spi.c

PostgreSQL7.4.6 for Linux

/*-------------------------------------------------------------------------
 *
 * spi.c
 *				Server Programming Interface
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *
 * IDENTIFICATION
 *	  $Header: /cvsroot/pgsql/src/backend/executor/spi.c,v 1.107 2003/10/01 21:30:52 tgl Exp $
 *
 *-------------------------------------------------------------------------
 */
#include "postgres.h"

#include "access/printtup.h"
#include "catalog/heap.h"
#include "executor/spi_priv.h"
#include "tcop/tcopprot.h"
#include "utils/lsyscache.h"


uint32		SPI_processed = 0;
Oid			SPI_lastoid = InvalidOid;
SPITupleTable *SPI_tuptable = NULL;
int			SPI_result;

static _SPI_connection *_SPI_stack = NULL;
static _SPI_connection *_SPI_current = NULL;
static int	_SPI_connected = -1;
static int	_SPI_curid = -1;

static int	_SPI_execute(const char *src, int tcount, _SPI_plan *plan);
static int	_SPI_pquery(QueryDesc *queryDesc, bool runit,
						bool useCurrentSnapshot, int tcount);

static int _SPI_execute_plan(_SPI_plan *plan,
							 Datum *Values, const char *Nulls,
							 bool useCurrentSnapshot, int tcount);

static void _SPI_cursor_operation(Portal portal, bool forward, int count,
					  DestReceiver *dest);

static _SPI_plan *_SPI_copy_plan(_SPI_plan *plan, int location);

static int	_SPI_begin_call(bool execmem);
static int	_SPI_end_call(bool procmem);
static MemoryContext _SPI_execmem(void);
static MemoryContext _SPI_procmem(void);
static bool _SPI_checktuples(void);


/* =================== interface functions =================== */

int
SPI_connect(void)
{
	_SPI_connection *new_SPI_stack;

	/*
	 * When procedure called by Executor _SPI_curid expected to be equal
	 * to _SPI_connected
	 */
	if (_SPI_curid != _SPI_connected)
		return SPI_ERROR_CONNECT;

	if (_SPI_stack == NULL)
	{
		if (_SPI_connected != -1)
			elog(ERROR, "SPI stack corrupted");
		new_SPI_stack = (_SPI_connection *) malloc(sizeof(_SPI_connection));
	}
	else
	{
		if (_SPI_connected < 0)
			elog(ERROR, "SPI stack corrupted");
		new_SPI_stack = (_SPI_connection *) realloc(_SPI_stack,
						 (_SPI_connected + 2) * sizeof(_SPI_connection));
	}

	if (new_SPI_stack == NULL)
		ereport(ERROR,
				(errcode(ERRCODE_OUT_OF_MEMORY),
				 errmsg("out of memory")));

	/*
	 * We' returning to procedure where _SPI_curid == _SPI_connected - 1
	 */
	_SPI_stack = new_SPI_stack;
	_SPI_connected++;

	_SPI_current = &(_SPI_stack[_SPI_connected]);
	_SPI_current->processed = 0;
	_SPI_current->tuptable = NULL;

	/*
	 * Create memory contexts for this procedure
	 *
	 * XXX it would be better to use PortalContext as the parent context, but
	 * we may not be inside a portal (consider deferred-trigger
	 * execution).
	 */
	_SPI_current->procCxt = AllocSetContextCreate(TopTransactionContext,
												  "SPI Proc",
												ALLOCSET_DEFAULT_MINSIZE,
											   ALLOCSET_DEFAULT_INITSIZE,
											   ALLOCSET_DEFAULT_MAXSIZE);
	_SPI_current->execCxt = AllocSetContextCreate(TopTransactionContext,
												  "SPI Exec",
												ALLOCSET_DEFAULT_MINSIZE,
											   ALLOCSET_DEFAULT_INITSIZE,
											   ALLOCSET_DEFAULT_MAXSIZE);
	/* ... and switch to procedure's context */
	_SPI_current->savedcxt = MemoryContextSwitchTo(_SPI_current->procCxt);

	return SPI_OK_CONNECT;
}

int
SPI_finish(void)
{
	int			res;

	res = _SPI_begin_call(false);		/* live in procedure memory */
	if (res < 0)
		return res;

	/* Restore memory context as it was before procedure call */
	MemoryContextSwitchTo(_SPI_current->savedcxt);

	/* Release memory used in procedure call */
	MemoryContextDelete(_SPI_current->execCxt);
	MemoryContextDelete(_SPI_current->procCxt);

	/*
	 * Reset result variables, especially SPI_tuptable which is probably
	 * pointing at a just-deleted tuptable
	 */
	SPI_processed = 0;
	SPI_lastoid = InvalidOid;
	SPI_tuptable = NULL;

