TimeoutReader.java

/*******************************************************************************
 * Copyright 2013
 * Ubiquitous Knowledge Processing (UKP) Lab
 * Technische Universität Darmstadt
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *   http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/
package de.tudarmstadt.ukp.csniper.webapp.search.cqp;

import java.io.IOException;
import java.io.Reader;

public class TimeoutReader extends Reader
{
	private Reader delegate;
	private int timeout = 15 * 1000;
	
	public TimeoutReader(final Reader aDelegate)
	{
		delegate = aDelegate;
	}
	
	public int getTimeout()
	{
		return timeout;
	}

	public void setTimeout(int aTimeout)
	{
		timeout = aTimeout;
	}

	public String readLine() throws IOException
	{
		long lastRead = System.currentTimeMillis();
		long now = System.currentTimeMillis();
		StringBuilder buffer = new StringBuilder();
		while (now - lastRead < timeout) {
			now = System.currentTimeMillis();
			if (delegate.ready()) {
				int ch = delegate.read();
				
				if (ch == '\n') {
					if(buffer.charAt(buffer.length()-1) == '\r') {
						buffer.deleteCharAt(buffer.length()-1);
					}
					return buffer.toString();
				}
				else {
					buffer.appendCodePoint(ch);
				}
				lastRead = now;
			}
			else {
				try {
					Thread.sleep(10);
				}
				catch (InterruptedException e) {
					// Nothing to do.
				}
			}
		}
		throw new IOException("Read timeout after " + timeout + "ms.");
	}

	@Override
	public int read(char[] aCbuf, int aOff, int aLen)
		throws IOException
	{
		throw new UnsupportedOperationException();
	}

	@Override
	public void close()
		throws IOException
	{
		delegate.close();
	}
}