Merge r1580154 from trunk. YARN-1776. Fixed DelegationToken renewal to survive RM failover. Contributed by Zhijie Shen

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1580156 13f79535-47bb-0310-9956-ffa450edef68

hadoop-yarn-project/CHANGES.txt

@@ -540,6 +540,9 @@ Release 2.4.0 - UNRELEASED
     YARN-1854. Fixed test failure in TestRMHA#testStartAndTransitions. (Rohith
     Sharma KS via vinodkv)
 
+    YARN-1776. Fixed DelegationToken renewal to survive RM failover. (Zhijie
+    Shen via jianhe)
+
 Release 2.3.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

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

@@ -36,6 +36,7 @@ import org.apache.hadoop.fs.FSDataOutputStream;
 import org.apache.hadoop.fs.FileStatus;
 import org.apache.hadoop.fs.FileSystem;
 import org.apache.hadoop.fs.Path;
+import org.apache.hadoop.fs.PathFilter;
 import org.apache.hadoop.io.DataInputByteBuffer;
 import org.apache.hadoop.security.Credentials;
 import org.apache.hadoop.security.token.delegation.DelegationKey;
@@ -73,7 +74,9 @@ public class FileSystemRMStateStore extends RMStateStore {
   protected FileSystem fs;
 
   private Path rootDirPath;
-  private Path rmDTSecretManagerRoot;
+  @Private
+  @VisibleForTesting
+  Path rmDTSecretManagerRoot;
   private Path rmAppRoot;
   private Path dtSequenceNumberPath = null;
 
@@ -157,6 +160,7 @@ public class FileSystemRMStateStore extends RMStateStore {
           new ArrayList<ApplicationAttemptState>();
 
       for (FileStatus appDir : fs.listStatus(rmAppRoot)) {
+        checkAndResumeUpdateOperation(appDir.getPath());
         for (FileStatus childNodeStatus : fs.listStatus(appDir.getPath())) {
           assert childNodeStatus.isFile();
           String childNodeName = childNodeStatus.getPath().getName();
@@ -250,7 +254,29 @@ public class FileSystemRMStateStore extends RMStateStore {
     return false;
   }
 
+  private void checkAndResumeUpdateOperation(Path path) throws Exception {
+    // Before loading the state information, check whether .new file exists.
+    // If it does, the prior updateFile is failed on half way. We need to
+    // complete replacing the old file first.
+    FileStatus[] newChildNodes =
+        fs.listStatus(path, new PathFilter() {
+      @Override
+      public boolean accept(Path path) {
+        return path.getName().endsWith(".new");
+      }
+    });
+    for(FileStatus newChildNodeStatus : newChildNodes) {
+      assert newChildNodeStatus.isFile();
+      String newChildNodeName = newChildNodeStatus.getPath().getName();
+      String childNodeName = newChildNodeName.substring(
+          0, newChildNodeName.length() - ".new".length());
+      Path childNodePath =
+          new Path(newChildNodeStatus.getPath().getParent(), childNodeName);
+      replaceFile(newChildNodeStatus.getPath(), childNodePath);
+    }
+  }
   private void loadRMDTSecretManagerState(RMState rmState) throws Exception {
+    checkAndResumeUpdateOperation(rmDTSecretManagerRoot);
     FileStatus[] childNodes = fs.listStatus(rmDTSecretManagerRoot);
 
