/**
 * 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.
 */
package org.apache.hadoop.hdfs.qjournal.client;

import static org.apache.hadoop.hdfs.qjournal.QJMTestUtil.FAKE_NSINFO;
import static org.apache.hadoop.hdfs.qjournal.QJMTestUtil.JID;
import static org.apache.hadoop.hdfs.qjournal.QJMTestUtil.verifyEdits;
import static org.apache.hadoop.hdfs.qjournal.QJMTestUtil.writeSegment;
import static org.apache.hadoop.hdfs.qjournal.QJMTestUtil.writeTxns;
import static org.apache.hadoop.hdfs.qjournal.client.SpyQJournalUtil.spyGetJournaledEdits;
import static org.apache.hadoop.hdfs.qjournal.client.TestQuorumJournalManagerUnit.futureThrows;
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 static org.junit.Assert.fail;
import static org.mockito.ArgumentMatchers.eq;
import java.io.Closeable;
import java.io.File;
import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.URI;
import java.net.URL;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicInteger;

import org.apache.hadoop.hdfs.server.common.Util;
import org.apache.hadoop.hdfs.server.protocol.RemoteEditLogManifest;
import org.apache.hadoop.net.MockDomainNameResolver;
import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.ListenableFuture;
import org.apache.hadoop.thirdparty.com.google.common.util.concurrent.SettableFuture;
import org.apache.hadoop.util.Lists;
import org.mockito.stubbing.Answer;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.apache.hadoop.conf.Configuration;
import org.apache.hadoop.fs.CommonConfigurationKeysPublic;
import org.apache.hadoop.hdfs.DFSConfigKeys;
import org.apache.hadoop.hdfs.qjournal.MiniJournalCluster;
import org.apache.hadoop.hdfs.qjournal.QJMTestUtil;
import org.apache.hadoop.hdfs.qjournal.protocol.QJournalProtocolProtos.SegmentStateProto;
import org.apache.hadoop.hdfs.qjournal.server.JournalFaultInjector;
import org.apache.hadoop.hdfs.qjournal.server.JournalNode;
import org.apache.hadoop.hdfs.server.namenode.EditLogInputStream;
import org.apache.hadoop.hdfs.server.namenode.EditLogOutputStream;
import org.apache.hadoop.hdfs.server.namenode.FileJournalManager;
import org.apache.hadoop.hdfs.server.namenode.FileJournalManager.EditLogFile;
import org.apache.hadoop.hdfs.server.namenode.NNStorage;
import org.apache.hadoop.hdfs.server.namenode.NameNodeLayoutVersion;
import org.apache.hadoop.io.IOUtils;
import org.apache.hadoop.ipc.ProtobufRpcEngine2;
import org.apache.hadoop.test.GenericTestUtils;
import org.junit.After;
import org.junit.Before;
import org.junit.Rule;
import org.junit.Test;
import org.junit.rules.TestName;
import org.mockito.Mockito;
import org.mockito.stubbing.Stubber;

import org.slf4j.event.Level;

/**
 * Functional tests for QuorumJournalManager.
 * For true unit tests, see {@link TestQuorumJournalManagerUnit}.
 */
public class TestQuorumJournalManager {
  private static final Logger LOG = LoggerFactory.getLogger(
      TestQuorumJournalManager.class);
  
  private MiniJournalCluster cluster;
  private Configuration conf;
  private QuorumJournalManager qjm;
  private List<AsyncLogger> spies;

  private final List<QuorumJournalManager> toClose = Lists.newLinkedList();
  
  static {
    GenericTestUtils.setLogLevel(ProtobufRpcEngine2.LOG, Level.TRACE);
  }

  @Rule
  public TestName name = new TestName();

  @Before
  public void setup() throws Exception {
    conf = new Configuration();
    if (!name.getMethodName().equals("testSelectThreadCounts")) {
      // Don't retry connections - it just slows down the tests.
      conf.setInt(
          CommonConfigurationKeysPublic.IPC_CLIENT_CONNECT_MAX_RETRIES_KEY, 0);
    }
    // Turn off IPC client caching to handle daemon restarts.
    conf.setInt(
        CommonConfigurationKeysPublic.IPC_CLIENT_CONNECTION_MAXIDLETIME_KEY, 0);
    conf.setBoolean(DFSConfigKeys.DFS_HA_TAILEDITS_INPROGRESS_KEY, true);
    
    cluster = new MiniJournalCluster.Builder(conf)
        .baseDir(GenericTestUtils.getRandomizedTestDir().getAbsolutePath())
        .build();
    cluster.waitActive();
    
    qjm = createSpyingQJM();
    spies = qjm.getLoggerSetForTests().getLoggersForTests();

    qjm.format(QJMTestUtil.FAKE_NSINFO, false);
    qjm.recoverUnfinalizedSegments();
    assertEquals(1, qjm.getLoggerSetForTests().getEpoch());
  }

  @After
  public void shutdown() throws IOException, InterruptedException,
      TimeoutException {
    IOUtils.cleanupWithLogger(LOG, toClose.toArray(new Closeable[0]));

    // Should not leak clients between tests -- this can cause flaky tests.
    // (See HDFS-4643)
    // Wait for IPC clients to terminate to avoid flaky tests
    GenericTestUtils.waitForThreadTermination(".*IPC Client.*", 100, 1000);
    
    if (cluster != null) {
      cluster.shutdown();
      cluster = null;
    }
  }

  /**
   * Enqueue a QJM for closing during shutdown. This makes the code a little
   * easier to follow, with fewer try..finally clauses necessary.
   */
  private QuorumJournalManager closeLater(QuorumJournalManager qjm) {
    toClose.add(qjm);
    return qjm;
  }
  
  @Test
  public void testSingleWriter() throws Exception {
    writeSegment(cluster, qjm, 1, 3, true);
    
    // Should be finalized
    checkRecovery(cluster, 1, 3);
    
    // Start a new segment
    writeSegment(cluster, qjm, 4, 1, true);

    // Should be finalized
    checkRecovery(cluster, 4, 4);
  }
  
  @Test
  public void testFormat() throws Exception {
    QuorumJournalManager qjm = closeLater(new QuorumJournalManager(
        conf, cluster.getQuorumJournalURI("testFormat-jid"), FAKE_NSINFO));
    assertFalse(qjm.hasSomeData());
    qjm.format(FAKE_NSINFO, false);
    assertTrue(qjm.hasSomeData());
  }
  
