tlopo-ruby/tlopo-retry

# tlopo-retry
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A reusable retry mechanism which supports exponential backoff

## Installation

A simple `gem install tlopo-retry` will do

## Usage

Retry accepts 4 parameters: 
* `tries` : number of attempts, default: `3`
*  `interval` : time in between attempts in seconds, default: `1` (float is accepted but be aware of it's effect when using exponential backoff)
*  `error_types`: a list of error types to retry on, default: `[StandardError]`
*  `exponential_backoff`: when true the interval will be raised to the power of current count, default: `false`
  

Full retry usage 

```ruby
require 'socket'
require 'logger'
require 'tlopo/retry'

LOGGER = Logger.new $stdout

count = 1
Tlopo::Retry.new(tries: 3, interval: 2, exponential_backoff: true, error_types: [ IO::TimeoutError ]).run do 
  LOGGER.info "Trying #{count}"
  count += 1
  TCPSocket.new('www.google.co.uk','8080', connect_timeout: 1).close
end
```
## Tips

### Float interval < 1 with exponential backoff

It may not be intuitive, but when using a float less than 1 for the interval together with exponential_backoff, the time to sleep will be shorter at every run: 
```bash
ruby -e 'interval=0.5; (1..5).each{|count| puts interval ** count}'
0.5
0.25
0.125
0.0625
0.03125
```

### Usage Styles

Retry supports 3 usage styles: Keyword args, Fluent (method chaining) and DSL:

kwargs:
```ruby
Tlopo::Retry.new(tries: 3, interval: 2, exponential_backoff: true, error_types: [ SomeError, SomeError2 ]).run do 
  do_something
end
```
Fluent: 
```ruby
Tlopo::Retry.new.tries(3).interval(2).exponential_backoff(true).error_types([SomeError, SomeError2]).run do
  do_something
end
```

DSL: 
```ruby
Tlopo::Retry.new.run do
  tries 3
  interval 2
  exponential_backoff true
  error_types [SomeError, SomeError2]
  do_something
end
```

## Contributing

1. Fork it ( https://github.com/tlopo-ruby/tlopo-retry/fork )
2. Create your feature branch (`git checkout -b my-new-feature`)
3. Test your changes with `rake test rubocop`, add new tests if needed.
4. If you added a new functionality, add it to README
5. Commit your changes (`git commit -am 'Add some feature'`)
6. Push to the branch (`git push origin my-new-feature`)
7. Create a new Pull Request

## Tests

This library is tested with Minitest.
Please run all tests before submitting a Pull Request, and add new tests for new functionality.

Running tests:
```ruby
rake test
```