Add HTTP/2 Netty tiles example

Motivation:

Adding an example that showcases Netty’s HTTP/2 codec and that is
slightly more complex than the existing hello-world example. It is
based on the Gopher tiles example available here:
https://http2.golang.org/gophertiles?latency=0

Modifications:

Moved current http2 example to http2/helloworld.
Added http2 tiles example under http2/tiles.

Result:

A Netty tiles example is available.

example/src/main/java/io/netty/example/http2/Http2ExampleUtil.java

@@ -14,6 +14,15 @@
  */
 package io.netty.example.http2;
 
+import static io.netty.util.internal.ObjectUtil.checkNotNull;
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
+import io.netty.handler.codec.http.QueryStringDecoder;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.List;
+
 /**
  * Utility methods used by the example client and server.
  */
@@ -24,5 +33,51 @@ public final class Http2ExampleUtil {
      */
     public static final String UPGRADE_RESPONSE_HEADER = "Http-To-Http2-Upgrade";
 
+    /**
+     * Size of the block to be read from the input stream.
+     */
+    private static final int BLOCK_SIZE = 1024;
+
     private Http2ExampleUtil() { }
+
+    /**
+     * @param string the string to be converted to an integer.
+     * @param defaultValue the default value
+     * @return the integer value of a string or the default value, if the string is either null or empty.
+     */
+    public static int toInt(String string, int defaultValue) {
+        if (string != null && !string.isEmpty()) {
+            return Integer.valueOf(string);
+        }
+        return defaultValue;
+    }
+
+    /**
+     * Reads an InputStream into a byte array.
+     * @param input the InputStream.
+     * @return a byte array representation of the InputStream.
+     * @throws IOException if an I/O exception of some sort happens while reading the InputStream.
+     */
+    public static ByteBuf toByteBuf(InputStream input) throws IOException {
+        ByteBuf buf = Unpooled.buffer();
+        int n = 0;
+        do {
+            n = buf.writeBytes(input, BLOCK_SIZE);
+        } while (n > 0);
+        return buf;
+    }
+
+    /**
+     * @param query the decoder of query string
+     * @param key the key to lookup
+     * @return the first occurrence of that key in the string parameters
+     */
+    public static String firstValue(QueryStringDecoder query, String key) {
+        checkNotNull(query, "Query can't be null!");
+        List<String> values = query.parameters().get(key);
+        if (values == null || values.isEmpty()) {
+            return null;
+        }
+        return values.get(0);
+    }
 }

example/src/main/java/io/netty/example/http2/client/Http2Client.java → example/src/main/java/io/netty/example/http2/helloworld/client/Http2Client.java

@@ -12,7 +12,7 @@
  * or implied. See the License for the specific language governing permissions and limitations under
  * the License.
  */
-package io.netty.example.http2.client;
+package io.netty.example.http2.helloworld.client;
 
 import io.netty.bootstrap.Bootstrap;
 import io.netty.buffer.Unpooled;

example/src/main/java/io/netty/example/http2/client/Http2ClientInitializer.java → example/src/main/java/io/netty/example/http2/helloworld/client/Http2ClientInitializer.java

@@ -12,7 +12,7 @@
  * or implied. See the License for the specific language governing permissions and limitations under
  * the License.
  */
-package io.netty.example.http2.client;
+package io.netty.example.http2.helloworld.client;
 
 import static io.netty.handler.logging.LogLevel.INFO;
 

example/src/main/java/io/netty/example/http2/client/Http2SettingsHandler.java → example/src/main/java/io/netty/example/http2/helloworld/client/Http2SettingsHandler.java

@@ -12,7 +12,7 @@
  * or implied. See the License for the specific language governing permissions and limitations under
  * the License.
  */
-package io.netty.example.http2.client;
+package io.netty.example.http2.helloworld.client;
 
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelPromise;

example/src/main/java/io/netty/example/http2/client/HttpResponseHandler.java → example/src/main/java/io/netty/example/http2/helloworld/client/HttpResponseHandler.java

