sync0arr.c

这是linux下运行的mysql软件包,可用于linux 下安装 php + mysql + apach 的网络配置

			rwlock->last_x_file_name,
			(ulong) rwlock->last_x_line);
	} else {
		ut_error;
	}

        if (!cell->waiting) {
		fputs("wait has ended\n", file);
	}

        if (cell->event_set) {
		fputs("wait is ending\n", file);
	}
}

#ifdef UNIV_SYNC_DEBUG
/**********************************************************************
Looks for a cell with the given thread id. */
static
sync_cell_t*
sync_array_find_thread(
/*===================*/
				/* out: pointer to cell or NULL
				if not found */
        sync_array_t*	arr,	/* in: wait array */
	os_thread_id_t	thread)	/* in: thread id */
{
        ulint           i;
        sync_cell_t*   	cell;

        for (i = 0; i < arr->n_cells; i++) {

		cell = sync_array_get_nth_cell(arr, i);        	

                if (cell->wait_object != NULL
		    && os_thread_eq(cell->thread, thread)) {

		    	return(cell);	/* Found */
                }
        }

	return(NULL);	/* Not found */
}

/**********************************************************************
Recursion step for deadlock detection. */
static
ibool
sync_array_deadlock_step(
/*=====================*/
				/* out: TRUE if deadlock detected */
        sync_array_t*	arr,	/* in: wait array; NOTE! the caller must
        			own the mutex to array */
	sync_cell_t*	start,	/* in: cell where recursive search
				started */
	os_thread_id_t	thread,	/* in: thread to look at */
	ulint		pass,	/* in: pass value */
	ulint		depth)	/* in: recursion depth */
{
	sync_cell_t*	new;
	ibool		ret;

	depth++;

	if (pass != 0) {
		/* If pass != 0, then we do not know which threads are
		responsible of releasing the lock, and no deadlock can
		be detected. */

		return(FALSE);
	}
			    	
	new = sync_array_find_thread(arr, thread);

	if (new == start) {
		/* Stop running of other threads */

		ut_dbg_stop_threads = TRUE;

		/* Deadlock */
		fputs("########################################\n"
			"DEADLOCK of threads detected!\n", stderr);

		return(TRUE);

	} else if (new) {
		ret = sync_array_detect_deadlock(arr, start, new, depth);

		if (ret) {
			return(TRUE);
		}
	}
	return(FALSE);
}

/**********************************************************************
This function is called only in the debug version. Detects a deadlock
of one or more threads because of waits of semaphores. */
static
ibool
sync_array_detect_deadlock(
/*=======================*/
				/* out: TRUE if deadlock detected */
        sync_array_t*	arr,	/* in: wait array; NOTE! the caller must
        			own the mutex to array */
	sync_cell_t*	start,	/* in: cell where recursive search started */
	sync_cell_t*	cell,	/* in: cell to search */
	ulint		depth)	/* in: recursion depth */
{
	mutex_t*	mutex;
	rw_lock_t*	lock;
	os_thread_id_t	thread;
	ibool		ret;
	rw_lock_debug_t*debug;
	
        ut_a(arr && start && cell);
	ut_ad(cell->wait_object);
	ut_ad(os_thread_get_curr_id() == start->thread);
	ut_ad(depth < 100);
	
	depth++;
	
	if (cell->event_set || !cell->waiting) {

		return(FALSE); /* No deadlock here */
	}
	
	if (cell->request_type == SYNC_MUTEX) {

		mutex = cell->wait_object;

		if (mutex_get_lock_word(mutex) != 0) {

			thread = mutex->thread_id;

			/* Note that mutex->thread_id above may be
			also OS_THREAD_ID_UNDEFINED, because the
			thread which held the mutex maybe has not
			yet updated the value, or it has already
			released the mutex: in this case no deadlock
			can occur, as the wait array cannot contain
			a thread with ID_UNDEFINED value. */

			ret = sync_array_deadlock_step(arr, start, thread, 0,
								depth);
			if (ret) {
				fprintf(stderr,
			"Mutex %p owned by thread %lu file %s line %lu\n",
					mutex, (ulong) os_thread_pf(mutex->thread_id),
					mutex->file_name, (ulong) mutex->line);
				sync_array_cell_print(stderr, cell);

				return(TRUE);
			}
		}

		return(FALSE); /* No deadlock */

	} else if (cell->request_type == RW_LOCK_EX) {

	    lock = cell->wait_object;

	    debug = UT_LIST_GET_FIRST(lock->debug_list);

	    while (debug != NULL) {

		thread = debug->thread_id;

		if (((debug->lock_type == RW_LOCK_EX)
	             && !os_thread_eq(thread, cell->thread))
	            || ((debug->lock_type == RW_LOCK_WAIT_EX)
			&& !os_thread_eq(thread, cell->thread))
	            || (debug->lock_type == RW_LOCK_SHARED)) {