  @Test
  public void testReaderWhileAnotherWrites() throws Exception {
    QuorumJournalManager readerQjm = closeLater(createSpyingQJM());
    List<EditLogInputStream> streams = Lists.newArrayList();
    readerQjm.selectInputStreams(streams, 0, false);
    assertEquals(0, streams.size());
    writeSegment(cluster, qjm, 1, 3, true);

    readerQjm.selectInputStreams(streams, 0, false);
    try {
      assertEquals(1, streams.size());
      // Validate the actual stream contents.
      EditLogInputStream stream = streams.get(0);
      assertEquals(1, stream.getFirstTxId());
      assertEquals(3, stream.getLastTxId());
      
      verifyEdits(streams, 1, 3);
      assertNull(stream.readOp());
    } finally {
      IOUtils.cleanupWithLogger(LOG, streams.toArray(new Closeable[0]));
      streams.clear();
    }
    
    // Ensure correct results when there is a stream in-progress, but we don't
    // ask for in-progress.
    writeSegment(cluster, qjm, 4, 3, false);
    readerQjm.selectInputStreams(streams, 0, false);
    try {
      assertEquals(1, streams.size());
      EditLogInputStream stream = streams.get(0);
      assertEquals(1, stream.getFirstTxId());
      assertEquals(3, stream.getLastTxId());
      verifyEdits(streams, 1, 3);
    } finally {
      IOUtils.cleanupWithLogger(LOG, streams.toArray(new Closeable[0]));
      streams.clear();
    }
    
    // TODO: check results for selectInputStreams with inProgressOK = true.
    // This doesn't currently work, due to a bug where RedundantEditInputStream
    // throws an exception if there are any unvalidated in-progress edits in the list!
    // But, it shouldn't be necessary for current use cases.
    
    qjm.finalizeLogSegment(4, 6);
    readerQjm.selectInputStreams(streams, 0, false);
    try {
      assertEquals(2, streams.size());
      assertEquals(4, streams.get(1).getFirstTxId());
      assertEquals(6, streams.get(1).getLastTxId());

      verifyEdits(streams, 1, 6);
    } finally {
      IOUtils.cleanupWithLogger(LOG, streams.toArray(new Closeable[0]));
      streams.clear();
    }
  }
  
  /**
   * Regression test for HDFS-3725. One of the journal nodes is down
   * during the writing of one segment, then comes back up later to
   * take part in a later segment. Thus, its local edits are
   * not a contiguous sequence. This should be handled correctly.
   */
  @Test
  public void testOneJNMissingSegments() throws Exception {
    writeSegment(cluster, qjm, 1, 3, true);
    waitForAllPendingCalls(qjm.getLoggerSetForTests());
    cluster.getJournalNode(0).stopAndJoin(0);
    writeSegment(cluster, qjm, 4, 3, true);
    waitForAllPendingCalls(qjm.getLoggerSetForTests());
    cluster.restartJournalNode(0);
    writeSegment(cluster, qjm, 7, 3, true);
    waitForAllPendingCalls(qjm.getLoggerSetForTests());
    cluster.getJournalNode(1).stopAndJoin(0);
    
    QuorumJournalManager readerQjm = createSpyingQJM();
    List<EditLogInputStream> streams = Lists.newArrayList();
    try {
      readerQjm.selectInputStreams(streams, 1, false);
      verifyEdits(streams, 1, 9);
    } finally {
      IOUtils.cleanupWithLogger(LOG, streams.toArray(new Closeable[0]));
      readerQjm.close();
    }
  }
  
  /**
   * Regression test for HDFS-3891: selectInputStreams should throw
   * an exception when a majority of journalnodes have crashed.
   */
  @Test
  public void testSelectInputStreamsMajorityDown() throws Exception {
    // Shut down all of the JNs.
    cluster.shutdown();

    List<EditLogInputStream> streams = Lists.newArrayList();
    try {
      qjm.selectInputStreams(streams, 0, false);
      fail("Did not throw IOE");
    } catch (QuorumException ioe) {
      GenericTestUtils.assertExceptionContains(
          "Got too many exceptions", ioe);
      assertTrue(streams.isEmpty());
    }
  }
  
  /**
   * Test the case where the NN crashes after starting a new segment
   * on all nodes, but before writing the first transaction to it.
   */
  @Test
  public void testCrashAtBeginningOfSegment() throws Exception {
    writeSegment(cluster, qjm, 1, 3, true);
    waitForAllPendingCalls(qjm.getLoggerSetForTests());
    
    EditLogOutputStream stm = qjm.startLogSegment(4,
        NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    try {
      waitForAllPendingCalls(qjm.getLoggerSetForTests());
    } finally {
      stm.abort();
    }
    
    
    // Make a new QJM
    qjm = closeLater(new QuorumJournalManager(
        conf, cluster.getQuorumJournalURI(JID), FAKE_NSINFO));
    qjm.recoverUnfinalizedSegments();
    checkRecovery(cluster, 1, 3);

    writeSegment(cluster, qjm, 4, 3, true);
  }
  
  @Test
  public void testOutOfSyncAtBeginningOfSegment0() throws Exception {
    doTestOutOfSyncAtBeginningOfSegment(0);
  }
  
  @Test
  public void testOutOfSyncAtBeginningOfSegment1() throws Exception {
    doTestOutOfSyncAtBeginningOfSegment(1);
  }

  @Test
  public void testOutOfSyncAtBeginningOfSegment2() throws Exception {
    doTestOutOfSyncAtBeginningOfSegment(2);
  }
  
  /**
   * Test the case where, at the beginning of a segment, transactions
   * have been written to one JN but not others.
   */
  public void doTestOutOfSyncAtBeginningOfSegment(int nodeWithOneTxn)
      throws Exception {
    
    int nodeWithEmptySegment = (nodeWithOneTxn + 1) % 3;
    int nodeMissingSegment = (nodeWithOneTxn + 2) % 3;
    
    writeSegment(cluster, qjm, 1, 3, true);
    waitForAllPendingCalls(qjm.getLoggerSetForTests());
    cluster.getJournalNode(nodeMissingSegment).stopAndJoin(0);
    
