[Package Signing] Make the Revalidate Certificate job initialize once per day

[loic-sharma]

The Job infrastructure used to call the job's Init method on each invocation of the job loop, which caused the Revalidate job to load secrets repeatedly. This change adds the option to have a minimum wait time in between a job's Init calls.

[scottbommarito]

To be honest, this seems like a hack around the job runner. With this change, the job is responsible for looping its code over and over again until it determines it has been running for too long and needs to initialize, which should be a responsibility of the job runner. Additionally, preventing config from being reloaded too frequently sounds like something that all jobs could benefit from.

I think a better change would be to add some sort of InitMinimumFrequencySeconds config that is used by JsonConfigurationJob or JobRunner itself to determine whether or not it needs to re-initialize.

[loic-sharma]

@scottbommarito I added ReinitializeAfterSeconds CLI argument that JobRunner uses to determine whether or not it should re-initialize.

[scottbommarito]

nit: you can make this one big boolean return!

(note: I changed the comment on the second condition)

return
    // If there is no wait time between reinitializations, always reinitialize.
    !reinitializeAfterSeconds.HasValue ||

    // A null time since last initialization indicates that the job hasn't been initialized yet.
    timeSinceInitialization == null ||

    // Otherwise, only reinitialize if the reinitialization threshold has been reached.
    (timeSinceInitialization.Elapsed.TotalSeconds > reinitializeAfterSeconds.Value);

[loic-sharma]

I considered that as well, but I think that it's a little easier to grok as it is.

[loic-sharma]

Updated the comment with the comment you suggested.