syntax change proposal

[Martin Pala]

Hi,

i though about solution of event refactoring side effect - it is 
described in CHANGES.txt (in cvs):

--8<--
Monit doesn't reset checksum, timestamp, size, uid, gid or permission
value after detected failure. This way monit is able to watch for
value recovery - on the other side following construct behavior
changed:

CHECK FILE httpd.conf WITH PATH /usr/local/apache/conf/httpd.conf
 IF FAILED CHECKSUM THEN EXEC "/usr/local/apache/bin/apachectl graceful"

In previous monit version this configuration caused the apache reload
on monitored configuration file change. Then the value was reseted so
the test passed next cycles until the file was changed again.
Refactored event engine monitors for checksum value recovery, i.e 
whether it changed to the original value - in such case it will evaluate 
recovery action, otherwise the test keeps failed state. Because the 
value in this usage context will not correspond to the original, monit 
will evaluate action (reload apache) each cycle until the checksum will 
recover (which is unlikely for configuration file).
--8<--

Problem is in present syntax. I think it will be good to strictly 
separate 'changes' and 'failed' aimed tests, and generaly consolidate 
syntax like this:

(1) IF FAILED rule THEN action [ELSE IF RECOVERED THEN action]
(2) IF CHANGED rule THEN action

... in the case (1) will monit watch constant value of 'rule' in the 
failed/passed state sense.

... in the case (2) is monit aimed to changes only, i.e. the rule 
variable value is reseted and action evaluated each time its change is 
detected.


This will involve syntax change of 'checksum', 'size' and 'timestamp' 
tests syntax, which are ommiting FAILED word in the rule definition 
currently.

For example suppose timestamp test:

PRESENT SYNTAX:
  IF TIMESTAMP [CHANGED|operator NUMBER value] THEN action
 [ELSE IF RECOVERED THEN action]

PROPOSED SYNTAX:
1.) constant value test:
  IF FAILED TIMESTAMP [operator NUMBER value] THEN action
 [ELSE IF RECOVERED THEN action]

2.) variable value test (aimed to testing changes - value is reseted):
  IF CHANGED TIMESTAMP THEN action


What do you think?

Martin