     for(FileStatus childNodeStatus : childNodes) {
@@ -380,15 +406,44 @@ public class FileSystemRMStateStore extends RMStateStore {
   public synchronized void storeRMDelegationTokenAndSequenceNumberState(
       RMDelegationTokenIdentifier identifier, Long renewDate,
       int latestSequenceNumber) throws Exception {
+    storeOrUpdateRMDelegationTokenAndSequenceNumberState(
+        identifier, renewDate,latestSequenceNumber, false);
+  }
+
+  @Override
+  public synchronized void removeRMDelegationTokenState(
+      RMDelegationTokenIdentifier identifier) throws Exception {
+    Path nodeCreatePath = getNodePath(rmDTSecretManagerRoot,
+      DELEGATION_TOKEN_PREFIX + identifier.getSequenceNumber());
+    LOG.info("Removing RMDelegationToken_" + identifier.getSequenceNumber());
+    deleteFile(nodeCreatePath);
+  }
+
+  @Override
+  protected void updateRMDelegationTokenAndSequenceNumberInternal(
+      RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate,
+      int latestSequenceNumber) throws Exception {
+    storeOrUpdateRMDelegationTokenAndSequenceNumberState(
+        rmDTIdentifier, renewDate,latestSequenceNumber, true);
+  }
+
+  private void storeOrUpdateRMDelegationTokenAndSequenceNumberState(
+      RMDelegationTokenIdentifier identifier, Long renewDate,
+      int latestSequenceNumber, boolean isUpdate) throws Exception {
     Path nodeCreatePath =
         getNodePath(rmDTSecretManagerRoot,
           DELEGATION_TOKEN_PREFIX + identifier.getSequenceNumber());
     ByteArrayOutputStream os = new ByteArrayOutputStream();
     DataOutputStream fsOut = new DataOutputStream(os);
-    LOG.info("Storing RMDelegationToken_" + identifier.getSequenceNumber());
     identifier.write(fsOut);
     fsOut.writeLong(renewDate);
-    writeFile(nodeCreatePath, os.toByteArray());
+    if (isUpdate) {
+      LOG.info("Updating RMDelegationToken_" + identifier.getSequenceNumber());
+      updateFile(nodeCreatePath, os.toByteArray());
+    } else {
+      LOG.info("Storing RMDelegationToken_" + identifier.getSequenceNumber());
+      writeFile(nodeCreatePath, os.toByteArray());
+    }
     fsOut.close();
 
     // store sequence number
@@ -408,15 +463,6 @@ public class FileSystemRMStateStore extends RMStateStore {
     dtSequenceNumberPath = latestSequenceNumberPath;
   }
 
-  @Override
-  public synchronized void removeRMDelegationTokenState(
-      RMDelegationTokenIdentifier identifier) throws Exception {
-    Path nodeCreatePath = getNodePath(rmDTSecretManagerRoot,
-      DELEGATION_TOKEN_PREFIX + identifier.getSequenceNumber());
-    LOG.info("Removing RMDelegationToken_" + identifier.getSequenceNumber());
-    deleteFile(nodeCreatePath);
-  }
-
   @Override
   public synchronized void storeRMDTMasterKeyState(DelegationKey masterKey)
       throws Exception {
@@ -477,14 +523,28 @@ public class FileSystemRMStateStore extends RMStateStore {
     fs.rename(tempPath, outputPath);
   }
 
+  /*
+   * In order to make this update atomic as a part of write we will first write
+   * data to .new file and then rename it. Here we are assuming that rename is
+   * atomic for underlying file system.
+   */
   protected void updateFile(Path outputPath, byte[] data) throws Exception {
-    if (fs.exists(outputPath)) {
-      deleteFile(outputPath);
+    Path newPath = new Path(outputPath.getParent(), outputPath.getName() + ".new");
+    // use writeFile to make sure .new file is created atomically
+    writeFile(newPath, data);
+    replaceFile(newPath, outputPath);
+  }
+
+  protected void replaceFile(Path srcPath, Path dstPath) throws Exception {
+    if (fs.exists(dstPath)) {
+      deleteFile(dstPath);
     }
-    writeFile(outputPath, data);
+    fs.rename(srcPath, dstPath);
   }
 
-  private boolean renameFile(Path src, Path dst) throws Exception {
+  @Private
+  @VisibleForTesting
+  boolean renameFile(Path src, Path dst) throws Exception {
     return fs.rename(src, dst);
   }
 
