Fix #1256 Socket Mode connection error issue (#1265)

Author: seratch

slack-api-client/src/main/java/com/slack/api/socket_mode/SocketModeClient.java

@@ -57,6 +57,14 @@ enum Backend {
      */
     boolean verifyConnection();
 
+    /**
+     * Returns true if the client tries to reconnect when onClose listeners are called
+     * plus isAutoReconnectEnabled() is true. Default: false
+     */
+    boolean isAutoReconnectOnCloseEnabled();
+
+    void setAutoReconnectOnCloseEnabled(boolean autoReconnectOnCloseEnabled);
+
     /**
      * Connects to a new WSS endpoint and starts a new WebSocket session.
      */
@@ -256,11 +264,30 @@ default void runCloseListenersAndAutoReconnectAsNecessary(Integer code, String r
         for (WebSocketCloseListener listener : getWebSocketCloseListeners()) {
             listener.handle(code, reason);
         }
-        if (isAutoReconnectEnabled() && !verifyConnection()) {
-            try {
-                connectToNewEndpoint();
-            } catch (IOException e) {
-                getLogger().error("Failed to reconnect to the Socket Mode server: {}", e.getMessage(), e);
+        if (isAutoReconnectOnCloseEnabled()) {
+            // Starting in December 2023, the Socket Mode server changed its behavior.
+            // As a result, the logic here can result in a rate-limited error.
+            //
+            // Reported issues:
+            // * https://github.com/slackapi/java-slack-sdk/issues/1256
+            // * https://github.com/slackapi/java-slack-sdk/issues/1223
+            //
+            // Originally, this logic was added to let this client get back online even more quickly when something is wrong.
+            // However, it seems that the logic has been relying on the server's past behavior characteristics.
+            // Note that, even when the underlying connection is closed due to "reason: Closed abnormally." or similar,
+            // the session monitor under the hood continues to try to reconnect for you.
+            // For this reason, disabling this logic should be safe for any situations.
+            // If there is an exception this assumption does not cover, we may need to improve the logic to ensure better stability.
+            //
+            // Therefore, in v1.37.0, this SDK disabled this by default.
+            // If you want to turn it on again, set the isAutoReconnectOnCloseEnabled to true.
+
+            if (isAutoReconnectEnabled() && !verifyConnection()) {
+                try {
+                    connectToNewEndpoint();
+                } catch (IOException e) {
+                    getLogger().error("Failed to reconnect to the Socket Mode server: {}", e.getMessage(), e);
+                }
             }
         }
     }

slack-api-client/src/main/java/com/slack/api/socket_mode/impl/SocketModeClientJavaWSImpl.java

@@ -41,6 +41,7 @@ public class SocketModeClientJavaWSImpl implements SocketModeClient {
     private final Gson gson;
     private URI wssUri;
     private boolean autoReconnectEnabled;
+    private boolean autoReconnectOnCloseEnabled;
     private SocketModeMessageQueue messageQueue;
     private ScheduledExecutorService messageProcessorExecutor;
     private boolean sessionMonitorEnabled;
@@ -110,6 +111,8 @@ public SocketModeClientJavaWSImpl(
 
         setMessageQueue(messageQueue);
         setAutoReconnectEnabled(autoReconnectEnabled);
+        // You can use the setter method if you set the value to true
+        setAutoReconnectOnCloseEnabled(false);
         setSessionMonitorEnabled(sessionMonitorEnabled);
         initializeSessionMonitorExecutor(sessionMonitorIntervalMillis);
         initializeMessageProcessorExecutor(concurrency);
@@ -156,6 +159,16 @@ public boolean verifyConnection() {
         return false;
     }
 
+    @Override
+    public boolean isAutoReconnectOnCloseEnabled() {
+        return this.autoReconnectOnCloseEnabled;
+    }
+
+    @Override
+    public void setAutoReconnectOnCloseEnabled(boolean autoReconnectOnCloseEnabled) {
+        this.autoReconnectOnCloseEnabled = autoReconnectOnCloseEnabled;
+    }
+
     @Override
     public void disconnect() {
         setAutoReconnectEnabled(false);

slack-api-client/src/main/java/com/slack/api/socket_mode/impl/SocketModeClientTyrusImpl.java

@@ -43,6 +43,7 @@ public class SocketModeClientTyrusImpl implements SocketModeClient {
     private final Gson gson;
     private URI wssUri;
     private boolean autoReconnectEnabled;
+    private boolean autoReconnectOnCloseEnabled;
     private SocketModeMessageQueue messageQueue;
     private ScheduledExecutorService messageProcessorExecutor;
     private boolean sessionMonitorEnabled;
@@ -121,6 +122,8 @@ public SocketModeClientTyrusImpl(
 
         setMessageQueue(messageQueue);
         setAutoReconnectEnabled(autoReconnectEnabled);
+        // You can use the setter method if you set the value to true
+        setAutoReconnectOnCloseEnabled(false);
         setSessionMonitorEnabled(sessionMonitorEnabled);
         initializeSessionMonitorExecutor(sessionMonitorIntervalMillis);
         initializeMessageProcessorExecutor(concurrency);
@@ -217,6 +220,16 @@ public boolean verifyConnection() {
         return false;
     }
 
+    @Override
+    public boolean isAutoReconnectOnCloseEnabled() {
+        return this.autoReconnectOnCloseEnabled;
+    }
+
+    @Override
+    public void setAutoReconnectOnCloseEnabled(boolean autoReconnectOnCloseEnabled) {
+        this.autoReconnectOnCloseEnabled = autoReconnectOnCloseEnabled;
+    }
+
     @Override
     public void disconnect() throws IOException {
         setAutoReconnectEnabled(false);