Add a documented way to select finished ecto queue jobs

[futpib]

I want to select all items that have been successfully processed by honeydew, I guessed by looking at the source code that I can use where([x], is_nil(x.honeydew_whatever_lock)) to do this, but this couples my code tightly against honeydew implementation details, I'd like a more "official" or "public" way to achieve this.

honeydew/lib/honeydew/sources/ecto_source.ex

Lines 8 to 14 in b60b639

	# 2. Indicates the status of the job, it can be either:
	# - "ready", between zero and SQL.ready()
	# - "delayed", between SQL.ready() and the beginning of the stale window
	# - "in progress", from now until now + stale_timeout
	# - "stale", within a year ago ago from now
	# - "abandoned", -1
	# - "finished", nil

A documented way to select jobs in a different state would be nice too, but this is not something I'm struggling with currently.

[koudelka]

Hey there. :)

What's your ideal API look like for this? An SQL fragment, or a function that adds a where clause to an Ecto query maybe?

[futpib]

Maybe a macro you can use in a where clause?

query
|> where([x], honeydew_is_finished(x, :classify_photos) and x.enabled == true)

It could expand into a right fragment.