Re: (ITS#7775) LMDB terminates Postfix daemon process without logfile record

[wietse@porcupine.org]

Hallvard Breien Furuseth:
> > - Invoke an application call-back function with the error code and 
> >   problem description text.  If the error code is MDB_PANIC then
> >   the application knows that it needs to make final arrangements.
> 
> Sounds good to me for now, since it doesn't mean walking all over
> the code.  mdb.c can just #define its own assert().  No error
> code, the context is just "we're about to abort" and I don't know
> of other planned callbacks which the code would help.
> 
> /** User-settable callback for assert(), called before abort()
>  * instead of printing the message.
>  *
>  * assert(some user errors) might be unaffected.  This hack
>  * should become obsolete as lmdb's error handling matures.
>  * @param[in] msg The assertion message, not including newline.
>  * @parem[in] info Currently NULL. Might change in the future.
>  */
> extern void (*mdb_assert_cb)(char *msg, void *info);
> 
> (Or maybe call it -before- printing the message, you can abort or
> longjmp yourself if you don't want the message.)

Looks good. I'll code up an example implementation to set and use
the callback. The "info" argument should be sufficient to figure
out which database is failing.

	Wietse