PG_FINALLY

This gives an alternative way of catching exceptions, for the common
case where the cleanup code is the same in the error and non-error
cases.  So instead of

    PG_TRY();
    {
        ... code that might throw ereport(ERROR) ...
    }
    PG_CATCH();
    {
        cleanup();
	PG_RE_THROW();
    }
    PG_END_TRY();
    cleanup();

one can write

    PG_TRY();
    {
        ... code that might throw ereport(ERROR) ...
    }
    PG_FINALLY();
    {
        cleanup();
    }
    PG_END_TRY();

Discussion: https://www.postgresql.org/message-id/flat/95a822c3-728b-af0e-d7e5-71890507ae0c%402ndquadrant.com

contrib/auto_explain/auto_explain.c

@@ -320,12 +320,10 @@ explain_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction,
 			prev_ExecutorRun(queryDesc, direction, count, execute_once);
 		else
 			standard_ExecutorRun(queryDesc, direction, count, execute_once);
-		nesting_level--;
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		nesting_level--;
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 }
@@ -343,12 +341,10 @@ explain_ExecutorFinish(QueryDesc *queryDesc)
 			prev_ExecutorFinish(queryDesc);
 		else
 			standard_ExecutorFinish(queryDesc);
-		nesting_level--;
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		nesting_level--;
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 }

contrib/dblink/dblink.c

@@ -776,19 +776,14 @@ dblink_record_internal(FunctionCallInfo fcinfo, bool is_async)
 			}
 		}
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		/* if needed, close the connection to the database */
 		if (freeconn)
 			PQfinish(conn);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-	/* if needed, close the connection to the database */
-	if (freeconn)
-		PQfinish(conn);
-
 	return (Datum) 0;
 }
 
@@ -952,14 +947,11 @@ materializeResult(FunctionCallInfo fcinfo, PGconn *conn, PGresult *res)
 			/* clean up and return the tuplestore */
 			tuplestore_donestoring(tupstore);
 		}
-
-		PQclear(res);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		/* be sure to release the libpq result */
 		PQclear(res);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 }
@@ -1464,19 +1456,14 @@ dblink_exec(PG_FUNCTION_ARGS)
 					 errmsg("statement returning results not allowed")));
 		}
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		/* if needed, close the connection to the database */
 		if (freeconn)
 			PQfinish(conn);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-	/* if needed, close the connection to the database */
-	if (freeconn)
-		PQfinish(conn);
-
 	PG_RETURN_TEXT_P(sql_cmd_status);
 }
 

contrib/hstore_plpython/hstore_plpython.c

@@ -180,14 +180,11 @@ plpython_to_hstore(PG_FUNCTION_ARGS)
 		pcount = hstoreUniquePairs(pairs, pcount, &buflen);
 		out = hstorePairs(pairs, pcount, buflen);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		Py_DECREF(items);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-	Py_DECREF(items);
-
 	PG_RETURN_POINTER(out);
 }

contrib/jsonb_plpython/jsonb_plpython.c

@@ -307,15 +307,12 @@ PLyMapping_ToJsonbValue(PyObject *obj, JsonbParseState **jsonb_state)
 
 		out = pushJsonbValue(jsonb_state, WJB_END_OBJECT, NULL);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		Py_DECREF(items);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-	Py_DECREF(items);
-
 	return out;
 }
 

contrib/pg_stat_statements/pg_stat_statements.c

@@ -892,12 +892,10 @@ pgss_ExecutorRun(QueryDesc *queryDesc, ScanDirection direction, uint64 count,
 			prev_ExecutorRun(queryDesc, direction, count, execute_once);
 		else
 			standard_ExecutorRun(queryDesc, direction, count, execute_once);
-		nested_level--;
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		nested_level--;
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 }
@@ -915,12 +913,10 @@ pgss_ExecutorFinish(QueryDesc *queryDesc)
 			prev_ExecutorFinish(queryDesc);
 		else
 			standard_ExecutorFinish(queryDesc);
-		nested_level--;
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		nested_level--;
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 }
@@ -1007,12 +1003,10 @@ pgss_ProcessUtility(PlannedStmt *pstmt, const char *queryString,
 				standard_ProcessUtility(pstmt, queryString,
 										context, params, queryEnv,
 										dest, completionTag);
-			nested_level--;
 		}
-		PG_CATCH();
+		PG_FINALLY();
 		{
 			nested_level--;
-			PG_RE_THROW();
 		}
 		PG_END_TRY();
 

contrib/pg_trgm/trgm_regexp.c

@@ -555,15 +555,12 @@ createTrgmNFA(text *text_re, Oid collation,
 	{
 		trg = createTrgmNFAInternal(&regex, graph, rcontext);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		pg_regfree(&regex);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-	pg_regfree(&regex);
-
 	/* Clean up all the cruft we created */
 	MemoryContextSwitchTo(oldcontext);
 	MemoryContextDelete(tmpcontext);

contrib/postgres_fdw/connection.c

@@ -631,15 +631,12 @@ pgfdw_report_error(int elevel, PGresult *res, PGconn *conn,
 				 message_context ? errcontext("%s", message_context) : 0,
 				 sql ? errcontext("remote SQL command: %s", sql) : 0));
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		if (clear)
 			PQclear(res);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
-	if (clear)
-		PQclear(res);
 }
 
