added httpserver

Author: n.plaschke

build.gradle

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+group 'io.github.chumper'
+version '1.0-SNAPSHOT'
+
+apply plugin: 'java'
+
+sourceCompatibility = 1.8
+
+repositories {
+    mavenCentral()
+}
+
+dependencies {
+    testCompile group: 'junit', name: 'junit', version: '4.11'
+    testCompile group: 'org.apache.httpcomponents', name: 'httpclient', version: '4.5.2'
+    testCompile group: 'org.apache.httpcomponents', name: 'fluent-hc', version: '4.5.2'
+
+    compile "com.typesafe:config:1.3.1"
+    compile "org.mongodb:mongo-java-driver:3.3.0"
+}
+
+//create a single Jar with all dependencies
+task fatJar(type: Jar) {
+    manifest {
+        attributes 'Main-Class': 'io.github.chumper.webserver.Main'
+    }
+    baseName = project.name + '-all'
+    from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
+    with jar
+}

src/main/java/io/github/chumper/webserver/Main.java

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+package io.github.chumper.webserver;
+
+import com.typesafe.config.Config;
+import com.typesafe.config.ConfigFactory;
+
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.concurrent.ExecutionException;
+
+import io.github.chumper.webserver.core.HttpServer;
+import io.github.chumper.webserver.data.MongoDbCommentRepository;
+import io.github.chumper.webserver.handler.HttpCommentHandler;
+import io.github.chumper.webserver.handler.HttpETagHandler;
+import io.github.chumper.webserver.handler.HttpFileHandler;
+import io.github.chumper.webserver.handler.HttpKeepAliveHandler;
+import io.github.chumper.webserver.handler.HttpRequestLogHandler;
+import io.github.chumper.webserver.handler.HttpRootHandler;
+import io.github.chumper.webserver.util.ConsoleLogger;
+import io.github.chumper.webserver.util.Logger;
+
+/**
+ * Main bootstrap class used to parse all configurations, to configure and start the server
+ */
+public class Main {
+
+  private static final Logger logger = new ConsoleLogger();
+
+  public static void main(String... args)
+      throws ExecutionException, InterruptedException, IOException {
+
+    // Load the configuration from the environment as well as the arguments
+    Config config = ConfigFactory.load();
+
+    // create an http server
+    HttpServer server = new HttpServer(
+        config.getInt("server.port"),
+        config.getInt("server.threads")
+    );
+
+    // add handler that will work on /
+    server.addHttpHandler(new HttpRootHandler());
+
+    // if comments are active, add handler for that and give it a mongo repository
+    if(config.getBoolean("server.comments.active")) {
+      server.addHttpHandler(new HttpCommentHandler(
+          new MongoDbCommentRepository(
+            config.getString("server.comments.host"),
+            config.getInt("server.comments.port")
+          )
+      ));
+    }
+
+    // if files are active add the handler and the etag handling
+    if(config.getBoolean("server.files.active")) {
+      server.addHttpHandler(new HttpFileHandler(config.getString("server.files.root")));
+      server.addHttpHandler(new HttpETagHandler());
+    }
+
+    // add the keep alive handler so sockets can be reused
+    server.addHttpHandler(new HttpKeepAliveHandler());
+
+    // add logging handler if active
+    if(config.getBoolean("server.logging.active")) {
+      server.addHttpHandler(new HttpRequestLogHandler());
+    }
+
+    // start the server and wait until it is started
+    server.start().get();
+
+    logger.log("Press RETURN to stop the server");
+
+    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+    br.readLine();
+
+    // Stop the server
+    server.stop();
+  }
+}

