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* Licensed to Elasticsearch under one or more contributor
* license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright
* ownership. Elasticsearch 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.elasticsearch.common.util;
import java.util.function.Supplier;
/**
* A {@link Supplier} that caches its return value. This may be useful to make
* a {@link Supplier} idempotent or for performance reasons if always returning
* the same instance is acceptable.
*/
public final class CachedSupplier implements Supplier {
private Supplier supplier;
private T result;
private boolean resultSet;
public CachedSupplier(Supplier supplier) {
this.supplier = supplier;
}
@Override
public synchronized T get() {
if (resultSet == false) {
result = supplier.get();
resultSet = true;
}
return result;
}
}