Fix plpython's overoptimistic caching of information about the rowtype of

a trigger's target table.  The rowtype could change from one call to the
next, so cope in such cases, while avoiding doing repetitive catalog lookups.
Per bug #3847 from Mark Reid.

Backpatch to 8.2.x.  Likely this fix should go further back, but I can't test
it because I no longer have a machine with a pre-2.5 Python installation.
(Maybe we should rethink that idea about not supporting Python 2.5 in the
older branches.)

diff --git a/src/pl/plpython/plpython.c b/src/pl/plpython/plpython.c
index 2b6e49d47beb758247e72f1fc6e5b1dc64aeca9d..afbb3abeda8f50b129131d1ded06c9edba33a591 100644 (file)
--- a/src/pl/plpython/plpython.c
+++ b/src/pl/plpython/plpython.c
@@ -1,7 +1,7 @@
 /**********************************************************************
  * plpython.c - python as a procedural language for PostgreSQL
  *
- * $PostgreSQL: pgsql/src/pl/plpython/plpython.c,v 1.105 2007/11/23 01:46:34 alvherre Exp $
+ * $PostgreSQL: pgsql/src/pl/plpython/plpython.c,v 1.106 2008/01/02 03:10:27 tgl Exp $
  *
  *********************************************************************
  */
@@ -79,7 +79,8 @@ typedef PyObject *(*PLyDatumToObFunc) (const char *);
 typedef struct PLyDatumToOb
 {
    PLyDatumToObFunc func;
-   FmgrInfo    typfunc;
+   FmgrInfo    typfunc;        /* The type's output function */
+   Oid         typoid;         /* The OID of the type */
    Oid         typioparam;
    bool        typbyval;
 }  PLyDatumToOb;
@@ -212,6 +213,7 @@ static void PLy_elog(int, const char *,...);
 static char *PLy_traceback(int *);
 
 static void *PLy_malloc(size_t);
+static void *PLy_malloc0(size_t);
 static char *PLy_strdup(const char *);
 static void PLy_free(void *);
 
@@ -231,9 +233,8 @@ static PyObject *PLy_procedure_call(PLyProcedure *, char *, PyObject *);
 static PLyProcedure *PLy_procedure_get(FunctionCallInfo fcinfo,
                  Oid tgreloid);
 
-static PLyProcedure *PLy_procedure_create(FunctionCallInfo fcinfo,
-                    Oid tgreloid,
-                    HeapTuple procTup, char *key);
+static PLyProcedure *PLy_procedure_create(HeapTuple procTup, Oid tgreloid,
+                                         char *key);
 
 static void PLy_procedure_compile(PLyProcedure *, const char *);
 static char *PLy_procedure_munge_source(const char *, const char *);
@@ -1123,7 +1124,24 @@ PLy_procedure_get(FunctionCallInfo fcinfo, Oid tgreloid)
    }
 
    if (proc == NULL)
-       proc = PLy_procedure_create(fcinfo, tgreloid, procTup, key);
+       proc = PLy_procedure_create(procTup, tgreloid, key);
+
+   if (OidIsValid(tgreloid))
+   {
+       /*
+        * Input/output conversion for trigger tuples.  Use the result
+        * TypeInfo variable to store the tuple conversion info.  We
+        * do this over again on each call to cover the possibility that
+        * the relation's tupdesc changed since the trigger was last called.
+        * PLy_input_tuple_funcs and PLy_output_tuple_funcs are responsible
+        * for not doing repetitive work.
+        */
+       TriggerData *tdata = (TriggerData *) fcinfo->context;
+
+       Assert(CALLED_AS_TRIGGER(fcinfo));
+       PLy_input_tuple_funcs(&(proc->result), tdata->tg_relation->rd_att);
+       PLy_output_tuple_funcs(&(proc->result), tdata->tg_relation->rd_att);
+   }
 
    ReleaseSysCache(procTup);
 
@@ -1131,8 +1149,7 @@ PLy_procedure_get(FunctionCallInfo fcinfo, Oid tgreloid)
 }
 
 static PLyProcedure *
-PLy_procedure_create(FunctionCallInfo fcinfo, Oid tgreloid,
-                    HeapTuple procTup, char *key)
+PLy_procedure_create(HeapTuple procTup, Oid tgreloid, char *key)
 {
    char        procName[NAMEDATALEN + 256];
    Form_pg_proc procStruct;
@@ -1152,13 +1169,13 @@ PLy_procedure_create(FunctionCallInfo fcinfo, Oid tgreloid,
        rv = snprintf(procName, sizeof(procName),
                      "__plpython_procedure_%s_%u_trigger_%u",
                      NameStr(procStruct->proname),
-                     fcinfo->flinfo->fn_oid,
+                     HeapTupleGetOid(procTup),
                      tgreloid);
    else
        rv = snprintf(procName, sizeof(procName),
                      "__plpython_procedure_%s_%u",
                      NameStr(procStruct->proname),
-                     fcinfo->flinfo->fn_oid);
+                     HeapTupleGetOid(procTup));
    if (rv >= sizeof(procName) || rv < 0)
        elog(ERROR, "procedure name would overrun buffer");
 
