taskmanager.java

SMC takes a state machine stored in a .sm file and generates a State pattern in twelve programming l

    public void checkTaskQueue()
    {
        if (_runnableTaskQueue.size() > 0)
        {
            // Create a timer which will expire immediately.
            setTimer("Run Task", 0);
        }

        return;
    }

    // Return the currently running task.
    public Task getRunningTask()
    {
        return (_runningTask);
    }

    // Return the number of runnable tasks.
    public int getRunnableTaskCount()
    {
        return (_runnableTaskQueue.size());
    }

    // Return the number of blocked tasks.
    public int getBlockedTaskCount()
    {
        return (_blockedTaskList.size());
    }

    // Check if there are any tasks to run.
    public boolean areTasksQueued()
    {
        return (_runnableTaskQueue.size() > 0);
    }

    // Task the highest priority task off the runnable queue
    // and have it start running.
    public void startTask()
    {
        ListIterator taskIt;
        Task task;
        int index;
        int taskIndex;
        int taskPriority;
        int currentMinPriority;

        // Find the task with the lowest priority.
        for (taskIt = _runnableTaskQueue.listIterator(0),
                     currentMinPriority = Integer.MAX_VALUE,
                     index = 0,
                     taskIndex = -1;
             taskIt.hasNext() == true;
             ++index)
        {
            task = (Task) taskIt.next();
            taskPriority = task.getDynamicPriority();

            // Is the new task's priority less than
            // the current task. 
            if (taskPriority < currentMinPriority)
            {
                taskIndex = index;
                currentMinPriority = taskPriority;
            }
        }

        // Was a task found?
        if (taskIndex >= 0)
        {
            TaskController control = new TaskController();

            _runningTask =
                    (Task) _runnableTaskQueue.remove(taskIndex);
             sendMessage(2,
                         "Attempting to run task " +
                         _runningTask.getName() +
                         ".");

             control.postMessage(_runningTask.getName(),
                                 "start");
        }

        return;
    }

    // Cancel all existing timers.
    public void stopAllTimers()
    {
        Iterator entryIt;
        Map.Entry mapEntry;
        Timer timer;

        for (entryIt = _timerTable.entrySet().iterator();
             entryIt.hasNext() == true;
             )
        {
            mapEntry = (Map.Entry) entryIt.next();
            timer = (Timer) mapEntry.getValue();
            timer.stop();
        }

        _timerTable.clear();

        return;
    }

    public void stopAllTasks()
    {
        TaskController control = new TaskController();
        ListIterator listIt;
        Task task;

        // Put all tasks into the blocked list. As they report
        // that they are stopped, remove the tasks.
        //
        // Do the blocked list first.
        for (listIt = _blockedTaskList.listIterator(0);
             listIt.hasNext() == true;
             )
        {
            task = (Task) listIt.next();

            sendMessage(3,
                        "Stopping task " +
                        task.getName() +
                        ".");
            control.postMessage(task.getName(),
                                "stop");
        }

        // Do the runnable tasks next.
        for (listIt = _runnableTaskQueue.listIterator(0);
             listIt.hasNext() == true;
             )
        {
            task = (Task) listIt.next();

            sendMessage(3,
                        "Stopping task " +
                        task.getName() +
                        ".");
            control.postMessage(task.getName(),
                                "stop");
            _blockedTaskList.add(task);
        }
        _runnableTaskQueue.clear();

        // Do the running task last.
        if (_runningTask != null)
        {
            sendMessage(3,
                        "Stopping task " +
                        _runningTask.getName() +
                        ".");
            control.postMessage(_runningTask.getName(),
                                "stop");
            _blockedTaskList.add(_runningTask);
            _runningTask = null;
        }

        return;
    }

    public void deleteRunningTask()
    {
        if (_runningTask != null)
        {
            _runningTask = null;
        }

        return;
    }

    // Forcibly delete all existing tasks with extreme prejudice.
    public void deleteAllTasks()
    {
        _runningTask = null;
        _runnableTaskQueue.clear();
        _blockedTaskList.clear();

        return;
    }

    public void exitApplication()
    {
        // Wait another 1.5 secs before actually dying.
        setTimer("Exit", 1500);
        return;
    }

    public Task findTask(String taskName)
    {
        ListIterator taskIt;
        Task task;
        Task retval;

        retval = null;

