HDFS-8055. NullPointerException when topology script is missing. Contributed by Anu Engineer.

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -497,6 +497,9 @@ Release 2.8.0 - UNRELEASED
     HDFS-6666. Abort NameNode and DataNode startup if security is enabled but
     block access token is not enabled. (Vijay Bhat via cnauroth)
 
+    HDFS-8055. NullPointerException when topology script is missing.
+    (Anu Engineer via cnauroth)
+
 Release 2.7.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/blockmanagement/DatanodeManager.java

@@ -372,9 +372,17 @@ public void sortLocatedBlocks(final String targethost,
     if (client == null) {
       List<String> hosts = new ArrayList<String> (1);
       hosts.add(targethost);
-      String rName = dnsToSwitchMapping.resolve(hosts).get(0);
+      List<String> resolvedHosts = dnsToSwitchMapping.resolve(hosts);
-      if (rName != null)
+      if (resolvedHosts != null && !resolvedHosts.isEmpty()) {
-        client = new NodeBase(rName + NodeBase.PATH_SEPARATOR_STR + targethost);
+        String rName = resolvedHosts.get(0);
+        if (rName != null) {
+          client = new NodeBase(rName + NodeBase.PATH_SEPARATOR_STR +
+            targethost);
+        }
+      } else {
+        LOG.error("Node Resolution failed. Please make sure that rack " +
+          "awareness scripts are functional.");
+      }
     }
     
     Comparator<DatanodeInfo> comparator = avoidStaleDataNodesForRead ?

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestDatanodeManager.java

@@ -19,6 +19,10 @@
 package org.apache.hadoop.hdfs.server.blockmanagement;
 
 import java.io.IOException;
+import java.net.URISyntaxException;
+import java.net.URL;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.Iterator;
@@ -31,6 +35,7 @@
 import org.apache.commons.logging.LogFactory;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
+import org.apache.hadoop.fs.FileUtil;
 import org.apache.hadoop.fs.StorageType;
 import org.apache.hadoop.hdfs.DFSConfigKeys;
 import org.apache.hadoop.hdfs.protocol.DatanodeInfo;
@@ -40,10 +45,10 @@
 import org.apache.hadoop.hdfs.protocol.DatanodeInfoWithStorage;
 import org.apache.hadoop.hdfs.server.protocol.DatanodeRegistration;
 import org.apache.hadoop.net.DNSToSwitchMapping;
+import org.apache.hadoop.util.Shell;
 import org.junit.Assert;
 import org.junit.Test;
 import org.mockito.Mockito;
-
 import static org.hamcrest.core.Is.is;
 import static org.junit.Assert.*;
 
@@ -224,12 +229,60 @@ public void reloadCachedMappings(List<String> names) {
    * with the storage ids and storage types.
    */
   @Test
-  public void testSortLocatedBlocks() throws IOException {
+  public void testSortLocatedBlocks() throws IOException, URISyntaxException {
+    HelperFunction(null);
+  }
+
+  /**
+   * Execute a functional topology script and make sure that helper
+   * function works correctly
+   *
+   * @throws IOException
+   * @throws URISyntaxException
+   */
+  @Test
+  public void testgoodScript() throws IOException, URISyntaxException {
+    HelperFunction("/" + Shell.appendScriptExtension("topology-script"));
+  }
+
+
+  /**
+   * Run a broken script and verify that helper function is able to
+   * ignore the broken script and work correctly
+   *
+   * @throws IOException
+   * @throws URISyntaxException
+   */
+  @Test
+  public void testBadScript() throws IOException, URISyntaxException {
+    HelperFunction("/"+ Shell.appendScriptExtension("topology-broken-script"));
+  }
+
+
+  /**
+   * Helper function that tests the DatanodeManagers SortedBlock function
+   * we invoke this function with and without topology scripts
+   *
+   * @param scriptFileName - Script Name or null
+   *
+   * @throws URISyntaxException
+   * @throws IOException
+   */
+  public void HelperFunction(String scriptFileName)
+    throws URISyntaxException, IOException {
     // create the DatanodeManager which will be tested
+    Configuration conf = new Configuration();
     FSNamesystem fsn = Mockito.mock(FSNamesystem.class);
     Mockito.when(fsn.hasWriteLock()).thenReturn(true);
+    if (scriptFileName != null && !scriptFileName.isEmpty()) {
+      URL shellScript = getClass().getResource(scriptFileName);
+      Path resourcePath = Paths.get(shellScript.toURI());
+      FileUtil.setExecutable(resourcePath.toFile(), true);
+      conf.set(DFSConfigKeys.NET_TOPOLOGY_SCRIPT_FILE_NAME_KEY,
+        resourcePath.toString());
+    }
     DatanodeManager dm = new DatanodeManager(Mockito.mock(BlockManager.class),
-        fsn, new Configuration());
+      fsn, conf);
 