@@ -492,7 +552,10 @@ public class FileSystemRMStateStore extends RMStateStore {
     return fs.createNewFile(newFile);
   }
 
-  private Path getNodePath(Path root, String nodeName) {
+  @Private
+  @VisibleForTesting
+  Path getNodePath(Path root, String nodeName) {
     return new Path(root, nodeName);
   }
+
 }

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

@@ -35,7 +35,6 @@ import org.apache.hadoop.yarn.security.client.RMDelegationTokenIdentifier;
 import org.apache.hadoop.yarn.server.resourcemanager.recovery.records.RMStateVersion;
 import org.apache.hadoop.yarn.server.resourcemanager.recovery.records.impl.pb.ApplicationAttemptStateDataPBImpl;
 import org.apache.hadoop.yarn.server.resourcemanager.recovery.records.impl.pb.ApplicationStateDataPBImpl;
-import org.apache.hadoop.yarn.util.ConverterUtils;
 
 import com.google.common.annotations.VisibleForTesting;
 
@@ -201,6 +200,15 @@ public class MemoryRMStateStore extends RMStateStore {
     rmDTState.remove(rmDTIdentifier);
   }
 
+  @Override
+  protected void updateRMDelegationTokenAndSequenceNumberInternal(
+      RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate,
+      int latestSequenceNumber) throws Exception {
+    removeRMDelegationTokenState(rmDTIdentifier);
+    storeRMDelegationTokenAndSequenceNumberState(
+        rmDTIdentifier, renewDate, latestSequenceNumber);
+  }
+
   @Override
   public synchronized void storeRMDTMasterKeyState(DelegationKey delegationKey)
       throws Exception {
@@ -239,4 +247,5 @@ public class MemoryRMStateStore extends RMStateStore {
   protected RMStateVersion getCurrentVersion() {
     return null;
   }
+
 }

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

@@ -83,6 +83,13 @@ public class NullRMStateStore extends RMStateStore {
     // Do nothing
   }
 
+  @Override
+  protected void updateRMDelegationTokenAndSequenceNumberInternal(
+      RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate,
+      int latestSequenceNumber) throws Exception {
+    // Do nothing
+  }
+
   @Override
   public void storeRMDTMasterKeyState(DelegationKey delegationKey) throws Exception {
     // Do nothing
@@ -125,4 +132,5 @@ public class NullRMStateStore extends RMStateStore {
     // Do nothing
     return null;
   }
+
 }

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

@@ -477,6 +477,30 @@ public abstract class RMStateStore extends AbstractService {
   protected abstract void removeRMDelegationTokenState(
       RMDelegationTokenIdentifier rmDTIdentifier) throws Exception;
 
+  /**
+   * RMDTSecretManager call this to update the state of a delegation token
+   * and sequence number
+   */
+  public synchronized void updateRMDelegationTokenAndSequenceNumber(
+      RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate,
+      int latestSequenceNumber) {
+    try {
+      updateRMDelegationTokenAndSequenceNumberInternal(rmDTIdentifier, renewDate,
+          latestSequenceNumber);
+    } catch (Exception e) {
+      notifyStoreOperationFailed(e);
+    }
+  }
+
+  /**
+   * Blocking API
+   * Derived classes must implement this method to update the state of
+   * RMDelegationToken and sequence number
+   */
+  protected abstract void updateRMDelegationTokenAndSequenceNumberInternal(
+      RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate,
+      int latestSequenceNumber) throws Exception;
+
   /**
    * RMDTSecretManager call this to store the state of a master key
    */

