qresult.c

关系型数据库 Postgresql 6.5.2

/* Module:          qresult.c
 *
 * Description:     This module contains functions related to 
 *                  managing result information (i.e, fetching rows from the backend,
 *                  managing the tuple cache, etc.) and retrieving it.
 *                  Depending on the situation, a QResultClass will hold either data
 *                  from the backend or a manually built result (see "qresult.h" to
 *                  see which functions/macros are for manual or backend results.
 *                  For manually built results, the QResultClass simply points to 
 *                  TupleList and ColumnInfo structures, which actually hold the data.
 *
 * Classes:         QResultClass (Functions prefix: "QR_")
 *
 * API functions:   none
 *
 * Comments:        See "notice.txt" for copyright and license information.
 *
 */

#include "qresult.h"
#include "misc.h"
#include <stdio.h>
#include <string.h>

#ifndef TRUE
#define TRUE	(BOOL)1
#endif
#ifndef FALSE
#define FALSE	(BOOL)0
#endif

extern GLOBAL_VALUES globals;

/*  Used for building a Manual Result only */
/*	All info functions call this function to create the manual result set. */
void 
QR_set_num_fields(QResultClass *self, int new_num_fields)
{
	mylog("in QR_set_num_fields\n");

    CI_set_num_fields(self->fields, new_num_fields);
    if(self->manual_tuples) 
        TL_Destructor(self->manual_tuples);

    self->manual_tuples = TL_Constructor(new_num_fields);

	mylog("exit QR_set_num_fields\n");
}

void 
QR_set_position(QResultClass *self, int pos)
{
	self->tupleField = self->backend_tuples + ((self->base + pos) * self->num_fields);
}

void
QR_set_cache_size(QResultClass *self, int cache_size)
{
	self->cache_size = cache_size;
}

void 
QR_set_rowset_size(QResultClass *self, int rowset_size)
{
	self->rowset_size = rowset_size;
}

void
QR_inc_base(QResultClass *self, int base_inc)
{
	self->base += base_inc;
}

/************************************/
/* CLASS QResult                    */
/************************************/

QResultClass *
QR_Constructor(void)
{
QResultClass *rv;

	mylog("in QR_Constructor\n");
	rv = (QResultClass *) malloc(sizeof(QResultClass));

	if (rv != NULL) {
		rv->status = PGRES_EMPTY_QUERY;

		/* construct the column info */
		if ( ! (rv->fields = CI_Constructor())) {
			free(rv);
			return NULL;
		}
		rv->manual_tuples = NULL;	
		rv->backend_tuples = NULL;	
		rv->message = NULL;
		rv->command = NULL;
		rv->notice = NULL;
		rv->conn = NULL;
		rv->inTuples = FALSE;
		rv->fcount = 0;
		rv->fetch_count = 0;
		rv->base = 0;
		rv->currTuple = -1;
		rv->num_fields = 0;
		rv->tupleField = NULL;
		rv->cursor = NULL;

		rv->cache_size = globals.fetch_max;
		rv->rowset_size = 1;

	}

	mylog("exit QR_Constructor\n");
	return rv;
}

void
QR_Destructor(QResultClass *self)
{
	mylog("QResult: in DESTRUCTOR\n");

	/* manual result set tuples */
	if (self->manual_tuples)
		TL_Destructor(self->manual_tuples);

	//	If conn is defined, then we may have used "backend_tuples",
	//	so in case we need to, free it up.  Also, close the cursor.
	if (self->conn && self->conn->sock && CC_is_in_trans(self->conn))
		QR_close(self);			// close the cursor if there is one

	QR_free_memory(self);	// safe to call anyway

	//	Should have been freed in the close() but just in case...
	if (self->cursor)
		free(self->cursor);

	/*	Free up column info */
	if (self->fields)
		CI_Destructor(self->fields);

	/*	Free command info (this is from strdup()) */
	if (self->command)
		free(self->command);

	/*	Free notice info (this is from strdup()) */
	if (self->notice)
		free(self->notice);

	free(self);

	mylog("QResult: exit DESTRUCTOR\n");

