Class: Hedra::CircuitBreaker

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

Overview

Circuit breaker pattern to prevent cascading failures

Constant Summary collapse

FAILURE_THRESHOLD = 
5
TIMEOUT_SECONDS = 
60
HALF_OPEN_ATTEMPTS = 
3

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(failure_threshold: FAILURE_THRESHOLD, timeout: TIMEOUT_SECONDS) ⇒ CircuitBreaker

Returns a new instance of CircuitBreaker.



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

def initialize(failure_threshold: FAILURE_THRESHOLD, timeout: TIMEOUT_SECONDS)
  @failure_threshold = failure_threshold
  @timeout = timeout
  @failure_count = 0
  @last_failure_time = nil
  @state = :closed
  @half_open_attempts = 0
end

Instance Attribute Details

#failure_count ⇒ Object (readonly)

Returns the value of attribute failure_count.



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# File 'lib/hedra/circuit_breaker.rb', line 10

def failure_count
  @failure_count
end

#last_failure_time ⇒ Object (readonly)

Returns the value of attribute last_failure_time.



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# File 'lib/hedra/circuit_breaker.rb', line 10

def last_failure_time
  @last_failure_time
end

#state ⇒ Object (readonly)

Returns the value of attribute state.



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# File 'lib/hedra/circuit_breaker.rb', line 10

def state
  @state
end

Instance Method Details

#call ⇒ Object

Raises:



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# File 'lib/hedra/circuit_breaker.rb', line 21

def call
  raise CircuitOpenError, 'Circuit breaker is open' if open? && !should_attempt_reset?

  if open? && should_attempt_reset?
    @state = :half_open
    @half_open_attempts = 0
  end

  begin
    result = yield
    on_success
    result
  rescue StandardError => e
    on_failure
    raise e
  end
end

#closed? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/hedra/circuit_breaker.rb', line 43

def closed?
  @state == :closed
end

#half_open? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/hedra/circuit_breaker.rb', line 47

def half_open?
  @state == :half_open
end

#open? ⇒ Boolean

Returns:

  • (Boolean) 


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

def open?
  @state == :open
end