diff options
Diffstat (limited to 'include/my_atomic.h')
| -rw-r--r-- | include/my_atomic.h | 156 |
1 files changed, 156 insertions, 0 deletions
diff --git a/include/my_atomic.h b/include/my_atomic.h new file mode 100644 index 00000000..270134a6 --- /dev/null +++ b/include/my_atomic.h @@ -0,0 +1,156 @@ +#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 */ |