Implements websocket client auto-reconnect

pandalib-ws-client/src/main/java/fr/pandacube/lib/ws/client/AbstractClientWS.java

@@ -1,6 +1,5 @@
 package fr.pandacube.lib.ws.client;
 
-import fr.pandacube.lib.util.Log;
 import fr.pandacube.lib.util.ThrowableUtil;
 import fr.pandacube.lib.ws.AbstractWS;
 
@@ -16,7 +15,6 @@ import java.util.concurrent.CompletionException;
 import java.util.concurrent.CompletionStage;
 import java.util.concurrent.atomic.AtomicReference;
 
-// TODO implement auto-reconnect
 /**
  * Minimal implementation of a Websocket client endpoint using the java.net.http Websocket API.
  */
@@ -24,6 +22,7 @@ public abstract class AbstractClientWS implements AbstractWS {
 
     private final URI uri;
     private boolean autoReconnect;
+    private boolean isConnecting;
     private final AtomicReference<WebSocket> socket = new AtomicReference<>();
 
 
@@ -48,14 +47,27 @@ public abstract class AbstractClientWS implements AbstractWS {
 
         @Override
         public CompletionStage<?> onClose(WebSocket webSocket, int statusCode, String reason) {
-            AbstractClientWS.this.onClose(statusCode, reason);
-            return Listener.super.onClose(webSocket, statusCode, reason);
+            try {
+                AbstractClientWS.this.onClose(statusCode, reason);
+            } finally {
+                synchronized (socket) {
+                    socket.set(null);
+                    reconnectIfNecessary();
+                }
+            }
+            return null;
         }
 
         @Override
         public void onError(WebSocket webSocket, Throwable error) {
-            AbstractClientWS.this.onError(error);
-            Listener.super.onError(webSocket, error);
+            try {
+                AbstractClientWS.this.onError(error);
+            } finally {
+                synchronized (socket) {
+                    socket.set(null);
+                    reconnectIfNecessary();
+                }
+            }
         }
     };
 
@@ -69,21 +81,40 @@ public abstract class AbstractClientWS implements AbstractWS {
     public AbstractClientWS(String uri, boolean autoReconnect) throws URISyntaxException {
         this.uri = new URI(uri);
         this.autoReconnect = autoReconnect;
-        if (autoReconnect) {
-            Log.warning("Websocket client auto-reconnect is not yet implemented.");
-        }
         connect();
     }
 
 
+    private void reconnectIfNecessary() {
+        synchronized (socket) {
+            if (autoReconnect && !isConnecting && socket.get() == null) {
+                connect();
+            }
+        }
+    }
+
+
     private void connect() {
         synchronized (socket) {
-            socket.set(HttpClient.newHttpClient()
+            isConnecting = true;
+            HttpClient.newHttpClient()
                     .newWebSocketBuilder()
-                    .connectTimeout(Duration.ofSeconds(2))
+                    .connectTimeout(Duration.ofSeconds(5))
                     .buildAsync(uri, receiveListener)
-                    .join()
-            );
+                    .whenCompleteAsync((ws, ex) -> {
+                        synchronized (socket) {
+                            isConnecting = false;
+                            if (ws != null) {
+                                socket.set(ws);
+                            }
+                        }
+                        if (ex instanceof IOException) {
+                            reconnectIfNecessary();
+                        }
+                        else {
+                            logError("Error connecting (not trying to reconnect even if asked): ", ex);
+                        }
+                    });
         }
     }
 
@@ -92,7 +123,11 @@ public abstract class AbstractClientWS implements AbstractWS {
     public final void sendString(String message) throws IOException {
         try {
             synchronized (socket) {
-                socket.get().sendText(message, true).join();
+                WebSocket ws = socket.get();
+                if (ws != null)
+                    ws.sendText(message, true).join();
+                else
+                    throw new IOException("Connection is currently closed");
             }
         } catch (CompletionException ce) {
             if (ce.getCause() instanceof IOException ioe)
@@ -110,7 +145,9 @@ public abstract class AbstractClientWS implements AbstractWS {
     public final void sendClose(int code, String reason) throws IOException {
         synchronized (socket) {
             autoReconnect = false; // if we ask for closing connection, dont reconnect automatically
-            socket.get().sendClose(code, reason).join();
+            WebSocket ws = socket.get();
+            if (ws != null)
+                ws.sendClose(code, reason).join();
         }
     }
 

pandalib-ws-server/src/main/java/fr/pandacube/lib/ws/server/AbstractServerWS.java

