WebServer.java

package com.team254.frc2015.web;

import com.team254.frc2015.web.handlers.*;
import com.team254.lib.util.TaskQueue;
import org.eclipse.jetty.server.Server;
import org.eclipse.jetty.servlet.DefaultServlet;
import org.eclipse.jetty.servlet.ServletContextHandler;
import org.eclipse.jetty.servlet.ServletHolder;

import java.util.ArrayList;

public class WebServer {
    private static Server server;
    private static ArrayList<StateStreamSocket> updateStreams = new ArrayList<StateStreamSocket>();
    private static TaskQueue streamUpdate = new TaskQueue(200);

    public static void startServer() {
        if (server != null) {
            return;
        }
        server = new Server(5800);
        ServletContextHandler context = new ServletContextHandler(ServletContextHandler.SESSIONS);
        context.setContextPath("/");
        server.setHandler(context);

        // Add websocket servlet
        ServletHolder wsHolder = new ServletHolder("echo", new StateStreamServlet());
        context.addServlet(wsHolder, "/state");

        ServletHolder statesHolder = new ServletHolder("states", new GetAllStatesServlet());
        context.addServlet(statesHolder, "/all_states");

        ServletHolder keysHolder = new ServletHolder("keys", new GetKeysServlet());
        context.addServlet(keysHolder, "/keys");

        ServletHolder constantsHolder = new ServletHolder("constants", new ConstantsServlet());
        context.addServlet(constantsHolder, "/constants");

        ServletHolder getAutoModesHolder = new ServletHolder("autoModes", new GetAutoModesServlet());
        context.addServlet(getAutoModesHolder, "/autoModes");

        ServletHolder getCurrentAutoModeHolder = new ServletHolder("currentAutoModes", new GetCurrentAutoModeServlet());
        context.addServlet(getCurrentAutoModeHolder, "/currentAutoMode");

        ServletHolder setAutoModeHolder = new ServletHolder("setAutoMode", new SetAutoModeServlet());
        context.addServlet(setAutoModeHolder, "/setAutoMode");

        ServletHolder pingHolder = new ServletHolder("ping", new PingServlet());
        context.addServlet(pingHolder, "/ping");

        //noinspection ConstantConditions
        String appDir = WebServer.class.getClassLoader().getResource("app/").toExternalForm();
        ServletHolder holderPwd = new ServletHolder("default", new DefaultServlet());
        holderPwd.setInitParameter("resourceBase", appDir);
        holderPwd.setInitParameter("dirAllowed", "true");
        context.addServlet(holderPwd, "/");

        Thread serverThread = new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    server.start();
                    server.join();
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
        serverThread.setPriority(Thread.MIN_PRIORITY);
        serverThread.start();
        streamUpdate.start();
    }

    public static void registerStateStreamSocket(StateStreamSocket s) {
        updateStreams.add(s);
    }

    public static void unregisterStateStreamSocket(StateStreamSocket s) {
        updateStreams.remove(s);
    }

    public static Runnable updateRunner = new Runnable() {
        public void run() {
            for (int i = 0; i < updateStreams.size(); ++i) {
                StateStreamSocket s = updateStreams.get(i);
                if (s != null && s.isConnected() && !s.canBeUpdated()) {
                } else if ((s == null || !s.isConnected() || !s.update()) && i < updateStreams.size()) {
                    updateStreams.remove(i);
                }
            }
        }
    };

    public static void updateAllStateStreams() {
        boolean runUpdate = false;
        for (StateStreamSocket s : updateStreams) {
            runUpdate = (s != null && s.canBeUpdated());
            if (runUpdate) {
                break;
            }
        }
        if (runUpdate) {
            streamUpdate.addTask(updateRunner);
        }
    }
}