que0que.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

/******************************************************
Query graph

(c) 1996 Innobase Oy

Created 5/27/1996 Heikki Tuuri
*******************************************************/

#include "que0que.h"
 
#ifdef UNIV_NONINL
#include "que0que.ic"
#endif

#include "srv0que.h"
#include "usr0sess.h"
#include "trx0trx.h"
#include "trx0roll.h"
#include "row0undo.h"
#include "row0ins.h"
#include "row0upd.h"
#include "row0sel.h"
#include "row0purge.h"
#include "dict0crea.h"
#include "log0log.h"
#include "eval0proc.h"
#include "eval0eval.h"

#define QUE_PARALLELIZE_LIMIT	(64 * 256 * 256 * 256)
#define QUE_ROUND_ROBIN_LIMIT	(64 * 256 * 256 * 256)
#define QUE_MAX_LOOPS_WITHOUT_CHECK	16

/* If the following flag is set TRUE, the module will print trace info
of SQL execution in the UNIV_SQL_DEBUG version */
ibool	que_trace_on		= FALSE;

ibool	que_always_false	= FALSE;

/* How a stored procedure containing COMMIT or ROLLBACK commands
is executed?

The commit or rollback can be seen as a subprocedure call.
The problem is that if there are several query threads
currently running within the transaction, their action could
mess the commit or rollback operation. Or, at the least, the
operation would be difficult to visualize and keep in control.

Therefore the query thread requesting a commit or a rollback
sends to the transaction a signal, which moves the transaction
to TRX_QUE_SIGNALED state. All running query threads of the
transaction will eventually notice that the transaction is now in
this state and voluntarily suspend themselves. Only the last
query thread which suspends itself will trigger handling of
the signal.

When the transaction starts to handle a rollback or commit
signal, it builds a query graph which, when executed, will
roll back or commit the incomplete transaction. The transaction
is moved to the TRX_QUE_ROLLING_BACK or TRX_QUE_COMMITTING state.
If specified, the SQL cursors opened by the transaction are closed.
When the execution of the graph completes, it is like returning
from a subprocedure: the query thread which requested the operation
starts running again. */

/**************************************************************************
Moves a thread from another state to the QUE_THR_RUNNING state. Increments
the n_active_thrs counters of the query graph and transaction.
***NOTE***: This is the only function in which such a transition is allowed
to happen! */
static
void
que_thr_move_to_run_state(
/*======================*/
	que_thr_t*	thr);	/* in: an query thread */

/***************************************************************************
Adds a query graph to the session's list of graphs. */

void
que_graph_publish(
/*==============*/
	que_t*	graph,	/* in: graph */
	sess_t*	sess)	/* in: session */
{
#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&kernel_mutex));
#endif /* UNIV_SYNC_DEBUG */

	UT_LIST_ADD_LAST(graphs, sess->graphs, graph);
}

/***************************************************************************
Creates a query graph fork node. */

que_fork_t*
que_fork_create(
/*============*/
					/* out, own: fork node */
	que_t*		graph,		/* in: graph, if NULL then this
					fork node is assumed to be the
					graph root */
	que_node_t*	parent,		/* in: parent node */
	ulint		fork_type,	/* in: fork type */
	mem_heap_t*	heap)		/* in: memory heap where created */
{
	que_fork_t*	fork;

	ut_ad(heap);
	
	fork = mem_heap_alloc(heap, sizeof(que_fork_t));

	fork->common.type = QUE_NODE_FORK;
	fork->n_active_thrs = 0;

	fork->state = QUE_FORK_COMMAND_WAIT;

	if (graph != NULL) {
		fork->graph = graph;
	} else {
		fork->graph = fork;
	}
	
	fork->common.parent = parent;
	fork->fork_type = fork_type;

	fork->caller = NULL;

