MySQL数据库

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os0thread.c：源码内容
							/******************************************************
The interface to the operating system thread control primitives
(c) 1995 Innobase Oy
Created 9/8/1995 Heikki Tuuri
*******************************************************/
#include "os0thread.h"
#ifdef UNIV_NONINL
#include "os0thread.ic"
#endif
#ifdef __WIN__
#include <windows.h>
#endif
#include "srv0srv.h"
#include "os0sync.h"
/*******************************************************************
Compares two thread ids for equality. */
ibool
os_thread_eq(
/*=========*/
				/* out: TRUE if equal */
	os_thread_id_t	a,	/* in: OS thread or thread id */
	os_thread_id_t	b)	/* in: OS thread or thread id */
{
#ifdef __WIN__
	if (a == b) {
		return(TRUE);
	}
	return(FALSE);
#else
	if (pthread_equal(a, b)) {
		return(TRUE);
	}
	return(FALSE);
#endif
}
/********************************************************************
Converts an OS thread id to a ulint. It is NOT guaranteed that the ulint is
unique for the thread though! */
ulint
os_thread_pf(
/*=========*/
	os_thread_id_t	a)
{
#ifdef UNIV_HPUX10
        /* In HP-UX-10.20 a pthread_t is a struct of 3 fields: field1, field2,
        field3. We do not know if field1 determines the thread uniquely. */
	return((ulint)(a.field1));
#else
	return((ulint)a);
#endif
}
/*********************************************************************
Returns the thread identifier of current thread. Currently the thread
identifier in Unix is the thread handle itself. Note that in HP-UX
pthread_t is a struct of 3 fields. */
os_thread_id_t
os_thread_get_curr_id(void)
/*=======================*/
{
#ifdef __WIN__
	return(GetCurrentThreadId());
#else
	return(pthread_self());
#endif
}
/********************************************************************
Creates a new thread of execution. The execution starts from
the function given. The start function takes a void* parameter
and returns an ulint. */
os_thread_t
os_thread_create(
/*=============*/
						/* out: handle to the thread */
#ifndef __WIN__
		 os_posix_f_t            start_f,
#else
	ulint (*start_f)(void*),		/* in: pointer to function
						from which to start */
#endif
	void*			arg,		/* in: argument to start
						function */
	os_thread_id_t*		thread_id)	/* out: id of the created
						thread */
{
#ifdef __WIN__
	os_thread_t	thread;
	DWORD		win_thread_id;
	os_mutex_enter(os_sync_mutex);
	os_thread_count++;
	os_mutex_exit(os_sync_mutex);
	thread = CreateThread(NULL,	/* no security attributes */
				0,	/* default size stack */
				(LPTHREAD_START_ROUTINE)start_f,
				arg,
				0,	/* thread runs immediately */
				&win_thread_id);
	if (srv_set_thread_priorities) {
	        /* Set created thread priority the same as a normal query
	        in MYSQL: we try to prevent starvation of threads by
	        assigning same priority QUERY_PRIOR to all */
	        ut_a(SetThreadPriority(thread, srv_query_thread_priority));
	}
	*thread_id = win_thread_id;
	return(thread);
#else
	int		ret;
	os_thread_t	pthread;
	pthread_attr_t  attr;
#if !(defined(UNIV_HOTBACKUP) && defined(UNIV_HPUX10))
        pthread_attr_init(&attr);
#endif
        
#ifdef UNIV_AIX
	/* We must make sure a thread stack is at least 32 kB, otherwise
	InnoDB might crash; we do not know if the default stack size on
	AIX is always big enough. An empirical test on AIX-4.3 suggested
	the size was 96 kB, though. */
	ret = pthread_attr_setstacksize(&attr,
			      (size_t)(PTHREAD_STACK_MIN + 32 * 1024));
        if (ret) {
	         fprintf(stderr,
          "InnoDB: Error: pthread_attr_setstacksize returned %dn", ret);
		 exit(1);
	}
#endif
	os_mutex_enter(os_sync_mutex);
	os_thread_count++;
	os_mutex_exit(os_sync_mutex);
#if defined(UNIV_HOTBACKUP) && defined(UNIV_HPUX10)
	ret = pthread_create(&pthread, pthread_attr_default, start_f, arg);
#else
	ret = pthread_create(&pthread, &attr, start_f, arg);
#endif
        if (ret) {
	         fprintf(stderr,
          "InnoDB: Error: pthread_create returned %dn", ret);
		 exit(1);
	}
#if !(defined(UNIV_HOTBACKUP) && defined(UNIV_HPUX10))
	pthread_attr_destroy(&attr);
#endif
	if (srv_set_thread_priorities) {
	
