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package org.apache.lucene.util;
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import java.util.concurrent.atomic.AtomicLong;
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership.
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* The ASF licenses this file to You under the Apache License, Version 2.0
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.apache.org/licenses/LICENSE-2.0
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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* Simple counter class
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* @lucene.experimental
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public abstract class Counter {
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* Adds the given delta to the counters current value
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* @return the counters updated value
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public abstract long addAndGet(long delta);
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* Returns the counters current value
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* @return the counters current value
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public abstract long get();
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* Returns a new counter. The returned counter is not thread-safe.
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public static Counter newCounter() {
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return newCounter(false);
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* Returns a new counter.
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* <code>true</code> if the returned counter can be used by multiple
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* threads concurrently.
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* @return a new counter.
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public static Counter newCounter(boolean threadSafe) {
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return threadSafe ? new AtomicCounter() : new SerialCounter();
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private final static class SerialCounter extends Counter {
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private long count = 0;
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public long addAndGet(long delta) {
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return count += delta;
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private final static class AtomicCounter extends Counter {
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private final AtomicLong count = new AtomicLong();
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public long addAndGet(long delta) {
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return count.addAndGet(delta);