class Mosquito::Queue

• Mosquito::Queue
• Reference
• Object

Overview

A named Queue.

Named Queues exist in Redis and have 4 ordered lists: waiting, pending, scheduled, and dead.

• The Waiting list is for jobs which need to be executed as soon as possible.
• The Pending list is for jobs which are currently being executed.
• The Scheduled list is indexed by execution time and holds jobs which need to be executed at a later time.
• The Dead list is for jobs which have been retried too many times and are no longer viable.

A task is represented in a queue by its id.

A task flows through the queues in this manner:

 Time=0: Task does not exist yet, lists are empty

   Waiting  Pending  Scheduled    Dead

 ---------------------------------
 Time=1: Task is enqueued

   Waiting  Pending  Scheduled    Dead
    Task#1

 ---------------------------------
 Time=2: Task begins running. Task is moved to pending and executed

   Waiting  Pending  Scheduled    Dead
             Task#1

 ---------------------------------
 Time=3: Tasks are Enqueued.

   Waiting  Pending  Scheduled    Dead
    Task#2   Task#1
    Task#3

 ---------------------------------
 Time=4: Task succeeds, next task begins.

   Waiting  Pending  Scheduled    Dead
    Task#3   Task#2

 ---------------------------------
 Time=5: Task fails and is scheduled for later, next task begins.

   Waiting  Pending  Scheduled     Dead
             Task#3  t=7:Task#2

 ---------------------------------
 Time=6: Task succeeds. Nothing is executing.

   Waiting  Pending  Scheduled     Dead
                     t=7:Task#2

 ---------------------------------
 Time=7: Scheduled task is due and is moved to waiting. Nothing is executing.

   Waiting  Pending  Scheduled     Dead
    Task#2

 ---------------------------------
 Time=8: Task begins executing (for the second time).

   Waiting  Pending  Scheduled     Dead
             Task#2

 ---------------------------------
 Time=9: Task finished successfully. No more tasks present.

   Waiting  Pending  Scheduled     Dead

Defined in:

mosquito/queue.cr

Constant Summary

ID_PREFIX = {"mosquito"}

QUEUES = ["waiting", "scheduled", "pending", "dead", "config"] of ::String

Constructors

• .new(name : String)

Class Method Summary

• .list_queues : Array(String)
• .redis_key(*parts)

Instance Method Summary

• #==(other : self) : Bool

  Returns true if this reference is the same as other.

• #banish(task : Task)
• #config_q
• #dead_q
• #dequeue : Task | Nil
• #dequeue_scheduled : Array(Task)
• #empty? : Bool
• #enqueue(task : Task, in interval : Time::Span)
• #enqueue(task : Task, at execute_time : Time)
• #enqueue(task : Task)
• #flush
• #forget(task : Task)
• #length : Int32

  TODO does this make sense?

• #name : String
• #pending_q
• #rate_limited? : Bool

  Determines if a task needs to be throttled and not dequeued

• #redis_key(*parts)
• #reschedule(task : Task, execution_time)
• #scheduled_q
• #waiting_q

Constructor Detail

Class Method Detail

Instance Method Detail