HADOOP-14773. Extend ZKCuratorManager API for more reusability. (Íñigo Goiri via Subru).

(cherry picked from commit 75dd866bfb8b63cb9f13179d4365b05c48e0907d)

hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/util/curator/ZKCuratorManager.java

@@ -33,9 +33,12 @@
 import org.apache.hadoop.util.ZKUtil;
 import org.apache.zookeeper.CreateMode;
 import org.apache.zookeeper.data.ACL;
+import org.apache.zookeeper.data.Stat;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import com.google.common.base.Preconditions;
+
 /**
  * Helper class that provides utility methods specific to ZK operations.
  */
@@ -179,7 +182,6 @@ public List<ACL> getACL(final String path) throws Exception {
   /**
    * Get the data in a ZNode.
    * @param path Path of the ZNode.
-   * @param stat Output statistics of the ZNode.
    * @return The data in the ZNode.
    * @throws Exception If it cannot contact Zookeeper.
    */
@@ -187,6 +189,28 @@ public byte[] getData(final String path) throws Exception {
     return curator.getData().forPath(path);
   }
 
+  /**
+   * Get the data in a ZNode.
+   * @param path Path of the ZNode.
+   * @param stat
+   * @return The data in the ZNode.
+   * @throws Exception If it cannot contact Zookeeper.
+   */
+  public byte[] getData(final String path, Stat stat) throws Exception {
+    return curator.getData().storingStatIn(stat).forPath(path);
+  }
+
+  /**
+   * Get the data in a ZNode.
+   * @param path Path of the ZNode.
+   * @return The data in the ZNode.
+   * @throws Exception If it cannot contact Zookeeper.
+   */
+  public String getStringData(final String path) throws Exception {
+    byte[] bytes = getData(path);
+    return new String(bytes, Charset.forName("UTF-8"));
+  }
+
   /**
    * Get the data in a ZNode.
    * @param path Path of the ZNode.
@@ -194,8 +218,8 @@ public byte[] getData(final String path) throws Exception {
    * @return The data in the ZNode.
    * @throws Exception If it cannot contact Zookeeper.
    */
-  public String getSringData(final String path) throws Exception {
+  public String getStringData(final String path, Stat stat) throws Exception {
-    byte[] bytes = getData(path);
+    byte[] bytes = getData(path, stat);
     return new String(bytes, Charset.forName("UTF-8"));
   }
 
@@ -271,15 +295,37 @@ public boolean create(final String path, List<ACL> zkAcl) throws Exception {
     return created;
   }
 
+  /**
+   * Utility function to ensure that the configured base znode exists.
+   * This recursively creates the znode as well as all of its parents.
+   * @param path Path of the znode to create.
+   * @throws Exception If it cannot create the file.
+   */
+  public void createRootDirRecursively(String path) throws Exception {
+    String[] pathParts = path.split("/");
+    Preconditions.checkArgument(
+        pathParts.length >= 1 && pathParts[0].isEmpty(),
+        "Invalid path: %s", path);
+    StringBuilder sb = new StringBuilder();
+
+    for (int i = 1; i < pathParts.length; i++) {
+      sb.append("/").append(pathParts[i]);
+      create(sb.toString());
+    }
+  }
+
   /**
    * Delete a ZNode.
    * @param path Path of the ZNode.
+   * @return If the znode was deleted.
    * @throws Exception If it cannot contact ZooKeeper.
    */
-  public void delete(final String path) throws Exception {
+  public boolean delete(final String path) throws Exception {
     if (exists(path)) {
       curator.delete().deletingChildrenIfNeeded().forPath(path);
+      return true;
     }
+    return false;
   }
 
   /**

hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/util/curator/TestZKCuratorManager.java

@@ -67,7 +67,7 @@ public void testReadWriteData() throws Exception {
     curator.create(testZNode);
     assertTrue(curator.exists(testZNode));
     curator.setData(testZNode, expectedString, -1);
-    String testString = curator.getSringData("/test");
+    String testString = curator.getStringData("/test");
     assertEquals(expectedString, testString);
   }
 

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/ZKRMStateStore.java

@@ -19,7 +19,6 @@
 package org.apache.hadoop.yarn.server.resourcemanager.recovery;
 
 import com.google.common.annotations.VisibleForTesting;
-import com.google.common.base.Preconditions;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.curator.framework.CuratorFramework;
@@ -338,7 +337,7 @@ public synchronized void initInternal(Configuration conf)
   @Override
   public synchronized void startInternal() throws Exception {
     // ensure root dirs exist
-    createRootDirRecursively(znodeWorkingPath);
+    zkManager.createRootDirRecursively(znodeWorkingPath);
     create(zkRootNodePath);
     setRootNodeAcls();
     delete(fencingNodePath);
@@ -1147,22 +1146,6 @@ private void addOrUpdateReservationState(
     }
   }
 
-  /**
-   * Utility function to ensure that the configured base znode exists.
-   * This recursively creates the znode as well as all of its parents.
-   */
-  private void createRootDirRecursively(String path) throws Exception {
-    String pathParts[] = path.split("/");
-    Preconditions.checkArgument(pathParts.length >= 1 && pathParts[0].isEmpty(),
-        "Invalid path: %s", path);
-    StringBuilder sb = new StringBuilder();
-
-    for (int i = 1; i < pathParts.length; i++) {
-      sb.append("/").append(pathParts[i]);
-      create(sb.toString());
-    }
-  }
-
   /**
    * Get alternate path for app id if path according to configured split index
    * does not exist. We look for path based on all possible split indices.