my_atomic_casptr_strong_explicit(P, E, D, S, F) \ my_atomic_casptr((P), (E), (D)) #endif #endif /* MY_ATOMIC_INCLUDED */