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Re: LDAP Debug messages & severity levels

Hallvard B Furuseth wrote: 
slapd is often too silent when something fails.
One may need -d -1 or something to find out what is wrong -
and then useful messages can drown in others.

Also, if OpenLDAP is configured with --disable-debug, often
we get no error messages at all. That's plain wrong - fatal
error messages are not what one normally calls debugging.

I agree. Compiling with --disable-debug disables too much, leaving debug on enables too much (like asserts...)

I'd like to try again to introduce severity levels, this
time something simpler than the NEW_LOGGING experiment.

I suggest:

- Replace at least Debug() messages giving warnings and
  errors, with macros that indicate severity level.
  Info(), Error(), Warn(), etc.

configure --disable-debug would not disable the most severe
macros.

OK

- Run-time configuration of which severity levels to log,
  configured independently of the loglevel (which isn't really
  a log "level", just a bit mask of different things to log).

  Not sure how the loglevel and severity level should interact.
  The most severe messages should be given independently of
  loglevel, so maybe their macros do not need a loglevel.

With the others - log the message if both loglevel and
severity level is satisfied? That's inconsistent with severe
messages that are logged just due to severity level though.
Maybe it'll be easier to decide after the debug messages
have been classified by severity.

I think you're going the right direction. Genuine Error and Warning messages should not need any further qualification. It is only Info/Debug messages that really need the fine-grain "loglevel" differentiators, so they can be selectively turned on and off. 
- Maybe the "loglevel" should be renamed (retaining the old
  name for backwards compatibility), to avoid confusion with
  the severity level which really is a "level".

- I think 4-5 severity levels should be enough: debug, (info),
  warning, error, (fatal).

Could fold Info into Debug or Fatal into Error. I haven't
looked at just what Debug() is used for at the moment.
Statslog() would have level Info if Statslog is included in
this scheme at all, I don't know what else fits level Info.

There are some parts of the documentation that state that Statslog is always available, even with --disable-debug. I think that doc is now wrong, but it reflects an intention that we should probably restore. That pretty much means Stats/Info, Warn, and Error are never disabled.
include/ldap_log.h #defines twelve LDAP_LEVEL_* constants,
but they only seem to be used in the unused debug2syslog().

Left over from NEW_LOGGING ? 
- The severity levels would be mapped to different syslog
  levels, if syslog is enabled.

If anything more complicated is needed, we can worry about
that later rather than introducing something too complex and
later abandoning it, like NEW_LOGGING.

--
 -- Howard Chu
 Chief Architect, Symas Corp.  http://www.symas.com
 Director, Highland Sun        http://highlandsun.com/hyc
 OpenLDAP Core Team            http://www.openldap.org/project/