    // Open segment on 2/3 nodes
    EditLogOutputStream stm = qjm.startLogSegment(4,
        NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    try {
      waitForAllPendingCalls(qjm.getLoggerSetForTests());
      
      // Write transactions to only 1/3 nodes
      failLoggerAtTxn(spies.get(nodeWithEmptySegment), 4);
      try {
        writeTxns(stm, 4, 1);
        fail("Did not fail even though 2/3 failed");
      } catch (QuorumException qe) {
        GenericTestUtils.assertExceptionContains("mock failure", qe);
      }
    } finally {
      stm.abort();
    }
    
    // Bring back the down JN.
    cluster.restartJournalNode(nodeMissingSegment);
    
    // Make a new QJM. At this point, the state is as follows:
    // A: nodeWithEmptySegment: 1-3 finalized, 4_inprogress (empty)    
    // B: nodeWithOneTxn:       1-3 finalized, 4_inprogress (1 txn)
    // C: nodeMissingSegment:   1-3 finalized
    GenericTestUtils.assertGlobEquals(
        cluster.getCurrentDir(nodeWithEmptySegment, JID),
        "edits_.*",
        NNStorage.getFinalizedEditsFileName(1, 3),
        NNStorage.getInProgressEditsFileName(4));
    GenericTestUtils.assertGlobEquals(
        cluster.getCurrentDir(nodeWithOneTxn, JID),
        "edits_.*",
        NNStorage.getFinalizedEditsFileName(1, 3),
        NNStorage.getInProgressEditsFileName(4));
    GenericTestUtils.assertGlobEquals(
        cluster.getCurrentDir(nodeMissingSegment, JID),
        "edits_.*",
        NNStorage.getFinalizedEditsFileName(1, 3));
    

    // Stop one of the nodes. Since we run this test three
    // times, rotating the roles of the nodes, we'll test
    // all the permutations.
    cluster.getJournalNode(2).stopAndJoin(0);
  
    qjm = createSpyingQJM();
    qjm.recoverUnfinalizedSegments();
    
    if (nodeWithOneTxn == 0 ||
        nodeWithOneTxn == 1) {
      // If the node that had the transaction committed was one of the nodes
      // that responded during recovery, then we should have recovered txid
      // 4.
      checkRecovery(cluster, 4, 4);
      writeSegment(cluster, qjm, 5, 3, true);
    } else {
      // Otherwise, we should have recovered only 1-3 and should be able to
      // start a segment at 4.
      checkRecovery(cluster, 1, 3);
      writeSegment(cluster, qjm, 4, 3, true);
    }
  }

  
  /**
   * Test case where a new writer picks up from an old one with no failures
   * and the previous unfinalized segment entirely consistent -- i.e. all
   * the JournalNodes end at the same transaction ID.
   */
  @Test
  public void testChangeWritersLogsInSync() throws Exception {
    writeSegment(cluster, qjm, 1, 3, false);
    QJMTestUtil.assertExistsInQuorum(cluster,
        NNStorage.getInProgressEditsFileName(1));

    // Make a new QJM
    qjm = closeLater(new QuorumJournalManager(
        conf, cluster.getQuorumJournalURI(JID), FAKE_NSINFO));
    qjm.recoverUnfinalizedSegments();
    checkRecovery(cluster, 1, 3);
  }
  
  /**
   * Test case where a new writer picks up from an old one which crashed
   * with the three loggers at different txnids
   */
  @Test
  public void testChangeWritersLogsOutOfSync1() throws Exception {
    // Journal states:  [3, 4, 5]
    // During recovery: [x, 4, 5]
    // Should recovery to txn 5
    doOutOfSyncTest(0, 5L);
  }

  @Test
  public void testChangeWritersLogsOutOfSync2() throws Exception {
    // Journal states:  [3, 4, 5]
    // During recovery: [3, x, 5]
    // Should recovery to txn 5
    doOutOfSyncTest(1, 5L);
  }

  @Test
  public void testChangeWritersLogsOutOfSync3() throws Exception {
    // Journal states:  [3, 4, 5]
    // During recovery: [3, 4, x]
    // Should recovery to txn 4
    doOutOfSyncTest(2, 4L);
  }

  
  private void doOutOfSyncTest(int missingOnRecoveryIdx,
      long expectedRecoveryTxnId) throws Exception {
    setupLoggers345();
    
    QJMTestUtil.assertExistsInQuorum(cluster,
        NNStorage.getInProgressEditsFileName(1));

    // Shut down the specified JN, so it's not present during recovery.
    cluster.getJournalNode(missingOnRecoveryIdx).stopAndJoin(0);

    // Make a new QJM
    qjm = createSpyingQJM();
    
    qjm.recoverUnfinalizedSegments();
    checkRecovery(cluster, 1, expectedRecoveryTxnId);
  }
  
  
  private void failLoggerAtTxn(AsyncLogger spy, long txid) {
    TestQuorumJournalManagerUnit.futureThrows(new IOException("mock failure"))
      .when(spy).sendEdits(Mockito.anyLong(),
        Mockito.eq(txid), Mockito.eq(1), Mockito.<byte[]>any());
  }
  
  /**
   * Test the case where one of the loggers misses a finalizeLogSegment()
   * call, and then misses the next startLogSegment() call before coming
   * back to life.
   * 
   * Previously, this caused it to keep on writing to the old log segment,
   * such that one logger had eg edits_1-10 while the others had edits_1-5 and
   * edits_6-10. This caused recovery to fail in certain cases.
   */
  @Test
  public void testMissFinalizeAndNextStart() throws Exception {
    
    // Logger 0: miss finalize(1-3) and start(4)
    futureThrows(new IOException("injected")).when(spies.get(0))
      .finalizeLogSegment(Mockito.eq(1L), Mockito.eq(3L));
    futureThrows(new IOException("injected")).when(spies.get(0))
        .startLogSegment(Mockito.eq(4L),
            Mockito.eq(NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION));
    
    // Logger 1: fail at txn id 4
    failLoggerAtTxn(spies.get(1), 4L);
    
    writeSegment(cluster, qjm, 1, 3, true);
    EditLogOutputStream stm = qjm.startLogSegment(4,
        NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    try {
      writeTxns(stm, 4, 1);
      fail("Did not fail to write");
    } catch (QuorumException qe) {
      // Should fail, because logger 1 had an injected fault and
      // logger 0 should detect writer out of sync
      GenericTestUtils.assertExceptionContains("Writer out of sync",
          qe);
    } finally {
      stm.abort();
      qjm.close();
    }
    
