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/*-------------------------------------------------------------------------
*
* funcapi.c
* Utility and convenience functions for fmgr functions that return
* sets and/or composite types.
*
* Copyright (c) 2002-2003, PostgreSQL Global Development Group
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/utils/fmgr/funcapi.c,v 1.13 2003/12/19 00:02:11 joe Exp $
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "funcapi.h"
#include "catalog/pg_type.h"
#include "utils/syscache.h"
static void shutdown_MultiFuncCall(Datum arg);
/*
* init_MultiFuncCall
* Create an empty FuncCallContext data structure
* and do some other basic Multi-function call setup
* and error checking
*/
FuncCallContext *
init_MultiFuncCall(PG_FUNCTION_ARGS)
{
FuncCallContext *retval;
/*
* Bail if we're called in the wrong context
*/
if (fcinfo->resultinfo == NULL || !IsA(fcinfo->resultinfo, ReturnSetInfo))
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("set-valued function called in context that cannot accept a set")));
if (fcinfo->flinfo->fn_extra == NULL)
{
/*
* First call
*/
ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
/*
* Allocate suitably long-lived space and zero it
*/
retval = (FuncCallContext *)
MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
sizeof(FuncCallContext));
MemSet(retval, 0, sizeof(FuncCallContext));
/*
* initialize the elements
*/
retval->call_cntr = 0;
retval->max_calls = 0;
retval->slot = NULL;
retval->user_fctx = NULL;
retval->attinmeta = NULL;
retval->multi_call_memory_ctx = fcinfo->flinfo->fn_mcxt;
/*
* save the pointer for cross-call use
*/
fcinfo->flinfo->fn_extra = retval;
/*
* Ensure we will get shut down cleanly if the exprcontext is not
* run to completion.
*/
RegisterExprContextCallback(rsi->econtext,
shutdown_MultiFuncCall,
PointerGetDatum(fcinfo->flinfo));
}
else
{
/* second and subsequent calls */
elog(ERROR, "init_MultiFuncCall may not be called more than once");
/* never reached, but keep compiler happy */
retval = NULL;
}
return retval;
}
/*
* per_MultiFuncCall
*
* Do Multi-function per-call setup
*/
FuncCallContext *
per_MultiFuncCall(PG_FUNCTION_ARGS)
{
FuncCallContext *retval = (FuncCallContext *) fcinfo->flinfo->fn_extra;
/*
* Clear the TupleTableSlot, if present. This is for safety's sake:
* the Slot will be in a long-lived context (it better be, if the
* FuncCallContext is pointing to it), but in most usage patterns the
* tuples stored in it will be in the function's per-tuple context. So
* at the beginning of each call, the Slot will hold a dangling
* pointer to an already-recycled tuple. We clear it out here. (See
* also the definition of TupleGetDatum() in funcapi.h!)
*/
if (retval->slot != NULL)
ExecClearTuple(retval->slot);
return retval;
}
/*
* end_MultiFuncCall
* Clean up after init_MultiFuncCall
*/
void
end_MultiFuncCall(PG_FUNCTION_ARGS, FuncCallContext *funcctx)
{
ReturnSetInfo *rsi = (ReturnSetInfo *) fcinfo->resultinfo;
/* Deregister the shutdown callback */
UnregisterExprContextCallback(rsi->econtext,
shutdown_MultiFuncCall,
PointerGetDatum(fcinfo->flinfo));
/* But use it to do the real work */
shutdown_MultiFuncCall(PointerGetDatum(fcinfo->flinfo));
}
/*
* shutdown_MultiFuncCall
* Shutdown function to clean up after init_MultiFuncCall
*/
static void
shutdown_MultiFuncCall(Datum arg)
{
FmgrInfo *flinfo = (FmgrInfo *) DatumGetPointer(arg);
FuncCallContext *funcctx = (FuncCallContext *) flinfo->fn_extra;
/* unbind from flinfo */
flinfo->fn_extra = NULL;
/*
* Caller is responsible to free up memory for individual struct
* elements other than att_in_funcinfo and elements.
*/
if (funcctx->attinmeta != NULL)
pfree(funcctx->attinmeta);
pfree(funcctx);
}
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