Implement WebSocket keep alive by sending WS PING once per minute for

alwaysOn devices. The PONG will restart the watchdog. WS connection idle
time has been reduced to 5 min, which means about 4 retries if the
devices does not respond once per minute.

Signed-off-by: Markus Michels <markus7017@gmail.com>

Author: markus7017

bundles/org.openhab.binding.shelly/src/main/java/org/openhab/binding/shelly/internal/api/ShellyApiInterface.java

@@ -37,7 +37,7 @@ public interface ShellyApiInterface extends ShellyDiscoveryInterface {
 
     void setConfig(String thingName, ShellyThingConfiguration config);
 
-    ShellySettingsStatus getStatus() throws ShellyApiException;
+    ShellySettingsStatus getStatus(boolean ping) throws ShellyApiException;
 
     void setLedStatus(String ledName, boolean value) throws ShellyApiException;
 

bundles/org.openhab.binding.shelly/src/main/java/org/openhab/binding/shelly/internal/api1/Shelly1HttpApi.java

@@ -167,7 +167,7 @@ public boolean isInitialized() {
      * @throws ShellyApiException
      */
     @Override
-    public ShellySettingsStatus getStatus() throws ShellyApiException {
+    public ShellySettingsStatus getStatus(boolean ping) throws ShellyApiException {
         String json = "";
         try {
             json = httpRequest(SHELLY_URL_STATUS);

bundles/org.openhab.binding.shelly/src/main/java/org/openhab/binding/shelly/internal/api2/Shelly2ApiRpc.java

@@ -334,7 +334,7 @@ public ShellyDeviceProfile getDeviceProfile(ThingTypeUID thingTypeUID, @Nullable
         }
 
         if (!profile.initialized && profile.alwaysOn) {
-            getStatus(); // make sure profile.status is initialized (e.g,. relay/meter status)
+            getStatus(false); // make sure profile.status is initialized (e.g,. relay/meter status)
             asyncApiRequest(SHELLYRPC_METHOD_GETSTATUS); // request periodic status updates from device
         }
         profile.initialized = true;
@@ -747,6 +747,13 @@ public void onMessage(String message) {
         incProtErrors();
     }
 
+    @Override
+    public void onPong() {
+        if (thing != null) {
+            thing.restartWatchdog();
+        }
+    }
+
     @Override
     public void onClose(int statusCode, String description) {
         try {
@@ -790,7 +797,7 @@ private void thingOffline(String reason) {
     }
 
     @Override
-    public ShellySettingsStatus getStatus() throws ShellyApiException {
+    public ShellySettingsStatus getStatus(boolean ping) throws ShellyApiException {
         ShellyDeviceProfile profile = getProfile();
         ShellySettingsStatus status = profile.status;
         Shelly2DeviceStatusResult ds = apiRequest(SHELLYRPC_METHOD_GETSTATUS, null, Shelly2DeviceStatusResult.class);
@@ -853,9 +860,23 @@ public ShellySettingsStatus getStatus() throws ShellyApiException {
             }
         }
 
+        if (ping) {
+            sendPing();
+        }
+
         return status;
     }
 
+    private void sendPing() {
+        Shelly2RpcSocket rpcSocket;
+        synchronized (this) {
+            rpcSocket = this.rpcSocket;
+        }
+        if (rpcSocket != null) {
+            rpcSocket.ping();
+        }
+    }
+
     @Override
     public void setSleepTime(int value) throws ShellyApiException {
     }
@@ -864,7 +885,7 @@ public void setSleepTime(int value) throws ShellyApiException {
     public ShellyStatusRelay getRelayStatus(int relayIndex) throws ShellyApiException {
         if (getProfile().status.wifiSta.ssid == null) {
             // Update status when not yet initialized
-            getStatus();
+            getStatus(false);
         }
         return relayStatus;
     }

bundles/org.openhab.binding.shelly/src/main/java/org/openhab/binding/shelly/internal/api2/Shelly2RpcSocket.java