	UT_LIST_INIT(fork->thrs);

	fork->sym_tab = NULL;
	
	fork->heap = heap;
	
	return(fork);
}

/***************************************************************************
Creates a query graph thread node. */

que_thr_t*
que_thr_create(
/*===========*/
				/* out, own: query thread node */
	que_fork_t*	parent,	/* in: parent node, i.e., a fork node */
	mem_heap_t*	heap)	/* in: memory heap where created */
{
	que_thr_t*	thr;
	
	ut_ad(parent && heap);
	
	thr = mem_heap_alloc(heap, sizeof(que_thr_t));

	thr->common.type = QUE_NODE_THR;
	thr->common.parent = parent;

	thr->magic_n = QUE_THR_MAGIC_N;

	thr->graph = parent->graph;

	thr->state = QUE_THR_COMMAND_WAIT;

	thr->is_active = FALSE;	

	thr->run_node = NULL;
	thr->resource = 0;
  thr->lock_state = QUE_THR_LOCK_NOLOCK;

	UT_LIST_ADD_LAST(thrs, parent->thrs, thr);

	return(thr);
}

/**************************************************************************
Moves a suspended query thread to the QUE_THR_RUNNING state and may release
a single worker thread to execute it. This function should be used to end
the wait state of a query thread waiting for a lock or a stored procedure
completion. */

void
que_thr_end_wait(
/*=============*/
	que_thr_t*	thr,		/* in: query thread in the
					QUE_THR_LOCK_WAIT,
					or QUE_THR_PROCEDURE_WAIT, or
					QUE_THR_SIG_REPLY_WAIT state */
	que_thr_t**	next_thr)	/* in/out: next query thread to run;
					if the value which is passed in is
					a pointer to a NULL pointer, then the
					calling function can start running
					a new query thread; if NULL is passed
					as the parameter, it is ignored */
{
	ibool	was_active;

#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&kernel_mutex));
#endif /* UNIV_SYNC_DEBUG */
	ut_ad(thr);
	ut_ad((thr->state == QUE_THR_LOCK_WAIT)
	      || (thr->state == QUE_THR_PROCEDURE_WAIT)
	      || (thr->state == QUE_THR_SIG_REPLY_WAIT));
	ut_ad(thr->run_node);

	thr->prev_node = thr->run_node;

	was_active = thr->is_active;
	
	que_thr_move_to_run_state(thr);

	if (was_active) {

		return;
	}	

	if (next_thr && *next_thr == NULL) {
		*next_thr = thr;
	} else {
		ut_a(0);
		srv_que_task_enqueue_low(thr);
	}
}	

/**************************************************************************
Same as que_thr_end_wait, but no parameter next_thr available. */

void
que_thr_end_wait_no_next_thr(
/*=========================*/
	que_thr_t*	thr)	/* in: query thread in the QUE_THR_LOCK_WAIT,
				or QUE_THR_PROCEDURE_WAIT, or
				QUE_THR_SIG_REPLY_WAIT state */
{
	ibool	was_active;

	ut_a(thr->state == QUE_THR_LOCK_WAIT);	/* In MySQL this is the
						only possible state here */
#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&kernel_mutex));
#endif /* UNIV_SYNC_DEBUG */
	ut_ad(thr);
	ut_ad((thr->state == QUE_THR_LOCK_WAIT)
	      || (thr->state == QUE_THR_PROCEDURE_WAIT)
	      || (thr->state == QUE_THR_SIG_REPLY_WAIT));

	was_active = thr->is_active;
	
	que_thr_move_to_run_state(thr);

	if (was_active) {

		return;
	}

	/* In MySQL we let the OS thread (not just the query thread) to wait
	for the lock to be released: */
	
	srv_release_mysql_thread_if_suspended(thr);

	/* srv_que_task_enqueue_low(thr); */
}

/**************************************************************************
Inits a query thread for a command. */
UNIV_INLINE
void
que_thr_init_command(
/*=================*/
	que_thr_t*	thr)	/* in: query thread */
{
	thr->run_node = thr;
	thr->prev_node = thr->common.parent;

	que_thr_move_to_run_state(thr);
}

/**************************************************************************
Starts execution of a command in a query fork. Picks a query thread which
is not in the QUE_THR_RUNNING state and moves it to that state. If none
can be chosen, a situation which may arise in parallelized fetches, NULL
is returned. */

que_thr_t*
que_fork_start_command(
/*===================*/
				/* out: a query thread of the graph moved to
				QUE_THR_RUNNING state, or NULL; the query
				thread should be executed by que_run_threads
				by the caller */
	que_fork_t* 	fork)	/* in: a query fork */
{
	que_thr_t*	thr;

	fork->state = QUE_FORK_ACTIVE;
	
	fork->last_sel_node = NULL;