    // State:
    // Logger 0: 1-3 in-progress (since it missed finalize)
    // Logger 1: 1-3 finalized
    // Logger 2: 1-3 finalized, 4 in-progress with one txn
    
    // Shut down logger 2 so it doesn't participate in recovery
    cluster.getJournalNode(2).stopAndJoin(0);
    
    qjm = createSpyingQJM();
    long recovered = QJMTestUtil.recoverAndReturnLastTxn(qjm);
    assertEquals(3L, recovered);
  }
  
  /**
   * edit lengths [3,4,5]
   * first recovery:
   * - sees [3,4,x]
   * - picks length 4 for recoveryEndTxId
   * - calls acceptRecovery()
   * - crashes before finalizing
   * second recovery:
   * - sees [x, 4, 5]
   * - should pick recovery length 4, even though it saw
   *   a larger txid, because a previous recovery accepted it
   */
  @Test
  public void testRecoverAfterIncompleteRecovery() throws Exception {
    setupLoggers345();

    // Shut down the logger that has length = 5
    cluster.getJournalNode(2).stopAndJoin(0);

    qjm = createSpyingQJM();
    spies = qjm.getLoggerSetForTests().getLoggersForTests();

    // Allow no logger to finalize
    for (AsyncLogger spy : spies) {
      TestQuorumJournalManagerUnit.futureThrows(new IOException("injected"))
        .when(spy).finalizeLogSegment(Mockito.eq(1L),
            Mockito.eq(4L));
    }
    try {
      qjm.recoverUnfinalizedSegments();
      fail("Should have failed recovery since no finalization occurred");
    } catch (IOException ioe) {
      GenericTestUtils.assertExceptionContains("injected", ioe);
    }
    
    // Now bring back the logger that had 5, and run recovery again.
    // We should recover to 4, even though there's a longer log.
    cluster.getJournalNode(0).stopAndJoin(0);
    cluster.restartJournalNode(2);
    
    qjm = createSpyingQJM();
    spies = qjm.getLoggerSetForTests().getLoggersForTests();
    qjm.recoverUnfinalizedSegments();
    checkRecovery(cluster, 1, 4);
  }
  
  /**
   * Set up the loggers into the following state:
   * - JN0: edits 1-3 in progress
   * - JN1: edits 1-4 in progress
   * - JN2: edits 1-5 in progress
   * 
   * None of the loggers have any associated paxos info.
   */
  private void setupLoggers345() throws Exception {
    EditLogOutputStream stm = qjm.startLogSegment(1,
        NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    
    failLoggerAtTxn(spies.get(0), 4);
    failLoggerAtTxn(spies.get(1), 5);
    
    writeTxns(stm, 1, 3);
    
    // This should succeed to 2/3 loggers
    writeTxns(stm, 4, 1);
    
    // This should only succeed to 1 logger (index 2). Hence it should
    // fail
    try {
      writeTxns(stm, 5, 1);
      fail("Did not fail to write when only a minority succeeded");
    } catch (QuorumException qe) {
      GenericTestUtils.assertExceptionContains(
          "too many exceptions to achieve quorum size 2/3",
          qe);
    }
  }

  /**
   * Set up the following tricky edge case state which is used by
   * multiple tests:
   * 
   * Initial writer:
   * - Writing to 3 JNs: JN0, JN1, JN2:
   * - A log segment with txnid 1 through 100 succeeds.
   * - The first transaction in the next segment only goes to JN0
   *   before the writer crashes (eg it is partitioned)
   *   
   * Recovery by another writer:
   * - The new NN starts recovery and talks to all three. Thus, it sees
   *   that the newest log segment which needs recovery is 101.
   * - It sends the prepareRecovery(101) call, and decides that the
   *   recovery length for 101 is only the 1 transaction.
   * - It sends acceptRecovery(101-101) to only JN0, before crashing
   * 
   * This yields the following state:
   * - JN0: 1-100 finalized, 101_inprogress, accepted recovery: 101-101
   * - JN1: 1-100 finalized, 101_inprogress.empty
   * - JN2: 1-100 finalized, 101_inprogress.empty
   *  (the .empty files got moved aside during recovery)
   * @throws Exception 
   */
  private void setupEdgeCaseOneJnHasSegmentWithAcceptedRecovery() throws Exception {
    // Log segment with txns 1-100 succeeds 
    writeSegment(cluster, qjm, 1, 100, true);

    // startLogSegment only makes it to one of the three nodes
    failLoggerAtTxn(spies.get(1), 101);
    failLoggerAtTxn(spies.get(2), 101);
    
    try {
      writeSegment(cluster, qjm, 101, 1, true);
      fail("Should have failed");
    } catch (QuorumException qe) {
      GenericTestUtils.assertExceptionContains("mock failure", qe);
    } finally {
      qjm.close();
    }
    
    // Recovery 1:
    // make acceptRecovery() only make it to the node which has txid 101
    // this should fail because only 1/3 accepted the recovery
    qjm = createSpyingQJM();
    spies = qjm.getLoggerSetForTests().getLoggersForTests();
    futureThrows(new IOException("mock failure")).when(spies.get(1))
      .acceptRecovery(Mockito.<SegmentStateProto>any(), Mockito.<URL>any());
    futureThrows(new IOException("mock failure")).when(spies.get(2))
      .acceptRecovery(Mockito.<SegmentStateProto>any(), Mockito.<URL>any());
    
    try {
      qjm.recoverUnfinalizedSegments();
      fail("Should have failed to recover");
    } catch (QuorumException qe) {
      GenericTestUtils.assertExceptionContains("mock failure", qe);
    } finally {
      qjm.close();
    }
    