@@ -12,7 +12,7 @@
  * or implied. See the License for the specific language governing permissions and limitations under
  * the License.
  */
-package io.netty.example.http2.client;
+package io.netty.example.http2.helloworld.client;
 
 import io.netty.buffer.ByteBuf;
 import io.netty.channel.ChannelHandlerContext;

example/src/main/java/io/netty/example/http2/server/HelloWorldHttp1Handler.java → example/src/main/java/io/netty/example/http2/helloworld/server/HelloWorldHttp1Handler.java

@@ -13,7 +13,7 @@
  * License for the specific language governing permissions and limitations
  * under the License.
  */
-package io.netty.example.http2.server;
+package io.netty.example.http2.helloworld.server;
 
 import static io.netty.util.internal.ObjectUtil.checkNotNull;
 import io.netty.buffer.ByteBuf;

example/src/main/java/io/netty/example/http2/server/HelloWorldHttp2Handler.java → example/src/main/java/io/netty/example/http2/helloworld/server/HelloWorldHttp2Handler.java

@@ -13,7 +13,7 @@
  * the License.
  */
 
-package io.netty.example.http2.server;
+package io.netty.example.http2.helloworld.server;
 
 import static io.netty.buffer.Unpooled.copiedBuffer;
 import static io.netty.buffer.Unpooled.unreleasableBuffer;

example/src/main/java/io/netty/example/http2/server/Http2OrHttpHandler.java → example/src/main/java/io/netty/example/http2/helloworld/server/Http2OrHttpHandler.java

@@ -12,7 +12,7 @@
  * or implied. See the License for the specific language governing permissions and limitations under
  * the License.
  */
-package io.netty.example.http2.server;
+package io.netty.example.http2.helloworld.server;
 
 import io.netty.channel.ChannelHandler;
 import io.netty.handler.codec.http2.Http2ConnectionHandler;

example/src/main/java/io/netty/example/http2/server/Http2Server.java → example/src/main/java/io/netty/example/http2/helloworld/server/Http2Server.java

@@ -14,7 +14,7 @@
  * under the License.
  */
 
-package io.netty.example.http2.server;
+package io.netty.example.http2.helloworld.server;
 
 import io.netty.bootstrap.ServerBootstrap;
 import io.netty.channel.Channel;
@@ -71,12 +71,11 @@ public static void main(String[] args) throws Exception {
             sslCtx = null;
         }
         // Configure the server.
-        EventLoopGroup bossGroup = new NioEventLoopGroup(1);
-        EventLoopGroup workerGroup = new NioEventLoopGroup();
+        EventLoopGroup group = new NioEventLoopGroup();
         try {
             ServerBootstrap b = new ServerBootstrap();
             b.option(ChannelOption.SO_BACKLOG, 1024);
-            b.group(bossGroup, workerGroup)
+            b.group(group)
              .channel(NioServerSocketChannel.class)
              .handler(new LoggingHandler(LogLevel.INFO))
              .childHandler(new Http2ServerInitializer(sslCtx));
@@ -88,8 +87,7 @@ public static void main(String[] args) throws Exception {
 
             ch.closeFuture().sync();
         } finally {
-            bossGroup.shutdownGracefully();
-            workerGroup.shutdownGracefully();
+            group.shutdownGracefully();
         }
     }
 }

example/src/main/java/io/netty/example/http2/server/Http2ServerInitializer.java → example/src/main/java/io/netty/example/http2/helloworld/server/Http2ServerInitializer.java

