A utility class to perform periodic sweeping of resources.

Sweepable resources may be added to or removed from a Sweeper and the resource implementation decides whether it should be swept or not.

If a Sweepable resources is itself a container of other sweepable resources, it will forward the sweep operation to children resources, and so on recursively.

Typical usage is to add Sweeper as a bean to an existing container:

Server server = new Server();
server.addBean(new Sweeper(), true);
server.start();

Code that knows it has sweepable resources can then lookup the Sweeper and offer the sweepable resources to it:

class MyComponent implements Sweeper.Sweepable
{
    private final long creation;
    private volatile destroyed;

    MyComponent(Server server)
    {
        this.creation = System.nanoTime();
        Sweeper sweeper = server.getBean(Sweeper.class);
        sweeper.offer(this);
    }

    void destroy()
    {
        destroyed = true;
    }

    @Override
    public boolean sweep()
    {
        return destroyed;
    }
}