Respawn

Yet another gem to retry failed operations.

Documentation is not yet available, as the API is not yet stable.

Call Respawn.try { ... } with a block of code to retry the logic if the code raises network/io related exception. Method .try accepts set of parameters, with the most important (and their corresponding defaults) being:

• tries: 5 How many times the code in block will be retried in case of detected failure. This is total number of tries, including the first one. Setting this value to 1 will cause the logic to be executed only once.

• wait: 0.5 How much time (in seconds) to wait between retries.

• ex: [...] List of exceptions which should be rescued for retry. By default the gem will detect common network / io related exceptions defined in the application. This will only happen once, on the first usage of the retry logic. The exception class must be defined at this moment. See the ExceptionDetector class for full list of currently predefined exceptions.

• onfail: :raise What should happen on the retry limit is reached and last retry resulted in exceptions. The default :raise means the final exception will be raised and it's up to the caller to either handle this case or simply let the default flow continue.

The onfail parameter can be on of the predefined symbols:

• :raise (default) Final exception will be raised. In usual context, the program (or request) will finish with error. If your application uses any kind of exception tracker, the error will get properly logged.

• :notify The error will be sent to default exception tracker using native method call. Gem will try to detect which exception tracker API is available in the application.

Basic usage based on specs:

Respawn.try do
  Faraday.get("https://example.com")
end

http_response = Data.define(:status, :body)

responses = [
  http_response.new(500, "error"),
  http_response.new(200, "error"),
  http_response.new(500, "error"),
  http_response.new(201, "created"),
]

predicates = [
  proc { it.status >= 500 },
  proc { it.body == "error" },
]

result =
  Respawn.try(onfail: :handler, predicate: predicats) do |handler|
    handler.define do |exception|
      "This failed due to #{exception.class}"
    end

    responses[handler.retry_number]
  end

expect(result).to eq http_response.new(201, "created")