	/*
	 * After _SPI_begin_call _SPI_connected == _SPI_curid. Now we are
	 * closing connection to SPI and returning to upper Executor and so
	 * _SPI_connected must be equal to _SPI_curid.
	 */
	_SPI_connected--;
	_SPI_curid--;
	if (_SPI_connected == -1)
	{
		free(_SPI_stack);
		_SPI_stack = NULL;
		_SPI_current = NULL;
	}
	else
	{
		_SPI_connection *new_SPI_stack;

		new_SPI_stack = (_SPI_connection *) realloc(_SPI_stack,
						 (_SPI_connected + 1) * sizeof(_SPI_connection));
		/* This could only fail with a pretty stupid malloc package ... */
		if (new_SPI_stack == NULL)
			ereport(ERROR,
					(errcode(ERRCODE_OUT_OF_MEMORY),
					 errmsg("out of memory")));
		_SPI_stack = new_SPI_stack;
		_SPI_current = &(_SPI_stack[_SPI_connected]);
	}

	return SPI_OK_FINISH;

}

/*
 * Clean up SPI state at transaction commit or abort (we don't care which).
 */
void
AtEOXact_SPI(void)
{
	/*
	 * Note that memory contexts belonging to SPI stack entries will be
	 * freed automatically, so we can ignore them here.  We just need to
	 * restore our static variables to initial state.
	 */
	if (_SPI_stack != NULL)		/* there was abort */
		free(_SPI_stack);
	_SPI_current = _SPI_stack = NULL;
	_SPI_connected = _SPI_curid = -1;
	SPI_processed = 0;
	SPI_lastoid = InvalidOid;
	SPI_tuptable = NULL;
}

void
SPI_push(void)
{
	_SPI_curid++;
}

void
SPI_pop(void)
{
	_SPI_curid--;
}

int
SPI_exec(const char *src, int tcount)
{
	int			res;

	if (src == NULL || tcount < 0)
		return SPI_ERROR_ARGUMENT;

	res = _SPI_begin_call(true);
	if (res < 0)
		return res;

	res = _SPI_execute(src, tcount, NULL);

	_SPI_end_call(true);
	return res;
}

int
SPI_execp(void *plan, Datum *Values, const char *Nulls, int tcount)
{
	int			res;

	if (plan == NULL || tcount < 0)
		return SPI_ERROR_ARGUMENT;

	if (((_SPI_plan *) plan)->nargs > 0 && Values == NULL)
		return SPI_ERROR_PARAM;

	res = _SPI_begin_call(true);
	if (res < 0)
		return res;

	res = _SPI_execute_plan((_SPI_plan *) plan, Values, Nulls, false, tcount);

	_SPI_end_call(true);
	return res;
}

/*
 * SPI_execp_current -- identical to SPI_execp, except that we expose the
 * Executor option to use a current snapshot instead of the normal
 * QuerySnapshot.  This is currently not documented in spi.sgml because
 * it is only intended for use by RI triggers.
 */
int
SPI_execp_current(void *plan, Datum *Values, const char *Nulls,
				  bool useCurrentSnapshot, int tcount)
{
	int			res;

	if (plan == NULL || tcount < 0)
		return SPI_ERROR_ARGUMENT;

	if (((_SPI_plan *) plan)->nargs > 0 && Values == NULL)
		return SPI_ERROR_PARAM;

	res = _SPI_begin_call(true);
	if (res < 0)
		return res;

	res = _SPI_execute_plan((_SPI_plan *) plan, Values, Nulls,
							useCurrentSnapshot, tcount);

	_SPI_end_call(true);
	return res;
}

void *
SPI_prepare(const char *src, int nargs, Oid *argtypes)
{
	_SPI_plan  *plan;

	if (src == NULL || nargs < 0 || (nargs > 0 && argtypes == NULL))
	{
		SPI_result = SPI_ERROR_ARGUMENT;
		return NULL;
	}

	SPI_result = _SPI_begin_call(true);
	if (SPI_result < 0)
		return NULL;

	plan = (_SPI_plan *) palloc(sizeof(_SPI_plan));		/* Executor context */
	plan->argtypes = argtypes;
	plan->nargs = nargs;

	SPI_result = _SPI_execute(src, 0, plan);

	if (SPI_result >= 0)		/* copy plan to procedure context */
		plan = _SPI_copy_plan(plan, _SPI_CPLAN_PROCXT);
	else
		plan = NULL;

	_SPI_end_call(true);

	return (void *) plan;
}

void *
SPI_saveplan(void *plan)
{
	_SPI_plan  *newplan;

	if (plan == NULL)
	{
		SPI_result = SPI_ERROR_ARGUMENT;
		return NULL;
	}

	SPI_result = _SPI_begin_call(false);		/* don't change context */
	if (SPI_result < 0)
		return NULL;

	newplan = _SPI_copy_plan((_SPI_plan *) plan, _SPI_CPLAN_TOPCXT);

	_SPI_curid--;
	SPI_result = 0;

	return (void *) newplan;

}

int
SPI_freeplan(void *plan)
{
	_SPI_plan  *spiplan = (_SPI_plan *) plan;

	if (plan == NULL)
		return SPI_ERROR_ARGUMENT;

