Global Hooks Proposal

Background

DJ 2.1 introduced a callback mechanism, allowing jobs to receive notifications at various points in the lifecycle. While useful, this is limited in that the callback methods need to be implemented on a job class, can't be used by PerformableMethod, and have to be implemented/mixed in to each Job class individually.

Proposal

Global hooks would simplify most callback use cases and allow straightforward integration of third-party tools (Hoptoad, stats tracking, etc) while still providing custom behavior on a per-job basis.

Configuration

Global hooks are configured at the worker level using a block which receives the job.

Delayed::Worker.hook :name, lambda {|job| ... }

Multiple blocks can be configured as a chain and will be executed in the order defined.

Delayed::Worker.hook :name, lambda{|job| puts "First"}

Delayed::Worker.hook :name, lambda{|job| puts "Second"}

Global hooks have the same names as the callback methods on the job class (before, success, after, error, etc).

Behavior Notes

• job-specific hooks should be invoked before global hooks.

Questions

• Should global hooks be cancelable by returning false from a job hook?
• Should global hook blocks in the chain be allowed to cancel execution like rails filter chains?