@@ -5,12 +5,15 @@ import org.eclipse.jetty.websocket.api.Session;
 import org.eclipse.jetty.websocket.api.WebSocketAdapter;
 
 import java.io.IOException;
+import java.nio.channels.ClosedChannelException;
 import java.time.Duration;
 
 /**
  * Minimal implementation of a Websocket server endpoint using the Jetty Websocket API.
  */
 public abstract class AbstractServerWS extends WebSocketAdapter implements AbstractWS {
+
+	private boolean isClosed = false;
 	
 	@Override
 	public final void onWebSocketConnect(Session sess)
@@ -37,6 +40,8 @@ public abstract class AbstractServerWS extends WebSocketAdapter implements Abstr
 
 	@Override
 	public final void onWebSocketError(Throwable cause) {
+		if (isClosed && cause instanceof ClosedChannelException)
+			return; // ignore because this exception is expected when we just sent a close packet.
 		onError(cause);
 	}
 
@@ -53,6 +58,7 @@ public abstract class AbstractServerWS extends WebSocketAdapter implements Abstr
 	@Override
 	public final void sendClose(int code, String reason) throws IOException {
 		getSession().close(code, reason);
+		isClosed = true;
 	}
 
 	@Override

pandalib-ws/src/main/java/fr/pandacube/lib/ws/AbstractWS.java

@@ -32,15 +32,26 @@ public interface AbstractWS {
             return;
         }
 
-        try {
-            onReceivePayload(payload);
-        } catch (Throwable t) {
-            trySendAsJson(new ErrorPayload("Error handling payload: " + t));
-            if (t instanceof Exception)
-                logError("Error handling payload", t);
-            else
-                throw t;
+        if (payload instanceof ErrorPayload errorPayload) {
+            try {
+                onReceiveErrorPayload(errorPayload);
+            } catch(Exception e) {
+                logError("Error while handling received error payload", e);
+            }
         }
+        else {
+            try {
+                onReceivePayload(payload);
+            } catch (Throwable t) {
+                trySendAsJson(new ErrorPayload("Error while handling your payload: " + t));
+                if (t instanceof Exception)
+                    logError("Error while handling received payload", t);
+                else
+                    throw t;
+            }
+        }
+
+
     }
 
     /**
@@ -62,6 +73,15 @@ public interface AbstractWS {
      */
     void onReceivePayload(Payload payload);
 
+    /**
+     * Called on reception of a valid {@link ErrorPayload}.
+     * @param error the received {@link ErrorPayload}.
+     * @implNote default implementation will log the received error.
+     */
+    default void onReceiveErrorPayload(ErrorPayload error) {
+        logError("Received the following error from the remote side: " + error.message, error.throwable);
+    }
+
     /**
      * Called on reception of a websocket Close packet.
      * The connection is closed after this method call.

pandalib-ws/src/main/java/fr/pandacube/lib/ws/PayloadRegistry.java

@@ -49,12 +49,12 @@ public class PayloadRegistry {
     public static Payload fromString(String message) {
         String[] split = message.split(Pattern.quote(PAYLOAD_TYPE_SEPARATOR), 2);
         if (split.length != 2) {
-            throw new IllegalArgumentException("Malformed message: does not respect format '<type>" + PAYLOAD_TYPE_SEPARATOR + "<jsonObject>'.");
+            throw new IllegalArgumentException("Malformed message: does not respect format ‘<type>" + PAYLOAD_TYPE_SEPARATOR + "<jsonObject>’.");
         }
 
         Class<? extends Payload> detectedClass = payloadClasses.get(split[0]);
         if (detectedClass == null) {
-            throw new IllegalArgumentException("Unrecognized data type '" + split[0] + "'.");
+            throw new IllegalArgumentException("Unrecognized data type ‘" + split[0] + "’.");
         }
 
         try {