@@ -1186,7 +1203,7 @@ PLy_procedure_create(FunctionCallInfo fcinfo, Oid tgreloid,
         * get information required for output conversion of the return value,
         * but only if this isn't a trigger.
         */
-       if (!CALLED_AS_TRIGGER(fcinfo))
+       if (!OidIsValid(tgreloid))
        {
            HeapTuple   rvTypeTup;
            Form_pg_type rvTypeStruct;
@@ -1228,28 +1245,18 @@ PLy_procedure_create(FunctionCallInfo fcinfo, Oid tgreloid,
 
            ReleaseSysCache(rvTypeTup);
        }
-       else
-       {
-           /*
-            * input/output conversion for trigger tuples.  use the result
-            * TypeInfo variable to store the tuple conversion info.
-            */
-           TriggerData *tdata = (TriggerData *) fcinfo->context;
-
-           PLy_input_tuple_funcs(&(proc->result), tdata->tg_relation->rd_att);
-           PLy_output_tuple_funcs(&(proc->result), tdata->tg_relation->rd_att);
-       }
 
        /*
         * now get information required for input conversion of the
         * procedure's arguments.
         */
-       proc->nargs = fcinfo->nargs;
+       proc->nargs = procStruct->pronargs;
        if (proc->nargs)
        {
            argnames = SysCacheGetAttr(PROCOID, procTup, Anum_pg_proc_proargnames, &isnull);
            if (!isnull)
            {
+               /* XXX this code is WRONG if there are any output arguments */
                deconstruct_array(DatumGetArrayTypeP(argnames), TEXTOID, -1, false, 'i',
                                  &elems, NULL, &nelems);
                if (nelems != proc->nargs)
@@ -1260,7 +1267,7 @@ PLy_procedure_create(FunctionCallInfo fcinfo, Oid tgreloid,
                memset(proc->argnames, 0, sizeof(char *) * proc->nargs);
            }
        }
-       for (i = 0; i < fcinfo->nargs; i++)
+       for (i = 0; i < proc->nargs; i++)
        {
            HeapTuple   argTypeTup;
            Form_pg_type argTypeStruct;
@@ -1453,10 +1460,15 @@ PLy_input_tuple_funcs(PLyTypeInfo * arg, TupleDesc desc)
 
    if (arg->is_rowtype == 0)
        elog(ERROR, "PLyTypeInfo struct is initialized for a Datum");
-
    arg->is_rowtype = 1;
-   arg->in.r.natts = desc->natts;
-   arg->in.r.atts = PLy_malloc(desc->natts * sizeof(PLyDatumToOb));
+
+   if (arg->in.r.natts != desc->natts)
+   {
+       if (arg->in.r.atts)
+           PLy_free(arg->in.r.atts);
+       arg->in.r.natts = desc->natts;
+       arg->in.r.atts = PLy_malloc0(desc->natts * sizeof(PLyDatumToOb));
+   }
 
    for (i = 0; i < desc->natts; i++)
    {
@@ -1465,6 +1477,9 @@ PLy_input_tuple_funcs(PLyTypeInfo * arg, TupleDesc desc)
        if (desc->attrs[i]->attisdropped)
            continue;
 
+       if (arg->in.r.atts[i].typoid == desc->attrs[i]->atttypid)
+           continue;           /* already set up this entry */
+
        typeTup = SearchSysCache(TYPEOID,
                                 ObjectIdGetDatum(desc->attrs[i]->atttypid),
                                 0, 0, 0);
@@ -1487,10 +1502,15 @@ PLy_output_tuple_funcs(PLyTypeInfo * arg, TupleDesc desc)
 
    if (arg->is_rowtype == 0)
        elog(ERROR, "PLyTypeInfo struct is initialized for a Datum");
-
    arg->is_rowtype = 1;
-   arg->out.r.natts = desc->natts;
-   arg->out.r.atts = PLy_malloc(desc->natts * sizeof(PLyDatumToOb));
+
+   if (arg->out.r.natts != desc->natts)
+   {
+       if (arg->out.r.atts)
+           PLy_free(arg->out.r.atts);
+       arg->out.r.natts = desc->natts;
+       arg->out.r.atts = PLy_malloc0(desc->natts * sizeof(PLyDatumToOb));
+   }
 
    for (i = 0; i < desc->natts; i++)
    {
@@ -1499,6 +1519,9 @@ PLy_output_tuple_funcs(PLyTypeInfo * arg, TupleDesc desc)
        if (desc->attrs[i]->attisdropped)
            continue;
 
+       if (arg->out.r.atts[i].typoid == desc->attrs[i]->atttypid)
+           continue;           /* already set up this entry */
+
        typeTup = SearchSysCache(TYPEOID,
                                 ObjectIdGetDatum(desc->attrs[i]->atttypid),
                                 0, 0, 0);
@@ -1548,6 +1571,7 @@ PLy_input_datum_func2(PLyDatumToOb * arg, Oid typeOid, HeapTuple typeTup)
 
    /* Get the type's conversion information */
    perm_fmgr_info(typeStruct->typoutput, &arg->typfunc);
+   arg->typoid = HeapTupleGetOid(typeTup);
    arg->typioparam = getTypeIOParam(typeTup);
    arg->typbyval = typeStruct->typbyval;
 
@@ -3015,6 +3039,15 @@ PLy_malloc(size_t bytes)
    return ptr;
 }
 
+static void *
+PLy_malloc0(size_t bytes)
+{
+   void       *ptr = PLy_malloc(bytes);
+
+   MemSet(ptr, 0, bytes);
+   return ptr;
+}
+
 static char *
 PLy_strdup(const char *str)
 {