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POMultiple http requests on the same long running operation with Sinatra and EventMachine
 

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    <p>I'm trying to understand how to use evented web servers with a combination of async sinatra and EventMachine. </p> <p>In the code below each request on '/' will generate a new async http request to google. Is there an elegant solution for detecting that a request is already ongoing and waiting for its execution ? </p> <p>If I have 100 concurrent requests on '/', this will generate 100 requests to the google backend. It would be much better to have a way to detect there is already an ongoing backend request and wait for its execution.</p> <p>thanks for the answer.</p> <pre><code>require 'sinatra' require 'json' require 'eventmachine' require 'em-http-request' require 'sinatra/async' Sinatra.register Sinatra::Async def get_data puts "Start request" http = EventMachine::HttpRequest.new("http://www.google.com").get http.callback { puts "Request completed" yield http.response } end aget '/' do get_data {|data| body data} end </code></pre> <p><strong>Update</strong></p> <p>I actually discovered you can add several callbacks to the same http request. So, it's easy to implement: </p> <pre><code>class Request def get_data if !@http || @http.response_header.status != 0 #puts "Creating new request" @http = EventMachine::HttpRequest.new("http://www.bbc.com").get end #puts "Adding callback" @http.callback do #puts "Request completed" yield @http.response end end end $req = Request.new aget '/' do $req.get_data {|data| body data} end </code></pre> <p>This gives a very high number of requests per second. Cool!</p>
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