        // Is the running task the one we are looking for?
        if (_runningTask != null &&
            taskName.compareTo(_runningTask.getName()) == 0)
        {
            retval = _runningTask;
        }
        else
        {
            // Is the task in the runnable queue?
            for (taskIt = _runnableTaskQueue.listIterator(0);
                 taskIt.hasNext() == true && retval == null;
                )
            {
                task = (Task) taskIt.next();
                if (taskName.compareTo(task.getName()) == 0)
                {
                    retval = task;
                }
            }

            // Is this task in the blocked list?
            if (retval == null)
            {
                for (taskIt = _blockedTaskList.listIterator(0);
                     taskIt.hasNext() == true && retval == null;
                    )
                {
                    task = (Task) taskIt.next();
                    if (taskName.compareTo(task.getName()) == 0)
                    {
                        retval = task;
                    }
                }
            }
        }

        return(retval);
    }

    // Does a task already exist with this name?
    public boolean taskExists(String name)
    {
        return(findTask(name) == null ? false : true);
    }

    // Issue the state machine transition associated with this timer
    // name. Also, remove the now defunct timer from the timer
    // table.
    public void handleEvent(String eventName, Map args)
    {
        String taskName;

        if (eventName.compareTo("Create Task") == 0)
        {
            Integer runtime;
            Integer priority;

            taskName = (String) args.get("Task Name");
            runtime = (Integer) args.get("Runtime");
            priority = (Integer) args.get("Priority");
            createTask(taskName,
                       runtime.intValue(),
                       priority.intValue());
        }
        else if (eventName.compareTo("Run Task") == 0)
        {
            _fsm.RunTask();
        }
        else if (eventName.compareTo("Slice Timeout") == 0)
        {
            _fsm.SliceTimeout();
        }
        else if (eventName.compareTo("Reply Timeout") == 0)
        {
            _fsm.ReplyTimeout();
        }
        else if (eventName.compareTo("Suspend Task") == 0)
        {
            suspendTask();
        }
        else if (eventName.compareTo("Block Task") == 0)
        {
            taskName = (String) args.get("Task Name");
            blockTask(taskName);
        }
        else if (eventName.compareTo("Unblock Task") == 0)
        {
            taskName = (String) args.get("Task Name");
            unblockTask(taskName);
        }
        else if (eventName.compareTo("Delete Task") == 0)
        {
            taskName = (String) args.get("Task Name");
            deleteTask(taskName);            
        }
        else if (eventName.compareTo("Task Suspended") == 0)
        {
            taskName = (String) args.get("Task Name");
            sendMessage(2,
                        "Task " +
                        taskName +
                        " has been suspended.");

            _fsm.TaskSuspended();
        }
        else if (eventName.compareTo("Task Done") == 0)
        {
            taskName = (String) args.get("Task Name");
            taskDone(taskName);
        }
        else if (eventName.compareTo("Task Stopped") == 0)
        {
            taskName = (String) args.get("Task Name");
            taskStopped(taskName);
        }
        else if (eventName.compareTo("Task Deleted") == 0)
        {
            taskName = (String) args.get("Task Name");
            taskDeleted(taskName);
        }
        else if (eventName.compareTo("Shutdown") == 0)
        {
            Integer exitCode;

            exitCode = (Integer) args.get("Exit Code");
            _exitCode = exitCode.intValue();

            _fsm.Shutdown();
        }
        else if (eventName.compareTo("Exit") == 0)
        {
            System.exit(_exitCode);
        }
        else if (eventName.compareTo("ShutdownTimeout") == 0)
        {
            _fsm.ShutdownTimeout();
        }

        return;
    }

// Member Data.

    private TaskManagerContext _fsm;

    // Runnable task queue, sorted by priority.
    private LinkedList _runnableTaskQueue;

    // Blocked task list.
    private LinkedList _blockedTaskList;

    // The currently running task.
    private Task _runningTask;

    // Task manager's various timers.
    private Map _timerTable;

    // The application's exit code.
    private int _exitCode;

// Inner classes.

    private final class TimerListener
        implements ActionListener
    {
        public TimerListener(String name,
                             TaskManager owner)
        {
            _timerName = name;
            _owner = owner;
        }

        public void actionPerformed(ActionEvent e)
        {
            Map args = new HashMap();

            _owner.handleEvent(_timerName, args);
            return;
        }

        private String _timerName;
        private TaskManager _owner;
    }
}