	/* Choose the query thread to run: usually there is just one thread,
	but in a parallelized select, which necessarily is non-scrollable,
	there may be several to choose from */

	/*---------------------------------------------------------------
	First we try to find a query thread in the QUE_THR_COMMAND_WAIT state */
	
	thr = UT_LIST_GET_FIRST(fork->thrs);

	while (thr != NULL) {
		if (thr->state == QUE_THR_COMMAND_WAIT) {

			/* We have to send the initial message to query thread
			to start it */

			que_thr_init_command(thr);

			return(thr);
		}

		ut_ad(thr->state != QUE_THR_LOCK_WAIT);
		
		thr = UT_LIST_GET_NEXT(thrs, thr);
	}

	/*----------------------------------------------------------------
	Then we try to find a query thread in the QUE_THR_SUSPENDED state */

	thr = UT_LIST_GET_FIRST(fork->thrs);

	while (thr != NULL) {
		if (thr->state == QUE_THR_SUSPENDED) {
			/* In this case the execution of the thread was
			suspended: no initial message is needed because
			execution can continue from where it was left */

			que_thr_move_to_run_state(thr);

			return(thr);
		}

		thr = UT_LIST_GET_NEXT(thrs, thr);
	}

	/*-----------------------------------------------------------------
	Then we try to find a query thread in the QUE_THR_COMPLETED state */
	
	thr = UT_LIST_GET_FIRST(fork->thrs);

	while (thr != NULL) {
		if (thr->state == QUE_THR_COMPLETED) {
			que_thr_init_command(thr);

			return(thr);
		}

		thr = UT_LIST_GET_NEXT(thrs, thr);
	}

	/* Else we return NULL */
	return(NULL);
}

/**************************************************************************
After signal handling is finished, returns control to a query graph error
handling routine. (Currently, just returns the control to the root of the
graph so that the graph can communicate an error message to the client.) */

void
que_fork_error_handle(
/*==================*/
	trx_t*	trx __attribute__((unused)),	/* in: trx */
	que_t*	fork)	/* in: query graph which was run before signal
			handling started, NULL not allowed */
{
	que_thr_t*	thr;

#ifdef UNIV_SYNC_DEBUG
	ut_ad(mutex_own(&kernel_mutex));
#endif /* UNIV_SYNC_DEBUG */
	ut_ad(trx->sess->state == SESS_ERROR);
	ut_ad(UT_LIST_GET_LEN(trx->reply_signals) == 0);
	ut_ad(UT_LIST_GET_LEN(trx->wait_thrs) == 0);

	thr = UT_LIST_GET_FIRST(fork->thrs);

	while (thr != NULL) {
		ut_ad(!thr->is_active);
		ut_ad(thr->state != QUE_THR_SIG_REPLY_WAIT);
		ut_ad(thr->state != QUE_THR_LOCK_WAIT);
		
		thr->run_node = thr;
		thr->prev_node = thr->child;
		thr->state = QUE_THR_COMPLETED;
		
		thr = UT_LIST_GET_NEXT(thrs, thr);
	}

	thr = UT_LIST_GET_FIRST(fork->thrs);
	
	que_thr_move_to_run_state(thr);

	ut_a(0);
	srv_que_task_enqueue_low(thr);
}

/********************************************************************
Tests if all the query threads in the same fork have a given state. */
UNIV_INLINE
ibool
que_fork_all_thrs_in_state(
/*=======================*/
				/* out: TRUE if all the query threads in the
				same fork were in the given state */
	que_fork_t*	fork,	/* in: query fork */
	ulint		state)	/* in: state */
{
	que_thr_t*	thr_node;

	thr_node = UT_LIST_GET_FIRST(fork->thrs);

	while (thr_node != NULL) {
		if (thr_node->state != state) {

			return(FALSE);
		}

		thr_node = UT_LIST_GET_NEXT(thrs, thr_node);
	}