package jutil;

import java.util.*;

/**
 * The thread manager is an extensible class that safely manages
 * a pool of worker threads.
 */
public class ThreadManager {
	/**
	 * The pool of worker threads to be managed.
	 */
	private List workers = new ArrayList();
	/**
	 * clear workers list.
	 */
	public void clear() { workers.clear(); }
	/**
	 * Add a worker thread to the pool.
	 * @param worker the worker to be added to the list.
	 */
	public void add(WorkerThread worker) { workers.add(worker); }
	/**
	 * Safely pauses all workers.
	 */
	public void pauseAll() {
		Iterator p = workers.iterator();
		while(p.hasNext()) {
			WorkerThread worker = (WorkerThread)p.next();
			worker.pause();
		}
	}
	/**
	 * Safely unpauses all the workers.
	 */
	public void unpauseAll() {
		Iterator p = workers.iterator();
		while(p.hasNext()) {
			WorkerThread worker = (WorkerThread)p.next();
			worker.unpause();
		}
	}
	/**
	 * Safely halts all workers
	 */
	public void haltAll() {
		Iterator p = workers.iterator();
		while(p.hasNext()) {
			WorkerThread worker = (WorkerThread)p.next();
			worker.halt();
		}
	}
	/**
	 * Start all workers.
	 */
	public void startAll() {
		Iterator p = workers.iterator();
		while(p.hasNext()) {
			WorkerThread worker = (WorkerThread)p.next();
			worker.start();
		}
	}

	public String toString() { return workers.toString(); }
	/**
	 * Joins all workers.
	 */
	public void joinAll() { joinAll(0); }
	/**
	 * Join all workers until the stop or a timeout occurs.
	 * @param msecs number of milliseconds until a timeout
	 */
	public void joinAll(long msecs) {
		Iterator p = workers.iterator();
		while(p.hasNext()) {
			WorkerThread worker = (WorkerThread)p.next();
			try {
				if (worker.isAlive()) worker.join(msecs);
				if (worker.isAlive()) worker.halt();
			} catch(InterruptedException ie) {
		         System.err.println(ie.getMessage());
		         if (worker.isAlive()) worker.destroy();
			} finally {
				System.out.println(worker.getName() + " has died");
			}
		}
		System.out.println("The manager will now die ... ");
	}
}