    // Check that we have entered the expected state as described in the
    // method javadoc.
    GenericTestUtils.assertGlobEquals(cluster.getCurrentDir(0, JID),
        "edits_.*",
        NNStorage.getFinalizedEditsFileName(1, 100),
        NNStorage.getInProgressEditsFileName(101));
    GenericTestUtils.assertGlobEquals(cluster.getCurrentDir(1, JID),
        "edits_.*",
        NNStorage.getFinalizedEditsFileName(1, 100),
        NNStorage.getInProgressEditsFileName(101) + ".empty");
    GenericTestUtils.assertGlobEquals(cluster.getCurrentDir(2, JID),
        "edits_.*",
        NNStorage.getFinalizedEditsFileName(1, 100),
        NNStorage.getInProgressEditsFileName(101) + ".empty");

    File paxos0 = new File(cluster.getCurrentDir(0, JID), "paxos");
    File paxos1 = new File(cluster.getCurrentDir(1, JID), "paxos");
    File paxos2 = new File(cluster.getCurrentDir(2, JID), "paxos");
    
    GenericTestUtils.assertGlobEquals(paxos0, ".*", "101");
    GenericTestUtils.assertGlobEquals(paxos1, ".*");
    GenericTestUtils.assertGlobEquals(paxos2, ".*");
  }
  
  /**
   * Test an edge case discovered by randomized testing.
   * 
   * Starts with the edge case state set up by
   * {@link #setupEdgeCaseOneJnHasSegmentWithAcceptedRecovery()}
   * 
   * Recovery 2:
   * - New NN starts recovery and only talks to JN1 and JN2. JN0 has
   *   crashed. Since they have no logs open, they say they don't need
   *   recovery.
   * - Starts writing segment 101, and writes 50 transactions before crashing.
   *
   * Recovery 3:
   * - JN0 has come back to life.
   * - New NN starts recovery and talks to all three. All three have
   *   segments open from txid 101, so it calls prepareRecovery(101)
   * - JN0 has an already-accepted value for segment 101, so it replies
   *   "you should recover 101-101"
   * - Former incorrect behavior: NN truncates logs to txid 101 even though
   *   it should have recovered through 150.
   *   
   * In this case, even though there is an accepted recovery decision,
   * the newer log segments should take precedence, since they were written
   * in a newer epoch than the recorded decision.
   */
  @Test
  public void testNewerVersionOfSegmentWins() throws Exception {
    setupEdgeCaseOneJnHasSegmentWithAcceptedRecovery();
    
    // Now start writing again without JN0 present:
    cluster.getJournalNode(0).stopAndJoin(0);
    
    qjm = createSpyingQJM();
    try {
      assertEquals(100, QJMTestUtil.recoverAndReturnLastTxn(qjm));
      
      // Write segment but do not finalize
      writeSegment(cluster, qjm, 101, 50, false);
    } finally {
      qjm.close();
    }
    
    // Now try to recover a new writer, with JN0 present,
    // and ensure that all of the above-written transactions are recovered.
    cluster.restartJournalNode(0);
    qjm = createSpyingQJM();
    try {
      assertEquals(150, QJMTestUtil.recoverAndReturnLastTxn(qjm));
    } finally {
      qjm.close();
    }
  }
  
  /**
   * Test another edge case discovered by randomized testing.
   * 
   * Starts with the edge case state set up by
   * {@link #setupEdgeCaseOneJnHasSegmentWithAcceptedRecovery()}
   * 
   * Recovery 2:
   * - New NN starts recovery and only talks to JN1 and JN2. JN0 has
   *   crashed. Since they have no logs open, they say they don't need
   *   recovery.
   * - Before writing any transactions, JN0 comes back to life and
   *   JN1 crashes.
   * - Starts writing segment 101, and writes 50 transactions before crashing.
   *
   * Recovery 3:
   * - JN1 has come back to life. JN2 crashes.
   * - New NN starts recovery and talks to all three. All three have
   *   segments open from txid 101, so it calls prepareRecovery(101)
   * - JN0 has an already-accepted value for segment 101, so it replies
   *   "you should recover 101-101"
   * - Former incorrect behavior: NN truncates logs to txid 101 even though
   *   it should have recovered through 150.
   *   
   * In this case, even though there is an accepted recovery decision,
   * the newer log segments should take precedence, since they were written
   * in a newer epoch than the recorded decision.
   */
  @Test
  public void testNewerVersionOfSegmentWins2() throws Exception {
    setupEdgeCaseOneJnHasSegmentWithAcceptedRecovery();

    // Recover without JN0 present.
    cluster.getJournalNode(0).stopAndJoin(0);
    
    qjm = createSpyingQJM();
    try {
      assertEquals(100, QJMTestUtil.recoverAndReturnLastTxn(qjm));

      // After recovery, JN0 comes back to life and JN1 crashes.
      cluster.restartJournalNode(0);
      cluster.getJournalNode(1).stopAndJoin(0);
      
      // Write segment but do not finalize
      writeSegment(cluster, qjm, 101, 50, false);
    } finally {
      qjm.close();
    }
    
    // State:
    // JN0: 1-100 finalized, 101_inprogress (txns up to 150)
    // Previously, JN0 had an accepted recovery 101-101 from an earlier recovery
    // attempt.
    // JN1: 1-100 finalized
    // JN2: 1-100 finalized, 101_inprogress (txns up to 150)
    
    // We need to test that the accepted recovery 101-101 on JN0 doesn't
    // end up truncating the log back to 101.

    cluster.restartJournalNode(1);
    cluster.getJournalNode(2).stopAndJoin(0);

    qjm = createSpyingQJM();
    try {
      assertEquals(150, QJMTestUtil.recoverAndReturnLastTxn(qjm));
    } finally {
      qjm.close();
    }
  }
  
  @Test(timeout=20000)
  public void testCrashBetweenSyncLogAndPersistPaxosData() throws Exception {
    JournalFaultInjector faultInjector =
        JournalFaultInjector.instance = Mockito.mock(JournalFaultInjector.class);

    setupLoggers345();

    // Run recovery where the client only talks to JN0, JN1, such that it
    // decides that the correct length is through txid 4.
    // Only allow it to call acceptRecovery() on JN0.
    qjm = createSpyingQJM();
    spies = qjm.getLoggerSetForTests().getLoggersForTests();    
    cluster.getJournalNode(2).stopAndJoin(0);
    injectIOE().when(spies.get(1)).acceptRecovery(
        Mockito.<SegmentStateProto>any(), Mockito.<URL>any());
    
    tryRecoveryExpectingFailure();

    cluster.restartJournalNode(2);
    
