Improvement - PubSub channels should be reconnected back to Slave from Master node if SubscriptionMode = SLAVE #5199

redisson/src/main/java/org/redisson/connection/MasterSlaveEntry.java

@@ -242,6 +242,20 @@ public class MasterSlaveEntry {
         nodeDown(masterEntry);
     }
 
+    private void reattachPubSub() {
+        for (RedisPubSubConnection connection : masterEntry.getAllSubscribeConnections()) {
+            connection.closeAsync();
+            connectionManager.getSubscribeService().reattachPubSub(connection);
+        }
+        while (true) {
+            RedisConnection connection = masterEntry.pollSubscribeConnection();
+            if (connection == null) {
+                break;
+            }
+        }
+        masterEntry.getAllSubscribeConnections().clear();
+    }
+
     public boolean nodeDown(ClientConnectionsEntry entry) {
         entry.reset();
         
@@ -445,6 +459,9 @@ public class MasterSlaveEntry {
         CompletableFuture<Boolean> downFuture = slaveDownAsync(addr, FreezeReason.SYSTEM);
         return downFuture.thenApply(r -> {
             if (r) {
+                if (config.getSubscriptionMode() == SubscriptionMode.SLAVE) {
+                    reattachPubSub();
+                }
                 log.info("master {} excluded from slaves", addr);
             }
             return r;
@@ -459,6 +476,9 @@ public class MasterSlaveEntry {
         CompletableFuture<Boolean> downFuture = slaveDownAsync(addr, FreezeReason.SYSTEM);
         return downFuture.thenApply(r -> {
             if (r) {
+                if (config.getSubscriptionMode() == SubscriptionMode.SLAVE) {
+                    reattachPubSub();
+                }
                 log.info("master {} excluded from slaves", addr);
             }
             return r;