Add an optional buffering mechanism for bad network connections

Author: hannesbraun

config.txt

@@ -31,6 +31,8 @@ Auto-Connect         : true
 Auto-Connect Delay   : 1000
 Default Server       : localhost:3200
 Drawing Port         : 32769
+Monitor Step         : 0.04
+Network Buffer       : false
 # To store more servers, just insert more "Server" lines
 Server               : localhost:3200
 

src/main/java/rv/comm/rcssserver/ServerComm.java

@@ -24,11 +24,9 @@
 import java.io.PrintWriter;
 import java.net.Socket;
 import java.text.ParseException;
-import java.util.Arrays;
-import java.util.Calendar;
-import java.util.List;
-import java.util.Locale;
+import java.util.*;
 import java.util.concurrent.CopyOnWriteArrayList;
+import java.util.concurrent.LinkedBlockingQueue;
 import javax.swing.Timer;
 import jsgl.math.vector.Vec3f;
 import org.apache.logging.log4j.LogManager;
@@ -69,40 +67,79 @@ public MessageReceiver(String host, int port)
 		@Override
 		public void run()
 		{
-			try {
-				socket = new Socket(host, port);
-				out = new PrintWriter(socket.getOutputStream(), true);
-				in = new DataInputStream(socket.getInputStream());
-
-				setConnected(true);
-				if (recordLogs)
-					setupNewLogfile();
-
-				String message;
-				do {
-					message = readMessage();
-					if (message != null) {
-						try {
-							parser.parse(message);
-							if (logfileOutput != null)
-								writeToLogfile(message);
-						} catch (ParseException e) {
-							LOGGER.error("Unable to parse server message", e);
-						}
+			// Receive messages in a separate thread and put them in a queue
+			LinkedBlockingQueue<Optional<String>> messages = new LinkedBlockingQueue<>(3000);
+			new Thread(() -> {
+				try {
+					socket = new Socket(host, port);
+					out = new PrintWriter(socket.getOutputStream(), true);
+					in = new DataInputStream(socket.getInputStream());
+					setConnected(true);
+					String message;
+					do {
+						message = readMessage();
+						messages.put(Optional.ofNullable(message));
+					} while (message != null);
+				} catch (IOException | InterruptedException e) {
+					// This is fine, just leave.
+					// The surrounding thread will quit when receiving an
+					// empty optional.
+					try {
+						messages.put(Optional.empty());
+					} catch (InterruptedException ignored) {
 					}
-				} while (message != null);
+				}
 
 				// If the thread gets to this point the server has stopped
 				// sending messages by closing the connection
 				// DebugInfo.println(getClass(), "rcssserver3d closed TCP connection");
 				disconnect();
 				if (autoConnectTimer != null)
 					autoConnectTimer.start();
-			} catch (IOException e) {
-				disconnect();
-				if (autoConnectTimer != null)
-					autoConnectTimer.start();
+			}).start();
+
+			if (recordLogs) {
+				setupNewLogfile();
 			}
+
+			Optional<String> message = Optional.empty();
+			long lastUpdateTimestamp = 0;
+			long monitorStepMillis = Math.round(Networking.INSTANCE.getMonitorStep() * 1000.0);
+			do {
+				// Retrieve a message from the queue
+				try {
+					message = messages.take();
+				} catch (InterruptedException e) {
+					continue;
+				}
+
+				if (Networking.INSTANCE.getUseBuffer()) {
+					// Wait until the time for one monitor frame elapsed.
+					// This ensures that two messages are not applied immediately after each
+					// other. That may be the case with a bad network connection.
+					long elapsed = System.currentTimeMillis() - lastUpdateTimestamp;
+					long timeLeft = monitorStepMillis - elapsed;
+					if (timeLeft > 0) {
+						try {
+							Thread.sleep(timeLeft);
+						} catch (InterruptedException e) {
+							e.printStackTrace();
+						}
+					}
+					lastUpdateTimestamp = System.currentTimeMillis();
+				}
+
+				// Process message
+				message.ifPresent(msg -> {
+					try {
+						parser.parse(msg);
+						if (logfileOutput != null)
+							writeToLogfile(msg);
+					} catch (ParseException e) {
+						LOGGER.error("Unable to parse server message", e);
+					}
+				});
+			} while (message.isPresent());
 		}
 
