TaskManager.java

package lbms.plugins.mldht.kad;

import java.util.ArrayList;
import java.util.Deque;
import java.util.List;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;

/**
 * Manages all dht tasks.
 *
 * @author Damokles
 */
public class TaskManager {

	private Map<Integer, Task>	tasks;
	private Deque<Task>			queued;
	private int					next_id;

	public TaskManager () {
		tasks = new HashMap<Integer, Task>();
		queued = new LinkedList<Task>();
		next_id = 1;
	}
	
	void addTask(Task task)
	{
		addTask(task, false);
	}

	/**
	 * Add a task to manage.
	 * @param task
	 */
	void addTask (Task task, boolean isPriority) {
		int id = next_id++;
		task.setTaskID(id);
		if (task.isQueued()) {
			synchronized (queued) {
				if(isPriority)
					queued.addFirst(task);
				else
					queued.addLast(task);
			}
		} else {
			synchronized (tasks) {
				tasks.put(id, task);

			}
		}
	}

	/**
	 * Remove all finished tasks.
	 * @param dh_table Needed to ask permission to start a task
	 */
	void removeFinishedTasks (DHTBase dh_table) {
		synchronized (tasks) {

			List<Integer> rm = new ArrayList<Integer>(tasks.size());
			for (Task task : tasks.values()) {
				if (task.isFinished()) {
					rm.add(task.getTaskID());
				}
			}

			for (Integer i : rm) {
				tasks.remove(i);
			}
			synchronized (queued) {
				while (dh_table.canStartTask() && queued.size() > 0) {
					Task t = queued.removeFirst();
					//Out(SYS_DHT|LOG_NOTICE) << "DHT: starting queued task" << endl;
					t.start();
					tasks.put(t.getTaskID(), t);
				}
			}
		}
	}

	/// Get the number of running tasks
	int getNumTasks () {
		return tasks.size();
	}

	/// Get the number of queued tasks
	int getNumQueuedTasks () {
		return queued.size();
	}

	public Task[] getActiveTasks () {
		synchronized (tasks) {
			return tasks.values().toArray(new Task[tasks.size()]);
		}
	}

	public Task[] getQueuedTasks () {
		synchronized (queued) {
			return queued.toArray(new Task[queued.size()]);
		}
	}

}