Awesome
Rack::Worker
Rack middleware that implements the Worker Pattern.
It processes GET requests with a worker backend and only serves them straight from a cache.
While processing the request it serves empty HTTP 202 responses.
Your web frontend is never blocked processing the request.
How it works
When GET requests hit your app, the middleware tries to serve them from the cache.
If the request is not found, it stores the environment data in the cache. A worker
process will then use the App.call(env)
convention from Rack to run the request through
your webapp in the background as if it were a normal Rack request. The status, headers,
and body are then stored in the cache so they can be served.
What makes this technique different from a standard HTTP caching approach is that your web server never processes the long HTTP request. The middleware will return empty HTTP 202 responses unless the response is found in the cache. Every request that generates a 202 will only queue one background job per URL.
Installation
Add this line to your application's Gemfile:
gem 'rack-worker'
And then execute:
$ bundle
Or install it yourself as:
$ gem install rack-worker
Usage
class App < Sinatra::Base
use Rack::Worker
get '/long_ass_request' do
long_ass_work
end
end
That's it! Now GETs to /long_ass_request
will be processed in the background and only
serve HTTP 202 responses until they are processed, after which they will return whatever your
app would have returned.
If you already have queue_classic
and dalli
installed, everything will just work.
See configuration for setting an expiry time on records.
Configuration
Rack::Worker.cache = Dalli::Client.new(nil, {:expires_in => 300})
The cache
can be anything that responds to get(key)
and add(key, string)
Rack::Worker.queue = QC
The queue
can be anything that responds to enqueue(method, *params)
Clients
Here's an example of a polling GET request in javascript using jQuery:
Lib.get = function(path, params, callback) {
var success_callback = function(data, textStatus, xhr){
if(xhr.status == 202){
setTimeout(function() {
return Lib.get(path, params, callback)
}, 500)
}else{
return callback(data)
}
}
$.ajax({
url: path,
success: success_callback,
'data': params,
dataType: 'json'
})
}
Contributing
- Fork it
- Create your feature branch (
git checkout -b my-new-feature
) - Commit your changes (
git commit -am 'Added some feature'
) - Push to the branch (
git push origin my-new-feature
) - Create new Pull Request