Author: sebb
Date: Tue Sep 16 09:03:14 2008
New Revision: 695951
URL: http://svn.apache.org/viewvc?rev=695951&view=rev
Log:
LANG-459 HashCodeBuilder.reflectionHashCode() can generate incorrect hashcodes
Added:
commons/proper/lang/trunk/src/java/org/apache/commons/lang/IDKey.java
(with props)
Modified:
commons/proper/lang/trunk/src/java/org/apache/commons/lang/builder/HashCodeBuilder.java
Added: commons/proper/lang/trunk/src/java/org/apache/commons/lang/IDKey.java
URL:
http://svn.apache.org/viewvc/commons/proper/lang/trunk/src/java/org/apache/commons/lang/IDKey.java?rev=695951&view=auto
==============================================================================
--- commons/proper/lang/trunk/src/java/org/apache/commons/lang/IDKey.java
(added)
+++ commons/proper/lang/trunk/src/java/org/apache/commons/lang/IDKey.java Tue
Sep 16 09:03:14 2008
@@ -0,0 +1,72 @@
+/*
+ * 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.commons.lang;
+
+// adapted from org.apache.axis.utils.IDKey
+
+/**
+* Wrap an identity key (System.identityHashCode())
+* so that an object can only be equal() to itself.
+*
+* This is necessary to disambiguate the occasional duplicate
+* identityHashCodes that can occur.
+*
+*/
+public final class IDKey {
+ private final Object value;
+ private final int id;
+
+ /**
+ * Constructor for IDKey
+ * @param _value
+ */
+ public IDKey(Object _value) {
+ // This is the Object hashcode
+ id = System.identityHashCode(_value);
+ // There have been some cases (LANG-459) that return the
+ // same identity hash code for different objects. So
+ // the value is also added to disambiguate these cases.
+ value = _value;
+ }
+
+ /**
+ * returns hashcode - i.e. the system identity hashcode.
+ * @return the hashcode
+ */
+ public int hashCode() {
+ return id;
+ }
+
+ /**
+ * checks if instances are equal
+ * @param other
+ * @return if the instances are for the same object
+ */
+ public boolean equals(Object other) {
+ if (!(other instanceof IDKey)) {
+ return false;
+ }
+ IDKey idKey = (IDKey) other;
+ if (id != idKey.id) {
+ return false;
+ }
+ // Note that identity equals is used.
+ return value == idKey.value;
+ }
+}
Propchange:
commons/proper/lang/trunk/src/java/org/apache/commons/lang/IDKey.java
------------------------------------------------------------------------------
svn:eol-style = native
Propchange:
commons/proper/lang/trunk/src/java/org/apache/commons/lang/IDKey.java
------------------------------------------------------------------------------
svn:keywords = Author Date Id Revision
Modified:
commons/proper/lang/trunk/src/java/org/apache/commons/lang/builder/HashCodeBuilder.java
URL:
http://svn.apache.org/viewvc/commons/proper/lang/trunk/src/java/org/apache/commons/lang/builder/HashCodeBuilder.java?rev=695951&r1=695950&r2=695951&view=diff
==============================================================================
---
commons/proper/lang/trunk/src/java/org/apache/commons/lang/builder/HashCodeBuilder.java
(original)
+++
commons/proper/lang/trunk/src/java/org/apache/commons/lang/builder/HashCodeBuilder.java
Tue Sep 16 09:03:14 2008
@@ -27,6 +27,8 @@
import java.util.List;
import java.util.Set;
+import org.apache.commons.lang.IDKey;
+
/**
* <p>
* Assists in implementing [EMAIL PROTECTED] Object#hashCode()} methods.
@@ -110,6 +112,23 @@
}
};
+ /*
+ * N.B. we cannot store the actual objects in a HashSet, as that would use
the very hashCode()
+ * we are in the process of calculating.
+ *
+ * So we generate a one-to-one mapping from the original object to a new
object.
+ *
+ * Now HashSet uses equals() to determine if two elements with the same
hashcode really
+ * are equal, so we also need to ensure that the replacement objects are
only equal
+ * if the original objects are identical.
+ *
+ * The original implementation (2.4 and before) used the
System.indentityHashCode()
+ * method - however this is not guaranteed to generate unique ids (e.g.
LANG-459)
+ *
+ * We now use the IDKey helper class (adapted from
org.apache.axis.utils.IDKey)
+ * to disambiguate the duplicate ids.
+ */
+
/**
* <p>
* Returns the registry of objects being traversed by the reflection
methods in the current thread.
@@ -134,7 +153,7 @@
* @since 2.3
*/
static boolean isRegistered(Object value) {
- return getRegistry().contains(toIdentityHashCodeInteger(value));
+ return getRegistry().contains(new IDKey(value));
}
/**
@@ -506,19 +525,7 @@
* The object to register.
*/
static void register(Object value) {
- getRegistry().add(toIdentityHashCodeInteger(value));
- }
-
- /**
- * Returns an Integer for the given object's default hash code.
- *
- * @see System#identityHashCode(Object)
- * @param value
- * object for which the hashCode is to be calculated
- * @return Default int hash code
- */
- private static Integer toIdentityHashCodeInteger(Object value) {
- return new Integer(System.identityHashCode(value));
+ getRegistry().add(new IDKey(value));
}
/**
@@ -534,7 +541,7 @@
* @since 2.3
*/
static void unregister(Object value) {
- getRegistry().remove(toIdentityHashCodeInteger(value));
+ getRegistry().remove(new IDKey(value));
}
/**
