Class: Hungrytable::CircuitBreaker

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

Overview

Circuit Breaker pattern to prevent cascading failures when API is down

States:

  • CLOSED: Normal operation, requests pass through
  • OPEN: Too many failures, requests fail immediately
  • HALF_OPEN: Testing if service recovered

Usage:

Hungrytable::CircuitBreaker.call do
# Make API request
end

Defined Under Namespace

Classes: CircuitOpenError

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ CircuitBreaker

Returns a new instance of CircuitBreaker.



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# File 'lib/hungrytable/circuit_breaker.rb', line 75

def initialize
  @state = :closed
  @failure_count = 0
  @success_count = 0
  @last_failure_time = nil
  @mutex = Mutex.new

  # Default configuration
  @config = {
    failure_threshold: 5,     # Open after 5 failures
    timeout: 60,              # Try again after 60 seconds
    success_threshold: 2      # Close after 2 successes in half-open
  }
end

Instance Attribute Details

#failure_count ⇒ Object (readonly)

Returns the value of attribute failure_count.



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# File 'lib/hungrytable/circuit_breaker.rb', line 73

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/hungrytable/circuit_breaker.rb', line 73

def last_failure_time
  @last_failure_time
end

#state ⇒ Object (readonly)

Returns the value of attribute state.



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# File 'lib/hungrytable/circuit_breaker.rb', line 73

def state
  @state
end

#success_count ⇒ Object (readonly)

Returns the value of attribute success_count.



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# File 'lib/hungrytable/circuit_breaker.rb', line 73

def success_count
  @success_count
end

Class Method Details

.call { ... } ⇒ Object

Execute a block with circuit breaker protection

Yields:

  • Block to execute

Returns:

  • Result of the block

Raises:



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# File 'lib/hungrytable/circuit_breaker.rb', line 27

def call(&block)
  instance.call(&block)
end

.configure(failure_threshold: 5, timeout: 60, success_threshold: 2) ⇒ Object

Configure circuit breaker

Parameters:

  • failure_threshold (Integer) (defaults to: 5) —

    Number of failures before opening

  • timeout (Integer) (defaults to: 60) —

    Seconds to wait before entering half-open state

  • success_threshold (Integer) (defaults to: 2) —

    Successes needed in half-open to close



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# File 'lib/hungrytable/circuit_breaker.rb', line 58

def configure(failure_threshold: 5, timeout: 60, success_threshold: 2)
  instance.configure(
    failure_threshold: failure_threshold,
    timeout: timeout,
    success_threshold: success_threshold
  )
end

.open? ⇒ Boolean

Check if circuit is open

Returns:

  • (Boolean) 


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# File 'lib/hungrytable/circuit_breaker.rb', line 33

def open?
  instance.open?
end

.reset! ⇒ Object

Reset the circuit breaker



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# File 'lib/hungrytable/circuit_breaker.rb', line 50

def reset!
  instance.reset!
end

.state ⇒ Symbol

Get current state

Returns:

  • (Symbol) —

    :closed, :open, or :half_open



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

def state
  instance.state
end

.stats ⇒ Hash

Get circuit breaker statistics

Returns:

  • (Hash) —

    statistics



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# File 'lib/hungrytable/circuit_breaker.rb', line 45

def stats
  instance.stats
end

Instance Method Details

#call ⇒ Object 



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

def call
  @mutex.synchronize do
    check_state_transition

    if @state == :open
      raise CircuitOpenError
    end
  end

  begin
    result = yield
    record_success
    result
  rescue UnauthorizedError, ServerError, HTTPError => e
    record_failure
    raise e
  end
end

#configure(failure_threshold: nil, timeout: nil, success_threshold: nil) ⇒ Object 



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# File 'lib/hungrytable/circuit_breaker.rb', line 90

def configure(failure_threshold: nil, timeout: nil, success_threshold: nil)
  @mutex.synchronize do
    @config[:failure_threshold] = failure_threshold if failure_threshold
    @config[:timeout] = timeout if timeout
    @config[:success_threshold] = success_threshold if success_threshold
  end
end

#open? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/hungrytable/circuit_breaker.rb', line 117

def open?
  @state == :open
end

#reset! ⇒ Object 



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# File 'lib/hungrytable/circuit_breaker.rb', line 131

def reset!
  @mutex.synchronize do
    @state = :closed
    @failure_count = 0
    @success_count = 0
    @last_failure_time = nil
  end
end

#stats ⇒ Object 



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# File 'lib/hungrytable/circuit_breaker.rb', line 121

def stats
  {
    state: @state,
    failure_count: @failure_count,
    success_count: @success_count,
    last_failure_time: @last_failure_time,
    config: @config
  }
end