    // State at this point:
    // JN0: edit log for 1-4, paxos recovery data for txid 4
    // JN1: edit log for 1-4,
    // JN2: edit log for 1-5
    
    // Run recovery again, but don't allow JN0 to respond to the
    // prepareRecovery() call. This will cause recovery to decide
    // on txid 5.
    // Additionally, crash all of the nodes before they persist
    // any new paxos data.
    qjm = createSpyingQJM();
    spies = qjm.getLoggerSetForTests().getLoggersForTests();    
    injectIOE().when(spies.get(0)).prepareRecovery(Mockito.eq(1L));

    Mockito.doThrow(new IOException("Injected")).when(faultInjector)
      .beforePersistPaxosData();
    tryRecoveryExpectingFailure();
    Mockito.reset(faultInjector);
    
    // State at this point:
    // JN0: edit log for 1-5, paxos recovery data for txid 4
    // !!!   This is the interesting bit, above. The on-disk data and the
    //       paxos data don't match up!
    // JN1: edit log for 1-5,
    // JN2: edit log for 1-5,

    // Now, stop JN2, and see if we can still start up even though
    // JN0 is in a strange state where its log data is actually newer
    // than its accepted Paxos state.

    cluster.getJournalNode(2).stopAndJoin(0);
    
    qjm = createSpyingQJM();
    try {
      long recovered = QJMTestUtil.recoverAndReturnLastTxn(qjm);
      assertTrue(recovered >= 4); // 4 was committed to a quorum
    } finally {
      qjm.close();
    }
  }
  
  private void tryRecoveryExpectingFailure() throws IOException {
    try {
      QJMTestUtil.recoverAndReturnLastTxn(qjm);
      fail("Expected to fail recovery");
    } catch (QuorumException qe) {
      GenericTestUtils.assertExceptionContains("Injected", qe);
    } finally {
      qjm.close();
    }

  }
  
  private Stubber injectIOE() {
    return futureThrows(new IOException("Injected"));
  }

  @Test
  public void testPurgeLogs() throws Exception {
    for (int txid = 1; txid <= 5; txid++) {
      writeSegment(cluster, qjm, txid, 1, true);
    }
    File curDir = cluster.getCurrentDir(0, JID);
    GenericTestUtils.assertGlobEquals(curDir, "edits_.*",
        NNStorage.getFinalizedEditsFileName(1, 1),
        NNStorage.getFinalizedEditsFileName(2, 2),
        NNStorage.getFinalizedEditsFileName(3, 3),
        NNStorage.getFinalizedEditsFileName(4, 4),
        NNStorage.getFinalizedEditsFileName(5, 5));
    File paxosDir = new File(curDir, "paxos");
    GenericTestUtils.assertExists(paxosDir);

    // Create new files in the paxos directory, which should get purged too.
    assertTrue(new File(paxosDir, "1").createNewFile());
    assertTrue(new File(paxosDir, "3").createNewFile());
    
    GenericTestUtils.assertGlobEquals(paxosDir, "\\d+",
        "1", "3");
    
    // Create some temporary files of the sort that are used during recovery.
    assertTrue(new File(curDir,
        "edits_inprogress_0000000000000000001.epoch=140").createNewFile());
    assertTrue(new File(curDir,
        "edits_inprogress_0000000000000000002.empty").createNewFile());
    
    qjm.purgeLogsOlderThan(3);
    
    // Log purging is asynchronous, so we have to wait for the calls
    // to be sent and respond before verifying.
    waitForAllPendingCalls(qjm.getLoggerSetForTests());
    
    // Older edits should be purged
    GenericTestUtils.assertGlobEquals(curDir, "edits_.*",
        NNStorage.getFinalizedEditsFileName(3, 3),
        NNStorage.getFinalizedEditsFileName(4, 4),
        NNStorage.getFinalizedEditsFileName(5, 5));
   
    // Older paxos files should be purged
    GenericTestUtils.assertGlobEquals(paxosDir, "\\d+",
        "3");
  }
  
  @Test
  public void testToString() throws Exception {
    GenericTestUtils.assertMatches(
        qjm.toString(),
        "QJM to \\[127.0.0.1:\\d+, 127.0.0.1:\\d+, 127.0.0.1:\\d+\\]");
  }
  
  @Test
  public void testSelectInputStreamsNotOnBoundary() throws Exception {
    final int txIdsPerSegment = 10; 
    for (int txid = 1; txid <= 5 * txIdsPerSegment; txid += txIdsPerSegment) {
      writeSegment(cluster, qjm, txid, txIdsPerSegment, true);
    }
    File curDir = cluster.getCurrentDir(0, JID);
    GenericTestUtils.assertGlobEquals(curDir, "edits_.*",
        NNStorage.getFinalizedEditsFileName(1, 10),
        NNStorage.getFinalizedEditsFileName(11, 20),
        NNStorage.getFinalizedEditsFileName(21, 30),
        NNStorage.getFinalizedEditsFileName(31, 40),
        NNStorage.getFinalizedEditsFileName(41, 50));
    
    ArrayList<EditLogInputStream> streams = new ArrayList<EditLogInputStream>();
    qjm.selectInputStreams(streams, 25, false);
    
    verifyEdits(streams, 25, 50);
  }

  @Test
  public void testInProgressRecovery() throws Exception {
    // Test the case when in-progress edit log tailing is on, and
    // new active performs recovery when the old active crashes
    // without closing the last log segment.
    // See HDFS-13145 for more details.

