Class: Brow::BackoffPolicy

Inherits:
Object
  • Object
show all
Defined in:
lib/brow/backoff_policy.rb

Constant Summary collapse

MIN_TIMEOUT_MS =

Private: The default minimum timeout between intervals in milliseconds.

100
MAX_TIMEOUT_MS =

Private: The default maximum timeout between intervals in milliseconds.

10_000
MULTIPLIER =

Private: The value to multiply the current interval with for each retry attempt.

1.5
RANDOMIZATION_FACTOR =

Private: The randomization factor to use to create a range around the retry interval.

0.5

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ BackoffPolicy

Public: Create new instance of backoff policy.

options - The Hash of options.

:min_timeout_ms - The minimum backoff timeout.
:max_timeout_ms - The maximum backoff timeout.
:multiplier - The value to multiply the current interval with for each
              retry attempt.
:randomization_factor - The randomization factor to use to create a range
                        around the retry interval.



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# File 'lib/brow/backoff_policy.rb', line 34

def initialize(options = {})
  @min_timeout_ms = options.fetch(:min_timeout_ms) {
    ENV.fetch("BROW_BACKOFF_MIN_TIMEOUT_MS", MIN_TIMEOUT_MS).to_i
  }
  @max_timeout_ms = options.fetch(:max_timeout_ms) {
    ENV.fetch("BROW_BACKOFF_MAX_TIMEOUT_MS", MAX_TIMEOUT_MS).to_i
  }
  @multiplier = options.fetch(:multiplier) {
    ENV.fetch("BROW_BACKOFF_MULTIPLIER", MULTIPLIER).to_f
  }
  @randomization_factor = options.fetch(:randomization_factor) {
    ENV.fetch("BROW_BACKOFF_RANDOMIZATION_FACTOR", RANDOMIZATION_FACTOR).to_f
  }

  unless @min_timeout_ms >= 0
    raise ArgumentError, ":min_timeout_ms must be >= 0 but was #{@min_timeout_ms.inspect}"
  end

  unless @max_timeout_ms >= 0
    raise ArgumentError, ":max_timeout_ms must be >= 0 but was #{@max_timeout_ms.inspect}"
  end

  unless @min_timeout_ms <= max_timeout_ms
    raise ArgumentError, ":min_timeout_ms (#{@min_timeout_ms.inspect}) must be <= :max_timeout_ms (#{@max_timeout_ms.inspect})"
  end

  @attempts = 0
end

Instance Attribute Details

#attempts ⇒ Object (readonly)

Private



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# File 'lib/brow/backoff_policy.rb', line 23

def attempts
  @attempts
end

#max_timeout_ms ⇒ Object (readonly)

Private



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# File 'lib/brow/backoff_policy.rb', line 20

def max_timeout_ms
  @max_timeout_ms
end

#min_timeout_ms ⇒ Object (readonly)

Private



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# File 'lib/brow/backoff_policy.rb', line 20

def min_timeout_ms
  @min_timeout_ms
end

#multiplier ⇒ Object (readonly)

Private



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# File 'lib/brow/backoff_policy.rb', line 20

def multiplier
  @multiplier
end

#randomization_factor ⇒ Object (readonly)

Private



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# File 'lib/brow/backoff_policy.rb', line 20

def randomization_factor
  @randomization_factor
end

Instance Method Details

#next_interval ⇒ Object

Public: Returns the next backoff interval in milliseconds.



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# File 'lib/brow/backoff_policy.rb', line 64

def next_interval
  interval = @min_timeout_ms * (@multiplier**@attempts)
  interval = add_jitter(interval, @randomization_factor)

  @attempts += 1

  [interval, @max_timeout_ms].min
end

#reset ⇒ Object 



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# File 'lib/brow/backoff_policy.rb', line 73

def reset
  @attempts = 0
end