@@ -14,7 +14,7 @@
  * under the License.
  */
 
-package io.netty.example.http2.server;
+package io.netty.example.http2.helloworld.server;
 
 import io.netty.channel.ChannelHandlerContext;
 import io.netty.channel.ChannelInboundHandlerAdapter;

example/src/main/java/io/netty/example/http2/tiles/FallbackRequestHandler.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright 2015 The Netty Project
+ *
+ * The Netty Project 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 io.netty.example.http2.tiles;
+
+import static io.netty.buffer.Unpooled.copiedBuffer;
+import static io.netty.buffer.Unpooled.unmodifiableBuffer;
+import static io.netty.buffer.Unpooled.unreleasableBuffer;
+import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_LENGTH;
+import static io.netty.handler.codec.http.HttpHeaderNames.CONTENT_TYPE;
+import static io.netty.handler.codec.http.HttpResponseStatus.CONTINUE;
+import static io.netty.handler.codec.http.HttpResponseStatus.OK;
+import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
+import static io.netty.util.CharsetUtil.UTF_8;
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelFutureListener;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.SimpleChannelInboundHandler;
+import io.netty.handler.codec.http.DefaultFullHttpResponse;
+import io.netty.handler.codec.http.FullHttpResponse;
+import io.netty.handler.codec.http.HttpHeaderUtil;
+import io.netty.handler.codec.http.HttpRequest;
+import io.netty.handler.codec.http2.Http2CodecUtil;
+
+/**
+ * Handles the exceptional case where HTTP 1.x was negotiated under TLS.
+ */
+public final class FallbackRequestHandler extends SimpleChannelInboundHandler<HttpRequest> {
+
+    private static final ByteBuf response = unmodifiableBuffer(unreleasableBuffer(copiedBuffer("<!DOCTYPE html>"
+            + "<html><body><h2>To view the example you need a browser that supports HTTP/2 ("
+            + Http2CodecUtil.TLS_UPGRADE_PROTOCOL_NAME
+            + ")</h2></body></html>", UTF_8)));
+
+    @Override
+    protected void channelRead0(ChannelHandlerContext ctx, HttpRequest req) throws Exception {
+        if (HttpHeaderUtil.is100ContinueExpected(req)) {
+            ctx.write(new DefaultFullHttpResponse(HTTP_1_1, CONTINUE));
+        }
+
+        ByteBuf content = ctx.alloc().buffer();
+        content.writeBytes(response.duplicate());
+
+        FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, OK, content);
+        response.headers().set(CONTENT_TYPE, "text/html; charset=UTF-8");
+        response.headers().setInt(CONTENT_LENGTH, response.content().readableBytes());
+
+        ctx.write(response).addListener(ChannelFutureListener.CLOSE);
+    }
+
+    @Override
+    public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
+        ctx.flush();
+    }
+
+    @Override
+    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
+        cause.printStackTrace();
+        ctx.close();
+    }
+}

