54 lines
1.9 KiB
Scala
54 lines
1.9 KiB
Scala
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/**
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* Copyright (C) 2009 Scalable Solutions.
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*/
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/**
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* Implements the Reactor pattern as defined in: [http://www.cs.wustl.edu/~schmidt/PDF/reactor-siemens.pdf].
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* See also this article: [http://today.java.net/cs/user/print/a/350].
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*
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* Based on code from the actorom actor framework by Sergio Bossa [http://code.google.com/p/actorom/].
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*/
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package se.scalablesolutions.akka.kernel.reactor
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object EventBasedDispatcher extends MessageDispatcherBase {
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start
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//def dispatch(messageQueue: MessageQueue) = if (!active) {
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def start = if (!active) {
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active = true
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val messageDemultiplexer = new EventBasedDemultiplexer(messageQueue)
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selectorThread = new Thread {
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override def run = {
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while (active) {
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guard.synchronized { /* empty */ } // prevents risk for deadlock as described in [http://developers.sun.com/learning/javaoneonline/2006/coreplatform/TS-1315.pdf]
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try {
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messageDemultiplexer.select
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} catch { case e: InterruptedException => active = false }
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val queue = messageDemultiplexer.acquireSelectedQueue
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for (index <- 0 until queue.size) {
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val handle = queue.remove
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val handler = messageHandlers.get(handle.sender)
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if (handler != null) handler.handle(handle)
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}
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}
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}
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}
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selectorThread.start
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}
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}
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class EventBasedDemultiplexer(private val messageQueue: MessageQueue) extends MessageDemultiplexer {
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import java.util.{LinkedList, Queue}
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private val selectedQueue: Queue[MessageHandle] = new LinkedList[MessageHandle]
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def select = messageQueue.read(selectedQueue)
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def acquireSelectedQueue: Queue[MessageHandle] = selectedQueue
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def releaseSelectedQueue = throw new UnsupportedOperationException("EventBasedDemultiplexer can't release its queue")
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def wakeUp = throw new UnsupportedOperationException("EventBasedDemultiplexer can't be woken up")
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}
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