			/* The (wait) x-lock request can block infinitely
			only if someone (can be also cell thread) is holding
			s-lock, or someone (cannot be cell thread) (wait)
			x-lock, and he is blocked by start thread */

			ret = sync_array_deadlock_step(arr, start, thread,
							debug->pass,
							depth);
			if (ret) {
			print:
				fprintf(stderr, "rw-lock %p ", lock);
				sync_array_cell_print(stderr, cell);
				rw_lock_debug_print(debug);
				return(TRUE);
			}
		}

		debug = UT_LIST_GET_NEXT(list, debug);
	    }

	    return(FALSE);

	} else if (cell->request_type == RW_LOCK_SHARED) {

	    lock = cell->wait_object;
	    debug = UT_LIST_GET_FIRST(lock->debug_list);

	    while (debug != NULL) {

		thread = debug->thread_id;

		if ((debug->lock_type == RW_LOCK_EX)
	            || (debug->lock_type == RW_LOCK_WAIT_EX)) {

			/* The s-lock request can block infinitely only if
			someone (can also be cell thread) is holding (wait)
			x-lock, and he is blocked by start thread */

			ret = sync_array_deadlock_step(arr, start, thread,
							debug->pass,
							depth);
			if (ret) {
				goto print;
			}
		}

		debug = UT_LIST_GET_NEXT(list, debug);
	    }

	    return(FALSE);

	} else {
		ut_error;
	}

	return(TRUE); 	/* Execution never reaches this line: for compiler
			fooling only */
}
#endif /* UNIV_SYNC_DEBUG */

/**********************************************************************
Determines if we can wake up the thread waiting for a sempahore. */
static
ibool
sync_arr_cell_can_wake_up(
/*======================*/
	sync_cell_t*	cell)	/* in: cell to search */
{
	mutex_t*	mutex;
	rw_lock_t*	lock;
	
	if (cell->request_type == SYNC_MUTEX) {

		mutex = cell->wait_object;

		if (mutex_get_lock_word(mutex) == 0) {

			return(TRUE);
		}

	} else if (cell->request_type == RW_LOCK_EX) {

	    	lock = cell->wait_object;

	    	if (rw_lock_get_reader_count(lock) == 0
		    && rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED) {

			return(TRUE);
		}

	    	if (rw_lock_get_reader_count(lock) == 0
		    && rw_lock_get_writer(lock) == RW_LOCK_WAIT_EX
		    && os_thread_eq(lock->writer_thread, cell->thread)) {

			return(TRUE);
		}

	} else if (cell->request_type == RW_LOCK_SHARED) {
	    	lock = cell->wait_object;

		if (rw_lock_get_writer(lock) == RW_LOCK_NOT_LOCKED) {
		
			return(TRUE);
		}
	}

	return(FALSE);
}

/**********************************************************************
Frees the cell. NOTE! sync_array_wait_event frees the cell
automatically! */

void
sync_array_free_cell(
/*=================*/
	sync_array_t*	arr,	/* in: wait array */
        ulint    	index)  /* in: index of the cell in array */
{
        sync_cell_t*   	cell;
        
        sync_array_enter(arr);

        cell = sync_array_get_nth_cell(arr, index);

        ut_a(cell->wait_object != NULL);

	cell->wait_object =  NULL;

	ut_a(arr->n_reserved > 0);
	arr->n_reserved--;

        sync_array_exit(arr);
}

/**************************************************************************
Looks for the cells in the wait array which refer to the wait object
specified, and sets their corresponding events to the signaled state. In this
way releases the threads waiting for the object to contend for the object.
It is possible that no such cell is found, in which case does nothing. */

void
sync_array_signal_object(
/*=====================*/
	sync_array_t*	arr,	/* in: wait array */
	void*		object)	/* in: wait object */
{
        sync_cell_t*   	cell;
        ulint           count;
        ulint           i;

        sync_array_enter(arr);