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

@@ -629,6 +629,54 @@ public class ZKRMStateStore extends RMStateStore {
       RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate,
       int latestSequenceNumber) throws Exception {
     ArrayList<Op> opList = new ArrayList<Op>();
+    addStoreOrUpdateOps(
+        opList, rmDTIdentifier, renewDate, latestSequenceNumber, false);
+    doMultiWithRetries(opList);
+  }
+
+  @Override
+  protected synchronized void removeRMDelegationTokenState(
+      RMDelegationTokenIdentifier rmDTIdentifier) throws Exception {
+    ArrayList<Op> opList = new ArrayList<Op>();
+    String nodeRemovePath =
+        getNodePath(delegationTokensRootPath, DELEGATION_TOKEN_PREFIX
+            + rmDTIdentifier.getSequenceNumber());
+    if (LOG.isDebugEnabled()) {
+      LOG.debug("Removing RMDelegationToken_"
+          + rmDTIdentifier.getSequenceNumber());
+    }
+    if (zkClient.exists(nodeRemovePath, true) != null) {
+      opList.add(Op.delete(nodeRemovePath, -1));
+    } else {
+      LOG.info("Attempted to delete a non-existing znode " + nodeRemovePath);
+    }
+    doMultiWithRetries(opList);
+  }
+
+  @Override
+  protected void updateRMDelegationTokenAndSequenceNumberInternal(
+      RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate,
+      int latestSequenceNumber) throws Exception {
+    ArrayList<Op> opList = new ArrayList<Op>();
+    String nodeRemovePath =
+        getNodePath(delegationTokensRootPath, DELEGATION_TOKEN_PREFIX
+            + rmDTIdentifier.getSequenceNumber());
+    if (zkClient.exists(nodeRemovePath, true) == null) {
+      // in case znode doesn't exist
+      addStoreOrUpdateOps(
+          opList, rmDTIdentifier, renewDate, latestSequenceNumber, false);
+      LOG.info("Attempted to update a non-existing znode " + nodeRemovePath);
+    } else {
+      // in case znode exists
+      addStoreOrUpdateOps(
+          opList, rmDTIdentifier, renewDate, latestSequenceNumber, true);
+    }
+    doMultiWithRetries(opList);
+  }
+
+  private void addStoreOrUpdateOps(ArrayList<Op> opList,
+      RMDelegationTokenIdentifier rmDTIdentifier, Long renewDate,
+      int latestSequenceNumber, boolean isUpdate) throws Exception {
     // store RM delegation token
     String nodeCreatePath =
         getNodePath(delegationTokensRootPath, DELEGATION_TOKEN_PREFIX
@@ -642,17 +690,21 @@ public class ZKRMStateStore extends RMStateStore {
       rmDTIdentifier.write(tokenOut);
       tokenOut.writeLong(renewDate);
       if (LOG.isDebugEnabled()) {
-        LOG.debug("Storing RMDelegationToken_" +
+        LOG.debug((isUpdate ? "Storing " : "Updating ") + "RMDelegationToken_" +
             rmDTIdentifier.getSequenceNumber());
       }
 
-      opList.add(Op.create(nodeCreatePath, tokenOs.toByteArray(), zkAcl,
-          CreateMode.PERSISTENT));
+      if (isUpdate) {
+        opList.add(Op.setData(nodeCreatePath, tokenOs.toByteArray(), -1));
+      } else {
+        opList.add(Op.create(nodeCreatePath, tokenOs.toByteArray(), zkAcl,
+            CreateMode.PERSISTENT));
+      }
 
 
      seqOut.writeInt(latestSequenceNumber);
      if (LOG.isDebugEnabled()) {
-        LOG.debug("Storing " + dtSequenceNumberPath +
+        LOG.debug((isUpdate ? "Storing " : "Updating ") + dtSequenceNumberPath +
             ". SequenceNumber: " + latestSequenceNumber);
       }
 
