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mikx
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deps/mysqllite/include/internal/my_atomic.h
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287
deps/mysqllite/include/internal/my_atomic.h
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#ifndef MY_ATOMIC_INCLUDED
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#define MY_ATOMIC_INCLUDED
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/* Copyright (C) 2006 MySQL AB
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; version 2 of 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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */
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/*
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This header defines five atomic operations:
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my_atomic_add#(&var, what)
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'Fetch and Add'
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add 'what' to *var, and return the old value of *var
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my_atomic_fas#(&var, what)
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'Fetch And Store'
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store 'what' in *var, and return the old value of *var
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my_atomic_cas#(&var, &old, new)
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An odd variation of 'Compare And Set/Swap'
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if *var is equal to *old, then store 'new' in *var, and return TRUE
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otherwise store *var in *old, and return FALSE
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Usually, &old should not be accessed if the operation is successful.
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my_atomic_load#(&var)
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return *var
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my_atomic_store#(&var, what)
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store 'what' in *var
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'#' is substituted by a size suffix - 8, 16, 32, 64, or ptr
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(e.g. my_atomic_add8, my_atomic_fas32, my_atomic_casptr).
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NOTE This operations are not always atomic, so they always must be
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enclosed in my_atomic_rwlock_rdlock(lock)/my_atomic_rwlock_rdunlock(lock)
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or my_atomic_rwlock_wrlock(lock)/my_atomic_rwlock_wrunlock(lock).
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Hint: if a code block makes intensive use of atomic ops, it make sense
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to take/release rwlock once for the whole block, not for every statement.
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On architectures where these operations are really atomic, rwlocks will
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be optimized away.
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8- and 16-bit atomics aren't implemented for windows (see generic-msvc.h),
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but can be added, if necessary.
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*/
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#ifndef my_atomic_rwlock_init
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#define intptr void *
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/**
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Currently we don't support 8-bit and 16-bit operations.
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It can be added later if needed.
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*/
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#undef MY_ATOMIC_HAS_8_16
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#ifndef MY_ATOMIC_MODE_RWLOCKS
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/*
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* Attempt to do atomic ops without locks
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*/
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#include "atomic/nolock.h"
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#endif
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#ifndef make_atomic_cas_body
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/* nolock.h was not able to generate even a CAS function, fall back */
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#include "atomic/rwlock.h"
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#endif
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/* define missing functions by using the already generated ones */
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#ifndef make_atomic_add_body
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#define make_atomic_add_body(S) \
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int ## S tmp=*a; \
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while (!my_atomic_cas ## S(a, &tmp, tmp+v)) ; \
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v=tmp;
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#endif
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#ifndef make_atomic_fas_body
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#define make_atomic_fas_body(S) \
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int ## S tmp=*a; \
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while (!my_atomic_cas ## S(a, &tmp, v)) ; \
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v=tmp;
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#endif
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#ifndef make_atomic_load_body
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#define make_atomic_load_body(S) \
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ret= 0; /* avoid compiler warning */ \
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(void)(my_atomic_cas ## S(a, &ret, ret));
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#endif
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#ifndef make_atomic_store_body
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#define make_atomic_store_body(S) \
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(void)(my_atomic_fas ## S (a, v));
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#endif
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/*
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transparent_union doesn't work in g++
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Bug ?
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Darwin's gcc doesn't want to put pointers in a transparent_union
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when built with -arch ppc64. Complains:
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warning: 'transparent_union' attribute ignored
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*/
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#if defined(__GNUC__) && !defined(__cplusplus) && \
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! (defined(__APPLE__) && (defined(_ARCH_PPC64) ||defined (_ARCH_PPC)))
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/*
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we want to be able to use my_atomic_xxx functions with
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both signed and unsigned integers. But gcc will issue a warning
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"passing arg N of `my_atomic_XXX' as [un]signed due to prototype"
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if the signedness of the argument doesn't match the prototype, or
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"pointer targets in passing argument N of my_atomic_XXX differ in signedness"
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if int* is used where uint* is expected (or vice versa).