}

void
QR_set_command(QResultClass *self, char *msg)
{
	if (self->command)
		free(self->command);

	self->command = msg ? strdup(msg) : NULL;
}

void 
QR_set_notice(QResultClass *self, char *msg)
{
	if (self->notice)
		free(self->notice);

	self->notice = msg ? strdup(msg) : NULL;
}

void 
QR_free_memory(QResultClass *self)
{
register int lf, row;
register TupleField *tuple = self->backend_tuples;
int fcount = self->fcount;
int num_fields = self->num_fields;

	mylog("QResult: free memory in, fcount=%d\n", fcount);

	if ( self->backend_tuples) {

		for (row = 0; row < fcount; row++) {
			mylog("row = %d, num_fields = %d\n", row, num_fields);
			for (lf=0; lf < num_fields; lf++) {
				if (tuple[lf].value != NULL) {
					mylog("free [lf=%d] %u\n", lf, tuple[lf].value);
					free(tuple[lf].value);
				}
			}
			tuple += num_fields;  // next row
		}

		free(self->backend_tuples);
		self->backend_tuples = NULL;
	}

	self->fcount = 0;

	mylog("QResult: free memory out\n");
}

//	This function is called by send_query()
char
QR_fetch_tuples(QResultClass *self, ConnectionClass *conn, char *cursor)
{
int tuple_size;

	//	If called from send_query the first time (conn != NULL), 
	//	then set the inTuples state,
	//	and read the tuples.  If conn is NULL,
	//	it implies that we are being called from next_tuple(),
	//	like to get more rows so don't call next_tuple again!
	if (conn != NULL) {
		self->conn = conn;

		mylog("QR_fetch_tuples: cursor = '%s', self->cursor=%u\n",  (cursor==NULL)?"":cursor, self->cursor);

		if (self->cursor)
			free(self->cursor);

		if ( globals.use_declarefetch) {
			if (! cursor || cursor[0] == '\0') {
				self->status = PGRES_INTERNAL_ERROR;
				QR_set_message(self, "Internal Error -- no cursor for fetch");
				return FALSE;
			}
			self->cursor = strdup(cursor);
		}
 
		//	Read the field attributes.
		//	$$$$ Should do some error control HERE! $$$$
		if ( CI_read_fields(self->fields, self->conn)) {
			self->status = PGRES_FIELDS_OK;
			self->num_fields = CI_get_num_fields(self->fields);
		}
		else {
			self->status = PGRES_BAD_RESPONSE;
			QR_set_message(self, "Error reading field information");
			return FALSE;
		}

		mylog("QR_fetch_tuples: past CI_read_fields: num_fields = %d\n", self->num_fields);

		if (globals.use_declarefetch) 
			tuple_size = self->cache_size;
		else
			tuple_size = TUPLE_MALLOC_INC;

		/* allocate memory for the tuple cache */
		mylog("MALLOC: tuple_size = %d, size = %d\n", tuple_size, self->num_fields * sizeof(TupleField) * tuple_size);
		self->backend_tuples = (TupleField *) malloc(self->num_fields * sizeof(TupleField) * tuple_size);
		if ( ! self->backend_tuples) {
			self->status = PGRES_FATAL_ERROR; 
			QR_set_message(self, "Could not get memory for tuple cache.");
			return FALSE;
		}

		self->inTuples = TRUE;


		/*  Force a read to occur in next_tuple */
		self->fcount = tuple_size+1;
		self->fetch_count = tuple_size+1;
		self->base = 0;

		return QR_next_tuple(self);
	}
	else {

		//	Always have to read the field attributes.
		//	But we dont have to reallocate memory for them!

		if ( ! CI_read_fields(NULL, self->conn)) {
			self->status = PGRES_BAD_RESPONSE;
			QR_set_message(self, "Error reading field information");
			return FALSE;
		}
		return TRUE;
	}
}

//	Close the cursor and end the transaction (if no cursors left)
//	We only close cursor/end the transaction if a cursor was used.
int
QR_close(QResultClass *self)
{
QResultClass *res;

	if (globals.use_declarefetch && self->conn && self->cursor) {
		char buf[64];

		sprintf(buf, "close %s", self->cursor);
		mylog("QResult: closing cursor: '%s'\n", buf);

		res = CC_send_query(self->conn, buf, NULL);

		self->inTuples = FALSE;
		self->currTuple = -1;

		free(self->cursor);
		self->cursor = NULL;

		if (res == NULL) {
			self->status = PGRES_FATAL_ERROR;
			QR_set_message(self, "Error closing cursor.");
			return FALSE;