[GitHub] [hbase] maoling commented on a change in pull request #345: HBASE-22638 : Zookeeper Utility enhancements

[GitBox <gi...@apache.org>]

maoling commented on a change in pull request #345: HBASE-22638 : Zookeeper Utility enhancements
URL: https://github.com/apache/hbase/pull/345#discussion_r298863765
 
 

 ##########
 File path: hbase-zookeeper/src/main/java/org/apache/hadoop/hbase/zookeeper/ZKUtil.java
 ##########
 @@ -1859,31 +1873,33 @@ private static void getReplicationZnodesDump(ZKWatcher zkw, StringBuilder sb)
     // do a ls -r on this znode
     sb.append("\n").append(replicationZnode).append(": ");
     List<String> children = ZKUtil.listChildrenNoWatch(zkw, replicationZnode);
-    Collections.sort(children);
-    for (String child : children) {
-      String znode = ZNodePaths.joinZNode(replicationZnode, child);
-      if (znode.equals(zkw.getZNodePaths().peersZNode)) {
-        appendPeersZnodes(zkw, znode, sb);
-      } else if (znode.equals(zkw.getZNodePaths().queuesZNode)) {
-        appendRSZnodes(zkw, znode, sb);
-      } else if (znode.equals(zkw.getZNodePaths().hfileRefsZNode)) {
-        appendHFileRefsZnodes(zkw, znode, sb);
+    if (children != null) {
+      Collections.sort(children);
+      for (String child : children) {
+        String zNode = ZNodePaths.joinZNode(replicationZnode, child);
+        if (zNode.equals(zkw.getZNodePaths().peersZNode)) {
+          appendPeersZnodes(zkw, zNode, sb);
+        } else if (zNode.equals(zkw.getZNodePaths().queuesZNode)) {
+          appendRSZnodes(zkw, zNode, sb);
+        } else if (zNode.equals(zkw.getZNodePaths().hfileRefsZNode)) {
+          appendHFileRefsZnodes(zkw, zNode, sb);
+        }
       }
     }
   }
 
   private static void appendHFileRefsZnodes(ZKWatcher zkw, String hfileRefsZnode,
                                             StringBuilder sb) throws KeeperException {
     sb.append("\n").append(hfileRefsZnode).append(": ");
-    for (String peerIdZnode : ZKUtil.listChildrenNoWatch(zkw, hfileRefsZnode)) {
-      String znodeToProcess = ZNodePaths.joinZNode(hfileRefsZnode, peerIdZnode);
-      sb.append("\n").append(znodeToProcess).append(": ");
-      List<String> peerHFileRefsZnodes = ZKUtil.listChildrenNoWatch(zkw, znodeToProcess);
-      int size = peerHFileRefsZnodes.size();
-      for (int i = 0; i < size; i++) {
-        sb.append(peerHFileRefsZnodes.get(i));
-        if (i != size - 1) {
-          sb.append(", ");
+    final List<String> hFileRefChildrenNoWatchList =
+            ZKUtil.listChildrenNoWatch(zkw, hfileRefsZnode);
+    if (hFileRefChildrenNoWatchList != null) {
+      for (String peerIdZNode : hFileRefChildrenNoWatchList) {
 
 Review comment:
   - to avoid too deep nest.
   ```
   if (hFileRefChildrenNoWatchList == null) {
       return;
   }
   ```
   - Others,LGTM
   

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