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author | Mikael Ronstrom <mikael@mysql.com> | 2009-10-09 14:21:29 +0200 |
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committer | Mikael Ronstrom <mikael@mysql.com> | 2009-10-09 14:21:29 +0200 |
commit | a4785fc4a2abeb3f8fbc253b78f558540b949482 (patch) | |
tree | b01f63d310ec7286d7af99b941db923a3e02efb2 /include/my_atomic.h | |
parent | ee696e4163354b85c60c68cb791005fa127abcea (diff) | |
download | mariadb-git-a4785fc4a2abeb3f8fbc253b78f558540b949482.tar.gz |
Moved atomics from 6.0 codebase to prepare for using atomic increments in places where LOCK_thread_count previously was used
Diffstat (limited to 'include/my_atomic.h')
-rw-r--r-- | include/my_atomic.h | 273 |
1 files changed, 209 insertions, 64 deletions
diff --git a/include/my_atomic.h b/include/my_atomic.h index 03f7d081981..f62d3e32b42 100644 --- a/include/my_atomic.h +++ b/include/my_atomic.h @@ -1,3 +1,6 @@ +#ifndef MY_ATOMIC_INCLUDED +#define MY_ATOMIC_INCLUDED + /* Copyright (C) 2006 MySQL AB This program is free software; you can redistribute it and/or modify @@ -13,9 +16,51 @@ along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA */ +/* + This header defines five atomic operations: + + my_atomic_add#(&var, what) + add 'what' to *var, and return the old value of *var + + my_atomic_fas#(&var, what) + 'Fetch And Store' + store 'what' in *var, and return the old value of *var + + my_atomic_cas#(&var, &old, new) + '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 + + my_atomic_load#(&var) + return *var + + my_atomic_store#(&var, what) + store 'what' in *var + + '#' is substituted by a size suffix - 8, 16, 32, or ptr + (e.g. my_atomic_add8, my_atomic_fas32, my_atomic_casptr). + + NOTE This operations are not always atomic, so they always must be + enclosed in my_atomic_rwlock_rdlock(lock)/my_atomic_rwlock_rdunlock(lock) + or my_atomic_rwlock_wrlock(lock)/my_atomic_rwlock_wrunlock(lock). + Hint: if a code block makes intensive use of atomic ops, it make sense + to take/release rwlock once for the whole block, not for every statement. + + On architectures where these operations are really atomic, rwlocks will + be optimized away. + 8- and 16-bit atomics aren't implemented for windows (see generic-msvc.h), + but can be added, if necessary. +*/ + #ifndef my_atomic_rwlock_init #define intptr void * +/** + On most platforms we implement 8-bit, 16-bit, 32-bit and "pointer" + operations. Thus the symbol below is defined by default; platforms + where we leave out 8-bit or 16-bit operations should undefine it. +*/ +#define MY_ATOMIC_HAS_8_16 1 #ifndef MY_ATOMIC_MODE_RWLOCKS /* @@ -24,124 +69,223 @@ #include "atomic/nolock.h" #endif -#ifndef MY_ATOMIC_NOLOCK -/* - * Have to use rw-locks for atomic ops - */ +#ifndef make_atomic_cas_body +/* nolock.h was not able to generate even a CAS function, fall back */ #include "atomic/rwlock.h" -#endif - -#ifndef MY_ATOMICS_MADE - +#else +/* define missing functions by using the already generated ones */ #ifndef make_atomic_add_body -#define make_atomic_add_body(S) \ +#define make_atomic_add_body(S) \ int ## S tmp=*a; \ while (!my_atomic_cas ## S(a, &tmp, tmp+v)); \ v=tmp; #endif +#ifndef make_atomic_fas_body +#define make_atomic_fas_body(S) \ + int ## S tmp=*a; \ + while (!my_atomic_cas ## S(a, &tmp, v)); \ + v=tmp; +#endif +#ifndef make_atomic_load_body +#define make_atomic_load_body(S) \ + ret= 0; /* avoid compiler warning */ \ + (void)(my_atomic_cas ## S(a, &ret, ret)); +#endif +#ifndef make_atomic_store_body +#define make_atomic_store_body(S) \ + (void)(my_atomic_fas ## S (a, v)); +#endif +#endif + +/* + transparent_union doesn't work in g++ + Bug ? + + Darwin's gcc doesn't want to put pointers in a transparent_union + when built with -arch ppc64. Complains: + warning: 'transparent_union' attribute ignored +*/ +#if defined(__GNUC__) && !defined(__cplusplus) && \ + ! (defined(__APPLE__) && defined(_ARCH_PPC64)) +/* + we want to be able to use my_atomic_xxx functions with + both signed and unsigned integers. But gcc will issue a warning + "passing arg N of `my_atomic_XXX' as [un]signed due to prototype" + if the signedness of the argument doesn't match the prototype, or + "pointer targets in passing argument N of my_atomic_XXX differ in signedness" + if int* is used where uint* is expected (or vice versa). + Let's shut these warnings up +*/ +#define make_transparent_unions(S) \ + typedef union { \ + int ## S i; \ + uint ## S u; \ + } U_ ## S __attribute__ ((transparent_union)); \ + typedef union { \ + int ## S volatile *i; \ + uint ## S volatile *u; \ + } Uv_ ## S __attribute__ ((transparent_union)); +#define uintptr intptr +make_transparent_unions(8) +make_transparent_unions(16) +make_transparent_unions(32) +make_transparent_unions(ptr) +#undef uintptr +#undef make_transparent_unions +#define a U_a.i +#define cmp U_cmp.i +#define v U_v.i +#define set U_set.i +#else +#define U_8 int8 +#define U_16 int16 +#define U_32 int32 +#define U_ptr intptr +#define Uv_8 int8 +#define Uv_16 int16 +#define Uv_32 int32 +#define Uv_ptr intptr +#define U_a volatile *a +#define U_cmp *cmp +#define U_v v +#define U_set set +#endif /* __GCC__ transparent_union magic */ #ifdef HAVE_INLINE -#define make_atomic_add(S) \ -STATIC_INLINE int ## S my_atomic_add ## S( \ - int ## S volatile *a, int ## S v) \ -{ \ - make_atomic_add_body(S); \ - return v; \ +#define make_atomic_cas(S) \ +STATIC_INLINE int my_atomic_cas ## S(Uv_ ## S U_a, \ + Uv_ ## S U_cmp, U_ ## S U_set) \ +{ \ + int8 ret; \ + make_atomic_cas_body(S); \ + return ret; \ } -#define make_atomic_swap(S) \ -STATIC_INLINE int ## S my_atomic_swap ## S( \ - int ## S volatile *a, int ## S v) \ -{ \ - make_atomic_swap_body(S); \ - return v; \ +#define make_atomic_add(S) \ +STATIC_INLINE int ## S my_atomic_add ## S( \ + Uv_ ## S U_a, U_ ## S U_v) \ +{ \ + make_atomic_add_body(S); \ + return v; \ } -#define make_atomic_cas(S) \ -STATIC_INLINE int my_atomic_cas ## S(int ## S volatile *a, \ - int ## S *cmp, int ## S set) \ -{ \ - int8 ret; \ - make_atomic_cas_body(S); \ - return ret; \ +#define make_atomic_fas(S) \ +STATIC_INLINE int ## S my_atomic_fas ## S( \ + Uv_ ## S U_a, U_ ## S U_v) \ +{ \ + make_atomic_fas_body(S); \ + return v; \ } -#define make_atomic_load(S) \ -STATIC_INLINE int ## S my_atomic_load ## S(int ## S volatile *a) \ -{ \ - int ## S ret; \ - make_atomic_load_body(S); \ - return ret; \ +#define make_atomic_load(S) \ +STATIC_INLINE int ## S my_atomic_load ## S(Uv_ ## S U_a) \ +{ \ + int ## S ret; \ + make_atomic_load_body(S); \ + return ret; \ } -#define make_atomic_store(S) \ -STATIC_INLINE void my_atomic_store ## S( \ - int ## S volatile *a, int ## S v) \ -{ \ - make_atomic_store_body(S); \ +#define make_atomic_store(S) \ +STATIC_INLINE void my_atomic_store ## S( \ + Uv_ ## S U_a, U_ ## S U_v) \ +{ \ + make_atomic_store_body(S); \ } #else /* no inline functions */ -#define make_atomic_add(S) \ -extern int ## S my_atomic_add ## S(int ## S volatile *a, int ## S v); +#define make_atomic_add(S) \ +extern int ## S my_atomic_add ## S(Uv_ ## S U_a, U_ ## S U_v); -#define make_atomic_swap(S) \ -extern int ## S my_atomic_swap ## S(int ## S volatile *a, int ## S v); +#define make_atomic_fas(S) \ +extern int ## S my_atomic_fas ## S(Uv_ ## S U_a, U_ ## S U_v); -#define make_atomic_cas(S) \ -extern int my_atomic_cas ## S(int ## S volatile *a, int ## S *cmp, int ## S set); +#define make_atomic_cas(S) \ +extern int my_atomic_cas ## S(Uv_ ## S U_a, Uv_ ## S U_cmp, U_ ## S U_set); -#define make_atomic_load(S) \ -extern int ## S my_atomic_load ## S(int ## S volatile *a); +#define make_atomic_load(S) \ +extern int ## S my_atomic_load ## S(Uv_ ## S U_a); -#define make_atomic_store(S) \ -extern void my_atomic_store ## S(int ## S volatile *a, int ## S v); +#define make_atomic_store(S) \ +extern void my_atomic_store ## S(Uv_ ## S U_a, U_ ## S U_v); #endif /* HAVE_INLINE */ -make_atomic_cas( 8) +#ifdef MY_ATOMIC_HAS_8_16 +make_atomic_cas(8) make_atomic_cas(16) +#endif make_atomic_cas(32) make_atomic_cas(ptr) -make_atomic_add( 8) +#ifdef MY_ATOMIC_HAS_8_16 +make_atomic_add(8) make_atomic_add(16) +#endif make_atomic_add(32) -make_atomic_load( 8) +#ifdef MY_ATOMIC_HAS_8_16 +make_atomic_load(8) make_atomic_load(16) +#endif make_atomic_load(32) make_atomic_load(ptr) -make_atomic_store( 8) +#ifdef MY_ATOMIC_HAS_8_16 +make_atomic_fas(8) +make_atomic_fas(16) +#endif +make_atomic_fas(32) +make_atomic_fas(ptr) + +#ifdef MY_ATOMIC_HAS_8_16 +make_atomic_store(8) make_atomic_store(16) +#endif make_atomic_store(32) make_atomic_store(ptr) -make_atomic_swap( 8) -make_atomic_swap(16) -make_atomic_swap(32) -make_atomic_swap(ptr) +#ifdef _atomic_h_cleanup_ +#include _atomic_h_cleanup_ +#undef _atomic_h_cleanup_ +#endif +#undef U_8 +#undef U_16 +#undef U_32 +#undef U_ptr +#undef Uv_8 +#undef Uv_16 +#undef Uv_32 +#undef Uv_ptr +#undef a +#undef cmp +#undef v +#undef set +#undef U_a +#undef U_cmp +#undef U_v +#undef U_set #undef make_atomic_add #undef make_atomic_cas #undef make_atomic_load #undef make_atomic_store -#undef make_atomic_swap +#undef make_atomic_fas #undef make_atomic_add_body #undef make_atomic_cas_body #undef make_atomic_load_body #undef make_atomic_store_body -#undef make_atomic_swap_body +#undef make_atomic_fas_body #undef intptr -#endif /* MY_ATOMICS_MADE */ - -#ifdef _atomic_h_cleanup_ -#include _atomic_h_cleanup_ -#undef _atomic_h_cleanup_ +/* + the macro below defines (as an expression) the code that + will be run in spin-loops. Intel manuals recummend to have PAUSE there. + It is expected to be defined in include/atomic/ *.h files +*/ +#ifndef LF_BACKOFF +#define LF_BACKOFF (1) #endif #define MY_ATOMIC_OK 0 @@ -150,3 +294,4 @@ extern int my_atomic_initialize(); #endif +#endif /* MY_ATOMIC_INCLUDED */ |