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Let's shut these warnings up
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*/
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#define make_transparent_unions(S) \
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typedef union { \
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int ## S i; \
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uint ## S u; \
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} U_ ## S __attribute__ ((transparent_union)); \
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typedef union { \
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int ## S volatile *i; \
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uint ## S volatile *u; \
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} Uv_ ## S __attribute__ ((transparent_union));
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#define uintptr intptr
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make_transparent_unions(8)
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make_transparent_unions(16)
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make_transparent_unions(32)
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make_transparent_unions(64)
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make_transparent_unions(ptr)
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#undef uintptr
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#undef make_transparent_unions
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#define a U_a.i
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#define cmp U_cmp.i
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#define v U_v.i
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#define set U_set.i
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#else
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#define U_8 int8
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#define U_16 int16
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#define U_32 int32
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#define U_64 int64
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#define U_ptr intptr
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#define Uv_8 int8
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#define Uv_16 int16
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#define Uv_32 int32
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#define Uv_64 int64
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#define Uv_ptr intptr
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#define U_a volatile *a
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#define U_cmp *cmp
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#define U_v v
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#define U_set set
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#endif /* __GCC__ transparent_union magic */
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#define make_atomic_cas(S) \
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static inline int my_atomic_cas ## S(Uv_ ## S U_a, \
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Uv_ ## S U_cmp, U_ ## S U_set) \
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{ \
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int8 ret; \
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make_atomic_cas_body(S); \
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return ret; \
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}
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#define make_atomic_add(S) \
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static inline int ## S my_atomic_add ## S( \
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Uv_ ## S U_a, U_ ## S U_v) \
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{ \
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make_atomic_add_body(S); \
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return v; \
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}
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#define make_atomic_fas(S) \
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static inline int ## S my_atomic_fas ## S( \
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Uv_ ## S U_a, U_ ## S U_v) \
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{ \
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make_atomic_fas_body(S); \
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return v; \
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}
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#define make_atomic_load(S) \
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static inline int ## S my_atomic_load ## S(Uv_ ## S U_a) \
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{ \
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int ## S ret; \
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make_atomic_load_body(S); \
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return ret; \
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}
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#define make_atomic_store(S) \
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static inline void my_atomic_store ## S( \
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Uv_ ## S U_a, U_ ## S U_v) \
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{ \
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make_atomic_store_body(S); \
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}
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#ifdef MY_ATOMIC_HAS_8_16
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make_atomic_cas(8)
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make_atomic_cas(16)
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#endif
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make_atomic_cas(32)
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make_atomic_cas(64)
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make_atomic_cas(ptr)
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#ifdef MY_ATOMIC_HAS_8_16
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make_atomic_add(8)
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make_atomic_add(16)
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#endif
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make_atomic_add(32)
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make_atomic_add(64)
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#ifdef MY_ATOMIC_HAS_8_16
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make_atomic_load(8)
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make_atomic_load(16)
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#endif
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make_atomic_load(32)
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make_atomic_load(64)
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make_atomic_load(ptr)
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#ifdef MY_ATOMIC_HAS_8_16
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make_atomic_fas(8)
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make_atomic_fas(16)
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#endif
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make_atomic_fas(32)
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make_atomic_fas(64)
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make_atomic_fas(ptr)
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#ifdef MY_ATOMIC_HAS_8_16
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make_atomic_store(8)
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make_atomic_store(16)
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#endif
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make_atomic_store(32)
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make_atomic_store(64)
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make_atomic_store(ptr)
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#ifdef _atomic_h_cleanup_
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#include _atomic_h_cleanup_
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#undef _atomic_h_cleanup_
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#endif
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#undef U_8
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#undef U_16
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#undef U_32
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#undef U_64
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#undef U_ptr
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#undef Uv_8
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#undef Uv_16
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#undef Uv_32
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#undef Uv_64
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#undef Uv_ptr
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#undef a
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#undef cmp
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#undef v
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#undef set
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#undef U_a
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#undef U_cmp
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#undef U_v
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#undef U_set
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#undef make_atomic_add
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#undef make_atomic_cas
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#undef make_atomic_load
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#undef make_atomic_store
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#undef make_atomic_fas
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#undef make_atomic_add_body
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#undef make_atomic_cas_body
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#undef make_atomic_load_body
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#undef make_atomic_store_body
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#undef make_atomic_fas_body
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#undef intptr
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/*
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the macro below defines (as an expression) the code that
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will be run in spin-loops. Intel manuals recummend to have PAUSE there.
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It is expected to be defined in include/atomic/ *.h files
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*/
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#ifndef LF_BACKOFF
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#define LF_BACKOFF (1)
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#endif
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#define MY_ATOMIC_OK 0
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#define MY_ATOMIC_NOT_1CPU 1
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extern int my_atomic_initialize();
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#endif
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#endif /* MY_ATOMIC_INCLUDED */
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