@@ -661,21 +713,6 @@ public class ZKRMStateStore extends RMStateStore {
       tokenOs.close();
       seqOs.close();
     }
-
-    doMultiWithRetries(opList);
-  }
-
-  @Override
-  protected synchronized void removeRMDelegationTokenState(
-      RMDelegationTokenIdentifier rmDTIdentifier) throws Exception {
-    String nodeRemovePath =
-        getNodePath(delegationTokensRootPath, DELEGATION_TOKEN_PREFIX
-            + rmDTIdentifier.getSequenceNumber());
-    if (LOG.isDebugEnabled()) {
-      LOG.debug("Removing RMDelegationToken_"
-          + rmDTIdentifier.getSequenceNumber());
-    }
-    deleteWithRetries(nodeRemovePath, -1);
   }
 
   @Override
@@ -707,7 +744,11 @@ public class ZKRMStateStore extends RMStateStore {
     if (LOG.isDebugEnabled()) {
       LOG.debug("Removing RMDelegationKey_" + delegationKey.getKeyId());
     }
-    deleteWithRetries(nodeRemovePath, -1);
+    if (zkClient.exists(nodeRemovePath, true) != null) {
+      doMultiWithRetries(Op.delete(nodeRemovePath, -1));
+    } else {
+      LOG.info("Attempted to delete a non-existing znode " + nodeRemovePath);
+    }
   }
 
   // ZK related code
@@ -813,18 +854,6 @@ public class ZKRMStateStore extends RMStateStore {
     doMultiWithRetries(Op.create(path, data, acl, mode));
   }
 
-  private void deleteWithRetries(final String path, final int version)
-      throws Exception {
-    try {
-      doMultiWithRetries(Op.delete(path, version));
-    } catch (KeeperException.NoNodeException nne) {
-      // We tried to delete a node that doesn't exist
-      if (LOG.isDebugEnabled()) {
-        LOG.debug("Attempted to delete a non-existing znode " + path);
-      }
-    }
-  }
-
   @VisibleForTesting
   @Private
   @Unstable

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/main/java/org/apache/hadoop/yarn/server/resourcemanager/security/RMDelegationTokenSecretManager.java

@@ -122,9 +122,7 @@ public class RMDelegationTokenSecretManager extends
     try {
       LOG.info("updating RMDelegation token with sequence number: "
           + id.getSequenceNumber());
-      rmContext.getStateStore().removeRMDelegationToken(id,
-        delegationTokenSequenceNumber);
-      rmContext.getStateStore().storeRMDelegationTokenAndSequenceNumber(id,
+      rmContext.getStateStore().updateRMDelegationTokenAndSequenceNumber(id,
         renewDate, id.getSequenceNumber());
     } catch (Exception e) {
       LOG.error("Error in updating persisted RMDelegationToken with sequence number: "

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/RMStateStoreTestBase.java

@@ -244,6 +244,9 @@ public class RMStateStoreTestBase extends ClientBaseWithFixes{
     Thread.sleep(1000);
     store.close();
 
+    // give tester a chance to modify app state in the store
+    modifyAppState();
+
     // load state
     store = stateStoreHelper.getRMStateStore();
     store.setRMDispatcher(dispatcher);
@@ -363,6 +366,7 @@ public class RMStateStoreTestBase extends ClientBaseWithFixes{
     int sequenceNumber = 1111;
     store.storeRMDelegationTokenAndSequenceNumber(dtId1, renewDate1,
       sequenceNumber);
+    modifyRMDelegationTokenState();
     Map<RMDelegationTokenIdentifier, Long> token1 =
         new HashMap<RMDelegationTokenIdentifier, Long>();
     token1.put(dtId1, renewDate1);
@@ -380,6 +384,20 @@ public class RMStateStoreTestBase extends ClientBaseWithFixes{
     Assert.assertEquals(sequenceNumber,
         secretManagerState.getDTSequenceNumber());
 
