From 6737111a7ae1fac6b4781250be7c0719c5a7ed48 Mon Sep 17 00:00:00 2001 From: Thomas Munro Date: Thu, 17 Oct 2019 13:24:50 +1300 Subject: [PATCH] When restoring GUCs in parallel workers, show an error context. Otherwise it can be hard to see where an error is coming from, when the parallel worker sets all the GUCs that it received from the leader. Bug #15726. Back-patch to 9.5, where RestoreGUCState() appeared. Reported-by: Tiago Anastacio Reviewed-by: Daniel Gustafsson, Tom Lane Discussion: https://postgr.es/m/15726-6d67e4fa14f027b3%40postgresql.org --- src/backend/utils/misc/guc.c | 29 +++++++++++++++++++++++++++++ 1 file changed, 29 insertions(+) diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index f88386f048..eca51a7c4e 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -9594,6 +9594,21 @@ read_gucstate_binary(char **srcptr, char *srcend, void *dest, Size size) *srcptr += size; } +/* + * Callback used to add a context message when reporting errors that occur + * while trying to restore GUCs in parallel workers. + */ +static void +guc_restore_error_context_callback(void *arg) +{ + char **error_context_name_and_value = (char **) arg; + + if (error_context_name_and_value) + errcontext("while setting parameter \"%s\" to \"%s\"", + error_context_name_and_value[0], + error_context_name_and_value[1]); +} + /* * RestoreGUCState: * Reads the GUC state at the specified address and updates the GUCs with the @@ -9612,6 +9627,7 @@ RestoreGUCState(void *gucstate) char *srcend; Size len; int i; + ErrorContextCallback error_context_callback; /* See comment at can_skip_gucvar(). */ for (i = 0; i < num_guc_variables; i++) @@ -9624,9 +9640,16 @@ RestoreGUCState(void *gucstate) srcptr += sizeof(len); srcend = srcptr + len; + /* If the GUC value check fails, we want errors to show useful context. */ + error_context_callback.callback = guc_restore_error_context_callback; + error_context_callback.previous = error_context_stack; + error_context_callback.arg = NULL; + error_context_stack = &error_context_callback; + while (srcptr < srcend) { int result; + char *error_context_name_and_value[2]; varname = read_gucstate(&srcptr, srcend); varvalue = read_gucstate(&srcptr, srcend); @@ -9641,6 +9664,9 @@ RestoreGUCState(void *gucstate) read_gucstate_binary(&srcptr, srcend, &varscontext, sizeof(varscontext)); + error_context_name_and_value[0] = varname; + error_context_name_and_value[1] = varvalue; + error_context_callback.arg = &error_context_name_and_value[0]; result = set_config_option(varname, varvalue, varscontext, varsource, GUC_ACTION_SET, true, ERROR, true); if (result <= 0) @@ -9649,7 +9675,10 @@ RestoreGUCState(void *gucstate) errmsg("parameter \"%s\" could not be set", varname))); if (varsourcefile[0]) set_config_sourcefile(varname, varsourcefile, varsourceline); + error_context_callback.arg = NULL; } + + error_context_stack = error_context_callback.previous; } /* -- 2.50.0