HDFS-13836. RBF: Handle mount table znode with null value. Contributed by yanghuafeng.

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

@@ -196,8 +196,11 @@ public final class ZKCuratorManager {
    */
   public String getStringData(final String path) throws Exception {
     byte[] bytes = getData(path);
+    if (bytes != null) {
       return new String(bytes, Charset.forName("UTF-8"));
     }
+    return null;
+  }
 
   /**
    * Get the data in a ZNode.
@@ -208,8 +211,11 @@ public final class ZKCuratorManager {
    */
   public String getStringData(final String path, Stat stat) throws Exception {
     byte[] bytes = getData(path, stat);
+    if (bytes != null) {
       return new String(bytes, Charset.forName("UTF-8"));
     }
+    return null;
+  }
 
   /**
    * Set data into a ZNode.

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

@@ -19,6 +19,7 @@ package org.apache.hadoop.util.curator;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertNull;
 import static org.junit.Assert.assertTrue;
 
 import java.util.Arrays;
@@ -30,6 +31,7 @@ import org.apache.hadoop.fs.CommonConfigurationKeys;
 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.junit.After;
 import org.junit.Before;
 import org.junit.Test;
@@ -97,6 +99,27 @@ public class TestZKCuratorManager {
     assertEquals(2, children.size());
   }
 
+  @Test
+  public void testGetStringData() throws Exception {
+    String node1 = "/node1";
+    String node2 = "/node2";
+    assertFalse(curator.exists(node1));
+    curator.create(node1);
+    assertNull(curator.getStringData(node1));
+
+    byte[] setData = "setData".getBytes("UTF-8");
+    curator.setData(node1, setData, -1);
+    assertEquals("setData", curator.getStringData(node1));
+
+    Stat stat = new Stat();
+    assertFalse(curator.exists(node2));
+    curator.create(node2);
+    assertNull(curator.getStringData(node2, stat));
+
+    curator.setData(node2, setData, -1);
+    assertEquals("setData", curator.getStringData(node2, stat));
+
+  }
   @Test
   public void testTransaction() throws Exception {
     List<ACL> zkAcl = ZKUtil.parseACLs(CommonConfigurationKeys.ZK_ACL_DEFAULT);

hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/store/driver/TestStateStoreZK.java

@@ -18,6 +18,10 @@
 package org.apache.hadoop.hdfs.server.federation.store.driver;
 
 import static org.apache.hadoop.hdfs.server.federation.store.FederationStateStoreTestUtils.getStateStoreConfiguration;
+import static org.apache.hadoop.hdfs.server.federation.store.driver.impl.StateStoreZooKeeperImpl.FEDERATION_STORE_ZK_PARENT_PATH;
+import static org.apache.hadoop.hdfs.server.federation.store.driver.impl.StateStoreZooKeeperImpl.FEDERATION_STORE_ZK_PARENT_PATH_DEFAULT;
+import static org.junit.Assert.assertNotNull;
+import static org.junit.Assert.assertNull;
 
 import java.io.IOException;
 import java.util.concurrent.TimeUnit;
@@ -29,7 +33,14 @@ import org.apache.curator.test.TestingServer;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CommonConfigurationKeys;
 import org.apache.hadoop.hdfs.server.federation.router.RBFConfigKeys;
+import org.apache.hadoop.hdfs.server.federation.store.StateStoreUtils;
 import org.apache.hadoop.hdfs.server.federation.store.driver.impl.StateStoreZooKeeperImpl;
+import org.apache.hadoop.hdfs.server.federation.store.records.BaseRecord;
+import org.apache.hadoop.hdfs.server.federation.store.records.DisabledNameservice;
+import org.apache.hadoop.hdfs.server.federation.store.records.MembershipState;
+import org.apache.hadoop.hdfs.server.federation.store.records.MountTable;
+import org.apache.hadoop.hdfs.server.federation.store.records.RouterState;
+import org.apache.zookeeper.CreateMode;
 import org.junit.AfterClass;
 import org.junit.Before;
 import org.junit.BeforeClass;
@@ -42,6 +53,7 @@ public class TestStateStoreZK extends TestStateStoreDriverBase {
 
   private static TestingServer curatorTestingServer;
   private static CuratorFramework curatorFramework;
+  private static String baseZNode;
 
   @BeforeClass
   public static void setupCluster() throws Exception {
@@ -61,6 +73,9 @@ public class TestStateStoreZK extends TestStateStoreDriverBase {
     // Disable auto-repair of connection
     conf.setLong(RBFConfigKeys.FEDERATION_STORE_CONNECTION_TEST_MS,
         TimeUnit.HOURS.toMillis(1));
+
+    baseZNode = conf.get(FEDERATION_STORE_ZK_PARENT_PATH,
+        FEDERATION_STORE_ZK_PARENT_PATH_DEFAULT);
     getStateStore(conf);
   }
 
@@ -78,6 +93,44 @@ public class TestStateStoreZK extends TestStateStoreDriverBase {
     removeAll(getStateStoreDriver());
   }
 
+  private <T extends BaseRecord> String generateFakeZNode(
+      Class<T> recordClass) throws IOException {
+    String nodeName = StateStoreUtils.getRecordName(recordClass);
+    String primaryKey = "test";
+
+    if (nodeName != null) {
+      return baseZNode + "/" + nodeName + "/" + primaryKey;
+    }
+    return null;
+  }
+
+  private void testGetNullRecord(StateStoreDriver driver) throws Exception {
+    testGetNullRecord(driver, MembershipState.class);
+    testGetNullRecord(driver, MountTable.class);
+    testGetNullRecord(driver, RouterState.class);
+    testGetNullRecord(driver, DisabledNameservice.class);
+  }
+
+  private <T extends BaseRecord> void testGetNullRecord(
+      StateStoreDriver driver, Class<T> recordClass) throws Exception {
+    driver.removeAll(recordClass);
+
+    String znode = generateFakeZNode(recordClass);
+    assertNull(curatorFramework.checkExists().forPath(znode));
+
+    curatorFramework.create().withMode(CreateMode.PERSISTENT)
+        .withACL(null).forPath(znode, null);
+    assertNotNull(curatorFramework.checkExists().forPath(znode));
+
+    driver.get(recordClass);
+    assertNull(curatorFramework.checkExists().forPath(znode));
+  }
+
+  @Test
+  public void testGetNullRecord() throws Exception {
+    testGetNullRecord(getStateStoreDriver());
+  }
+
   @Test
   public void testInsert()
       throws IllegalArgumentException, IllegalAccessException, IOException {