EmulatorTCFQueue.java

/*
  EmulatorTCFQueue.java

  (c) 2011-2013 Edward Swartz

  All rights reserved. This program and the accompanying materials
  are made available under the terms of the Eclipse Public License v1.0
  which accompanies this distribution, and is available at
  http://www.eclipse.org/legal/epl-v10.html
 */
package v9t9.server.tcf;

import java.util.LinkedList;

import org.eclipse.tm.tcf.protocol.IEventQueue;
import org.eclipse.tm.tcf.protocol.Protocol;


/**
 * Implementation of Target Communication Framework event queue.
 */
public class EmulatorTCFQueue implements IEventQueue, Runnable {

    private final LinkedList<Runnable> queue = new LinkedList<Runnable>();
    private final Thread thread;
    private boolean waiting;
    private boolean shutdown;
    private int job_cnt;

    public EmulatorTCFQueue() {
        thread = new Thread(this);
        thread.setDaemon(true);
        thread.setName("TCF Event Dispatcher"); //$NON-NLS-1$
    }

    public void start() {
        thread.start();
    }

    public void shutdown() {
        try {
            synchronized (this) {
                shutdown = true;
                if (waiting) {
                    waiting = false;
                    notifyAll();
                }
            }
            thread.join();
        }
        catch (Exception e) {
            Protocol.log("Failed to shutdown TCF event dispatch thread", e); //$NON-NLS-1$
        }
    }

    private void error(Throwable x) {
        Protocol.log("Unhandled exception in TCF event dispatch", x); //$NON-NLS-1$
    }

    public void run() {
        for (;;) {
            try {
                Runnable r = null;
                synchronized (this) {
                    while (queue.size() == 0) {
                        if (shutdown) return;
                        waiting = true;
                        wait();
                    }
                    r = queue.removeFirst();
                }
                r.run();
            }
            catch (Throwable x) {
                error(x);
            }
        }
    }

    public synchronized void invokeLater(final Runnable r) {
        assert r != null;
        if (shutdown) throw new IllegalStateException("TCF event dispatcher has shut down"); //$NON-NLS-1$
        queue.add(r);
        if (waiting) {
            waiting = false;
            notifyAll();
        }
    }

    public boolean isDispatchThread() {
        return Thread.currentThread() == thread;
    }

    public synchronized int getCongestion() {
        int l0 = job_cnt / 10 - 100;
        int l1 = queue.size() / 10 - 100;
        if (l1 > l0) l0 = l1;
        if (l0 > 100) l0 = 100;
        return l0;
    }
}