/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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 async;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.atomic.AtomicInteger;
import javax.servlet.AsyncContext;
import javax.servlet.AsyncEvent;
import javax.servlet.AsyncListener;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import async.Stockticker.Stock;
import async.Stockticker.TickListener;
@douyu.mvc.Controller
public class AsyncStock implements TickListener, AsyncListener {
public static final String POLL = "POLL";
public static final String LONG_POLL = "LONG-POLL";
public static final String STREAM = "STREAM";
static ArrayList<Stock> ticks = new ArrayList<Stock>();
static ConcurrentLinkedQueue<AsyncContext> clients = new ConcurrentLinkedQueue<AsyncContext>();
static AtomicInteger clientcount = new AtomicInteger(0);
static Stockticker ticker = new Stockticker();
public AsyncStock() {
System.out.println("AsyncStockServlet created");
}
public void index(final HttpServletRequest req, final HttpServletResponse resp) throws IOException {
if (req.isAsyncStarted()) {
req.getAsyncContext().complete();
} else if (req.isAsyncSupported()) {
AsyncContext actx = req.startAsync();
actx.addListener(this);
resp.setContentType("text/plain");
actx.setTimeout(3000);
clients.add(actx);
if (clientcount.incrementAndGet() == 1) {
ticker.addTickListener(this);
}
} else {
new Exception("Async Not Supported").printStackTrace();
resp.sendError(400, "Async is not supported.");
}
}
@Override
public void tick(Stock stock) {
ticks.add((Stock) stock.clone());
Iterator<AsyncContext> it = clients.iterator();
while (it.hasNext()) {
AsyncContext actx = it.next();
writeStock(actx, stock);
}
}
public void writeStock(AsyncContext actx, Stock stock) {
HttpServletResponse response = (HttpServletResponse) actx.getResponse();
try {
PrintWriter writer = response.getWriter();
writer.write("STOCK#");//make client parsing easier
writer.write(stock.getSymbol());
writer.write("#");
writer.write(stock.getValueAsString());
writer.write("#");
writer.write(stock.getLastChangeAsString());
writer.write("#");
writer.write(String.valueOf(stock.getCnt()));
writer.write("\n");
writer.flush();
response.flushBuffer();
} catch (IOException x) {
try {
actx.complete();
} catch (Exception ignore) {/* Ignore */
}
}
}
@Override
public void onComplete(AsyncEvent event) throws IOException {
if (clients.remove(event.getAsyncContext()) && clientcount.decrementAndGet() == 0) {
ticker.removeTickListener(this);
}
}
@Override
public void onError(AsyncEvent event) throws IOException {
event.getAsyncContext().complete();
}
@Override
public void onTimeout(AsyncEvent event) throws IOException {
event.getAsyncContext().complete();
}
@Override
public void onStartAsync(AsyncEvent event) throws IOException {
// NOOP
}
}