src/main/java/io/github/chumper/webserver/core/HttpServer.java

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+package io.github.chumper.webserver.core;
+
+import io.github.chumper.webserver.core.http.HttpHandler;
+import io.github.chumper.webserver.core.http.HttpRequest;
+import io.github.chumper.webserver.core.pipeline.HttpPipeline;
+
+/**
+ * The {@link HttpServer} extends the {@link Server} and adds handler that will interpret the
+ * incoming messages as HTTP requests.
+ */
+public class HttpServer
+    extends Server {
+
+  /**
+   * The {@link HttpServer} will add a {@link HttpPipeline} to the server and accepts custom {@link
+   * HttpHandler} for processing the {@link HttpRequest}
+   */
+  private HttpPipeline httpPipeline = new HttpPipeline();
+
+  /**
+   * Creates a server that will listen on the given port when started
+   *
+   * @param port    The port number to listen on
+   * @param threads The number of threads for the worker pool
+   */
+  public HttpServer(int port,
+                    int threads) {
+    super(port, threads);
+  }
+
+  /**
+   * Will add the given handler to the Http pipeline
+   */
+  public void addHttpHandler(HttpHandler httpHandler) {
+    this.httpPipeline.addHttpHandler(httpHandler);
+  }
+
+  @Override
+  protected void registerHandler() {
+    // configure the server with the HTTP Pipeline
+    addPipelineHandler(httpPipeline);
+  }
+}

src/main/java/io/github/chumper/webserver/core/Server.java

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+package io.github.chumper.webserver.core;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+import java.net.ServerSocket;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.concurrent.CountDownLatch;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+
+import io.github.chumper.webserver.core.pipeline.SocketHandler;
+import io.github.chumper.webserver.util.ConsoleLogger;
+import io.github.chumper.webserver.util.Logger;
+
+/**
+ * This is the base class for all servers. Subclasses need to populate the pipeline with their
+ * custom handlers and can overwrite methods if needed
+ */
+public abstract class Server {
+
+  /**
+   * The port the server will listen on
+   */
+  private int port;
+  /**
+   * Used to start the server async and provide a method to listen when the server started and is
+   * ready to accept requests
+   */
+  private CountDownLatch startLatch = new CountDownLatch(1);
+  /**
+   * The executor that is responsible to process each request, this is the worker pool
+   */
+  private ExecutorService executor;
+  /**
+   * The socked that accepts the incomming messages
+   */
+  private ServerSocket ss;
+  /**
+   * Simple logger to log all events
+   */
+  private Logger logger = new ConsoleLogger();
+  /**
+   * The list of handlers that will transform the request and do stuff like HTTP parsing and
+   * processing
+   */
+  private List<SocketHandler> socketHandlers = new ArrayList<>();
+
+  /**
+   * Creates a server that will listen on the given port when started
+   *
+   * @param port    The port number to listen on
+   * @param threads The number of threads for the worker pool
+   */
+  public Server(int port,
+                int threads) {
+    this.port = port;
+    this.executor = Executors.newFixedThreadPool(threads);
+  }
+
+  /**
+   * Will add the given handler to the server processing pipeline
+   *
+   * @param handler The handler that transforms the request
+   */
+  public void addPipelineHandler(SocketHandler handler) {
+    this.socketHandlers.add(handler);
+  }
+
+  /**
+   * Will start the server in a new thread and returns a future that will complete when the server
+   * has been started
+   *
+   * @return A Future that completes when the server has been started
+   */
+  public CompletableFuture<Boolean> start() {
+    logger.log("Starting server on port {}", port);
+
+    registerHandler();
+
+    SocketListenerThread socketListener = new SocketListenerThread(port);
+    socketListener.start();
+
+    return CompletableFuture.supplyAsync(() -> {
+      try {
+        startLatch.await();
+      } catch (InterruptedException e) {
+        logger.log("Error while server start: {}", e.getMessage());
+      }
+      return socketListener.isBound();
+    });
+  }
+
+  /**
+   * Will stop the server and closes the sockets and shutdown the worker threads. All buffered
+   * request will be discarded and no new connections will be accepted.
+   */
+  public void stop() throws IOException {
+
+    ss.close();
+    executor.shutdown();
+
+    logger.log("Server stopped");
+  }
+
+  private class SocketListenerThread
+      extends Thread {
+
+    private int port;
+
+    SocketListenerThread(int port) {
+      this.port = port;
+      setName("SocketListenerThread");
+    }
+
+    public void run() {
+      try {
+        ss = new ServerSocket();
+        ss.setReuseAddress(true);
+        ss.setSoTimeout(0);
+        ss.bind(new InetSocketAddress(port), 20000);
+
+        logger.log("Server started on port {}, waiting for connections", port);
+
+        // count down the latch so that we can indicate that the server started
+        startLatch.countDown();
+
+        acceptData();
+      } catch (IOException e) {
+        // we dont want to clutter the console with stacktraces in this simple exercise
+        logger.log("Could not open the socket on port {}: {}", port, e.getMessage());
+        startLatch.countDown();
+      }
+    }
+
+    private void acceptData() {
+      while (true) {
+        try {
+          if (executor.isTerminated()) { break; }
+
+          executor.execute(new SocketProcessor(ss.accept(), socketHandlers));
+
+        } catch (IOException e) {
+          // I/O error in reading/writing data, or server closed while
+          // accepting data
+          if (!executor.isTerminated() && !ss.isClosed()) {
+            logger.log("Error occurred: {}", e.getMessage());
+          }
+        }
+      }
+    }
+
+    /**
+     * Will check whether the serverSocket is bound or not
+     *
+     * @return boolean true if the socket is bound, false otherwise
+     */
+    boolean isBound() {
+      return ss.isBound();
+    }
+  }
+
+  /**
+   * This methods needs to be overriden by other subclasses where they implement their own handler
+   * pipeline
+   */
+  protected abstract void registerHandler();
+}

