Class: Expeditor::Service

Inherits:
Object
  • Object
show all
Defined in:
lib/expeditor/service.rb

Direct Known Subclasses

Expeditor::Services::Default

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(opts = {}) ⇒ Service

Returns a new instance of Service.



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# File 'lib/expeditor/service.rb', line 8

def initialize(opts = {})
  @mutex = Mutex.new
  @executor = opts.fetch(:executor) { Concurrent::ThreadPoolExecutor.new }
  @threshold = opts.fetch(:threshold, 0.5)
  @non_break_count = opts.fetch(:non_break_count, 20)
  @sleep = opts.fetch(:sleep, 1)
  granularity = 10
  @rolling_number_opts = {
    size: granularity,
    per_time: opts.fetch(:period, 10).to_f / granularity
  }
  reset_status!
  @fallback_enabled = true
end

Instance Attribute Details

#executor ⇒ Object (readonly)

Returns the value of attribute executor.



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# File 'lib/expeditor/service.rb', line 5

def executor
  @executor
end

#fallback_enabled ⇒ Object

Returns the value of attribute fallback_enabled.



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# File 'lib/expeditor/service.rb', line 6

def fallback_enabled
  @fallback_enabled
end

Instance Method Details

#break ⇒ Object 



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# File 'lib/expeditor/service.rb', line 39

def break
  @rolling_number.increment :break
end

#breaking? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/expeditor/service.rb', line 51

def breaking?
  @breaking
end

#current_status ⇒ Object

Deprecated.

Use ‘#status` instead.



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# File 'lib/expeditor/service.rb', line 104

def current_status
  warn 'Expeditor::Service#current_status is deprecated. Please use #status instead.'
  @rolling_number.current
end

#dependency ⇒ Object 



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# File 'lib/expeditor/service.rb', line 43

def dependency
  @rolling_number.increment :dependency
end

#failure ⇒ Object 



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# File 'lib/expeditor/service.rb', line 27

def failure
  @rolling_number.increment :failure
end

#fallback_enabled? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/expeditor/service.rb', line 47

def fallback_enabled?
  !!fallback_enabled
end

#rejection ⇒ Object 



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# File 'lib/expeditor/service.rb', line 31

def rejection
  @rolling_number.increment :rejection
end

#reset_status! ⇒ Object 



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# File 'lib/expeditor/service.rb', line 109

def reset_status!
  @mutex.synchronize do
    @rolling_number = Expeditor::RollingNumber.new(**@rolling_number_opts)
    @breaking = false
    @break_start = nil
  end
end

#run_if_allowed ⇒ Object

Run given block when the request is allowed, otherwise raise Expeditor::CircuitBreakError. When breaking and sleep time was passed, the circuit breaker tries to close the circuit. So subsequent single command execution is allowed (will not be breaked) to check the service is healthy or not. The circuit breaker only allows one request so other subsequent requests will be aborted with CircuitBreakError. When the test request succeeds, the circuit breaker resets the service status and closes the circuit.



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# File 'lib/expeditor/service.rb', line 63

def run_if_allowed
  if @breaking
    now = Time.now

    # Only one thread can be allowed to execute single request when half-opened.
    allow_single_request = false
    @mutex.synchronize do
      allow_single_request = now - @break_start > @sleep
      @break_start = now if allow_single_request
    end

    if allow_single_request
      result = yield # This can be raise exception.
      # The execution succeed, then
      reset_status!
      result
    else
      raise CircuitBreakError
    end
  else
    open = calc_open
    if open
      change_state(true, Time.now)
      raise CircuitBreakError
    else
      yield
    end
  end
end

#shutdown ⇒ Object

shutdown thread pool after shutdown, if you create thread, RejectedExecutionError is raised.



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# File 'lib/expeditor/service.rb', line 95

def shutdown
  @executor.shutdown
end

#status ⇒ Object 



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# File 'lib/expeditor/service.rb', line 99

def status
  @rolling_number.total
end

#success ⇒ Object 



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# File 'lib/expeditor/service.rb', line 23

def success
  @rolling_number.increment :success
end

#timeout ⇒ Object 



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# File 'lib/expeditor/service.rb', line 35

def timeout
  @rolling_number.increment :timeout
end