	        my_pthread_setprio(pthread, srv_query_thread_priority);
	}
	*thread_id = pthread;
	return(pthread);
#endif
}
/*********************************************************************
Exits the current thread. */
void
os_thread_exit(
/*===========*/
	void*	exit_value)	/* in: exit value; in Windows this void*
				is cast as a DWORD */
{
#ifdef UNIV_DEBUG_THREAD_CREATION
	fprintf(stderr, "Thread exits, id %lun",
			      os_thread_pf(os_thread_get_curr_id()));
#endif
	os_mutex_enter(os_sync_mutex);
	os_thread_count--;
	os_mutex_exit(os_sync_mutex);
#ifdef __WIN__
        ExitThread((DWORD)exit_value);
#else
	pthread_exit(exit_value);
#endif
}
#ifdef HAVE_PTHREAD_JOIN
int
os_thread_join(
/*=============*/
  os_thread_id_t  thread_id)	/* in: id of the thread to join */
{
  return pthread_join(thread_id, NULL);
}
#endif
/*********************************************************************
Returns handle to the current thread. */
os_thread_t
os_thread_get_curr(void)
/*====================*/
{
#ifdef __WIN__
	return(GetCurrentThread());
#else
	return(pthread_self());
#endif
}
	
/*********************************************************************
Advises the os to give up remainder of the thread's time slice. */
void
os_thread_yield(void)
/*=================*/
{
#if defined(__WIN__)
	Sleep(0);
#elif (defined(HAVE_SCHED_YIELD) && defined(HAVE_SCHED_H))
        sched_yield();
#elif defined(HAVE_PTHREAD_YIELD_ZERO_ARG)
	pthread_yield();
#elif defined(HAVE_PTHREAD_YIELD_ONE_ARG)
	pthread_yield(0);
#else
        os_thread_sleep(0);
#endif
}
/*********************************************************************
The thread sleeps at least the time given in microseconds. */
void
os_thread_sleep(
/*============*/
	ulint	tm)	/* in: time in microseconds */
{
#ifdef __WIN__
	Sleep((DWORD) tm / 1000);
#elif defined(__NETWARE__)
	delay(tm / 1000);
#else
	struct timeval	t;
	t.tv_sec = tm / 1000000;
	t.tv_usec = tm % 1000000;
	
	select(0, NULL, NULL, NULL, &t);
#endif
}
/**********************************************************************
Sets a thread priority. */
void
os_thread_set_priority(
/*===================*/
	os_thread_t	handle,	/* in: OS handle to the thread */
	ulint		pri)	/* in: priority */
{
#ifdef __WIN__
	int	os_pri;
	if (pri == OS_THREAD_PRIORITY_BACKGROUND) {
		os_pri = THREAD_PRIORITY_BELOW_NORMAL;
	} else if (pri == OS_THREAD_PRIORITY_NORMAL) {
		os_pri = THREAD_PRIORITY_NORMAL;
	} else if (pri == OS_THREAD_PRIORITY_ABOVE_NORMAL) {
		os_pri = THREAD_PRIORITY_HIGHEST;
	} else {
		ut_error;
	}
	ut_a(SetThreadPriority(handle, os_pri));
#else
	UT_NOT_USED(handle);
	UT_NOT_USED(pri);
#endif
}
/**********************************************************************
Gets a thread priority. */
ulint
os_thread_get_priority(
/*===================*/
				/* out: priority */
	os_thread_t	handle __attribute__((unused)))	
                                /* in: OS handle to the thread */
{
#ifdef __WIN__
	int	os_pri;
	ulint	pri;
	os_pri = GetThreadPriority(handle);
	if (os_pri == THREAD_PRIORITY_BELOW_NORMAL) {
		pri = OS_THREAD_PRIORITY_BACKGROUND;
	} else if (os_pri == THREAD_PRIORITY_NORMAL) {
		pri = OS_THREAD_PRIORITY_NORMAL;
	} else if (os_pri == THREAD_PRIORITY_HIGHEST) {
		pri = OS_THREAD_PRIORITY_ABOVE_NORMAL;
	} else {
		ut_error;
	}
	return(pri);
#else
	return(0);
#endif
}
/**********************************************************************
Gets the last operating system error code for the calling thread. */
ulint
os_thread_get_last_error(void)
/*==========================*/
{
#ifdef __WIN__
	return(GetLastError());
#else
	return(0);
#endif
}

						