src/main/java/io/github/chumper/webserver/core/SocketProcessor.java

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+package io.github.chumper.webserver.core;
+
+import java.io.IOException;
+import java.net.Socket;
+import java.net.SocketException;
+import java.util.List;
+
+import io.github.chumper.webserver.core.pipeline.SocketHandler;
+import io.github.chumper.webserver.util.ConsoleLogger;
+import io.github.chumper.webserver.util.Logger;
+
+/**
+ * The main thread that processes a socket, will handle the handler and the lifecycle
+ */
+class SocketProcessor
+    implements Runnable {
+
+  private final Logger logger = new ConsoleLogger();
+
+  /**
+   * The socket to manage
+   */
+  private Socket socket;
+  /**
+   * A list of handlers that can manipulate the socket and interact with the manipulated request,
+   * similar to the netty pipeline but much more simple and less robust.
+   */
+  private List<SocketHandler> socketHandlers;
+
+  SocketProcessor(Socket socket,
+                  List<SocketHandler> socketHandlers) {
+    this.socket = socket;
+    this.socketHandlers = socketHandlers;
+  }
+
+  @Override
+  @SuppressWarnings("unchecked")
+  public void run() {
+    try {
+      // first we set a timeout so inactive sockets will not stop the server after a while
+      socket.setSoTimeout(3000);
+      // we will loop through all handlers until one closes the socket
+      while(!socket.isClosed()) {
+        SocketHandler.State state;
+        for (SocketHandler socketHandler : socketHandlers) {
+          state = socketHandler.process(socket);
+          // when a handler returns no response we will asume that the pipeline should be interrupted
+          // This could be more robust (e.g. exceptions or a pipeline status object) but should be enough for now.
+          if (state == SocketHandler.State.DISCARD) {
+            // closing of the socket is not the responsible of the handler it will be done in the
+            // finally block
+            return;
+          }
+        }
+      }
+    } catch (SocketException e) {
+      logger.log("Could not configure the socket: {}", e.getMessage());
+    } finally {
+      try {
+        // just in case a handler did not clean, we will do it here
+        socket.shutdownInput();
+        socket.shutdownOutput();
+        socket.close();
+      } catch (IOException e) {
+        logger.log("Could not close the socket: {}", e.getMessage());
+      }
+    }
+  }
+}