	MemoryContextDelete(spiplan->plancxt);
	return 0;
}

HeapTuple
SPI_copytuple(HeapTuple tuple)
{
	MemoryContext oldcxt = NULL;
	HeapTuple	ctuple;

	if (tuple == NULL)
	{
		SPI_result = SPI_ERROR_ARGUMENT;
		return NULL;
	}

	if (_SPI_curid + 1 == _SPI_connected)		/* connected */
	{
		if (_SPI_current != &(_SPI_stack[_SPI_curid + 1]))
			elog(ERROR, "SPI stack corrupted");
		oldcxt = MemoryContextSwitchTo(_SPI_current->savedcxt);
	}

	ctuple = heap_copytuple(tuple);

	if (oldcxt)
		MemoryContextSwitchTo(oldcxt);

	return ctuple;
}

TupleDesc
SPI_copytupledesc(TupleDesc tupdesc)
{
	MemoryContext oldcxt = NULL;
	TupleDesc	ctupdesc;

	if (tupdesc == NULL)
	{
		SPI_result = SPI_ERROR_ARGUMENT;
		return NULL;
	}

	if (_SPI_curid + 1 == _SPI_connected)		/* connected */
	{
		if (_SPI_current != &(_SPI_stack[_SPI_curid + 1]))
			elog(ERROR, "SPI stack corrupted");
		oldcxt = MemoryContextSwitchTo(_SPI_current->savedcxt);
	}

	ctupdesc = CreateTupleDescCopy(tupdesc);

	if (oldcxt)
		MemoryContextSwitchTo(oldcxt);

	return ctupdesc;
}

TupleTableSlot *
SPI_copytupleintoslot(HeapTuple tuple, TupleDesc tupdesc)
{
	MemoryContext oldcxt = NULL;
	TupleTableSlot *cslot;
	HeapTuple	ctuple;
	TupleDesc	ctupdesc;

	if (tuple == NULL || tupdesc == NULL)
	{
		SPI_result = SPI_ERROR_ARGUMENT;
		return NULL;
	}

	if (_SPI_curid + 1 == _SPI_connected)		/* connected */
	{
		if (_SPI_current != &(_SPI_stack[_SPI_curid + 1]))
			elog(ERROR, "SPI stack corrupted");
		oldcxt = MemoryContextSwitchTo(_SPI_current->savedcxt);
	}

	ctuple = heap_copytuple(tuple);
	ctupdesc = CreateTupleDescCopy(tupdesc);

	cslot = MakeTupleTableSlot();
	ExecSetSlotDescriptor(cslot, ctupdesc, true);
	cslot = ExecStoreTuple(ctuple, cslot, InvalidBuffer, true);

	if (oldcxt)
		MemoryContextSwitchTo(oldcxt);

	return cslot;
}

HeapTuple
SPI_modifytuple(Relation rel, HeapTuple tuple, int natts, int *attnum,
				Datum *Values, const char *Nulls)
{
	MemoryContext oldcxt = NULL;
	HeapTuple	mtuple;
	int			numberOfAttributes;
	Datum	   *v;
	char	   *n;
	bool		isnull;
	int			i;

	if (rel == NULL || tuple == NULL || natts < 0 || attnum == NULL || Values == NULL)
	{
		SPI_result = SPI_ERROR_ARGUMENT;
		return NULL;
	}

	if (_SPI_curid + 1 == _SPI_connected)		/* connected */
	{
		if (_SPI_current != &(_SPI_stack[_SPI_curid + 1]))
			elog(ERROR, "SPI stack corrupted");
		oldcxt = MemoryContextSwitchTo(_SPI_current->savedcxt);
	}
	SPI_result = 0;
	numberOfAttributes = rel->rd_att->natts;
	v = (Datum *) palloc(numberOfAttributes * sizeof(Datum));
	n = (char *) palloc(numberOfAttributes * sizeof(char));

	/* fetch old values and nulls */
	for (i = 0; i < numberOfAttributes; i++)
	{
		v[i] = heap_getattr(tuple, i + 1, rel->rd_att, &isnull);
		n[i] = (isnull) ? 'n' : ' ';
	}

	/* replace values and nulls */
	for (i = 0; i < natts; i++)
	{
		if (attnum[i] <= 0 || attnum[i] > numberOfAttributes)
			break;
		v[attnum[i] - 1] = Values[i];
		n[attnum[i] - 1] = (Nulls && Nulls[i] == 'n') ? 'n' : ' ';
	}

	if (i == natts)				/* no errors in *attnum */
	{
		mtuple = heap_formtuple(rel->rd_att, v, n);

		/*
		 * copy the identification info of the old tuple: t_ctid, t_self,
		 * and OID (if any)
		 */
		mtuple->t_data->t_ctid = tuple->t_data->t_ctid;
		mtuple->t_self = tuple->t_self;
		mtuple->t_tableOid = tuple->t_tableOid;