[syslog-ng] load failures in afsocket and afsql

[Matthew Hall]

I think this patch might well fix it.

I tried it with the patch just now and it seemed to launch OK.

Matthew.

On Thu, Dec 16, 2010 at 08:20:44PM -0800, Matthew Hall wrote:
> Untested patch:
> 
> --- /home/megahall/dbparser.c	2010-12-16 20:07:03.000000000 -0800
> +++ syslog-ng-3.2.1/modules/dbparser/dbparser.c	2010-12-16 20:14:59.000000000 -0800
> @@ -140,6 +140,11 @@
>    else
>      {
>        log_db_parser_reload_database(self);
> +      /* XXX: mhall: repair corruption of persistent config */
> +      if (self->db)
> +        {
> +          cfg_persist_config_add(cfg, log_db_parser_format_persist_name(self), self->db, (GDestroyNotify) pattern_db_free, FALSE);
> +        }
>      }
>  
>    self->timer_tick_id = g_timeout_add_seconds(1, log_db_parser_timer_tick, self);
> 
> Matthew.
> 
> On Thu, Dec 16, 2010 at 08:06:43PM -0800, Matthew Hall wrote:
> > On Thu, Dec 16, 2010 at 04:55:09PM -0600, Martin Holste wrote:
> > > Keep fighting the good fight, hopefully you'll get some hints soon.
> > > You're well outside the range of my debugging-fu at this point.
> > > 
> > > On Thu, Dec 16, 2010 at 3:34 PM, Matthew Hall <mhall at mhcomputing.net> wrote:
> > > > Getting closer.
> > > >
> > > > The problem goes away when the XML pattern DB is disabled. The problem
> > > > does not appear if the XML pattern db is used in one log {} per below.
> > > > Once it is used in two log {} blocks, KABOOM! I'm going to try debugging
> > > > the other half of this which writes to the persistent store to see if I
> > > > can sort out what's breaking the write. For what it's worth, the problem
> > > > shows up in both 32 and 64 bit.
> > > >
> > > > Matthew.
> > 
> > I think the problem could be found now. In the log_db_parser_deinit, 
> > there is a call to cfg_persist_config_add but there is no corresponding 
> > call in log_db_parser_init.
> > 
> > When the db_parser is referenced once in the config file, self->db is 
> > NULL, so log_db_parser_reload_database is called to create the right 
> > data structure. It's important to remember that this is going to set 
> > self->db_file_inode and self->db_file_mtime.
> > 
> > When the db_parser is referenced again in the config file, self->db 
> > should be non NULL because the db_parser was supposed to be persisted.
> > 
> > Bug 1) When we call cfg_persist_config_fetch but we get NULL again so we 
> > call log_db_parser_reload_database again.
> > 
> > Bug 2) (Unrelated to my issue) Even if we had stored the db_parser, if 
> > we call stat, we just copy the new inode and mtime, and do not reload 
> > the patterns. So configuration reloads will probably not refresh the 
> > pattern DB.
> > 
> > Now in my case when we go into log_db_parser_reload_database the second 
> > time, we have a check if the DB file exists. If no we have an error. 
> > Fair enough. But if yes, then we check if self->db_file_inode and 
> > self->sb_file_mtime have changed, or not.
> > 
> > If they have not changed, we return right away, without initializing the 
> > self->db. But we have already destroyed the valid self->db pointer from 
> > the first initialization, by replacing it with the retval from 
> > cfg_persist_config_fetch, which was NULL because the config was not 
> > persisted.
> > 
> > Now we check self->db again at the end of log_db_parser_init where we 
> > find it has become NULL. This we return a failing retval because we 
> > never suceeded in initializing the log_db_parser to a non-NULL value.
> > 
> > We pass this error many frames up the stack until we hit the "Error 
> > initializing message pipeline" in log_center_init.
> > 
> > This goes a few frames up, until we exit with an error code.
> > 
> > I think the patch would be adding code to log_db_parser_init and/or 
> > log_db_parser_reload_database, which calls cfg_persist_config_add. I am 
> > going to try this Monday since I'm off tomorrow and see what I get.
> > 
> > Could somebody else try making a config which references the EXACT SAME 
> > patterndb file twice in two log {} blocks and see if it blows up for 
> > them as well? I want to try to eliminate as many environment specific 
> > issues as possible. I described the config you need in my previous mail.
> > 
> > Regards,
> > Matthew.
> > 
> > static gboolean log_db_parser_init(LogParser *s, GlobalConfig *cfg)
> > {
> >   LogDBParser *self = (LogDBParser *) s;
> > 
> >   self->db = cfg_persist_config_fetch(cfg, ***log_db_parser_format_persist_name***(self));
> >   if (self->db)
> >     {
> >       struct stat st;
> > 
> >       if (stat(self->db_file, &st) < 0)
> >         {
> >           msg_error("Error stating pattern database file, no automatic reload will be performed",
> >                     evt_tag_str("error", g_strerror(errno)),
> >                     NULL);
> >         }
> >       else
> >         {
> >           self->db_file_inode = st.st_ino;
> >           self->db_file_mtime = st.st_mtime;
> >         }
> >     }
> >   else
> >     {
> >       log_db_parser_reload_database(self);
> >     }
> > 
> >   self->timer_tick_id = g_timeout_add_seconds(1, log_db_parser_timer_tick, self);
> >   return self->db != NULL;
> > }
> > 
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