 /*

contrib/postgres_fdw/postgres_fdw.c

@@ -3155,15 +3155,11 @@ get_remote_estimate(const char *sql, PGconn *conn,
 				   startup_cost, total_cost, rows, width);
 		if (n != 4)
 			elog(ERROR, "could not interpret EXPLAIN output: \"%s\"", line);
-
-		PQclear(res);
-		res = NULL;
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		if (res)
 			PQclear(res);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 }
@@ -3383,15 +3379,11 @@ fetch_more_data(ForeignScanState *node)
 
 		/* Must be EOF if we didn't get as many tuples as we asked for. */
 		fsstate->eof_reached = (numrows < fsstate->fetch_size);
-
-		PQclear(res);
-		res = NULL;
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		if (res)
 			PQclear(res);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
@@ -4404,15 +4396,11 @@ postgresAnalyzeForeignTable(Relation relation,
 		if (PQntuples(res) != 1 || PQnfields(res) != 1)
 			elog(ERROR, "unexpected result from deparseAnalyzeSizeSql query");
 		*totalpages = strtoul(PQgetvalue(res, 0, 0), NULL, 10);
-
-		PQclear(res);
-		res = NULL;
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		if (res)
 			PQclear(res);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
@@ -4925,16 +4913,11 @@ postgresImportForeignSchema(ImportForeignSchemaStmt *stmt, Oid serverOid)
 
 			commands = lappend(commands, pstrdup(buf.data));
 		}
-
-		/* Clean up */
-		PQclear(res);
-		res = NULL;
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		if (res)
 			PQclear(res);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 

contrib/sepgsql/hooks.c

@@ -372,13 +372,11 @@ sepgsql_utility_command(PlannedStmt *pstmt,
 									context, params, queryEnv,
 									dest, completionTag);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		sepgsql_context_info = saved_context_info;
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
-	sepgsql_context_info = saved_context_info;
 }
 
 /*

contrib/sepgsql/label.c

@@ -465,14 +465,11 @@ sepgsql_get_label(Oid classId, Oid objectId, int32 subId)
 		{
 			label = pstrdup(unlabeled);
 		}
-		PG_CATCH();
+		PG_FINALLY();
 		{
 			freecon(unlabeled);
-			PG_RE_THROW();
 		}
 		PG_END_TRY();
-
-		freecon(unlabeled);
 	}
 	return label;
 }
@@ -600,13 +597,11 @@ sepgsql_mcstrans_in(PG_FUNCTION_ARGS)
 	{
 		result = pstrdup(raw_label);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		freecon(raw_label);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
-	freecon(raw_label);
 
 	PG_RETURN_TEXT_P(cstring_to_text(result));
 }
@@ -640,13 +635,11 @@ sepgsql_mcstrans_out(PG_FUNCTION_ARGS)
 	{
 		result = pstrdup(qual_label);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		freecon(qual_label);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
-	freecon(qual_label);
 
 	PG_RETURN_TEXT_P(cstring_to_text(result));
 }
@@ -851,13 +844,11 @@ exec_object_restorecon(struct selabel_handle *sehnd, Oid catalogId)
 
 				SetSecurityLabel(&object, SEPGSQL_LABEL_TAG, context);
 			}
-			PG_CATCH();
+			PG_FINALLY();
 			{
 				freecon(context);
-				PG_RE_THROW();
 			}
 			PG_END_TRY();
-			freecon(context);
 		}
 		else if (errno == ENOENT)
 			ereport(WARNING,
@@ -937,14 +928,11 @@ sepgsql_restorecon(PG_FUNCTION_ARGS)
 		exec_object_restorecon(sehnd, AttributeRelationId);
 		exec_object_restorecon(sehnd, ProcedureRelationId);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		selabel_close(sehnd);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
 
-	selabel_close(sehnd);
-
 	PG_RETURN_BOOL(true);
 }

contrib/sepgsql/selinux.c

@@ -871,13 +871,11 @@ sepgsql_compute_create(const char *scontext,
 	{
 		result = pstrdup(ncontext);
 	}
-	PG_CATCH();
+	PG_FINALLY();
 	{
 		freecon(ncontext);
-		PG_RE_THROW();
 	}
 	PG_END_TRY();
-	freecon(ncontext);
 
 	return result;
 }

contrib/sepgsql/uavc.c

@@ -181,14 +181,11 @@ sepgsql_avc_unlabeled(void)
 		{
 			avc_unlabeled = MemoryContextStrdup(avc_mem_cxt, unlabeled);
 		}
-		PG_CATCH();
+		PG_FINALLY();
 		{
 			freecon(unlabeled);
-			PG_RE_THROW();
 		}
 		PG_END_TRY();
-
-		freecon(unlabeled);
 	}
 	return avc_unlabeled;
 }