Subversion Repositories programming

/*******************************************************************************

 * File: Scheduler.java

 *

 * Holds the Scheduler class, which has a generic scheduler class, from which

 * all schedulers should be derived.

 *

 * Copyright (c) 2006, Ira W. Snyder (devel@irasnyder.com)

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

 * copies of the Software, and to permit persons to whom the Software is

 * furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS

 * IN THE SOFTWARE.

 ******************************************************************************/

import java.util.Vector;

abstract class Scheduler

{

    protected Vector<Process> run_queue;

    protected Vector<LogEntry> log;

    protected int cur_time = 0;

    protected Process cur_proc;

    protected abstract boolean step ();

    /**

     * Add a new process to the run queue.

     *

     * If you need to support time-delayed processes, then you must override

     * this method, and handle pulling them into the run_queue yourself.

     */

    public void addProcess (Process proc, int add_time)

    {

        run_queue.add (new Process(proc));

    }

    /**

     * Expire the currently running process.

     *

     * This removes the current process from the cpu and re-adds it to the

     * run_queue.

     */

    protected void expireCurrent ()

    {

        assert (cur_proc.time_left > 0);

        cur_proc.finished_at = cur_time;

        run_queue.add (cur_proc);

        log.add (new LogEntry (cur_proc, cur_time, LogEntry.MsgType.EXPIRE));

        cur_proc = null;

    }

    protected void completeCurrent ()

    {

        assert (cur_proc.time_left == 0);

        cur_proc.finished_at = cur_time;

        log.add (new LogEntry (cur_proc, cur_time, LogEntry.MsgType.COMPLETE));

        cur_proc = null;

    }

    protected void startProcess (Process proc)

    {

        cur_proc = proc;

        cur_proc.started_at = cur_time;

        run_queue.remove (cur_proc);

        log.add (new LogEntry (cur_proc, cur_time, LogEntry.MsgType.START));

    }

    protected void scheduleCurrent ()

    {

        cur_proc.time_left--;

        cur_time++;

    }

    public Scheduler ()

    {

        this.run_queue = new Vector<Process> ();

        this.log = new Vector<LogEntry> ();

    }

    public void run ()

    {

        /* Keep step()ing until we're done */

        while (step ())

            ; // do nothing

        for (LogEntry e : log)

            System.out.println (e);

        /* Print time taken */

        System.out.println ("\nSimulation took " + cur_time + " time units to complete!");

    }

}

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