Author: markt
Date: Mon Sep 2 17:31:15 2013
New Revision: 1519481
URL: http://svn.apache.org/r1519481
Log:
Simple non-blocking write example. Primarily written to have something to test
AJP with. Sequential were chosen as it makes it easy to spot output corruption.
Added:
tomcat/trunk/webapps/examples/WEB-INF/classes/nonblocking/NumberWriter.java
(with props)
Modified:
tomcat/trunk/webapps/examples/WEB-INF/web.xml
tomcat/trunk/webapps/examples/servlets/index.html
Added:
tomcat/trunk/webapps/examples/WEB-INF/classes/nonblocking/NumberWriter.java
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/examples/WEB-INF/classes/nonblocking/NumberWriter.java?rev=1519481&view=auto
==============================================================================
--- tomcat/trunk/webapps/examples/WEB-INF/classes/nonblocking/NumberWriter.java
(added)
+++ tomcat/trunk/webapps/examples/WEB-INF/classes/nonblocking/NumberWriter.java
Mon Sep 2 17:31:15 2013
@@ -0,0 +1,148 @@
+/*
+ * 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 nonblocking;
+
+import java.io.IOException;
+import java.nio.charset.StandardCharsets;
+import java.util.concurrent.atomic.AtomicInteger;
+
+import javax.servlet.AsyncContext;
+import javax.servlet.ReadListener;
+import javax.servlet.ServletException;
+import javax.servlet.ServletInputStream;
+import javax.servlet.ServletOutputStream;
+import javax.servlet.WriteListener;
+import javax.servlet.http.HttpServlet;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+/**
+ * This doesn't do anything particularly useful - it just writes a series of
+ * numbers to the response body while demonstrating how to perform non-blocking
+ * writes.
+ */
+public class NumberWriter extends HttpServlet {
+
+ private static final long serialVersionUID = 1L;
+
+ @Override
+ protected void doGet(HttpServletRequest req, HttpServletResponse resp)
+ throws ServletException, IOException {
+
+ resp.setContentType("text/plain");
+ resp.setCharacterEncoding("UTF-8");
+
+ // Non-blocking IO requires async
+ AsyncContext ac = req.startAsync();
+
+ // Use a single listener for read and write. Listeners often need to
+ // share state to coordinate reads and writes and this is much easier
as
+ // a single object.
+ @SuppressWarnings("unused")
+ NumberWriterListener listener = new NumberWriterListener(
+ ac, req.getInputStream(), resp.getOutputStream());
+
+ }
+
+
+ /**
+ * Keep in mind that each call may well be on a different thread to the
+ * previous call. Ensure that changes in values will be visible across
+ * threads. There should only ever be one container thread at a time
calling
+ * the listener.
+ */
+ private static class NumberWriterListener implements ReadListener,
+ WriteListener {
+
+ private static final int LIMIT = 1000;
+
+ private final AsyncContext ac;
+ private final ServletInputStream sis;
+ private final ServletOutputStream sos;
+ private final AtomicInteger counter = new AtomicInteger(0);
+
+ private volatile boolean readFinished = false;
+ private byte[] buffer = new byte[8192];
+
+ private NumberWriterListener(AsyncContext ac, ServletInputStream sis,
+ ServletOutputStream sos) {
+ this.ac = ac;
+ this.sis = sis;
+ this.sos = sos;
+
+ // In Tomcat, the order the listeners are set controls the order
+ // that the first calls are made. In this case, the read listener
+ // will be called before the write listener.
+ sis.setReadListener(this);
+ sos.setWriteListener(this);
+ }
+
+ @Override
+ public void onDataAvailable() throws IOException {
+
+ // There should be no data to read
+
+ int read = 0;
+ // Loop as long as there is data to read. If isReady() returns
false
+ // the socket will be added to the poller and onDataAvailable()
will
+ // be called again as soon as there is more data to read.
+ while (sis.isReady() && read > -1) {
+ read = sis.read(buffer);
+ if (read > 0) {
+ throw new IOException("Data was present in input stream");
+ }
+ }
+ }
+
+ @Override
+ public void onAllDataRead() throws IOException {
+ readFinished = true;
+
+ // If sos is not ready to write data, the call to isReady() will
+ // register the socket with the poller which will trigger a call to
+ // onWritePossible() when the socket is ready to have data written
+ // to it.
+ if (sos.isReady()) {
+ onWritePossible();
+ }
+ }
+
+ @Override
+ public void onWritePossible() throws IOException {
+ if (readFinished) {
+ int i = counter.get();
+ boolean ready = true;
+ while (i < LIMIT && ready) {
+ i = counter.incrementAndGet();
+ String msg = String.format("%1$020d\n",
Integer.valueOf(i));
+ sos.write(msg.getBytes(StandardCharsets.UTF_8));
+ ready = sos.isReady();
+ }
+
+ if (i == LIMIT) {
+ ac.complete();
+ }
+ }
+ }
+
+ @Override
+ public void onError(Throwable throwable) {
+ // Should probably log the throwable
+ ac.complete();
+ }
+ }
+}
Propchange:
tomcat/trunk/webapps/examples/WEB-INF/classes/nonblocking/NumberWriter.java
------------------------------------------------------------------------------
svn:eol-style = native
Modified: tomcat/trunk/webapps/examples/WEB-INF/web.xml
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/examples/WEB-INF/web.xml?rev=1519481&r1=1519480&r2=1519481&view=diff
==============================================================================
--- tomcat/trunk/webapps/examples/WEB-INF/web.xml (original)
+++ tomcat/trunk/webapps/examples/WEB-INF/web.xml Mon Sep 2 17:31:15 2013
@@ -377,5 +377,14 @@
<servlet-name>bytecounter</servlet-name>
<url-pattern>/servlets/nonblocking/bytecounter</url-pattern>
</servlet-mapping>
+ <servlet>
+ <servlet-class>nonblocking.NumberWriter</servlet-class>
+ <servlet-name>numberwriter</servlet-name>
+ <async-supported>true</async-supported>
+ </servlet>
+ <servlet-mapping>
+ <servlet-name>numberwriter</servlet-name>
+ <url-pattern>/servlets/nonblocking/numberwriter</url-pattern>
+ </servlet-mapping>
</web-app>
Modified: tomcat/trunk/webapps/examples/servlets/index.html
URL:
http://svn.apache.org/viewvc/tomcat/trunk/webapps/examples/servlets/index.html?rev=1519481&r1=1519480&r2=1519481&view=diff
==============================================================================
--- tomcat/trunk/webapps/examples/servlets/index.html (original)
+++ tomcat/trunk/webapps/examples/servlets/index.html Mon Sep 2 17:31:15 2013
@@ -184,6 +184,13 @@ for clarity.</p>
</td>
<td WIDTH="30%"></td>
</tr>
+<tr VALIGN=TOP>
+ <td>Number Writer </td>
+ <td VALIGN=TOP WIDTH="30%">
+ <a href="nonblocking/numberwriter"><img SRC="images/execute.gif" HSPACE=4
BORDER=0 align=TOP> Execute</a>
+ </td>
+ <td WIDTH="30%"></td>
+</tr>
</table>
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