example/src/main/java/io/netty/example/http2/tiles/Html.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2015 The Netty Project
+ *
+ * The Netty Project 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 io.netty.example.http2.tiles;
+
+import static io.netty.util.CharsetUtil.UTF_8;
+
+import java.util.Random;
+
+/**
+ * Static and dynamically generated HTML for the example.
+ */
+public final class Html {
+
+    public static final String IP = System.getProperty("ip", "127.0.0.1");
+
+    public static final byte[] FOOTER = "</body></html>".getBytes(UTF_8);
+
+    public static final byte[] HEADER = ("<!DOCTYPE html><html><head lang=\"en\"><title>Netty HTTP/2 Example</title>"
+            + "<style>body {background:#DDD;} div#netty { line-height:0;}</style>"
+            + "<link rel=\"shortcut icon\" href=\"about:blank\">"
+            + "<meta charset=\"UTF-8\"></head><body>A grid of 200 tiled images is shown below. Compare:"
+            + "<p>[<a href='https://" + url(Http2Server.PORT) + "?latency=0'>HTTP/2, 0 latency</a>] [<a href='http://"
+            + url(HttpServer.PORT) + "?latency=0'>HTTP/1, 0 latency</a>]<br/>" + "[<a href='https://"
+            + url(Http2Server.PORT) + "?latency=30'>HTTP/2, 30ms latency</a>] [<a href='http://" + url(HttpServer.PORT)
+            + "?latency=30'>HTTP/1, 30ms latency</a>]<br/>" + "[<a href='https://" + url(Http2Server.PORT)
+            + "?latency=200'>HTTP/2, 200ms latency</a>] [<a href='http://" + url(HttpServer.PORT)
+            + "?latency=200'>HTTP/1, 200ms latency</a>]<br/>" + "[<a href='https://" + url(Http2Server.PORT)
+            + "?latency=1000'>HTTP/2, 1s latency</a>] [<a href='http://" + url(HttpServer.PORT)
+            + "?latency=1000'>HTTP/1, " + "1s latency</a>]<br/>").getBytes(UTF_8);
+
+    private static final int IMAGES_X_AXIS = 20;
+
+    private static final int IMAGES_Y_AXIS = 10;
+
+    private Html() {
+    }
+
+    private static String url(int port) {
+        return IP + ":" + port + "/http2";
+    }
+
+    public static byte[] body(int latency) {
+        int r = Math.abs(new Random().nextInt());
+        // The string to be built contains 13192 fixed characters plus the variable latency and random cache-bust.
+        int numberOfCharacters = 13192 + stringLength(latency) + stringLength(r);
+        StringBuilder sb = new StringBuilder(numberOfCharacters).append("<div id=\"netty\">");
+        for (int y = 0; y < IMAGES_Y_AXIS; y++) {
+            for (int x = 0; x < IMAGES_X_AXIS; x++) {
+                sb.append("<img width=30 height=29 src='/http2?x=")
+                .append(x)
+                .append("&y=").append(y)
+                .append("&cachebust=").append(r)
+                .append("&latency=").append(latency)
+                .append("'>");
+            }
+            sb.append("<br/>\r\n");
+        }
+        sb.append("</div>");
+        return sb.toString().getBytes(UTF_8);
+    }
+
+    private static int stringLength(int value) {
+        return Integer.toString(value).length() * IMAGES_X_AXIS * IMAGES_Y_AXIS;
+    }
+}

example/src/main/java/io/netty/example/http2/tiles/Http1RequestHandler.java

@@ -0,0 +1,62 @@
+/*
+ * Copyright 2015 The Netty Project
+ *
+ * The Netty Project 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 io.netty.example.http2.tiles;
+
+import static io.netty.handler.codec.http.HttpHeaderNames.CONNECTION;
+import static io.netty.handler.codec.http.HttpHeaderUtil.isKeepAlive;
+import static io.netty.handler.codec.http.HttpResponseStatus.CONTINUE;
+import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
+import io.netty.channel.ChannelFutureListener;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.handler.codec.http.DefaultFullHttpResponse;
+import io.netty.handler.codec.http.FullHttpRequest;
+import io.netty.handler.codec.http.FullHttpResponse;
+import io.netty.handler.codec.http.HttpHeaderUtil;
+import io.netty.handler.codec.http.HttpHeaderValues;
+
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Handles the requests for the tiled image using HTTP 1.x as a protocol.
+ */
+public final class Http1RequestHandler extends Http2RequestHandler {
+
+    @Override
+    protected void channelRead0(ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {
+        if (HttpHeaderUtil.is100ContinueExpected(request)) {
+            ctx.write(new DefaultFullHttpResponse(HTTP_1_1, CONTINUE));
+        }
+        super.channelRead0(ctx, request);
+    }
+
+    @Override
+    protected void sendResponse(final ChannelHandlerContext ctx, String streamId, int latency,
+            final FullHttpResponse response, final FullHttpRequest request) {
+        HttpHeaderUtil.setContentLength(response, response.content().readableBytes());
+        ctx.executor().schedule(new Runnable() {
+            @Override
+            public void run() {
+                if (isKeepAlive(request)) {
+                    response.headers().set(CONNECTION, HttpHeaderValues.KEEP_ALIVE);
+                    ctx.writeAndFlush(response);
+                } else {
+                    ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
+                }
+            }
+        }, latency, TimeUnit.MILLISECONDS);
+    }
+}