     // register 5 datanodes, each with different storage ID and type
     DatanodeInfo[] locs = new DatanodeInfo[5];
@@ -281,13 +334,13 @@ public void testSortLocatedBlocks() throws IOException {
     assertThat(storageIDs.length, is(5));
     assertThat(storageTypes.length, is(5));
     for (int i = 0; i < sortedLocs.length; i++) {
-      assertThat(((DatanodeInfoWithStorage)sortedLocs[i]).getStorageID(), is(storageIDs[i]));
+      assertThat(((DatanodeInfoWithStorage) sortedLocs[i]).getStorageID(),
-      assertThat(((DatanodeInfoWithStorage)sortedLocs[i]).getStorageType(), is(storageTypes[i]));
+        is(storageIDs[i]));
+      assertThat(((DatanodeInfoWithStorage) sortedLocs[i]).getStorageType(),
+        is(storageTypes[i]));
     }
-
     // Ensure the local node is first.
     assertThat(sortedLocs[0].getIpAddr(), is(targetIp));
-
     // Ensure the two decommissioned DNs were moved to the end.
     assertThat(sortedLocs[sortedLocs.length - 1].getAdminState(),
       is(DatanodeInfo.AdminStates.DECOMMISSIONED));
@@ -295,3 +348,4 @@ public void testSortLocatedBlocks() throws IOException {
       is(DatanodeInfo.AdminStates.DECOMMISSIONED));
   }
 }
+

hadoop-hdfs-project/hadoop-hdfs/src/test/resources/topology-broken-script.cmd

@@ -0,0 +1,22 @@
+@echo off
+@rem Licensed to the Apache Software Foundation (ASF) under one or more
+@rem contributor license agreements.  See the NOTICE file distributed with
+@rem this work for additional information regarding copyright ownership.
+@rem The ASF licenses this file to You under the Apache License, Version 2.0
+@rem (the "License"); you may not use this file except in compliance with
+@rem the License.  You may obtain a copy of the License at
+@rem
+@rem     http://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+@rem yes, this is a broken script, please don't fix this.
+@rem This is used in a test case to verify that we can handle broken
+@rem topology scripts.
+
+exit 1

hadoop-hdfs-project/hadoop-hdfs/src/test/resources/topology-broken-script.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+## yes, this is a broken script, please don't fix this.
+## This is used in a test case to verify that we can handle broken
+## topology scripts.
+
+exit 1
+

hadoop-hdfs-project/hadoop-hdfs/src/test/resources/topology-script.cmd

@@ -0,0 +1,18 @@
+@echo off
+@rem Licensed to the Apache Software Foundation (ASF) under one or more
+@rem contributor license agreements.  See the NOTICE file distributed with
+@rem this work for additional information regarding copyright ownership.
+@rem The ASF licenses this file to You under the Apache License, Version 2.0
+@rem (the "License"); you may not use this file except in compliance with
+@rem the License.  You may obtain a copy of the License at
+@rem
+@rem     http://www.apache.org/licenses/LICENSE-2.0
+@rem
+@rem Unless required by applicable law or agreed to in writing, software
+@rem distributed under the License is distributed on an "AS IS" BASIS,
+@rem WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+@rem See the License for the specific language governing permissions and
+@rem limitations under the License.
+@rem
+
+for /F "delims=- tokens=2" %%A in ("%1") do echo /rackID-%%A

hadoop-hdfs-project/hadoop-hdfs/src/test/resources/topology-script.sh

@@ -0,0 +1,21 @@
+#!/usr/bin/env bash
+
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+echo $1 | awk -F'-' '{printf("/rackID-%s",$2)}'
+