Re: [Condor-users] does dagman support the trigger condition ?

["R. Kent Wenger" <wenger@xxxxxxxxxxx>]

On Thu, 10 Jul 2008, zhang SunMoonStar wrote:

>  thanks  very much！ i found that the source of dagman was wriiten by 
> you.
Well, a number of people have worked on DAGMan.

>     the first question i asked is that if the dag graph supports the
> true-false trigger. e.g:  if the parent node A returns 0(true), then run 
> the child node B，else if the return value is 1(false),then run the 
> child C,not B.
> does dagman support the above situation?
Ah, I misunderstood what you meant by a trigger.  DAGMan does not 
*directly* support what you want to do, but you can implement this 
behavior by using POST scripts.  The way DAGMan works is that if a node 
returns a non-zero exit value, that node is considered failed and no 
children of that node will be run.  But a POST script can alter the return 
value of a node from what the actual node job returns.
So what you want to do is this:  your POST script should change the submit 
file of the next node according to the return value from the current 
node's job.  You can pass the job's exit code to the POST script using the 
$RETURN macro as an argument to the POST script.  Then the POST script 
should return an exit value of 0 so the DAG continues.
So you want something like this:

    JOB A A.submit
    SCRIPT POST A change_node_B $RETURN

    JOB B B.submit

    PARENT A CHILD B

Probably the simplest thing is to have two versions of B.submit, one for 
an exit code of 0, and one with an exit code of 1.  There are a couple of 
caveats here:
* B.submit must exist at the time the DAG is submitted (but it's okay to
change it during the DAG execution).

* But -- the changed version of B.submit must have the same log file
as the original version.

Hopefully that all makes sense.

Kent Wenger
Condor Team