+    // update RM delegation token;
+    renewDate1 = new Long(System.currentTimeMillis());
+    ++sequenceNumber;
+    store.updateRMDelegationTokenAndSequenceNumber(
+        dtId1, renewDate1, sequenceNumber);
+    token1.put(dtId1, renewDate1);
+
+    RMDTSecretManagerState updateSecretManagerState =
+        store.loadState().getRMDTSecretManagerState();
+    Assert.assertEquals(token1, updateSecretManagerState.getTokenState());
+    Assert.assertEquals(keySet, updateSecretManagerState.getMasterKeyState());
+    Assert.assertEquals(sequenceNumber,
+        updateSecretManagerState.getDTSequenceNumber());
+
     // check to delete delegationKey
     store.removeRMDTMasterKey(key);
     keySet.clear();
@@ -487,4 +505,13 @@ public class RMStateStoreTestBase extends ClientBaseWithFixes{
       }
     }
   }
+
+  protected void modifyAppState() throws Exception {
+
+  }
+
+  protected void modifyRMDelegationTokenState() throws Exception {
+
+  }
+
 }

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/TestFSRMStateStore.java

@@ -49,6 +49,8 @@ public class TestFSRMStateStore extends RMStateStoreTestBase {
 
   public static final Log LOG = LogFactory.getLog(TestFSRMStateStore.class);
 
+  private TestFSRMStateStoreTester fsTester;
+
   class TestFSRMStateStoreTester implements RMStateStoreHelper {
 
     Path workingDirPathURI;
@@ -134,7 +136,7 @@ public class TestFSRMStateStore extends RMStateStoreTestBase {
     MiniDFSCluster cluster =
         new MiniDFSCluster.Builder(conf).numDataNodes(1).build();
     try {
-      TestFSRMStateStoreTester fsTester = new TestFSRMStateStoreTester(cluster);
+      fsTester = new TestFSRMStateStoreTester(cluster);
       // If the state store is FileSystemRMStateStore then add corrupted entry.
       // It should discard the entry and remove it from file system.
       FSDataOutputStream fsOut = null;
@@ -162,6 +164,36 @@ public class TestFSRMStateStore extends RMStateStoreTestBase {
     }
   }
 
+  @Override
+  protected void modifyAppState() throws Exception {
+    // imitate appAttemptFile1 is still .new, but old one is deleted
+    String appAttemptIdStr1 = "appattempt_1352994193343_0001_000001";
+    ApplicationAttemptId attemptId1 =
+        ConverterUtils.toApplicationAttemptId(appAttemptIdStr1);
+    Path appDir =
+        fsTester.store.getAppDir(attemptId1.getApplicationId().toString());
+    Path appAttemptFile1 =
+        new Path(appDir, attemptId1.toString() + ".new");
+    FileSystemRMStateStore fileSystemRMStateStore =
+        (FileSystemRMStateStore) fsTester.getRMStateStore();
+    fileSystemRMStateStore.renameFile(appAttemptFile1,
+        new Path(appAttemptFile1.getParent(),
+            appAttemptFile1.getName() + ".new"));
+  }
+
+  @Override
+  protected void modifyRMDelegationTokenState() throws Exception {
+    // imitate dt file is still .new, but old one is deleted
+    Path nodeCreatePath =
+        fsTester.store.getNodePath(fsTester.store.rmDTSecretManagerRoot,
+            FileSystemRMStateStore.DELEGATION_TOKEN_PREFIX + 0);
+    FileSystemRMStateStore fileSystemRMStateStore =
+        (FileSystemRMStateStore) fsTester.getRMStateStore();
+    fileSystemRMStateStore.renameFile(nodeCreatePath,
+        new Path(nodeCreatePath.getParent(),
+            nodeCreatePath.getName() + ".new"));
+  }
+
   @Test (timeout = 30000)
   public void testFSRMStateStoreClientRetry() throws Exception {
     HdfsConfiguration conf = new HdfsConfiguration();

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-resourcemanager/src/test/java/org/apache/hadoop/yarn/server/resourcemanager/recovery/TestZKRMStateStore.java

@@ -20,7 +20,6 @@ package org.apache.hadoop.yarn.server.resourcemanager.recovery;
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
-import static org.mockito.Mockito.mock;
 
 import java.io.IOException;
 import java.util.List;