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require "lib/em-synchrony"
EM.synchrony do
# open 4 concurrent MySQL connections
db = EventMachine::Synchrony::ConnectionPool.new(size: 4) do
EventMachine::MySQL.new(host: "localhost")
end
# perform 4 http requests in parallel, and collect responses
multi = EventMachine::Synchrony::Multi.new
multi.add :page1, EventMachine::HttpRequest.new("http://service.com/page1").aget
multi.add :page2, EventMachine::HttpRequest.new("http://service.com/page2").aget
multi.add :page3, EventMachine::HttpRequest.new("http://service.com/page3").aget
multi.add :page4, EventMachine::HttpRequest.new("http://service.com/page4").aget
data = multi.perform.responses[:callback].values
# insert fetched HTTP data into a mysql database, using at most 2 connections at a time
# - note that we're writing async code within the callback!
EM::Synchrony::Iterator.new(data, 2).each do |page, iter|
db.aquery("INSERT INTO table (data) VALUES(#{page});")
db.callback { iter.return(http) }
end
puts "All done! Stopping event loop."
EventMachine.stop
end
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