Here is my solution. It is similar to the EM.queue solution, but just uses a hash.
require 'rubygems'
require 'em-websocket'
require 'json'
EM.run do
EM::WebSocket.start(:host => '0.0.0.0', :port => 3333) do |ws|
mutex = Mutex.new # to make thread safe. See https://github.com/eventmachine/eventmachine/blob/master/lib/eventmachine.rb#L981
queue = EM::Queue.new
ws.onmessage do |msg|
message_type = JSON.parse(msg)["type"]
op = proc do
mutex.synchronize do
if message_type == "preferred"
puts "killing non preferred\n"
queue.size.times { queue.pop {|thread| thread.kill } }
end
queue << Thread.current
end
puts "doing the long running process"
sleep 15 # Thread safe IO here that is safely killed
true
end
callback = proc do |result|
puts "Finished #{message_type} #{msg}"
end
EM.defer(op, callback)
end
end
end