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Replace guava multimap in PCBC with custom impl (Cherry-pick)
Descriptions of the changes in this PR: (cherry-pick apache#1569) For a long time PerChannelBookieClient has used guava LinkedListMultiMap to store conflicting V2 completion keys and values. This is problematic though. Completion keys are pooled objects. When a key-value pair is stored in a LinkedListMultiMap, if it is the first value for that key, a collection is created for the values, and added to a top-level map using the key, and then the key and the value are added to the collection. When a second value is added for the same key, the key and value are simply added to the collection. The problem occurs when the first key is removed. PBCB will recycle the key object, but this object is still being used in the multimap in the top-level map. This causes all sorts of fun like NullPointerException and IllegalStateException. Because of this, this patch introduces a very simple multimap implementation that only stores the key one time (in the collection) and uses the hashCode of the key to separate the collections into buckets. It's pretty inefficient, but this code it only hit in the rare case where a client is trying to read or write the same entry from the same ledger more than once at the same time. Author: Ivan Kelly <ivanivankelly.net> Reviewers: Enrico Olivelli <eolivelligmail.com> This closes apache#1569 from ivankelly/conc-test-flake Master Issue: apache#1569 Author: Ivan Kelly <ivan@ivankelly.net> Reviewers: Ivan Kelly <ivank@apache.org>, Enrico Olivelli <eolivelli@gmail.com> This closes apache#1618 from sijie/cherry-pick-pcbc (cherry picked from commit 83d3abe) Signed-off-by: JV Jujjuri <vjujjuri@salesforce.com>
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83 changes: 83 additions & 0 deletions
83
...server/src/main/java/org/apache/bookkeeper/util/collections/SynchronizedHashMultiMap.java
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| /* | ||
| * | ||
| * 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.bookkeeper.util.collections; | ||
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| import java.util.Collections; | ||
| import java.util.HashMap; | ||
| import java.util.HashSet; | ||
| import java.util.Iterator; | ||
| import java.util.Optional; | ||
| import java.util.Set; | ||
| import java.util.function.BiPredicate; | ||
| import org.apache.commons.lang3.tuple.Pair; | ||
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| /** | ||
| * Simple multimap implementation that only stores key reference once. | ||
| * | ||
| * <p>Implementation is aimed at storing PerChannelBookieClient completions when there | ||
| * are duplicates. If the key is a pooled object, it must not exist once the value | ||
| * has been removed from the map, which can happen with guava multimap implemenations. | ||
| * | ||
| * <p>With this map is implemented with pretty heavy locking, but this shouldn't be an | ||
| * issue as the multimap only needs to be used in rare cases, i.e. when a user tries | ||
| * to read or the same entry twice at the same time. This class should *NOT* be used | ||
| * in critical path code. | ||
| * | ||
| * <p>A unique key-value pair will only be stored once. | ||
| */ | ||
| public class SynchronizedHashMultiMap<K, V> { | ||
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| HashMap<Integer, Set<Pair<K, V>>> map = new HashMap<>(); | ||
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| public synchronized void put(K k, V v) { | ||
| map.computeIfAbsent(k.hashCode(), (ignore) -> new HashSet<>()).add(Pair.of(k, v)); | ||
| } | ||
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| public synchronized Optional<K> getAnyKey() { | ||
| return map.values().stream().findAny().flatMap(pairs -> pairs.stream().findAny().map(p -> p.getLeft())); | ||
| } | ||
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| public synchronized Optional<V> removeAny(K k) { | ||
| Set<Pair<K, V>> set = map.getOrDefault(k.hashCode(), Collections.emptySet()); | ||
| Optional<Pair<K, V>> pair = set.stream().filter(p -> p.getLeft().equals(k)).findAny(); | ||
| pair.ifPresent(p -> set.remove(p)); | ||
| return pair.map(p -> p.getRight()); | ||
| } | ||
