Re: Frontend error logging style

Robert Haas <robertmhaas@gmail.com> writes:
> On Fri, Nov 19, 2021 at 5:17 AM Peter Eisentraut
> <peter.eisentraut@enterprisedb.com> wrote:
>> If people want to do that kind of thing (I'm undecided whether the
>> complexity is worth it), then make it a different API.  The pg_log_*
>> calls are for writing formatted output.  They normalized existing
>> hand-coded patterns at the time.  We can wrap another API on top of them
>> that does flow control and output.  The pg_log_* stuff is more on the
>> level of syslog(), which also just outputs stuff.  Nobody is suggesting
>> that syslog(LOG_EMERG) should exit the program automatically.  But you
>> can wrap higher-level APIs such as ereport() on top of that that might
>> do that.

> Yeah, that might be a way forward.

This conversation seems to have tailed off without full resolution,
but I observe that pretty much everyone except Peter is on board
with defining pg_log_fatal as pg_log_error + exit(1).  So I think
we should just do that, unless Peter wants to produce a finished
alternative proposal.

I've now gone through and fleshed out the patch I sketched upthread.
This exercise convinced me that we absolutely should do something
very like this, because

(1) As it stands, this patch removes a net of just about 1000 lines
of code.  So we clearly need *something*.

(2) The savings would be even more, except that people have invented
macros for pg_log_error + exit(1) in at least four places already.
(None of them quite the same of course.)  Here I've just fixed those
macro definitions to use pg_log_fatal.  In the name of consistency, we
should probably get rid of those macros in favor of using pg_log_fatal
directly; but I've not done so here, since this patch is eyewateringly
long and boring already.

(3) The amount of inconsistency in how we add on details/hints right
now is even worse than I thought.  For example, we've got places
burying the lede like this:

-        pg_log_error("server version: %s; %s version: %s",
-                     remoteversion_str, progname, PG_VERSION);
-        fatal("aborting because of server version mismatch");
+        pg_log_error("aborting because of server version mismatch");
+        pg_log_error_detail("server version: %s; %s version: %s",
+                            remoteversion_str, progname, PG_VERSION);
+        exit(1);

or misidentifying the primary message altogether, like this:

     pg_log_error("query failed: %s",
                  PQerrorMessage(AH->connection));
-    fatal("query was: %s", query);
+    pg_log_error_detail("Query was: %s", query);
+    exit(1);

Thoughts?

			regards, tom lane