diff --git a/doc/src/sgml/pltcl.sgml b/doc/src/sgml/pltcl.sgml index d2175d5..d5c576d 100644 --- a/doc/src/sgml/pltcl.sgml +++ b/doc/src/sgml/pltcl.sgml @@ -775,6 +775,127 @@ CREATE EVENT TRIGGER tcl_a_snitch ON ddl_command_start EXECUTE PROCEDURE tclsnit + + Error Handling in PL/Tcl + + + error handling + in PL/Tcl + + + + All Tcl errors that are allowed to propagate back to the top level of the + interpreter, that is, errors not caught within the stored procedure + using the Tcl catch command will raise a database + error. + + + Tcl code within or called from the stored procedure can choose to + raise a database error by invoking the elog + command provided by PL/Tcl or by generating an error using the Tcl + error command and not catching it with Tcl's + catch command. + + + Database errors that occur from the PL/Tcl stored procedure's + use of spi_exec, spi_prepare, + and spi_execp are also catchable by Tcl's + catch command. + + + Tcl provides an errorCode variable that can + represent additional information about the error in a form that + is easy for programs to interpret. The contents are in Tcl list + format and the first word identifies the subsystem or + library responsible for the error and beyond that the contents are left + to the individual code or library. For example if Tcl's + open command is asked to open a file that doesn't + exist, errorCode + might contain POSIX ENOENT {no such file or directory} + where the third element may vary by locale but the first and second + will not. + + + When spi_exec, spi_prepare + or spi_execp cause a database error to be raised, + that database eror propagates back to Tcl as a Tcl error. + In this case errorCode is set to a list + where the first element is POSTGRES followed by a + copious decoding of the Postgres error structure. Since fields in the + structure may or may not be present depending on the nature of the + error, how the function was invoked, etc, PL/Tcl has adopted the + convention that subsequent elements of the errorCode + list are key-value pairs where the first value is the name of the + field and the second is its value. + + + Fields that may be present include message, + detail, detail_log, + hint, domain, + context_domain, context, + schema, table, + column, datatype, + constraint, cursor_position, + internalquery, internal_position, + filename, lineno and + funcname. + + + You might find it useful to load the results into an array. Code + for doing that might look like + + if {[lindex $errorCode 0] == "POSTGRES"} { + array set errorRow [lrange $errorCode 1 end] + } + + + + In the example below we cause an error by attempting to + SELECT from a table that doesn't exist. + +select tcl_eval('spi_exec "select * from foo;"'); + + + +ERROR: relation "foo" does not exist + + + + + Now we examine the error code. (The double-colons explicitly + reference errorCode as a global variable.) + +select tcl_eval('join $::errorCode "\n"'); + + + + tcl_eval +------------------------------- + POSTGRES + + message + + relation "foo" does not exist+ + domain + + postgres-9.6 + + context_domain + + postgres-9.6 + + cursorpos + + 0 + + internalquery + + select * from foo; + + internalpos + + 15 + + filename + + parse_relation.c + + lineno + + 1159 + + funcname + + parserOpenTable +(1 row) + + + + + Modules and the <function>unknown</> Command diff --git a/src/pl/tcl/expected/pltcl_setup.out b/src/pl/tcl/expected/pltcl_setup.out index e11718c..0592c48 100644 --- a/src/pl/tcl/expected/pltcl_setup.out +++ b/src/pl/tcl/expected/pltcl_setup.out @@ -555,3 +555,51 @@ NOTICE: tclsnitch: ddl_command_start DROP TABLE NOTICE: tclsnitch: ddl_command_end DROP TABLE drop event trigger tcl_a_snitch; drop event trigger tcl_b_snitch; +-- test error handling +/* + * The ugly hack of messsing with the verbosity is because the error context is + * set to the TCL variable errorInfo, which contains some unstable data (namely + * the full name of the TCL function created by the handler, which includes the + * Postgres backend PID). + */ +\set VERBOSITY terse +CREATE OR REPLACE FUNCTION pg_temp.tcl_eval (varchar) RETURNS varchar AS $$ +eval $1 +$$ LANGUAGE pltcl; +select pg_temp.tcl_eval('spi_exec "select * from foo;"'); +ERROR: relation "foo" does not exist +select pg_temp.tcl_eval($$ +set list [lindex $::errorCode 0]; +foreach "key value" [lrange $::errorCode 1 end] { + if {$key == "domain" || $key == "context_domain" || $key == "lineno"} { + regsub -all {[0-9]} $value "" value + } + lappend list $key $value +}; +return [join $list "\n"] +$$); + tcl_eval +------------------------------- + POSTGRES + + SQLSTATE + + 42P01 + + message + + relation "foo" does not exist+ + domain + + postgres-. + + context_domain + + postgres-. + + cursor_position + + 0 + + internalquery + + select * from foo; + + internal_position + + 15 + + filename + + parse_relation.c + + lineno + + + + funcname + + parserOpenTable +(1 row) + diff --git a/src/pl/tcl/pltcl.c b/src/pl/tcl/pltcl.c index 5b27c73..d8a8a89 100644 --- a/src/pl/tcl/pltcl.c +++ b/src/pl/tcl/pltcl.c @@ -1576,6 +1576,98 @@ compile_pltcl_function(Oid fn_oid, Oid tgreloid, return prodesc; } +/********************************************************************** + * pltcl_construct_errorCode() - construct