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8372256 : ClassCastException in ConcurrentHashMap#equals #28453

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8372256 : ClassCastException in ConcurrentHashMap#equals #28453

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18 changes: 13 additions & 5 deletions src/java.base/share/classes/java/util/concurrent/ConcurrentHashMap.java
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Original file line number Diff line number Diff line change
Expand Up @@ -1372,12 +1372,20 @@ public boolean equals(Object o) {
Node<K,V>[] t;
int f = (t = table) == null ? 0 : t.length;
Traverser<K,V> it = new Traverser<K,V>(t, f, 0, f);
for (Node<K,V> p; (p = it.advance()) != null; ) {
V val = p.val;
Object v = m.get(p.key);
if (v == null || (v != val && !v.equals(val)))
return false;

try {
for (Node<K,V> p; (p = it.advance()) != null; ) {
V val = p.val;
Object v = m.get(p.key);
if (v == null || (v != val && !v.equals(val)))
return false;
}
} catch (ClassCastException | NullPointerException _) {
// m.get(p.key) is contractually allowed to throw CCE or NPE
// but CHM doesn't allow null keys, so NPE shouldn't occur in practice
return false;
}

for (Map.Entry<?,?> e : m.entrySet()) {
Object mk, mv, v;
if ((mk = e.getKey()) == null ||
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19 changes: 19 additions & 0 deletions test/jdk/java/util/concurrent/tck/ConcurrentHashMapTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -40,6 +40,7 @@
import java.util.Collections;
import java.util.Enumeration;
import java.util.Iterator;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;
import java.util.Set;
Expand Down Expand Up @@ -878,6 +879,24 @@ public void testReentrantComputeIfAbsent() {
} catch (IllegalStateException success) {}
}

public void testMapEqualsIfClassCastExceptionOccurs() {
class MonotypeKeyMap extends HashMap<Byte, Object> {
@Override public Object get(Object key) {
return super.get((Byte)key); // Force cast, allowed by spec
}
}

var mkm = new MonotypeKeyMap();
mkm.put((byte)1, "value1");
var similar = new ConcurrentHashMap<Byte, Object>();
similar.put((byte)1, "value1");
var different = new ConcurrentHashMap<String, String>();
different.put("test1", "value1");

assertTrue(similar.equals(mkm));
assertFalse(different.equals(mkm));
}

private static Item findValue(ConcurrentHashMap<Item, Item> map,
Item key) {
return (key.value % 5 == 0) ? key :
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