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| public synchronized int removeIf(BiPredicate<K, V> predicate) { | ||
| int removedSum = map.values().stream().mapToInt( | ||
| pairs -> { | ||
| int removed = 0; | ||
| // Can't use removeIf because we need the count | ||
| Iterator<Pair<K, V>> iter = pairs.iterator(); | ||
| while (iter.hasNext()) { | ||
| Pair<K, V> kv = iter.next(); | ||
| if (predicate.test(kv.getLeft(), kv.getRight())) { | ||
| iter.remove(); | ||
| removed++; | ||
| } | ||
| } | ||
| return removed; | ||
| }).sum(); | ||
| map.values().removeIf((s) -> s.isEmpty()); | ||
| return removedSum; | ||
| } | ||
| } |
99 changes: 99 additions & 0 deletions
99
...er/src/test/java/org/apache/bookkeeper/util/collections/SynchronizedHashMultiMapTest.java
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| Original file line number | Diff line number | Diff line change |
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| /* | ||
| * | ||
| * 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.bookkeeper.util.collections; | ||
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| import java.util.Optional; | ||
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| import org.junit.Assert; | ||
| import org.junit.Test; | ||
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| /** | ||
| * Test for SynchronizedHashMultiMap. | ||
| */ | ||
| public class SynchronizedHashMultiMapTest { | ||
| @Test | ||
| public void testGetAnyKey() { | ||
| SynchronizedHashMultiMap<Integer, Integer> map = new SynchronizedHashMultiMap<>(); | ||
| Assert.assertFalse(map.getAnyKey().isPresent()); | ||
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| map.put(1, 2); | ||
| Assert.assertEquals(map.getAnyKey().get(), Integer.valueOf(1)); | ||
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| map.put(1, 3); | ||
| Assert.assertEquals(map.getAnyKey().get(), Integer.valueOf(1)); | ||
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| map.put(2, 4); | ||
| int res = map.getAnyKey().get(); | ||
| Assert.assertTrue(res == 1 || res == 2); | ||
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| map.removeIf((k, v) -> k == 1); | ||
| Assert.assertEquals(map.getAnyKey().get(), Integer.valueOf(2)); | ||
| } | ||
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| @Test | ||
| public void testRemoveAny() { | ||
| SynchronizedHashMultiMap<Integer, Integer> map = new SynchronizedHashMultiMap<>(); | ||
| Assert.assertFalse(map.removeAny(1).isPresent()); | ||
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| map.put(1, 2); | ||
| map.put(1, 3); | ||
| map.put(2, 4); | ||
| map.put(2, 4); | ||
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| Optional<Integer> v = map.removeAny(1); | ||
| int firstVal = v.get(); | ||
| Assert.assertTrue(firstVal == 2 || firstVal == 3); | ||
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| v = map.removeAny(1); | ||
| int secondVal = v.get(); | ||
| Assert.assertTrue(secondVal == 2 || secondVal == 3); | ||
| Assert.assertNotEquals(secondVal, firstVal); | ||
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| v = map.removeAny(2); | ||
| Assert.assertTrue(v.isPresent()); | ||
| Assert.assertEquals(v.get(), Integer.valueOf(4)); | ||
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| Assert.assertFalse(map.removeAny(1).isPresent()); | ||
| Assert.assertFalse(map.removeAny(2).isPresent()); | ||
| Assert.assertFalse(map.removeAny(3).isPresent()); | ||
| } | ||
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| @Test | ||
| public void testRemoveIf() { | ||
| SynchronizedHashMultiMap<Integer, Integer> map = new SynchronizedHashMultiMap<>(); | ||
| Assert.assertEquals(map.removeIf((k, v) -> true), 0); | ||
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| map.put(1, 2); | ||
| map.put(1, 3); | ||
| map.put(2, 4); | ||
| map.put(2, 4); | ||
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| Assert.assertEquals(map.removeIf((k, v) -> v == 4), 1); | ||
| Assert.assertEquals(map.removeIf((k, v) -> k == 1), 2); | ||
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| map.put(1, 2); | ||
| map.put(1, 3); | ||
| map.put(2, 4); | ||
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| Assert.assertEquals(map.removeIf((k, v) -> false), 0); | ||
| Assert.assertEquals(map.removeIf((k, v) -> true), 3); | ||
| } | ||
| } |