	arr->sg_count++;

	i = 0;
	count = 0;

        while (count < arr->n_reserved) {

        	cell = sync_array_get_nth_cell(arr, i);

                if (cell->wait_object != NULL) {

                        count++;
                        if (cell->wait_object == object) {

                        	sync_cell_event_set(cell);
                        }
                }

                i++;
        }

        sync_array_exit(arr);
}

/**************************************************************************
If the wakeup algorithm does not work perfectly at semaphore relases,
this function will do the waking (see the comment in mutex_exit). This
function should be called about every 1 second in the server. */

void
sync_arr_wake_threads_if_sema_free(void)
/*====================================*/
{
	sync_array_t*	arr 	= sync_primary_wait_array;
        sync_cell_t*   	cell;
        ulint           count;
        ulint           i;

        sync_array_enter(arr);

	i = 0;
	count = 0;

        while (count < arr->n_reserved) {

        	cell = sync_array_get_nth_cell(arr, i);

                if (cell->wait_object != NULL) {

                        count++;

                        if (sync_arr_cell_can_wake_up(cell)) {

                        	sync_cell_event_set(cell);
                        }
                }

                i++;
        }

        sync_array_exit(arr);
}

/**************************************************************************
Prints warnings of long semaphore waits to stderr. */

ibool
sync_array_print_long_waits(void)
/*=============================*/
			/* out: TRUE if fatal semaphore wait threshold
			was exceeded */
{
        sync_cell_t*   	cell;
        ibool		old_val;
	ibool		noticed = FALSE;
	ulint           i;
	ulint		fatal_timeout = srv_fatal_semaphore_wait_threshold;
	ibool		fatal = FALSE;

        for (i = 0; i < sync_primary_wait_array->n_cells; i++) {

        	cell = sync_array_get_nth_cell(sync_primary_wait_array, i);

                if (cell->wait_object != NULL
		    && difftime(time(NULL), cell->reservation_time) > 240) {
			fputs("InnoDB: Warning: a long semaphore wait:\n",
				stderr);
			sync_array_cell_print(stderr, cell);
			noticed = TRUE;
                }

                if (cell->wait_object != NULL
		    && difftime(time(NULL), cell->reservation_time)
		    > fatal_timeout) {
			fatal = TRUE;
                }
       	}

	if (noticed) {
		fprintf(stderr,
"InnoDB: ###### Starts InnoDB Monitor for 30 secs to print diagnostic info:\n");
        	old_val = srv_print_innodb_monitor;

		/* If some crucial semaphore is reserved, then also the InnoDB
		Monitor can hang, and we do not get diagnostics. Since in
		many cases an InnoDB hang is caused by a pwrite() or a pread()
		call hanging inside the operating system, let us print right
		now the values of pending calls of these. */

		fprintf(stderr,
"InnoDB: Pending preads %lu, pwrites %lu\n", (ulong)os_file_n_pending_preads,
				(ulong)os_file_n_pending_pwrites);

        	srv_print_innodb_monitor = TRUE;
		os_event_set(srv_lock_timeout_thread_event);

        	os_thread_sleep(30000000);

        	srv_print_innodb_monitor = old_val;
		fprintf(stderr,
"InnoDB: ###### Diagnostic info printed to the standard error stream\n");
	}

	return(fatal);
}

/**************************************************************************
Prints info of the wait array. */
static
void
sync_array_output_info(
/*===================*/
	FILE*		file,	/* in: file where to print */
	sync_array_t*	arr)	/* in: wait array; NOTE! caller must own the
				mutex */
{
        sync_cell_t*   	cell;
        ulint           count;
	ulint           i;

	fprintf(file,
		"OS WAIT ARRAY INFO: reservation count %ld, signal count %ld\n",
						(long) arr->res_count, (long) arr->sg_count);
	i = 0;
	count = 0;

        while (count < arr->n_reserved) {

        	cell = sync_array_get_nth_cell(arr, i);

                if (cell->wait_object != NULL) {
                        count++;
			sync_array_cell_print(file, cell);
                }

                i++;
       	}
}

/**************************************************************************
Prints info of the wait array. */

void
sync_array_print_info(
/*==================*/
	FILE*		file,	/* in: file where to print */
	sync_array_t*	arr)	/* in: wait array */
{
        sync_array_enter(arr);

	sync_array_output_info(file, arr);
        
        sync_array_exit(arr);
}