Retriable gem の使い方のめも

• GitHub - kamui/retriable: Retriable is an simple DSL to retry failed code blocks with randomized exponential backoff.

インストール

$ gem install retriable

実装例

require 'retriable'

class SampleError < RuntimeError
end

puts <<~EOS
  | exception       | try | elapsed_time | time         |
  |-----------------|-----|--------------|--------------|
EOS

Retriable.configure do |c|
  c.tries = 5
  c.base_interval = 1
  c.rand_factor = 0
  c.on = SampleError
  c.on_retry = -> (exception, try, elapsed_time, next_interval) {
    puts format('| %-15s | %3d | %12f | %-12s |', exception, try, elapsed_time, Time.now.strftime('%H:%M:%S.%L'))
  }
end

begin
  Retriable.retriable do |try|
    raise SampleError if try < 5
  end
  puts format('| %-15s | --- | ------------ | %-12s |', 'done', Time.now.strftime('%H:%M:%S.%L'))
rescue SampleError => e
  puts format('| %-15s | --- | ------------ | %-12s |', e, Time.now.strftime('%H:%M:%S.%L'))
end

実行。

$ ruby samle.rb
| exception       | try | elapsed_time | time         |
|-----------------|-----|--------------|--------------|
| SampleError     |   1 |     0.000040 | 13:29:53.806 |
| SampleError     |   2 |     1.005182 | 13:29:54.811 |
| SampleError     |   3 |     2.508871 | 13:29:56.315 |
| SampleError     |   4 |     4.764138 | 13:29:58.570 |
| done            | --- | ------------ | 13:30:01.948 |

リトライ回数を 3 回にしてみます。

# 略

Retriable.configure do |c|
  c.tries = 3
  # 略
end

# 略

実行。

$ ruby sample.rb 
| exception       | try | elapsed_time | time         |
|-----------------|-----|--------------|--------------|
| SampleError     |   1 |     0.000041 | 13:35:22.001 |
| SampleError     |   2 |     1.000827 | 13:35:23.002 |
| SampleError     |   3 |     2.501092 | 13:35:24.502 |
| SampleError     | --- | ------------ | 13:35:24.502 |