It looks like Kohsuke already did some work on this. https://github.com/jenkinsci/jenkins/commit/a31a186b264cc95776fb5056edea3eef 8df681a7
-- Dean On 4/8/12 7:37 PM , "Ryan Campbell" <[email protected]> wrote: > We would like to slightly randomize the crontabs in Jenkins for > DEV@Cloud so that when people all set their jobs to run @midnight, we > don't have thousands of slaves launch. Instead we want @midnight to > mean "once a day -- most likely not midnight' and perhaps let people > use a tag in the comments of a crontab line (like #exactly) if they > really need a job to run exactly at midnight. But most people don't > need this. > > Looking at how Crontabs work in Jenkins, I see that the expressions > are compiled using ANTLR into an array of Longs (and one Int) which > are used as bit arrays, with each bit specifying that a cron should be > triggered at that time for a given unit of measure. Right? > > So we want to do a random circular bit shift on each unit of measure. > Something like rotateRight(bitarray,rand(UOM_MAX),UOM_MAX) so that > (say) for the hour unit of measure, we would shuffle around everyone's > 0x1 @midnight bit randomly, but still preserve any intervals between > the bits (and hence the "spirit" of the cron). > > What I'm coming to is that I think I need a new extension point to > make this happen. I think the ideal signature would look like this: > > @Extension > public abstract class CronOverrider { > > /** Called when creating the context from a form submission or in readResolve > public abstract CrontabList override (CrontabList list, Object context); > } > > This (my approach) also requires an extra constructor of CronTab so > that you can create them from raw bit arrays instead of having to pass > in the expressions. > > So I can work up a patch, but wanted to see if people think this is > stupid for some reason. > > Ryan