a Tcl errorCode + * list with detailed information from the PostgreSQL server + **********************************************************************/ +static void +pltcl_construct_errorCode(Tcl_Interp *interp, ErrorData *edata) +{ + Tcl_Obj *obj = Tcl_NewObj(); + + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("POSTGRES", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("SQLSTATE", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(unpack_sql_state(edata->sqlerrcode), -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("message", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->message, -1)); + + if (edata->detail) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("detail", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->detail, -1)); + } + if (edata->detail_log) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("detail_log", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->detail_log, -1)); + } + if (edata->hint) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("hint", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->hint, -1)); + } + if (edata->domain) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("domain", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->domain, -1)); + } + if (edata->context_domain) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("context_domain", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->context_domain, -1)); + } + if (edata->context) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("context", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->context, -1)); + } + if (edata->schema_name) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("schema", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->schema_name, -1)); + } + if (edata->table_name) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("table", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->table_name, -1)); + } + if (edata->column_name) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("column", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->column_name, -1)); + } + if (edata->datatype_name) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("datatype", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->datatype_name, -1)); + } + if (edata->constraint_name) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("constraint", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->constraint_name, -1)); + } + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("cursor_position", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewIntObj(edata->cursorpos)); + if (edata->internalquery) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("internalquery", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->internalquery, -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("internal_position", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewIntObj(edata->internalpos)); + } + if (edata->filename) + { + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("filename", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->filename, -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("lineno", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewIntObj(edata->lineno)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj("funcname", -1)); + Tcl_ListObjAppendElement(interp, obj, Tcl_NewStringObj(edata->funcname, -1)); + } + + Tcl_SetObjErrorCode(interp, obj); +} + /********************************************************************** * pltcl_elog() - elog() support for PLTcl @@ -1610,6 +1702,8 @@ pltcl_elog(ClientData cdata, Tcl_Interp *interp, level = loglevels[priIndex]; + level = loglevels[priIndex]; + if (level == ERROR) { /* @@ -1652,6 +1746,7 @@ pltcl_elog(ClientData cdata, Tcl_Interp *interp, UTF_BEGIN; Tcl_SetObjResult(interp, Tcl_NewStringObj(UTF_E2U(edata->message), -1)); UTF_END; + pltcl_construct_errorCode(interp, edata); FreeErrorData(edata); return TCL_ERROR; @@ -1884,6 +1979,7 @@ pltcl_subtrans_abort(Tcl_Interp *interp, UTF_BEGIN; Tcl_SetResult(interp, UTF_E2U(edata->message), TCL_VOLATILE); UTF_END; + pltcl_construct_errorCode(interp, edata); FreeErrorData(edata); } diff --git a/src/pl/tcl/sql/pltcl_setup.sql b/src/pl/tcl/sql/pltcl_setup.sql index 53358ea..3ee8583 100644 --- a/src/pl/tcl/sql/pltcl_setup.sql +++ b/src/pl/tcl/sql/pltcl_setup.sql @@ -595,3 +595,29 @@ drop table foo; drop event trigger tcl_a_snitch; drop event trigger tcl_b_snitch; + + +-- test error handling + +/* + * The ugly hack of messsing with the verbosity is because the error context is + * set to the TCL variable errorInfo, which contains some unstable data (namely + * the full name of the TCL function created by the handler, which includes the + * Postgres backend PID). + */ +\set VERBOSITY terse +CREATE OR REPLACE FUNCTION pg_temp.tcl_eval (varchar) RETURNS varchar AS $$ +eval $1 +$$ LANGUAGE pltcl; + +select pg_temp.tcl_eval('spi_exec "select * from foo;"'); +select pg_temp.tcl_eval($$ +set list [lindex $::errorCode 0]; +foreach "key value" [lrange $::errorCode 1 end] { + if {$key == "domain" || $key == "context_domain" || $key == "lineno"} { + regsub -all {[0-9]} $value "" value + } + lappend list $key $value +}; +return [join $list "\n"] +$$);