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From: keith-turner <git@git.apache.org>
To: dev@accumulo.apache.org
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Subject: [GitHub] accumulo pull request: ACCUMULO-626 Iterator fuzzer/tester
Content-Type: text/plain
Message-Id: <20151109192511.7CF4CE05DB@git1-us-west.apache.org>
Date: Mon,  9 Nov 2015 19:25:11 +0000 (UTC)

Github user keith-turner commented on a diff in the pull request:

    https://github.com/apache/accumulo/pull/50#discussion_r44318310
  
    --- Diff: iterator-test-harness/src/main/java/org/apache/accumulo/iteratortest/testcases/ReSeekTestCase.java ---
    @@ -0,0 +1,107 @@
    +/*
    + * 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.accumulo.iteratortest.testcases;
    +
    +import java.io.IOException;
    +import java.util.Collections;
    +import java.util.Random;
    +import java.util.TreeMap;
    +
    +import org.apache.accumulo.core.data.ByteSequence;
    +import org.apache.accumulo.core.data.Key;
    +import org.apache.accumulo.core.data.Range;
    +import org.apache.accumulo.core.data.Value;
    +import org.apache.accumulo.core.iterators.SortedKeyValueIterator;
    +import org.apache.accumulo.iteratortest.IteratorTestInput;
    +import org.apache.accumulo.iteratortest.IteratorTestOutput;
    +import org.apache.accumulo.iteratortest.IteratorTestUtil;
    +import org.apache.accumulo.iteratortest.environments.SimpleIteratorEnvironment;
    +import org.slf4j.Logger;
    +import org.slf4j.LoggerFactory;
    +
    +/**
    + * Test case that verifies that an iterator can use the generated instance from {@code deepCopy}.
    + */
    +public class ReSeekTestCase extends OutputVerifyingTestCase {
    +  private static final Logger log = LoggerFactory.getLogger(ReSeekTestCase.class);
    +
    +  /**
    +   * Let N be a random number between [0, RESEEK_INTERVAL). After every Nth entry "returned" to the client, recreate and reseek the iterator.
    +   */
    +  private static final int RESEEK_INTERVAL = 4;
    +
    +  private final Random random;
    +
    +  public ReSeekTestCase() {
    +    this.random = new Random();
    +  }
    +
    +  @Override
    +  public IteratorTestOutput test(IteratorTestInput testInput) {
    +    final SortedKeyValueIterator<Key,Value> skvi = IteratorTestUtil.instantiateIterator(testInput);
    +    final SortedKeyValueIterator<Key,Value> source = IteratorTestUtil.createSource(testInput);
    +
    +    try {
    +      skvi.init(source, testInput.getIteratorOptions(), new SimpleIteratorEnvironment());
    +      skvi.seek(testInput.getRange(), Collections.<ByteSequence> emptySet(), false);
    +      return new IteratorTestOutput(consume(skvi, testInput));
    +    } catch (IOException e) {
    +      return new IteratorTestOutput(e);
    +    }
    +  }
    +
    +  TreeMap<Key,Value> consume(SortedKeyValueIterator<Key,Value> skvi, IteratorTestInput testInput) throws IOException {
    +    final TreeMap<Key,Value> data = new TreeMap<>();
    +    final Range origRange = testInput.getRange();
    +    int reseekCount = random.nextInt(RESEEK_INTERVAL);
    +
    +    int i = 0;
    +    while (skvi.hasTop()) {
    +      data.put(skvi.getTopKey(), skvi.getTopValue());
    +
    +      /*
    +       * One of the trickiest cases in writing iterators:
    +       * 
    +       * After any result is returned from a TabletServer to the client, the Iterator in the TabletServer's memory may be torn down. To preserve the state and
    +       * guarantee that all records are received, the TabletServer does remember the last Key it returned to the client. It will recreate the Iterator (stack),
    +       * and seek it using an updated Range. This range's start key is set to the last Key returned, non-inclusive.
    +       */
    +      if (i % RESEEK_INTERVAL == reseekCount) {
    +        // Last key
    +        Key reSeekStartKey = skvi.getTopKey();
    +
    +        // Deepcopy the iterator
    +        skvi = skvi.deepCopy(new SimpleIteratorEnvironment());
    --- End diff --
    
    creating a completely new iterator instance and initializing it would be more realistic


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