Class: Gcloud::Backoff

Inherits:
Object
  • Object
show all
Defined in:
lib/gcloud/backoff.rb

Overview

Backoff allows users to control how Google API calls are retried. If an API call fails the response will be checked to see if the call can be retried. If the response matches the criteria, then it will be retried with an incremental backoff. This means that an increasing delay will be added between each retried call. The first retry will be delayed one second, the second retry will be delayed two seconds, and so on.

require "gcloud/backoff"

Gcloud::Backoff.retries = 5 # Set a maximum of five retries per call

Class Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(options = {}) ⇒ Backoff

Creates a new Backoff object to catch common errors when calling the Google API and handle the error by retrying the call.

Gcloud::Backoff.new(options).execute do
  client.execute api_method: service.things.insert,
                 parameters: { thing: @thing },
                 body_object: { name: thing_name }
end



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# File 'lib/gcloud/backoff.rb', line 75

def initialize options = {} #:nodoc:
  @max_retries  = (options[:retries]    || Backoff.retries).to_i
  @http_codes   = (options[:http_codes] || Backoff.http_codes).to_a
  @reasons      = (options[:reasons]    || Backoff.reasons).to_a
  @backoff      =  options[:backoff]    || Backoff.backoff
end

Class Attribute Details

.backoff ⇒ Object

The code to run when a backoff is handled. This must be a Proc and must take the number of retries as an argument.

Note: This method is undocumented and may change.



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# File 'lib/gcloud/backoff.rb', line 58

def backoff
  @backoff
end

.http_codes ⇒ Object

The HTTP Status Codes that should be retried.

The default values are 500 and 503.



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# File 'lib/gcloud/backoff.rb', line 43

def http_codes
  @http_codes
end

.reasons ⇒ Object

The Google API error reasons that should be retried.

The default values are rateLimitExceeded and userRateLimitExceeded.



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# File 'lib/gcloud/backoff.rb', line 50

def reasons
  @reasons
end

.retries ⇒ Object

The number of times a retriable API call should be retried.

The default value is 3.



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# File 'lib/gcloud/backoff.rb', line 37

def retries
  @retries
end

Instance Method Details

#execute ⇒ Object

:nodoc:



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# File 'lib/gcloud/backoff.rb', line 82

def execute #:nodoc:
  current_retries = 0
  loop do
    result = yield # Expecting Google::APIClient::Result
    return result if result.success?
    break result unless retry? result, current_retries
    current_retries += 1
    @backoff.call current_retries
  end
end