Re: Gripes about walsender command processing - Mailing list pgsql-hackers

From Tom Lane
Subject Re: Gripes about walsender command processing
Date
Msg-id 1633417.1600274669@sss.pgh.pa.us
Whole thread Raw
In response to Gripes about walsender command processing  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> On 2020-Sep-15, Alvaro Herrera wrote:
>> I overlooked this in 2f9661311b83.  From this perspective, I agree it
>> looks wrong.  We still have to send *some* completion tag (the 'C'
>> message), but maybe we can invent a separate entry point in dest.c for
>> that -- EndReplicationCommand() or some such -- that takes values from a
>> separate enum?

> It seems simpler than that actually; we don't need to build a lot of
> infrastructure.

This looks moderately reasonable to me.  However, with the process
title reporting I want to add, we're going to end up with a switch
that looks like

         case T_IdentifySystemCmd:
+            set_ps_display("IDENTIFY_SYSTEM");
             IdentifySystem();
+            EndReplicationCommand("IDENTIFY_SYSTEM");
             break;
 
         case T_BaseBackupCmd:
+            set_ps_display("BASE_BACKUP");
             PreventInTransactionBlock(true, "BASE_BACKUP");
             SendBaseBackup((BaseBackupCmd *) cmd_node);
+            EndReplicationCommand("BASE_BACKUP");
             break;

which is starting to look a bit repetitive and copy-pasteo-prone.
I don't see an easy way to improve on it though.  The only obvious
alternative would be to put another switch before the main one that
just fills a "const char *cmdtag" variable, but that seems ugly.

            regards, tom lane



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