Improve ZookeeperDataSource to deal with bad connection when initializing (#597)

sentinel-extension/sentinel-datasource-zookeeper/src/main/java/com/alibaba/csp/sentinel/datasource/zookeeper/ZookeeperDataSource.java

@@ -103,17 +103,16 @@ public class ZookeeperDataSource<T> extends AbstractDataSource<String, T> {
             this.listener = new NodeCacheListener() {
                 @Override
                 public void nodeChanged() {
-                    String configInfo = null;
-                    ChildData childData = nodeCache.getCurrentData();
-                    if (null != childData && childData.getData() != null) {
 
-                        configInfo = new String(childData.getData());
+                    try {
+                        T newValue = loadConfig();
+                        RecordLog.info(String.format("[ZookeeperDataSource] New property value received for (%s, %s): %s",
+                                serverAddr, path, newValue));
+                        // Update the new value to the property.
+                        getProperty().updateValue(newValue);
+                    } catch (Exception ex) {
+                        RecordLog.warn("[ZookeeperDataSource] loadConfig exception", ex);
                     }
-                    RecordLog.info(String.format("[ZookeeperDataSource] New property value received for (%s, %s): %s",
-                        serverAddr, path, configInfo));
-                    T newValue = ZookeeperDataSource.this.parser.convert(configInfo);
-                    // Update the new value to the property.
-                    getProperty().updateValue(newValue);
                 }
             };
 
@@ -127,10 +126,6 @@ public class ZookeeperDataSource<T> extends AbstractDataSource<String, T> {
                         build();
             }
             this.zkClient.start();
-            Stat stat = this.zkClient.checkExists().forPath(this.path);
-            if (stat == null) {
-                this.zkClient.create().creatingParentContainersIfNeeded().withMode(CreateMode.PERSISTENT).forPath(this.path, null);
-            }
 
             this.nodeCache = new NodeCache(this.zkClient, this.path);
             this.nodeCache.getListenable().addListener(this.listener, this.pool);
@@ -146,11 +141,13 @@ public class ZookeeperDataSource<T> extends AbstractDataSource<String, T> {
         if (this.zkClient == null) {
             throw new IllegalStateException("Zookeeper has not been initialized or error occurred");
         }
-        byte[] data = this.zkClient.getData().forPath(this.path);
-        if (data != null) {
-            return new String(data);
+        String configInfo = null;
+        ChildData childData = nodeCache.getCurrentData();
+        if (null != childData && childData.getData() != null) {
+
+            configInfo = new String(childData.getData());
         }
-        return null;
+        return configInfo;
     }
 
     @Override