@@ -21,6 +21,7 @@
 import java.io.IOException;
 import java.net.URI;
 import java.net.URISyntaxException;
+import java.nio.ByteBuffer;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -35,8 +36,10 @@
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketClose;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketConnect;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketError;
+import org.eclipse.jetty.websocket.api.annotations.OnWebSocketFrame;
 import org.eclipse.jetty.websocket.api.annotations.OnWebSocketMessage;
 import org.eclipse.jetty.websocket.api.annotations.WebSocket;
+import org.eclipse.jetty.websocket.api.extensions.Frame;
 import org.eclipse.jetty.websocket.client.ClientUpgradeRequest;
 import org.eclipse.jetty.websocket.client.WebSocketClient;
 import org.openhab.binding.shelly.internal.api.ShellyApiException;
@@ -56,7 +59,7 @@
  * @author Markus Michels - Initial contribution
  */
 @NonNullByDefault
-@WebSocket(maxIdleTime = Integer.MAX_VALUE)
+@WebSocket(maxIdleTime = 5 * 60 * 1000)
 public class Shelly2RpcSocket implements WriteCallback {
     private final Logger logger = LoggerFactory.getLogger(Shelly2RpcSocket.class);
     private final Gson gson = new Gson();
@@ -377,10 +380,6 @@ public synchronized boolean isConnected() {
         return session != null && session.isOpen();
     }
 
-    public boolean isInbound() {
-        return inbound;
-    }
-
     /**
      * WebSocket closed, notify thing handler (close initiated by the binding)
      *
@@ -436,6 +435,45 @@ public void onError(Throwable cause) {
         }
     }
 
+    public void ping() {
+        Session session;
+        synchronized (this) {
+            session = this.session;
+        }
+        if (session != null && session.isOpen()) {
+            RemoteEndpoint remote = session.getRemote();
+            String ipAddress = remote.getInetSocketAddress().getHostString();
+            if (logger.isDebugEnabled()) {
+                logger.debug("{}: Sending WebSocket PING to {}", thingName, ipAddress);
+            }
+            try {
+                remote.sendPing(ByteBuffer.allocate(0));
+            } catch (IOException e) {
+                logger.debug("{}: Faied to send WebSocket PING to {}", thingName, ipAddress, e);
+            }
+        }
+    }
+
+    @OnWebSocketFrame
+    public void onFrame(Session session, Frame frame) {
+        switch (frame.getOpCode()) {
+            case 0xA: // PONG opcode
+            case 0x9: // PING opcode (optional)
+                // Jetty auto-responds with PONG by default
+                if (logger.isTraceEnabled()) {
+                    logger.trace("{}: WebSocket PONG received", thingName);
+                }
+                Shelly2RpctInterface websocketHandler;
+                synchronized (this) {
+                    websocketHandler = this.websocketHandler;
+                }
+                if (websocketHandler != null) {
+                    websocketHandler.onPong();
+                }
+                break;
+        }
+    }
+
     /**
      * Clears session and drops queued messages.
      * Must only be called when session has been/is being closed one way or another.

bundles/org.openhab.binding.shelly/src/main/java/org/openhab/binding/shelly/internal/api2/Shelly2RpctInterface.java

@@ -32,6 +32,8 @@ public interface Shelly2RpctInterface {
 
     void onNotifyEvent(String json) throws ShellyApiException;
 
+    void onPong();
+
     void onClose(int statusCode, String reason);
 
     void onError(Throwable cause);

bundles/org.openhab.binding.shelly/src/main/java/org/openhab/binding/shelly/internal/api2/ShellyBluApi.java

@@ -138,7 +138,7 @@ public ShellyDeviceProfile getDeviceProfile(ThingTypeUID thingTypeUID, @Nullable
     }
 
     @Override
-    public ShellySettingsStatus getStatus() throws ShellyApiException {
+    public ShellySettingsStatus getStatus(boolean ping) throws ShellyApiException {
         if (!connected) {
             throw new ShellyApiException("Thing is not yet initialized -> status not available");
         }

bundles/org.openhab.binding.shelly/src/main/java/org/openhab/binding/shelly/internal/handler/ShellyBaseHandler.java

@@ -368,7 +368,7 @@ thingName, getThing().getLabel(), thingType, config.deviceAddress.toUpperCase(),
             tmpPrf.updatePeriod = UPDATE_SETTINGS_INTERVAL_SECONDS + 10;
         }
 
-        tmpPrf.status = api.getStatus(); // update thing properties
+        tmpPrf.status = api.getStatus(false); // update thing properties
         tmpPrf.updateFromStatus(tmpPrf.status);
         addStateOptions(tmpPrf);
 
@@ -559,7 +559,7 @@ protected void refreshStatus() {
                     logger.debug("{}: Status update triggered thing initialization", thingName);
                     initializeThing(); // may fire an exception if initialization failed
                 }
-                ShellySettingsStatus status = api.getStatus();
+                ShellySettingsStatus status = api.getStatus(profile.alwaysOn);
                 boolean restarted = checkRestarted(status);
                 profile = getProfile(refreshSettings || restarted);
                 profile.status = status;