 		private String readMessage() throws IOException

src/main/kotlin/org/magmaoffenburg/roboviz/configuration/Config.kt

@@ -77,6 +77,9 @@ class Config(args: Array<String>) {
 
         var currentHost = defaultServerHost
         var currentPort = defaultServerPort
+
+        var monitorStep = 0.04
+        var useBuffer = false
     }
 
     object OverlayVisibility {
@@ -156,6 +159,8 @@ class Config(args: Array<String>) {
         parser.getValue("Auto-Connect")?.let { Networking.autoConnect = it.toBoolean() }
         parser.getValue("Auto-Connect Delay")?.let { Networking.autoConnectDelay = it.toInt() }
         parser.getValue("Drawing Port")?.let { Networking.listenPort = it.toInt() }
+        parser.getValue("Monitor Step")?.let { Networking.monitorStep = it.toDouble() }
+        parser.getValue("Network Buffer")?.let { Networking.useBuffer = it.toBoolean() }
 
         parser.getValuePairList("Server").forEach {
             Networking.servers.add(Pair(it.first, it.second.toInt()))
@@ -231,6 +236,9 @@ class Config(args: Array<String>) {
         parser.setValuePairList("Server", Networking.servers.map { Pair(it.first, it.second.toString()) })
         parser.setValue("Default Server", "${Networking.defaultServerHost}:${Networking.defaultServerPort}")
 
+        parser.setValue("Monitor Step", Networking.monitorStep.toString())
+        parser.setValue("Network Buffer", Networking.useBuffer.toString())
+
         // OverlayVisibility
         parser.setValue("Server Speed", OverlayVisibility.serverSpeed.toString())
         parser.setValue("Foul Overlay", OverlayVisibility.foulOverlay.toString())

src/main/kotlin/org/magmaoffenburg/roboviz/gui/windows/config/ServerPanel.kt

@@ -22,6 +22,9 @@ class ServerPanel: JPanel() {
     private val defaultServerPortSpinner = JSpinner(SpinnerNumberModel(Networking.defaultServerPort, 0, Int.MAX_VALUE, 1))
     private val drawingPortLabel = JLabel("Drawing Port:")
     private val drawingPortSpinner = JSpinner(SpinnerNumberModel(Networking.listenPort, 0, Int.MAX_VALUE, 1))
+    private val monitorStepLabel = JLabel("Monitor step duration:")
+    private val monitorStepSpinner = JSpinner(SpinnerNumberModel(Networking.monitorStep, 0.0, Double.MAX_VALUE, 0.01))
+    private val useBufferCB = JCheckBox("Use Buffer", Networking.useBuffer)
     private val serverListButton = JButton("Open Server List")
 
     init {
@@ -62,6 +65,11 @@ class ServerPanel: JPanel() {
                         .addComponent(drawingPortLabel, 0, 125, 125)
                         .addComponent(drawingPortSpinner, 0, 120, 120)
                 )
+                .addGroup(layout.createSequentialGroup()
+                    .addComponent(monitorStepLabel, 0, 125, 125)
+                    .addComponent(monitorStepSpinner, 0, 120, 120)
+                )
+                .addComponent(useBufferCB, 0, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE.toInt())
                 .addComponent(serverListButton, 0, GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE.toInt())
         )
 
@@ -87,6 +95,11 @@ class ServerPanel: JPanel() {
                         .addComponent(drawingPortLabel)
                         .addComponent(drawingPortSpinner)
                 )
+                .addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
+                    .addComponent(monitorStepLabel)
+                    .addComponent(monitorStepSpinner)
+                )
+                .addComponent(useBufferCB)
                 .addComponent(serverListButton)
         )
     }
@@ -124,6 +137,12 @@ class ServerPanel: JPanel() {
         serverListButton.addActionListener {
             ServerListDialog.showDialog()
         }
+        monitorStepSpinner.addChangeListener {
+            Networking.monitorStep = monitorStepSpinner.value as Double
+        }
+        useBufferCB.addActionListener {
+            Networking.useBuffer = useBufferCB.isSelected
+        }
     }
 
 }