Index: src/java/org/apache/lucene/util/StringHelper.java =================================================================== --- src/java/org/apache/lucene/util/StringHelper.java (revision 766478) +++ src/java/org/apache/lucene/util/StringHelper.java (working copy) @@ -24,7 +24,9 @@ * $Id$ */ public abstract class StringHelper { + public static StringInterner interner = new SimpleStringInterner(32); + /** * Compares two byte[] arrays, element by element, and returns the * number of elements common to both arrays. Index: src/java/org/apache/lucene/util/StringInterner.java =================================================================== --- src/java/org/apache/lucene/util/StringInterner.java (revision 0) +++ src/java/org/apache/lucene/util/StringInterner.java (revision 0) @@ -0,0 +1,29 @@ +package org.apache.lucene.util; +/** + * 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. + */ + +public class StringInterner { + /** interns a string according to this StringCreator instance. */ + public String intern(String s) { + return s.intern(); + } + + /** interns a string according to this StringCreator instance. */ + public String intern(char[] arr, int offset, int len) { + return intern(new String(arr, offset, len)); + } +} Property changes on: src/java/org/apache/lucene/util/StringInterner.java ___________________________________________________________________ Added: svn:executable + * Added: svn:keywords + Date Author Id Revision HeadURL Added: svn:eol-style + native Index: src/java/org/apache/lucene/util/SimpleStringInterner.java =================================================================== --- src/java/org/apache/lucene/util/SimpleStringInterner.java (revision 0) +++ src/java/org/apache/lucene/util/SimpleStringInterner.java (revision 0) @@ -0,0 +1,107 @@ +package org.apache.lucene.util; +/** + * 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. + */ + + +/** + * Simple lockless and memory barrier free String intern cache that is guaranteed + * to return the same String instance as String.intern() does. + */ +public class SimpleStringInterner extends StringInterner { + private String[] cache; + int numEntries; + + public SimpleStringInterner(int sz) { + cache = new String[BitUtil.nextHighestPowerOfTwo(sz)]; + } + + private String add(String s) { + synchronized(this) { + numEntries++; + // check if we are over the load factor of 75% + if (numEntries+(numEntries>>2) > cache.length) { + int newSz = cache.length<<1; + String[] newArr = new String[newSz]; + for (int i=0; i>7)|1)) & (newArr.length-1); + } + newArr[slot] = ss; + } + + // publish new cache... lack of read barriers by readers may + // cause false misses, but this is OK. + cache = newArr; + } + + // find the correct spot for the new String, keeping in + // mind that we may have already added it. + int h = s.hashCode(); + int slot = h & (cache.length-1); + for(;;) { + String ss = cache[slot]; + if (ss==null) { + // a new string... intern it first. + s = s.intern(); + cache[slot] = s; + return s; + } + if (h==ss.hashCode() && s.compareTo(ss)==0) { + // this string was already added. + numEntries--; + return ss; + } + slot = (slot + ((h>>7)|1)) & (cache.length-1); + } + } + } + + // @Override + public String intern(String s) { + // grab the latest visible reference and then only use that the rest + // of the time for consistency. + String[] arr = cache; + + int h = s.hashCode(); + int slot = h & (arr.length-1); + + for (;;) { + String other = arr[slot]; + if (other==null) { + // cache miss... insert it. + return add(s); + } + + // check cached hashCode first, and use compareTo to avoid + // dynamic type checking in equals(). + if (h == other.hashCode() && s.compareTo(other)==0) { + return s; + } + + // Adding an odd number to this power-of-two hash table is + // guaranteed to do a full traversal, so instead of re-hashing + // we jump straight to a "linear" traversal, but base the step size + // on the hash code for better dispersion. We don't use the lowest + // bits since they are ones that resulted in a collision. + slot = (slot + ((h>>7)|1)) & (arr.length-1); + } + } +} \ No newline at end of file Property changes on: src/java/org/apache/lucene/util/SimpleStringInterner.java ___________________________________________________________________ Added: svn:executable + * Added: svn:keywords + Date Author Id Revision HeadURL Added: svn:eol-style + native