Class: Circuitbox::CircuitBreaker

Inherits:
Object
  • Object
show all
Defined in:
lib/circuitbox/circuit_breaker.rb

Constant Summary collapse

DEFAULTS = 
{
  sleep_window:     300,
  volume_threshold: 5,
  error_threshold:  50,
  timeout_seconds:  1,
  time_window:      60,
}

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(service, options = {}) ⇒ CircuitBreaker

Configuration options

‘sleep_window` - seconds to sleep the circuit `volume_threshold` - number of requests before error rate calculation occurs `error_threshold` - percentage of failed requests needed to trip circuit `timeout_seconds` - seconds until it will timeout the request `exceptions` - exceptions other than Timeout::Error that count as failures `time_window` - interval of time used to calculate error_rate (in seconds) - default is 60s `logger` - Logger to use - defaults to Rails.logger if defined, otherwise STDOUT



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# File 'lib/circuitbox/circuit_breaker.rb', line 25

def initialize(service, options = {})
  @service = service
  @circuit_options = options
  @circuit_store   = options.fetch(:cache) { Circuitbox.circuit_store }
  @notifier        = options.fetch(:notifier_class) { Notifier }

  @exceptions = options.fetch(:exceptions) { [] }
  @exceptions = [Timeout::Error] if @exceptions.blank?

  @logger     = options.fetch(:logger) { defined?(Rails) ? Rails.logger : Logger.new(STDOUT) }
  @time_class   = options.fetch(:time_class) { Time }
  sanitize_options
end

Instance Attribute Details

#circuit_options ⇒ Object

Returns the value of attribute circuit_options.



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# File 'lib/circuitbox/circuit_breaker.rb', line 3

def circuit_options
  @circuit_options
end

#circuit_store ⇒ Object

Returns the value of attribute circuit_store.



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# File 'lib/circuitbox/circuit_breaker.rb', line 3

def circuit_store
  @circuit_store
end

#exceptions ⇒ Object

Returns the value of attribute exceptions.



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# File 'lib/circuitbox/circuit_breaker.rb', line 3

def exceptions
  @exceptions
end

#logger ⇒ Object

Returns the value of attribute logger.



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# File 'lib/circuitbox/circuit_breaker.rb', line 3

def logger
  @logger
end

#notifier ⇒ Object

Returns the value of attribute notifier.



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# File 'lib/circuitbox/circuit_breaker.rb', line 3

def notifier
  @notifier
end

#partition ⇒ Object

Returns the value of attribute partition.



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# File 'lib/circuitbox/circuit_breaker.rb', line 3

def partition
  @partition
end

#service ⇒ Object

Returns the value of attribute service.



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# File 'lib/circuitbox/circuit_breaker.rb', line 3

def service
  @service
end

Instance Method Details

#error_rate(failures = failure_count, success = success_count) ⇒ Object 



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# File 'lib/circuitbox/circuit_breaker.rb', line 95

def error_rate(failures = failure_count, success = success_count)
  all_count = failures + success
  return 0.0 unless all_count > 0
  failure_count.to_f / all_count.to_f * 100
end

#failure_count ⇒ Object 



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# File 'lib/circuitbox/circuit_breaker.rb', line 101

def failure_count
  circuit_store.load(stat_storage_key(:failure), raw: true).to_i
end

#open? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/circuitbox/circuit_breaker.rb', line 85

def open?
  if open_flag?
    true
  elsif passed_volume_threshold? && passed_rate_threshold?
    true
  else
    false
  end
end

#option_value(name) ⇒ Object 



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# File 'lib/circuitbox/circuit_breaker.rb', line 39

def option_value(name)
  value = circuit_options.fetch(name) { DEFAULTS.fetch(name) }
  value.is_a?(Proc) ? value.call : value
end

#run(run_options = {}) ⇒ Object 



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# File 'lib/circuitbox/circuit_breaker.rb', line 77

def run(run_options = {})
  begin
    run!(run_options, &Proc.new)
  rescue Circuitbox::Error
    nil
  end
end

#run!(run_options = {}) ⇒ Object 



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# File 'lib/circuitbox/circuit_breaker.rb', line 44

def run!(run_options = {})
  @partition = run_options.delete(:partition) # sorry for this hack.

  if open?
    logger.debug "[CIRCUIT] open: skipping #{service}"
    open! unless open_flag?
    skipped!
    raise Circuitbox::OpenCircuitError.new(service)
  else
    close! if was_open?
    logger.debug "[CIRCUIT] closed: querying #{service}"

    begin
      response = if exceptions.include? Timeout::Error
        timeout_seconds = run_options.fetch(:timeout_seconds) { option_value(:timeout_seconds) }
        timeout (timeout_seconds) { yield }
      else
        yield
      end

      logger.debug "[CIRCUIT] closed: #{service} querie success"
      success!
    rescue *exceptions => exception
      logger.debug "[CIRCUIT] closed: detected #{service} failure"
      failure!
      open! if half_open?
      raise Circuitbox::ServiceFailureError.new(service, exception)
    end
  end

  return response
end

#success_count ⇒ Object 



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# File 'lib/circuitbox/circuit_breaker.rb', line 105

def success_count
  circuit_store.load(stat_storage_key(:success), raw: true).to_i
end

#try_close_next_time ⇒ Object 



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# File 'lib/circuitbox/circuit_breaker.rb', line 109

def try_close_next_time
  circuit_store.delete(storage_key(:asleep))
end