    // Write two batches of edits. After these, the commitId on the
    // journals should be 5, and endTxnId should be 8.
    EditLogOutputStream stm = qjm.startLogSegment(1,
        NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    writeTxns(stm, 1, 5);
    writeTxns(stm, 6, 3);

    // Do recovery from a separate QJM, just like in failover.
    QuorumJournalManager qjm2 = createSpyingQJM();
    qjm2.recoverUnfinalizedSegments();
    checkRecovery(cluster, 1, 8);

    // When selecting input stream, we should see all txns up to 8.
    List<EditLogInputStream> streams = new ArrayList<>();
    qjm2.selectInputStreams(streams, 1, true, true);
    verifyEdits(streams, 1, 8);
  }

  @Test
  public void testSelectViaRpcWithDurableTransactions() throws Exception {
    // Two loggers will have up to ID 5, one will have up to ID 6
    failLoggerAtTxn(spies.get(0), 6);
    failLoggerAtTxn(spies.get(1), 6);
    EditLogOutputStream stm =
        qjm.startLogSegment(1, NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    writeTxns(stm, 1, 5);
    try {
      writeTxns(stm, 6, 1);
      fail("Did not fail to write when only a minority succeeded");
    } catch (QuorumException qe) {
      GenericTestUtils.assertExceptionContains(
          "too many exceptions to achieve quorum size 2/3", qe);
    }

    List<EditLogInputStream> streams = new ArrayList<>();
    qjm.selectInputStreams(streams, 1, true, true);
    verifyEdits(streams, 1, 5);
    IOUtils.closeStreams(streams.toArray(new Closeable[0]));
    for (AsyncLogger logger : spies) {
      Mockito.verify(logger, Mockito.times(1)).getJournaledEdits(1,
          QuorumJournalManager.QJM_RPC_MAX_TXNS_DEFAULT);
    }
  }

  @Test
  public void testSelectViaRpcWithoutDurableTransactions() throws Exception {
    setupLoggers345();
    futureThrows(new IOException()).when(spies.get(1)).getJournaledEdits(1,
        QuorumJournalManager.QJM_RPC_MAX_TXNS_DEFAULT);

    List<EditLogInputStream> streams = new ArrayList<>();
    qjm.selectInputStreams(streams, 1, true, false);
    verifyEdits(streams, 1, 5);
    IOUtils.closeStreams(streams.toArray(new Closeable[0]));
    for (AsyncLogger logger : spies) {
      Mockito.verify(logger, Mockito.times(1)).getJournaledEdits(1,
          QuorumJournalManager.QJM_RPC_MAX_TXNS_DEFAULT);
    }
  }

  @Test
  public void testSelectViaRpcOneDeadJN() throws Exception {
    EditLogOutputStream stm =
        qjm.startLogSegment(1, NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    writeTxns(stm, 1, 10);

    cluster.getJournalNode(0).stopAndJoin(0);

    List<EditLogInputStream> streams = new ArrayList<>();
    qjm.selectInputStreams(streams, 1, true, false);
    verifyEdits(streams, 1, 10);
    IOUtils.closeStreams(streams.toArray(new Closeable[0]));
  }

  @Test
  public void testSelectViaRpcTwoDeadJNs() throws Exception {
    EditLogOutputStream stm =
        qjm.startLogSegment(1, NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    writeTxns(stm, 1, 10);

    cluster.getJournalNode(0).stopAndJoin(0);
    cluster.getJournalNode(1).stopAndJoin(0);

    try {
      qjm.selectInputStreams(new ArrayList<>(), 1, true, false);
      fail("");
    } catch (QuorumException qe) {
      GenericTestUtils.assertExceptionContains(
          "too many exceptions to achieve quorum size 2/3", qe);
    }
  }

  @Test
  public void testSelectThreadCounts() throws Exception {
    EditLogOutputStream stm =
        qjm.startLogSegment(1, NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    writeTxns(stm, 1, 10);
    JournalNode jn0 = cluster.getJournalNode(0);
    String ipcAddr = cluster.getJournalNodeIpcAddress(0);
    jn0.stopAndJoin(0);
    for (int i = 0; i < 1000; i++) {
      qjm.selectInputStreams(new ArrayList<>(), 1, true, false);
    }
    String expectedName =
        "Logger channel (from parallel executor) to " + ipcAddr;
    long num = Thread.getAllStackTraces().keySet().stream()
        .filter((t) -> t.getName().contains(expectedName)).count();
    // The number of threads for the stopped jn shouldn't be more than the
    // configured value.
    assertTrue("Number of threads are : " + num,
        num <= DFSConfigKeys.DFS_QJOURNAL_PARALLEL_READ_NUM_THREADS_DEFAULT);
  }

  @Test
  public void testSelectViaRpcTwoJNsError() throws Exception {
    EditLogOutputStream stm =
        qjm.startLogSegment(1, NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    writeTxns(stm, 1, 10);
    writeTxns(stm, 11, 1);
    // One last sync whose transactions are not expected to be seen in the
    // input streams because the JournalNodes have not updated their concept
    // of the committed transaction ID yet
    writeTxns(stm, 12, 1);

    futureThrows(new IOException()).when(spies.get(0)).getJournaledEdits(1,
        QuorumJournalManager.QJM_RPC_MAX_TXNS_DEFAULT);
    futureThrows(new IOException()).when(spies.get(1)).getJournaledEdits(1,
        QuorumJournalManager.QJM_RPC_MAX_TXNS_DEFAULT);

    List<EditLogInputStream> streams = new ArrayList<>();
    qjm.selectInputStreams(streams, 1, true, true);
    // This should still succeed as the QJM should fall back to the streaming
    // mechanism for fetching edits
    verifyEdits(streams, 1, 11);
    IOUtils.closeStreams(streams.toArray(new Closeable[0]));

    for (AsyncLogger logger : spies) {
      Mockito.verify(logger, Mockito.times(1)).getEditLogManifest(1, true);
    }
  }

  /**
   * Test selecting EditLogInputStream after some journalNode jitter.
   * Suppose there are 3 journalNodes, JN0 ~ JN2.
   *  1. JN0 has some abnormal cases when Active Namenode is syncing 10 Edits with first txid 11.
   *  2. NameNode just ignore the abnormal JN0 and continue to sync Edits to Journal 1 and 2.
   *  3. JN0 backed to health.
   *  4. NameNode continue sync 10 Edits with first txid 21.
   *  5. At this point, there are no Edits 11 ~ 30 in the cache of JN0.
   *  6. Observer NameNode try to select EditLogInputStream through
   *     getJournaledEdits with since txId 21.
   *  7. JN2 has some abnormal cases and caused a slow response.
   */
  @Test
  public void testSelectViaRPCAfterJNJitter() throws Exception {
    EditLogOutputStream stm = qjm.startLogSegment(
        1, NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    SettableFuture<Void> slowLog = SettableFuture.create();
    Mockito.doReturn(slowLog).when(spies.get(0))
        .sendEdits(eq(1L), eq(11L), eq(10), Mockito.any());
    // Successfully write these edits to JN0 ~ JN2
    writeTxns(stm, 1, 10);
    // Failed write these edits to JN0, but successfully write them to JN1 ~ JN2
    writeTxns(stm, 11, 10);
    // Successfully write these edits to JN1 ~ JN2
    writeTxns(stm, 21, 20);

