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Windows improvements : manual backport of

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htttp://lists.mysql.com/commits/50957?f=plain
      
Always use TLS functions instead of __declspec(thread) to access 
thread local storage variables.
The change removes the necessity to recomplile the same source
files twice -  with USE_TLS for DLLs and without USE_TLS for EXEs.
Real benefit of this change is better readability and maintainability
of TLS functions within MySQL.
              
There is a performance loss using TlsXXX functions compared to __declspec 
but the difference is negligible in practice. In a sysbench-like benchmark 
I ran with with TlsGetValue, pthread_[get|set]_specific was called 600000000 
times and took 0.17sec of total 35min CPU time, or 0.008%.
This commit is contained in:
Vladislav Vaintroub
2009-09-30 03:22:57 +02:00
parent 28a7d5042b
commit 2bc1930c6c
8 changed files with 15 additions and 87 deletions
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24
include/my_pthread.h
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@ -100,7 +100,6 @@ struct timespec {
}
void win_pthread_init(void);
int win_pthread_setspecific(void *A,void *B,uint length);
int win_pthread_mutex_trylock(pthread_mutex_t *mutex);
int pthread_create(pthread_t *,pthread_attr_t *,pthread_handler,void *);
int pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *attr);
@ -126,33 +125,16 @@ void pthread_exit(void *a); /* was #define pthread_exit(A) ExitThread(A)*/
#define _REENTRANT 1
#define HAVE_PTHREAD_ATTR_SETSTACKSIZE 1
/*
Windows has two ways to use thread local storage. The most efficient
is using __declspec(thread), but that does not work properly when
used in a .dll that is loaded at runtime, after program load. So for
libmysql.dll and libmysqld.dll we define USE_TLS in order to use the
TlsXxx() API instead, which works in all cases.
*/
#ifdef USE_TLS /* For LIBMYSQL.DLL */
#undef SAFE_MUTEX /* This will cause conflicts */
#define pthread_key(T,V) DWORD V
#define pthread_key_create(A,B) ((*A=TlsAlloc())==0xFFFFFFFF)
#define pthread_key_delete(A) TlsFree(A)
#define my_pthread_setspecific_ptr(T,V) (!TlsSetValue((T),(V)))
#define pthread_setspecific(A,B) (!TlsSetValue((A),(B)))
#define pthread_getspecific(A) (TlsGetValue(A))
#define my_pthread_getspecific(T,A) ((T) TlsGetValue(A))
#define my_pthread_getspecific_ptr(T,V) ((T) TlsGetValue(V))
#define my_pthread_setspecific_ptr(T,V) (!TlsSetValue((T),(V)))
#define pthread_setspecific(A,B) (!TlsSetValue((A),(B)))
#else
#define pthread_key(T,V) __declspec(thread) T V
#define pthread_key_create(A,B) pthread_dummy(0)
#define pthread_key_delete(A) pthread_dummy(0)
#define pthread_getspecific(A) (&(A))
#define my_pthread_getspecific(T,A) (&(A))
#define my_pthread_getspecific_ptr(T,V) (V)
#define my_pthread_setspecific_ptr(T,V) ((T)=(V),0)
#define pthread_setspecific(A,B) win_pthread_setspecific(&(A),(B),sizeof(A))
#endif /* USE_TLS */
#define pthread_equal(A,B) ((A) == (B))
#define pthread_mutex_init(A,B) (InitializeCriticalSection(A),0)