https://github.com/awilliams/periodic_checker

Sugar for using many EventMachine::PeriodicTimer to watch something and execute on change
https://github.com/awilliams/periodic_checker

Last synced: about 1 month ago
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Sugar for using many EventMachine::PeriodicTimer to watch something and execute on change

• Host: GitHub
• URL: https://github.com/awilliams/periodic_checker
• Owner: awilliams
• License: mit
• Created: 2012-11-15T11:11:53.000Z (about 12 years ago)
• Default Branch: master
• Last Pushed: 2012-12-05T13:10:51.000Z (about 12 years ago)
• Last Synced: 2023-03-22T13:47:21.573Z (almost 2 years ago)
• Language: Ruby
• Size: 105 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# PeriodicChecker

Ruby library which helps create groups of EventMachine::PeriodicTimers. Each checker has a #check method which is called periodically and an #update method which is called when #check is true

## Installation

Add this line to your application's Gemfile:

    gem 'periodic_checker'

And then execute:

    $ bundle

Or install it yourself as:

    $ gem install periodic_checker

## Usage

### Basic Usage

```ruby

EventMachine.run do

  # create a watcher group and start all the watchers

  @checker = PeriodicChecker::Group.start! do |group|

    # create watcher which checks every 2s

    watcher = PeriodicChecker::Watch.new(2)

    # this block is checked every interval for changes (notice bang)

    watcher.check_for_change! { puts 'checking...'; rand(2) }

    # when a change happens, this block is executed

    watcher.do_on_change do |previous_value, current_value|

      puts "change detected, previously #{previous_value.inspect} is now #{current_value.inspect}"

    end

    # add this watcher to the watcher group

    group.add_watcher(watcher)

  end

  trap(:INT) {

    @checker.stop!

    puts "#{@checker.count} checkers & EventMachine stopped stopped"

  }

end

```

### Less Basic Usage

```ruby

EventMachine.run do

  def long_running_query(&on_query_result)

    # do some long running non-blocking stuff

    puts 'checking...'

    on_query_result.call(rand(2))

  end

  # create a watcher group and start all the watchers

  @checker = PeriodicChecker::Group.start! do |group|

    # create watcher which checks every 2s

    watcher = PeriodicChecker::Watch.new(2)

    # this block is checked every interval for changes (notice non-bang)

    # Watcher#to_proc is a proc which receives the value to compare with the previous value

    watcher.check_for_change { |w| long_running_query(&w) }

    # when a change happens, this block is executed

    watcher.do_on_change do |previous_value, current_value|

      puts "change detected, previously #{previous_value.inspect} is now #{current_value.inspect}"

    end

    # add this watcher to the watcher group

    group.add_watcher(watcher)

  end

  trap(:INT) {

    @checker.stop!

    puts "#{@checker.count} checkers & EventMachine stopped stopped"

  }

end

```

## Contributing

1. Fork it

2. Create your feature branch (`git checkout -b my-new-feature`)

3. Commit your changes (`git commit -am 'Added some feature'`)

4. Push to the branch (`git push origin my-new-feature`)

5. Create new Pull Request