opennlp.tools.util.jvm.CHMStringInterner Maven / Gradle / Ivy
/*
* 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 opennlp.tools.util.jvm;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import opennlp.tools.commons.Internal;
import opennlp.tools.commons.ThreadSafe;
/**
* A {@link StringInterner} implementation based on {@link ConcurrentHashMap} by Aleksey Shipilëv.
*
* Origin:
*
* https://shipilev.net/jvm/anatomy-quarks/10-string-intern/
*/
@Internal
@ThreadSafe
class CHMStringInterner implements StringInterner {
private final Map map;
public CHMStringInterner() {
map = new ConcurrentHashMap<>();
}
/**
* {@inheritDoc}
*/
@Override
public String intern(String sample) {
final String exist = map.putIfAbsent(sample, sample);
return (exist == null) ? sample : exist;
}
}