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Fix LRU comparison algorithm #18624
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Fix LRU comparison algorithm #18624
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Original file line number | Diff line number | Diff line change |
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@@ -125,20 +125,25 @@ public EvictionPolicyComparator getComparator() { | |
= new ArrayList<EvictionCandidate<Integer, CacheObjectRecord>>(); | ||
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long baseTime = System.currentTimeMillis(); | ||
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long minCreationTime = -1; | ||
for (int i = 0; i < recordCount; i++) { | ||
long creationTime = baseTime + (i * 100); | ||
minCreationTime = minCreationTime == -1 ? creationTime : Math.min(creationTime, minCreationTime); | ||
There was a problem hiding this comment. Choose a reason for hiding this commentThe reason will be displayed to describe this comment to others. Learn more. nit: could also initialize |
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CacheObjectRecord record = new CacheObjectRecord(i, creationTime, Long.MAX_VALUE); | ||
if (i == expectedEvictedRecordValue) { | ||
// The record in the middle will be minimum access time. | ||
// So, it will be selected for eviction | ||
record.setLastAccessTime(baseTime - 1000); | ||
// The record in the middle will be minimum access | ||
// time. So, it will be selected for eviction | ||
// (set creation-time also to keep this condition | ||
// true --> creation-time <= last-access-time) | ||
record.setCreationTime(minCreationTime); | ||
record.setLastAccessTime(minCreationTime + 1); | ||
} else if (i == expectedExpiredRecordValue) { | ||
record.setExpirationTime(System.currentTimeMillis()); | ||
} else { | ||
record.setLastAccessTime(creationTime + 1000); | ||
} | ||
records.add(new SimpleEvictionCandidate<Integer, CacheObjectRecord>(i, record)); | ||
records.add(new SimpleEvictionCandidate<>(i, record)); | ||
} | ||
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sleepAtLeastMillis(1); | ||
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149 changes: 149 additions & 0 deletions
149
...java/com/hazelcast/internal/eviction/impl/comparator/LRUEvictionPolicyComparatorTest.java
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,149 @@ | ||
/* | ||
* Copyright (c) 2008-2021, Hazelcast, Inc. All Rights Reserved. | ||
* | ||
* Licensed 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. | ||
*/ | ||
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package com.hazelcast.internal.eviction.impl.comparator; | ||
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import com.hazelcast.spi.eviction.EvictableEntryView; | ||
import com.hazelcast.test.HazelcastSerialClassRunner; | ||
import com.hazelcast.test.annotation.QuickTest; | ||
import org.junit.Test; | ||
import org.junit.experimental.categories.Category; | ||
import org.junit.runner.RunWith; | ||
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import java.util.Collections; | ||
import java.util.LinkedList; | ||
import java.util.List; | ||
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import static org.junit.Assert.assertEquals; | ||
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@RunWith(HazelcastSerialClassRunner.class) | ||
@Category(QuickTest.class) | ||
public class LRUEvictionPolicyComparatorTest { | ||
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private static final long NOW = 20; | ||
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@Test | ||
public void lru_comparator_does_not_prematurely_select_newly_created_entries() { | ||
// 0. Entries to sort | ||
List<TestEntryView> givenEntries = new LinkedList<>(); | ||
givenEntries.add(new TestEntryView(1, 1, 0)); | ||
givenEntries.add(new TestEntryView(2, 2, 3)); | ||
givenEntries.add(new TestEntryView(3, 2, 0)); | ||
givenEntries.add(new TestEntryView(4, 4, 4)); | ||
givenEntries.add(new TestEntryView(5, 5, 20)); | ||
givenEntries.add(new TestEntryView(6, 6, 6)); | ||
givenEntries.add(new TestEntryView(7, 7, 0)); | ||
givenEntries.add(new TestEntryView(8, 9, 15)); | ||
givenEntries.add(new TestEntryView(9, 10, 10)); | ||
givenEntries.add(new TestEntryView(10, 10, 0)); | ||
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// 1. Create expected list of ordered elements by | ||
// sorting entries based on their idle-times. Longest | ||
// idle time must be the first element of the list. | ||
List<TestEntryView> descOrderByIdleTimes = new LinkedList<>(givenEntries); | ||
Collections.sort(descOrderByIdleTimes, (o1, o2) -> -Long.compare(idleTime(o1), idleTime(o2))); | ||
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// 2. Then sort given entries by using LRU eviction comparator. | ||
Collections.sort(givenEntries, (o1, o2) -> LRUEvictionPolicyComparator.INSTANCE.compare(o1, o2)); | ||
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// 3. Check both lists are equal | ||
assertEquals(descOrderByIdleTimes, givenEntries); | ||
} | ||
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private static long idleTime(EvictableEntryView entryView) { | ||
return NOW - Math.max(entryView.getCreationTime(), entryView.getLastAccessTime()); | ||
} | ||
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private static class TestEntryView implements EvictableEntryView { | ||
private long id; | ||
private long creationTime; | ||
private long lastAccessTime; | ||
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TestEntryView(long id, long creationTime, long lastAccessTime) { | ||
this.id = id; | ||
this.creationTime = creationTime; | ||
this.lastAccessTime = lastAccessTime; | ||
} | ||
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@Override | ||
public long getCreationTime() { | ||
return creationTime; | ||
} | ||
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@Override | ||
public long getLastAccessTime() { | ||
return lastAccessTime; | ||
} | ||
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public long getId() { | ||
return id; | ||
} | ||
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@Override | ||
public boolean equals(Object o) { | ||
if (this == o) { | ||
return true; | ||
} | ||
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if (o == null || getClass() != o.getClass()) { | ||
return false; | ||
} | ||
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TestEntryView that = (TestEntryView) o; | ||
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if (id != that.id) { | ||
return false; | ||
} | ||
if (creationTime != that.creationTime) { | ||
return false; | ||
} | ||
return lastAccessTime == that.lastAccessTime; | ||
} | ||
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@Override | ||
public int hashCode() { | ||
int result = (int) (id ^ (id >>> 32)); | ||
result = 31 * result + (int) (creationTime ^ (creationTime >>> 32)); | ||
result = 31 * result + (int) (lastAccessTime ^ (lastAccessTime >>> 32)); | ||
return result; | ||
} | ||
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@Override | ||
public String toString() { | ||
return "TestEntryView{" | ||
+ "id=" + id | ||
+ ", now=" + NOW | ||
+ ", creationTime=" + creationTime | ||
+ ", lastAccessTime=" + lastAccessTime | ||
+ ", idleTime=" + idleTime(this) + '}'; | ||
} | ||
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@Override | ||
public Object getKey() { | ||
throw new UnsupportedOperationException(); | ||
} | ||
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@Override | ||
public Object getValue() { | ||
throw new UnsupportedOperationException(); | ||
} | ||
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@Override | ||
public long getHits() { | ||
throw new UnsupportedOperationException(); | ||
} | ||
} | ||
} |
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Do we need these comparisons after the change in
AbstractRecordStore
? I don't know exactly where the last access times can be changed, so it's just a question to learn the cases that need them.There was a problem hiding this comment.
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This comparator is a common one used by multiple data structures, it is not specific to IMap, i have also fixed it here.
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I think it would be better if we also apply the change made in
AbstractRecordStore
toAbstractCacheRecordStore
(and all others) to have a convenience on these last access times.There was a problem hiding this comment.
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There is no issue in the context of icache. Setting last-access-time is a missing requirement for imap after 4.2 improvements. No need for others now.