circuit_breaker

• http://github.com/wsargent/circuit_breaker
• http://rdoc.info/projects/wsargent/circuit_breaker
• Will Sargent will.sargent@gmail.com

CircuitBreaker is a relatively simple Ruby mixin that will wrap a call to a given service in a circuit breaker pattern.

The circuit starts off "closed" meaning that all calls will go through. However, consecutive failures are recorded and after a threshold is reached, the circuit will "trip", setting the circuit into an "open" state.

In an "open" state, every call to the service will fail by raising CircuitBrokenException.

The circuit will remain in an "open" state until the failure timeout has elapsed.

After the failure_timeout has elapsed, the circuit will go into a "half open" state and the call will go through. A failure will immediately pop the circuit open again, and a success will close the circuit and reset the failure count.

For services that can take an unmanagable amount of time to respond an invocation timeout threshold is provided. If the service fails to return before the invocation_timeout duration has passed, the circuit will "trip", setting the circuit into an "open" state.

require 'circuit_breaker'
class TestService
  include CircuitBreaker

  def call_remote_service() ...

  circuit_method :call_remote_service

  # Optional
  circuit_handler do |handler|
    handler.logger = Logger.new(STDOUT)
    handler.failure_threshold = 5
    handler.failure_timeout = 5
    handler.invocation_timeout = 10
    handler.excluded_exceptions = [NotConsideredFailureException]
  end

  # Optional
  circuit_handler_class MyCustomCircuitHandler
end

• Can run out of the box with minimal dependencies and a couple of lines of code.
• Easy to extend: add your own circuit breakers or states or extend the existing ones.
• Does not currently handle static class methods.

An implementation of Michael Nygard's Circuit Breaker pattern.

circuit_breaker has a dependency on AASM @ http://github.com/rubyist/aasm/tree/master

• gem install circuit_breaker

Copyright (c) 2016, Will Sargent All rights reserved.

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