Enhanced error context support in PL/Python

Extract the "while creating return value" and "while modifying trigger
row" parts of some error messages into another layer of error context.
This will simplify the upcoming patch to improve data type support, but
it can stand on its own.

1 files changed, 31 insertions, 3 deletions

diff --git a/src/pl/plpython/plpython.c b/src/pl/plpython/plpython.c
index eec0288e493..4aba4ba95ad 100644
--- 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 1.126 2009/08/25 08:14:42 petere Exp $
+ *	$PostgreSQL: pgsql/src/pl/plpython/plpython.c,v 1.127 2009/08/25 12:44:59 petere Exp $
  *
  *********************************************************************
  */
@@ -339,6 +339,20 @@ plpython_error_callback(void *arg)
 		errcontext("PL/Python function \"%s\"", PLy_procedure_name(PLy_curr_procedure));
 }
 
+static void
+plpython_trigger_error_callback(void *arg)
+{
+	if (PLy_curr_procedure)
+		errcontext("while modifying trigger row");
+}
+
+static void
+plpython_return_error_callback(void *arg)
+{
+	if (PLy_curr_procedure)
+		errcontext("while creating return value");
+}
+
 Datum
 plpython_call_handler(PG_FUNCTION_ARGS)
 {
@@ -506,6 +520,11 @@ PLy_modify_tuple(PLyProcedure *proc, PyObject *pltd, TriggerData *tdata,
 	Datum	   *volatile modvalues;
 	char	   *volatile modnulls;
 	TupleDesc	tupdesc;
+	ErrorContextCallback plerrcontext;
+
+	plerrcontext.callback = plpython_trigger_error_callback;
+	plerrcontext.previous = error_context_stack;
+	error_context_stack = &plerrcontext;
 
 	plntup = plkeys = platt = plval = plstr = NULL;
 	modattrs = NULL;
@@ -563,7 +582,7 @@ PLy_modify_tuple(PLyProcedure *proc, PyObject *pltd, TriggerData *tdata,
 			{
 				plstr = PyObject_Str(plval);
 				if (!plstr)
-					PLy_elog(ERROR, "could not compute string representation of Python object, while modifying trigger row");
+					PLy_elog(ERROR, "could not create string representation of Python object");
 				src = PyString_AsString(plstr);
 
 				modvalues[i] =
@@ -620,6 +639,8 @@ PLy_modify_tuple(PLyProcedure *proc, PyObject *pltd, TriggerData *tdata,
 	pfree(modvalues);
 	pfree(modnulls);
 
+	error_context_stack = plerrcontext.previous;
+
 	return rtup;
 }
 
@@ -811,6 +832,7 @@ PLy_function_handler(FunctionCallInfo fcinfo, PLyProcedure *proc)
 	PyObject   *volatile plrv = NULL;
 	PyObject   *volatile plrv_so = NULL;
 	char	   *plrv_sc;
+	ErrorContextCallback plerrcontext;
 
 	PG_TRY();
 	{
@@ -901,6 +923,10 @@ PLy_function_handler(FunctionCallInfo fcinfo, PLyProcedure *proc)
 			}
 		}
 
+		plerrcontext.callback = plpython_return_error_callback;
+		plerrcontext.previous = error_context_stack;
+		error_context_stack = &plerrcontext;
+
 		/*
 		 * If the function is declared to return void, the Python return value
 		 * must be None. For void-returning functions, we also treat a None
@@ -959,7 +985,7 @@ PLy_function_handler(FunctionCallInfo fcinfo, PLyProcedure *proc)
 			fcinfo->isnull = false;
 			plrv_so = PyObject_Str(plrv);
 			if (!plrv_so)
-				PLy_elog(ERROR, "could not create string representation of Python object, while creating return value");
+				PLy_elog(ERROR, "could not create string representation of Python object");
 			plrv_sc = PyString_AsString(plrv_so);
 			rv = InputFunctionCall(&proc->result.out.d.typfunc,
 								   plrv_sc,
@@ -977,6 +1003,8 @@ PLy_function_handler(FunctionCallInfo fcinfo, PLyProcedure *proc)
 	}
 	PG_END_TRY();
 
+	error_context_stack = plerrcontext.previous;
+
 	Py_XDECREF(plargs);
 	Py_DECREF(plrv);
 	Py_XDECREF(plrv_so);