retry
Retry an execution that terminates with an error
Overview
The Retry library provides basic retry functionality with a clear and simple API. It supports:
- Retrying on any error
- Retrying on a specific error
- Retrying based on a list of possible errors
- Retrying once or many times
- Backoff intervals that allow delaying between retries
Examples
Retry on Any Error
Any error will cause the block to retry. The block will only retry once.
tries = 0
Retry.() do
tries += 1
# RuntimeError will be raised during the first iteration
# The block will be executed once again without raising an error
# for a total of 2 executions
if tries == 1
raise RuntimeError
end
end
puts tries
# => 2Retry on a Specific Error
The block will be retried only if the specified error is raised in the block. The block will only retry once.
SomeError = Class.new(RuntimeError)
tries = 0
Retry.(SomeError) do
tries += 1
puts tries
# SomeError will be raised during the first iteration
# and the block will be executed once again
if tries == 1
raise SomeError
end
# Will raise RuntimeError in the second iteration
# RuntimeError is not retried, and so the program
# terminates with here RuntimeError
raise RuntimeError
end
# => 1
# => 2
# => RuntimeErrorRetry on Multiple Specific Errors
The block will be retried if any of the the specified errors are raised in the block. The block will only retry once.
SomeError = Class.new(RuntimeError)
SomeOtherError = Class.new(RuntimeError)
tries = 0
Retry.(SomeError, SomeOtherError) do
tries += 1
puts tries
# SomeOtherError will be raised during the first iteration
# and the block will be executed once again
if tries == 1
raise SomeOtherError
end
# Will raise RuntimeError in the second iteration
# RuntimeError is not retried, and so the program
# terminates here with RuntimeError
raise RuntimeError
end
# => 1
# => 2
# => RuntimeErrorRetry and Back Off
The millisecond_intervals parameter can be used without specifying a specific error, when specifying a specific error, or when specifying a list of possible errors.
The block will be retried up to the number of delay intervals specified.
SomeError = Class.new(RuntimeError)
SomeOtherError = Class.new(RuntimeError)
tries = 0
Retry.(SomeError, SomeOtherError, millisecond_intervals: [100, 200]) do
tries += 1
puts tries
raise SomeError
end
# => 1 (first attempt)
# => 2 (second attempt, after 100 ms delay)
# => 3 (third attempt, after 200 ms delay)
# => SomeErrorLicense
The retry library is released under the MIT License.
