Merge pull request #4 from Borjianamin98/main

Fix corner case of adding node to zookeeper

pom.xml

@@ -5,7 +5,7 @@
 
     <groupId>ir.sahab</groupId>
     <artifactId>zk-client</artifactId>
-    <version>1.0.0</version>
+    <version>1.1.0</version>
     <description>This is a client library for ZooKeeper. In fact it is a thin wrapper around curator that provides
         concise method calls with checked exceptions.
     </description>

src/main/java/ir/sahab/zk/client/ZkClient.java

@@ -308,6 +308,14 @@ public String addSequentiallyNamedNode(String parentPath, String namePrefix, byt
      */
     public void addPersistentNode(String path, byte[] data, boolean createParent)
             throws ZkClientException, InterruptedException {
+        // There is a corner case where Curator throws a ConnectionLoss but the ZK node is actually added.
+        // In order to be sure that the logic used for the exceptional case is correct,
+        // it is necessary to first check the existence of the path and if it exists, skip the rest
+        // of the operations.
+        if (exists(path)) {
+            throw new ZkClientException("Failed to add ZK node because node exists: " + path);
+        }
+
         try {
             if (createParent) {
                 curator.create().creatingParentsIfNeeded().withMode(CreateMode.PERSISTENT).forPath(path, data);
@@ -320,7 +328,14 @@ public void addPersistentNode(String path, byte[] data, boolean createParent)
         } catch (InterruptedException ex) {
             throw ex;
         } catch (Exception ex) {
-            throw new ZkClientException("Failed to add a persistent ZK node in path: " + path, ex);
+            // There is a corner case where Curator throws a ConnectionLoss but the ZK node is actually
+            // added, so when we retry we get NodeExists exception. In here, we check whether the node
+            // is created or not and ignore the exception if the node exists.
+            if (exists(path) && Arrays.equals(getData(path), data)) {
+                logger.warn("Retrieve error in creating ZK path but node created anyway: {}", path);
+            } else {
+                throw new ZkClientException("Failed to add a persistent ZK node: " + path, ex);
+            }
         }
     }