/*
Thread synchronization in java.nio.channels.Selector is completely fucked up, unsurprisingly since NIO was developed in this demented century.  This class works around the modern insanity.
*/

package org.eclipse.jetty.io.nio;

import java.io.IOException;
import java.nio.channels.Selector;
import java.nio.channels.SelectionKey;
import java.nio.channels.SelectableChannel;
import java.nio.channels.ClosedChannelException;
import java.util.Set;


public final class SaneSelector {
	private final Selector selector;
	private boolean inSelect = false;
	private boolean inUpdate = false;

	public SaneSelector() throws IOException {
		selector = Selector.open();
	}

	public void close() throws IOException {
		selector.close();
	}

	public boolean isOpen() {
		return selector.isOpen();
	}

	public int select() throws IOException {
		synchronized(this) {
			inSelect = true;
		}
		try {
			while(true) {
				int n = selector.select();
				synchronized(this) {
					boolean wasInUpdate = inUpdate;
					inUpdate = false;
					if( n > 0 || !wasInUpdate )
						return n;
				}
			}
		} finally {
			synchronized(this) {
				inSelect = false;
			}
		}
	}

	public Set<SelectionKey> selectedKeys() {
		return selector.selectedKeys();
	}

	public Set<SelectionKey> keys() {
		return selector.keys();
	}

	public synchronized SelectionKey register(SelectableChannel channel,int ops,Object att) throws ClosedChannelException {
		update();
		return channel.register(selector,ops,att);
	}

	public synchronized void update() {
		if( inSelect ) {
			inUpdate = true;
			selector.wakeup();
		}
	}
}