85 lines
2.1 KiB
Ruby
85 lines
2.1 KiB
Ruby
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module EventMachine
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# Creates and immediately starts an EventMachine::TickLoop
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def self.tick_loop(*a, &b)
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TickLoop.new(*a, &b).start
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end
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# A TickLoop is useful when one needs to distribute amounts of work
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# throughout ticks in order to maintain response times. It is also useful for
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# simple repeated checks and metrics.
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# @example
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# # Here we run through an array one item per tick until it is empty,
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# # printing each element.
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# # When the array is empty, we return :stop from the callback, and the
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# # loop will terminate.
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# # When the loop terminates, the on_stop callbacks will be called.
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# EM.run do
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# array = (1..100).to_a
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#
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# tickloop = EM.tick_loop do
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# if array.empty?
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# :stop
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# else
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# puts array.shift
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# end
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# end
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#
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# tickloop.on_stop { EM.stop }
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# end
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#
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class TickLoop
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# Arguments: A callback (EM::Callback) to call each tick. If the call
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# returns +:stop+ then the loop will be stopped. Any other value is
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# ignored.
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def initialize(*a, &b)
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@work = EM::Callback(*a, &b)
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@stops = []
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@stopped = true
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end
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# Arguments: A callback (EM::Callback) to call once on the next stop (or
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# immediately if already stopped).
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def on_stop(*a, &b)
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if @stopped
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EM::Callback(*a, &b).call
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else
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@stops << EM::Callback(*a, &b)
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end
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end
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# Stop the tick loop immediately, and call it's on_stop callbacks.
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def stop
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@stopped = true
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until @stops.empty?
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@stops.shift.call
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end
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end
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# Query if the loop is stopped.
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def stopped?
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@stopped
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end
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# Start the tick loop, will raise argument error if the loop is already
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# running.
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def start
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raise ArgumentError, "double start" unless @stopped
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@stopped = false
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schedule
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end
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private
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def schedule
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EM.next_tick do
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next if @stopped
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if @work.call == :stop
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stop
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else
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schedule
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end
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end
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self
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end
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end
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end
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