switch_board

Description

SwitchBoard is a utility gem designed to help in the coordination of locked objects by a set of "lockers". Think of a bank's cashiers, where customers are in line to be served. When a customer is served by a cashier, it is still in line to be served, but is now "locked".

Locking expiration is allowed so that if during "serving" a cashier got some other business to do and runs home, it will go back to the queue when lock expires.

The overall scope of the gem is:

• Allow "lockers" to register themselves
• Allow "lockers" to set a "lock" on object, with a predefined expiration period
• Allow lockers with special "roles" to force locks
• Allow external observes to see current state of locked object

Features

The system is light weight and is designed to have low number of "lockers" with many object to be locked. It is pluggable and well tested so should allow extensions as needed.

Examples

  require 'switch_board'


  #create a new switch_board configuration
  sb = SwitchBoard::Configuration.new #Redis backends
  dataset = sb.dataset

  #Register Lockers (unique identifier, Name/Alias)
  dataset.register_locker(1, "Django")
  dataset.register_locker(2, "Pier")
  dataset.register_locker(3, "Mark")

  #Print out the list of active users
  p dataset.list_lockers

  #Lock IDs for Pier - IDed as 2
  dataset.lock_id(2, "qwerfggj", 5) # lock for 5 seconds
  dataset.lock_id(2, "12345", 600) #Lock for 10 minutes

  #Check to see if ID is locked
  dataset.id_locked?("12345") #=> true
  dataset.id_locked?("qwerfggj") #=> true
  dataset.id_locked?("not_locked_id") #=> false

  #Show all locked objects
  dataset.get_all_locked_ids #=> {"12345"=>"2", "qwerfggj"=>"2"}

Other Gems

Worth mentioning that there are other nice gems that takes care of Redis-backed Mutex implementaion:

• https://github.com/dv/redis-semaphore
• https://github.com/mlanett/redis-lock
• https://github.com/kenn/redis-mutex

However, this gem is not target a protection on specific a single resource during operation, instead it is targated to manage Distrbition of work between multiple clients/lockers that can take longer time to process the locked resources. It is also not targated for high scale systems, locking is done by humans so there is little to no risk in race conditions. And lastly, the gem provides an API to get all currently locked IDs which is important for the "switch_board" problem where some high level managment of the currently locked ID is needed.

Install

  $ gem install switch_board

Copyright

See LICENSE.txt for details.