Class: ActiveJob::Continuation::Step

Inherits:
Object
  • Object
show all
Defined in:
lib/active_job/continuation/step.rb

Overview

Active Job Continuation Step

Represents a step within a continuable job.

When a step is completed, it is recorded in the job’s continuation state. If the job is interrupted, it will be resumed from after the last completed step.

Steps also have an optional cursor that can be used to track progress within the step. If a job is interrupted during a step, the cursor will be saved and passed back when the job is resumed.

It is the responsibility of the code in the step to use the cursor correctly to resume from where it left off.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(name, cursor, job:, resumed:) ⇒ Step

Returns a new instance of Step.



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# File 'lib/active_job/continuation/step.rb', line 25

def initialize(name, cursor, job:, resumed:)
  @name = name.to_sym
  @initial_cursor = cursor
  @cursor = cursor
  @resumed = resumed
  @job = job
end

Instance Attribute Details

#cursor ⇒ Object (readonly)

The cursor for the step.



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# File 'lib/active_job/continuation/step.rb', line 23

def cursor
  @cursor
end

#name ⇒ Object (readonly)

The name of the step.



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# File 'lib/active_job/continuation/step.rb', line 20

def name
  @name
end

Instance Method Details

#advance!(from: nil) ⇒ Object

Advance the cursor from the current or supplied value

The cursor will be advanced by calling the succ method on the cursor. An UnadvanceableCursorError error will be raised if the cursor does not implement succ.



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# File 'lib/active_job/continuation/step.rb', line 49

def advance!(from: nil)
  from = cursor if from.nil?

  begin
    to = from.succ
  rescue NoMethodError
    raise UnadvanceableCursorError, "Cursor class '#{from.class}' does not implement 'succ'"
  end

  set! to
end

#advanced? ⇒ Boolean

Has the cursor been advanced during this job execution?

Returns:

  • (Boolean) 


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# File 'lib/active_job/continuation/step.rb', line 67

def advanced?
  initial_cursor != cursor
end

#checkpoint! ⇒ Object

Check if the job should be interrupted, and if so raise an Interrupt exception. The job will be requeued for retry.



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# File 'lib/active_job/continuation/step.rb', line 35

def checkpoint!
  job.checkpoint!
end

#description ⇒ Object 



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# File 'lib/active_job/continuation/step.rb', line 75

def description
  "at '#{name}', cursor '#{cursor.inspect}'"
end

#resumed? ⇒ Boolean

Has this step been resumed from a previous job execution?

Returns:

  • (Boolean) 


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# File 'lib/active_job/continuation/step.rb', line 62

def resumed?
  @resumed
end

#set!(cursor) ⇒ Object

Set the cursor and interrupt the job if necessary.



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# File 'lib/active_job/continuation/step.rb', line 40

def set!(cursor)
  @cursor = cursor
  checkpoint!
end

#to_a ⇒ Object 



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# File 'lib/active_job/continuation/step.rb', line 71

def to_a
  [ name.to_s, cursor ]
end