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root/jsr166/jsr166/src/main/java/util/concurrent/ConcurrentHashMap.java

Comparing jsr166/src/main/java/util/concurrent/ConcurrentHashMap.java (file contents):
Revision 1.88 by jsr166, Sun May 28 23:36:29 2006 UTC vs.
Revision 1.89 by dl, Tue Jun 6 11:17:58 2006 UTC

#	Line 146 | Line 146 | public class ConcurrentHashMap<K, V> ext
146		/* ---------------- Small Utilities -------------- */
147
148		/**
149	<	* Returns a hash code for non-null Object x.
150	<	* Uses the same hash code spreader as most other java.util hash tables.
151	<	* @param x the object serving as a key
152	<	* @return the hash code
153	<	*/
154	<	static int hash(Object x) {
155	<	int h = x.hashCode();
156	<	h += ~(h << 9);
157	<	h ^=  (h >>> 14);
158	<	h +=  (h << 4);
159	<	h ^=  (h >>> 10);
160	<	return h;
149	>	* Applies a supplemental hash function to a given hashCode, which
150	>	* defends against poor quality hash functions.  This is critical
151	>	* because HashMap uses power-of two length hash tables, that
152	>	* otherwise encounter collisions for hashCodes that do not differ
153	>	* in lower bits.
154	>	*/
155	>	static int hash(int h) {
156	>	// This function ensures that hashCodes that differ only by
157	>	// constant multiples at each bit position have a bounded
158	>	// number of collisions (approximately 8 at default load factor).
159	>	h ^= (h >>> 20) ^ (h >>> 12);
160	>	return h ^ (h >>> 7) ^ (h >>> 4);
161		}
162
163		/**
#	Line 761 | Line 761 | public class ConcurrentHashMap<K, V> ext
761		* @throws NullPointerException if the specified key is null
762		*/
763		public V get(Object key) {
764	<	int hash = hash(key); // throws NullPointerException if key null
764	>	int hash = hash(key.hashCode());
765		return segmentFor(hash).get(key, hash);
766		}
767
#	Line 775 | Line 775 | public class ConcurrentHashMap<K, V> ext
775		* @throws NullPointerException if the specified key is null
776		*/
777		public boolean containsKey(Object key) {
778	<	int hash = hash(key); // throws NullPointerException if key null
778	>	int hash = hash(key.hashCode());
779		return segmentFor(hash).containsKey(key, hash);
780		}
781
#	Line 875 | Line 875 | public class ConcurrentHashMap<K, V> ext
875		public V put(K key, V value) {
876		if (value == null)
877		throw new NullPointerException();
878	<	int hash = hash(key);
878	>	int hash = hash(key.hashCode());
879		return segmentFor(hash).put(key, hash, value, false);
880		}
881
#	Line 889 | Line 889 | public class ConcurrentHashMap<K, V> ext
889		public V putIfAbsent(K key, V value) {
890		if (value == null)
891		throw new NullPointerException();
892	<	int hash = hash(key);
892	>	int hash = hash(key.hashCode());
893		return segmentFor(hash).put(key, hash, value, true);
894		}
895
#	Line 915 | Line 915 | public class ConcurrentHashMap<K, V> ext
915		* @throws NullPointerException if the specified key is null
916		*/
917		public V remove(Object key) {
918	<	int hash = hash(key);
918	>	int hash = hash(key.hashCode());
919		return segmentFor(hash).remove(key, hash, null);
920		}
921
#	Line 925 | Line 925 | public class ConcurrentHashMap<K, V> ext
925		* @throws NullPointerException if the specified key is null
926		*/
927		public boolean remove(Object key, Object value) {
928	<	int hash = hash(key); // throws NullPointerException if key null
928	>	int hash = hash(key.hashCode());
929		if (value == null)
930		return false;
931		return segmentFor(hash).remove(key, hash, value) != null;
#	Line 939 | Line 939 | public class ConcurrentHashMap<K, V> ext
939		public boolean replace(K key, V oldValue, V newValue) {
940		if (oldValue == null || newValue == null)
941		throw new NullPointerException();
942	<	int hash = hash(key);
942	>	int hash = hash(key.hashCode());
943		return segmentFor(hash).replace(key, hash, oldValue, newValue);
944		}
945
#	Line 953 | Line 953 | public class ConcurrentHashMap<K, V> ext
953		public V replace(K key, V value) {
954		if (value == null)
955		throw new NullPointerException();
956	<	int hash = hash(key);
956	>	int hash = hash(key.hashCode());
957		return segmentFor(hash).replace(key, hash, value);
958		}
959

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