[syslog-ng] load failures in afsocket and afsql

[Matthew Hall]

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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