Class: Semian::CircuitBreaker

Inherits:
Object
  • Object
show all
Extended by:
Forwardable
Includes:
CircuitBreakerBehaviour
Defined in:
lib/semian/circuit_breaker.rb

Overview

:nodoc:

Instance Attribute Summary collapse

Attributes included from CircuitBreakerBehaviour

#exceptions, #last_error, #name

Instance Method Summary collapse

Methods included from CircuitBreakerBehaviour

#closed?, #half_open?, #initialize_behaviour, #open?

Constructor Details

#initialize(name, exceptions:, success_threshold:, error_threshold:, error_timeout:, implementation:, half_open_resource_timeout: nil, error_threshold_timeout: nil, error_threshold_timeout_enabled: true, lumping_interval: 0, exponential_backoff_error_timeout: false, exponential_backoff_initial_timeout: 1, exponential_backoff_multiplier: 2) ⇒ CircuitBreaker

Returns a new instance of CircuitBreaker.



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# File 'lib/semian/circuit_breaker.rb', line 22

def initialize(name, exceptions:, success_threshold:, error_threshold:,
  error_timeout:, implementation:, half_open_resource_timeout: nil,
  error_threshold_timeout: nil, error_threshold_timeout_enabled: true,
  lumping_interval: 0, exponential_backoff_error_timeout: false,
  exponential_backoff_initial_timeout: 1, exponential_backoff_multiplier: 2)
  initialize_behaviour(name: name)

  @exceptions = exceptions
  @success_count_threshold = success_threshold
  @error_count_threshold = error_threshold
  @error_threshold_timeout = error_threshold_timeout || error_timeout
  @error_threshold_timeout_enabled = error_threshold_timeout_enabled.nil? ? true : error_threshold_timeout_enabled
  @error_timeout = error_timeout
  @half_open_resource_timeout = half_open_resource_timeout
  @lumping_interval = lumping_interval
  @exponential_backoff_error_timeout = exponential_backoff_error_timeout
  @exponential_backoff_initial_timeout = exponential_backoff_initial_timeout
  @exponential_backoff_multiplier = exponential_backoff_multiplier
  @current_error_timeout = exponential_backoff_error_timeout ? exponential_backoff_initial_timeout : error_timeout

  @errors = implementation::SlidingWindow.new(max_size: @error_count_threshold)
  @successes = implementation::Integer.new
  @state = implementation::State.new

  reset
end

Instance Attribute Details

#error_threshold_timeout_enabled ⇒ Object (readonly)

Returns the value of attribute error_threshold_timeout_enabled.



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# File 'lib/semian/circuit_breaker.rb', line 12

def error_threshold_timeout_enabled
  @error_threshold_timeout_enabled
end

#error_timeout ⇒ Object (readonly)

Returns the value of attribute error_timeout.



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# File 'lib/semian/circuit_breaker.rb', line 12

def error_timeout
  @error_timeout
end

#exponential_backoff_error_timeout ⇒ Object (readonly)

Returns the value of attribute exponential_backoff_error_timeout.



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# File 'lib/semian/circuit_breaker.rb', line 12

def exponential_backoff_error_timeout
  @exponential_backoff_error_timeout
end

#exponential_backoff_initial_timeout ⇒ Object (readonly)

Returns the value of attribute exponential_backoff_initial_timeout.



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# File 'lib/semian/circuit_breaker.rb', line 12

def exponential_backoff_initial_timeout
  @exponential_backoff_initial_timeout
end

#half_open_resource_timeout ⇒ Object (readonly)

Returns the value of attribute half_open_resource_timeout.



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# File 'lib/semian/circuit_breaker.rb', line 12

def half_open_resource_timeout
  @half_open_resource_timeout
end

#state ⇒ Object (readonly)

Returns the value of attribute state.



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# File 'lib/semian/circuit_breaker.rb', line 12

def state
  @state
end

Instance Method Details

#acquire(resource = nil, scope: nil, adapter: nil, &block) ⇒ Object

Raises:



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# File 'lib/semian/circuit_breaker.rb', line 49

def acquire(resource = nil, scope: nil, adapter: nil, &block)
  transition_to_half_open(scope: scope, adapter: adapter) if transition_to_half_open?

  raise OpenCircuitError unless request_allowed?

  result = nil
  begin
    result = maybe_with_half_open_resource_timeout(resource, &block)
  rescue *@exceptions => error
    if !error.respond_to?(:marks_semian_circuits?) || error.marks_semian_circuits?
      mark_failed(error, scope: scope, adapter: adapter)
    end
    raise error
  else
    mark_success(scope: scope, adapter: adapter)
  end
  result
end

#destroy ⇒ Object 



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# File 'lib/semian/circuit_breaker.rb', line 98

def destroy
  @errors.destroy
  @successes.destroy
  @state.destroy
end

#in_use? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/semian/circuit_breaker.rb', line 104

def in_use?
  !error_timeout_expired? && !@errors.empty?
end

#mark_failed(error, scope: nil, adapter: nil) ⇒ Object 



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# File 'lib/semian/circuit_breaker.rb', line 76

def mark_failed(error, scope: nil, adapter: nil)
  push_error(error)
  if closed?
    transition_to_open(scope: scope, adapter: adapter) if error_threshold_reached?
  elsif half_open?
    transition_to_open(scope: scope, adapter: adapter)
  end
end

#mark_success(scope: nil, adapter: nil) ⇒ Object 



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

def mark_success(scope: nil, adapter: nil)
  return unless half_open?

  @successes.increment
  transition_to_close(scope: scope, adapter: adapter) if success_threshold_reached?
end

#request_allowed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/semian/circuit_breaker.rb', line 72

def request_allowed?
  closed? || half_open? || transition_to_half_open?
end

#reset(scope: nil, adapter: nil) ⇒ Object 



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# File 'lib/semian/circuit_breaker.rb', line 92

def reset(scope: nil, adapter: nil)
  @errors.clear
  @successes.reset
  transition_to_close(scope: scope, adapter: adapter)
end

#transition_to_half_open? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/semian/circuit_breaker.rb', line 68

def transition_to_half_open?
  open? && error_timeout_expired? && !half_open?
end