test/src/main/java/org/apache/accumulo/test/functional/ScannerIT.java

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 * 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
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 * KIND, either express or implied.  See the License for the
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package org.apache.accumulo.test.functional;

import static org.junit.Assert.assertTrue;

import java.util.Iterator;
import java.util.Map.Entry;

import org.apache.accumulo.core.client.Accumulo;
import org.apache.accumulo.core.client.AccumuloClient;
import org.apache.accumulo.core.client.BatchWriter;
import org.apache.accumulo.core.client.IteratorSetting;
import org.apache.accumulo.core.client.Scanner;
import org.apache.accumulo.core.data.Key;
import org.apache.accumulo.core.data.Mutation;
import org.apache.accumulo.core.data.Range;
import org.apache.accumulo.core.data.Value;
import org.apache.accumulo.core.security.Authorizations;
import org.apache.accumulo.fate.util.UtilWaitThread;
import org.apache.accumulo.harness.AccumuloClusterHarness;
import org.junit.Test;

public class ScannerIT extends AccumuloClusterHarness {

  @Override
  protected int defaultTimeoutSeconds() {
    return 60;
  }

  @Test
  public void testScannerReadaheadConfiguration() throws Exception {
    final String table = getUniqueNames(1)[0];
    try (AccumuloClient c = Accumulo.newClient().from(getClientProps()).build()) {
      c.tableOperations().create(table);

      try (BatchWriter bw = c.createBatchWriter(table)) {
        Mutation m = new Mutation("a");
        for (int i = 0; i < 10; i++) {
          m.put(Integer.toString(i), "", "");
        }
        bw.addMutation(m);
      }

      IteratorSetting cfg;
      Iterator<Entry<Key,Value>> iterator;
      long nanosWithWait = 0;
      try (Scanner s = c.createScanner(table, new Authorizations())) {

        cfg = new IteratorSetting(100, SlowIterator.class);
        // A batch size of one will end up calling seek() for each element with no calls to next()
        SlowIterator.setSeekSleepTime(cfg, 100L);

        s.addScanIterator(cfg);
        // Never start readahead
        s.setReadaheadThreshold(Long.MAX_VALUE);
        s.setBatchSize(1);
        s.setRange(new Range());

        iterator = s.iterator();
        long startTime = System.nanoTime();
        while (iterator.hasNext()) {
          nanosWithWait += System.nanoTime() - startTime;

          // While we "do work" in the client, we should be fetching the next result
          UtilWaitThread.sleep(100L);
          iterator.next();
          startTime = System.nanoTime();
        }
        nanosWithWait += System.nanoTime() - startTime;
      }

      long nanosWithNoWait = 0;
      try (Scanner s = c.createScanner(table, new Authorizations())) {
        s.addScanIterator(cfg);
        s.setRange(new Range());
        s.setBatchSize(1);
        s.setReadaheadThreshold(0L);

        iterator = s.iterator();
        long startTime = System.nanoTime();
        while (iterator.hasNext()) {
          nanosWithNoWait += System.nanoTime() - startTime;

          // While we "do work" in the client, we should be fetching the next result
          UtilWaitThread.sleep(100L);
          iterator.next();
          startTime = System.nanoTime();
        }
        nanosWithNoWait += System.nanoTime() - startTime;

        // The "no-wait" time should be much less than the "wait-time"
        assertTrue(
            "Expected less time to be taken with immediate readahead (" + nanosWithNoWait
                + ") than without immediate readahead (" + nanosWithWait + ")",
            nanosWithNoWait < nanosWithWait);
      }
    }
  }
}