granicus.if.org Git - postgresql/blob - src/backend/utils/fmgr/funcapi.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * funcapi.c
   4  *        Utility and convenience functions for fmgr functions that return
   5  *        sets and/or composite types.
   6  *
   7  * Copyright (c) 2002, PostgreSQL Global Development Group
   8  *
   9  * IDENTIFICATION
  10  *        $Header: /cvsroot/pgsql/src/backend/utils/fmgr/funcapi.c,v 1.4 2002/08/29 17:14:33 tgl Exp $
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14 #include "postgres.h"
  15
  16 #include "funcapi.h"
  17 #include "catalog/pg_type.h"
  18 #include "utils/syscache.h"
  19
  20
  21 /*
  22  * init_MultiFuncCall
  23  * Create an empty FuncCallContext data structure
  24  * and do some other basic Multi-function call setup
  25  * and error checking
  26  */
  27 FuncCallContext *
  28 init_MultiFuncCall(PG_FUNCTION_ARGS)
  29 {
  30         FuncCallContext *retval;
  31
  32         /*
  33          * Bail if we're called in the wrong context
  34          */
  35         if (fcinfo->resultinfo == NULL || !IsA(fcinfo->resultinfo, ReturnSetInfo))
  36                 elog(ERROR, "function called in context that does not accept a set result");
  37
  38         if (fcinfo->flinfo->fn_extra == NULL)
  39         {
  40                 /*
  41                  * First call
  42                  *
  43                  * Allocate suitably long-lived space and zero it
  44                  */
  45                 retval = (FuncCallContext *)
  46                         MemoryContextAlloc(fcinfo->flinfo->fn_mcxt,
  47                                                            sizeof(FuncCallContext));
  48                 MemSet(retval, 0, sizeof(FuncCallContext));
  49
  50                 /*
  51                  * initialize the elements
  52                  */
  53                 retval->call_cntr = 0;
  54                 retval->max_calls = 0;
  55                 retval->slot = NULL;
  56                 retval->user_fctx = NULL;
  57                 retval->attinmeta = NULL;
  58                 retval->multi_call_memory_ctx = fcinfo->flinfo->fn_mcxt;
  59
  60                 /*
  61                  * save the pointer for cross-call use
  62                  */
  63                 fcinfo->flinfo->fn_extra = retval;
  64         }
  65         else    /* second and subsequent calls */
  66         {
  67                 elog(ERROR, "init_MultiFuncCall may not be called more than once");
  68
  69                 /* never reached, but keep compiler happy */
  70                 retval = NULL;
  71         }
  72
  73         return retval;
  74 }
  75
  76 /*
  77  * per_MultiFuncCall
  78  *
  79  * Do Multi-function per-call setup
  80  */
  81 FuncCallContext *
  82 per_MultiFuncCall(PG_FUNCTION_ARGS)
  83 {
  84         FuncCallContext *retval = (FuncCallContext *) fcinfo->flinfo->fn_extra;
  85
  86         /* make sure we start with a fresh slot */
  87         if(retval->slot != NULL)
  88                 ExecClearTuple(retval->slot);
  89
  90         return retval;
  91 }
  92
  93 /*
  94  * end_MultiFuncCall
  95  * Clean up after init_MultiFuncCall
  96  */
  97 void
  98 end_MultiFuncCall(PG_FUNCTION_ARGS, FuncCallContext *funcctx)
  99 {
 100         /* unbind from fcinfo */
 101         fcinfo->flinfo->fn_extra = NULL;
 102
 103         /*
 104          * Caller is responsible to free up memory for individual
 105          * struct elements other than att_in_funcinfo and elements.
 106          */
 107         if (funcctx->attinmeta != NULL)
 108                 pfree(funcctx->attinmeta);
 109
 110         pfree(funcctx);
 111 }