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API: Fix equals and hashCode in CharSequenceSet #9245

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Merged
aokolnychyi merged 1 commit into from
Dec 16, 2023
Merged

API: Fix equals and hashCode in CharSequenceSet #9245

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20 changes: 13 additions & 7 deletions api/src/main/java/org/apache/iceberg/util/CharSequenceSet.java
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Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,6 @@
import java.io.Serializable;
import java.util.Collection;
import java.util.Iterator;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;
import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
Expand Down Expand Up @@ -168,22 +167,29 @@ public void clear() {
}

@Override
public boolean equals(Object o) {
if (this == o) {
public boolean equals(Object other) {
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@aokolnychyi aokolnychyi Dec 8, 2023 •
edited
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See Set#equals() and AbstractSet#equals() for background.

if (this == other) {
return true;
} else if (!(other instanceof Set)) {
return false;
}

if (o == null || getClass() != o.getClass()) {
Set<?> that = (Set<?>) other;

if (size() != that.size()) {
return false;
}

CharSequenceSet that = (CharSequenceSet) o;
return wrapperSet.equals(that.wrapperSet);
try {
return containsAll(that);
} catch (ClassCastException | NullPointerException unused) {
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@aokolnychyi aokolnychyi Dec 8, 2023

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While this class does not throw these exceptions now, it may in the future. These exceptions are valid outcomes defined by the Set API. Therefore, I am respecting that to be safe.

return false;
}
}

@Override
public int hashCode() {
return Objects.hashCode(wrapperSet);
return wrapperSet.stream().mapToInt(CharSequenceWrapper::hashCode).sum();
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@aokolnychyi aokolnychyi Dec 8, 2023 •
edited
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The Set API requires the hash code to be a sum of hash codes of all elements. See Set#hashCode().

}

@Override
Expand Down
33 changes: 33 additions & 0 deletions api/src/test/java/org/apache/iceberg/util/TestCharSequenceSet.java
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Expand Up @@ -19,8 +19,10 @@
package org.apache.iceberg.util;

import java.util.Arrays;
import java.util.Collections;
import java.util.Set;
import org.apache.iceberg.relocated.com.google.common.collect.ImmutableList;
import org.apache.iceberg.relocated.com.google.common.collect.ImmutableSet;
import org.assertj.core.api.Assertions;
import org.junit.jupiter.api.Test;

Expand Down Expand Up @@ -79,4 +81,35 @@ public void testRemoveAll() {

Assertions.assertThat(set).isEmpty();
}

@Test
public void testEqualsAndHashCode() {
CharSequenceSet set1 = CharSequenceSet.empty();
CharSequenceSet set2 = CharSequenceSet.empty();

Assertions.assertThat(set1).isEqualTo(set2);
Assertions.assertThat(set1.hashCode()).isEqualTo(set2.hashCode());

set1.add("v1");
set1.add("v2");
set1.add("v3");

set2.add(new StringBuilder("v1"));
set2.add(new StringBuffer("v2"));
set2.add("v3");

Set<CharSequence> set3 = Collections.unmodifiableSet(set2);
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@aokolnychyi aokolnychyi Dec 7, 2023

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I am primarily interested in wrapping CharSequenceSet into UnmodifiableSet in CharSequenceMap.


Set<CharSequenceWrapper> set4 =
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@aokolnychyi aokolnychyi Dec 8, 2023

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This one works too now.

ImmutableSet.of(
CharSequenceWrapper.wrap("v1"),
CharSequenceWrapper.wrap(new StringBuffer("v2")),
CharSequenceWrapper.wrap(new StringBuffer("v3")));

Assertions.assertThat(set1).isEqualTo(set2).isEqualTo(set3).isEqualTo(set4);
Assertions.assertThat(set1.hashCode())
.isEqualTo(set2.hashCode())
.isEqualTo(set3.hashCode())
.isEqualTo(set4.hashCode());
}
}