retryable's Introduction

Kernel#retryable

PlEASE NOTE: Kernel#retryable has a new home!

Description

Runs a code block, and retries it when an exception occurs. It's great when working with flakey webservices (for example).

It's configured using two optional parameters --:tries and :on--, and runs the passed block. Should an exception occur, it'll retry for (n-1) times.

Should the number of retries be reached without success, the last exception will be raised.

Examples

Open an URL, retry up to two times when an OpenURI::HTTPError occurs.

require "retryable"
require "open-uri"

retryable( :tries => 3, :on => OpenURI::HTTPError ) do
  xml = open( "http://example.com/test.xml" ).read
end

Do something, retry up to four times for either ArgumentError or TimeoutError exceptions.

require "retryable"

retryable( :tries => 5, :on => [ ArgumentError, TimeoutError ] ) do
  # some crazy code
end

Defaults

:tries => 1, :on => Exception

Installation

First, make sure GitHub is a gem source. Then, install the gem:

sudo gem install carlo-retryable

Todo

Unit tests

Changelog

v1.2: FIX -- block would run twice when :tries was set to 0. (Thanks for the heads-up to Tuker.)

Thanks

Many thanks to Chu Yeow for this nifty piece of code. Look, I liked it enough to enhance it a little bit and build a gem from it! :)

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retryable's Issues

number of tries

shouldn't it be retry if (tries -= 1) > 1 instead of retry if (tries -= 1) > 0 ?

As it's written now, it does one extra try

>> retryable(:tries => 3) { puts "."; puts a }
.
.
.
.
NameError: undefined local variable or method `a' for #<Object:0x100177298>
    from (irb):5
    from /Users/barmstrong/NetBeansProjects/viper/lib/retryable.rb:14:in `retryable'
    from (irb):5

In any event, thanks for posting this we've found it super useful!

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