    Semaphore semaphore = new Semaphore(0);
    spyGetJournaledEdits(spies, 0, 21, () -> semaphore.release(1));
    spyGetJournaledEdits(spies, 1, 21, () -> semaphore.release(1));
    spyGetJournaledEdits(spies, 2, 21, () -> semaphore.acquireUninterruptibly(2));

    List<EditLogInputStream> streams = new ArrayList<>();
    qjm.selectInputStreams(streams, 21, true, true);

    assertEquals(1, streams.size());
    assertEquals(21, streams.get(0).getFirstTxId());
    assertEquals(40, streams.get(0).getLastTxId());
  }

  @Test
  public void testSelectViaRpcAfterJNRestart() throws Exception {
    EditLogOutputStream stm =
        qjm.startLogSegment(1, NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    writeTxns(stm, 1, 10);
    qjm.finalizeLogSegment(1, 10);

    // Close to avoid connections hanging around after the JNs are restarted
    for (int i = 0; i < cluster.getNumNodes(); i++) {
      cluster.restartJournalNode(i);
    }
    cluster.waitActive();

    qjm = createSpyingQJM();
    spies = qjm.getLoggerSetForTests().getLoggersForTests();
    List<EditLogInputStream> streams = new ArrayList<>();
    qjm.selectInputStreams(streams, 1, true, true);
    // This should still succeed as the QJM should fall back to the streaming
    // mechanism for fetching edits
    verifyEdits(streams, 1, 10);
    IOUtils.closeStreams(streams.toArray(new Closeable[0]));

    for (AsyncLogger logger : spies) {
      Mockito.verify(logger, Mockito.times(1)).getEditLogManifest(1, true);
    }
  }

  @Test
  public void testGetJournalAddressListWithResolution() throws Exception {
    Configuration configuration = new Configuration();
    configuration.setBoolean(
        DFSConfigKeys.DFS_NAMENODE_EDITS_QJOURNALS_RESOLUTION_ENABLED, true);
    configuration.set(
        DFSConfigKeys.DFS_NAMENODE_EDITS_QJOURNALS_RESOLUTION_RESOLVER_IMPL,
        MockDomainNameResolver.class.getName());

    URI uriWithDomain = URI.create("qjournal://"
        + MockDomainNameResolver.DOMAIN + ":1234" + "/testns");
    List<InetSocketAddress> result = Util.getAddressesList(uriWithDomain, configuration);
    assertEquals(2, result.size());
    assertEquals(new InetSocketAddress(MockDomainNameResolver.FQDN_1, 1234), result.get(0));
    assertEquals(new InetSocketAddress(MockDomainNameResolver.FQDN_2, 1234), result.get(1));

    uriWithDomain = URI.create("qjournal://"
        + MockDomainNameResolver.UNKNOW_DOMAIN + ":1234" + "/testns");
    try{
      Util.getAddressesList(uriWithDomain, configuration);
      fail("Should throw unknown host exception.");
    } catch (UnknownHostException e) {
      // expected
    }
  }

  private QuorumJournalManager createSpyingQJM() throws IOException {
    return closeLater(SpyQJournalUtil.createSpyingQJM(
        conf, cluster.getQuorumJournalURI(JID), FAKE_NSINFO, null));
  }

  private static void waitForAllPendingCalls(AsyncLoggerSet als)
      throws InterruptedException {
    for (AsyncLogger l : als.getLoggersForTests()) {
      IPCLoggerChannel ch = (IPCLoggerChannel)l;
      ch.waitForAllPendingCalls();
    }
  }

  private void checkRecovery(MiniJournalCluster cluster,
      long segmentTxId, long expectedEndTxId)
      throws IOException {
    int numFinalized = 0;
    for (int i = 0; i < cluster.getNumNodes(); i++) {
      File logDir = cluster.getCurrentDir(i, JID);
      EditLogFile elf = FileJournalManager.getLogFile(logDir, segmentTxId);
      if (elf == null) {
        continue;
      }
      if (!elf.isInProgress()) {
        numFinalized++;
        if (elf.getLastTxId() != expectedEndTxId) {
          fail("File " + elf + " finalized to wrong txid, expected " +
              expectedEndTxId);
        }
      }      
    }
    
    if (numFinalized < cluster.getQuorumSize()) {
      fail("Did not find a quorum of finalized logs starting at " +
          segmentTxId);
    }
  }

  @Test
  public void testSelectLatestEditsWithoutStreaming() throws Exception {
    EditLogOutputStream stm = qjm.startLogSegment(
        1, NameNodeLayoutVersion.CURRENT_LAYOUT_VERSION);
    // Successfully write these edits to JN0 ~ JN2
    writeTxns(stm, 1, 10);

    AtomicInteger atomicInteger = new AtomicInteger(0);
    spyGetEditLogManifest(0, 11, true, atomicInteger::incrementAndGet);
    spyGetEditLogManifest(1, 11, true, atomicInteger::incrementAndGet);
    spyGetEditLogManifest(2, 11, true, atomicInteger::incrementAndGet);

    List<EditLogInputStream> streams = new ArrayList<>();
    qjm.selectInputStreams(streams, 1, true, true);
    assertEquals(1, streams.size());
    assertEquals(1, streams.get(0).getFirstTxId());
    assertEquals(10, streams.get(0).getLastTxId());

    streams.clear();
    qjm.selectInputStreams(streams, 11, true, true);
    assertEquals(0, streams.size());
    assertEquals(0, atomicInteger.get());
  }

  private void spyGetEditLogManifest(int jnSpyIdx, long fromTxId,
      boolean inProgressOk, Runnable preHook) {
    Mockito.doAnswer((Answer<ListenableFuture<RemoteEditLogManifest>>) invocation -> {
      preHook.run();
      @SuppressWarnings("unchecked")
      ListenableFuture<RemoteEditLogManifest> result =
          (ListenableFuture<RemoteEditLogManifest>) invocation.callRealMethod();
      return result;
    }).when(spies.get(jnSpyIdx)).getEditLogManifest(fromTxId, inProgressOk);
  }
}
