org.codelibs.elasticsearch.common.util.concurrent.RefCounted Maven / Gradle / Ivy
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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.codelibs.elasticsearch.common.util.concurrent;
/**
* An interface for objects that need to be notified when all reference
* to itself are not in user anymore. This implements basic reference counting
* for instance if async operations holding on to services that are close concurrently
* but should be functional until all async operations have joined
* Classes implementing this interface should ref counted at any time ie. if an object is used it's reference count should
* be increased before using it by calling #incRef and a corresponding #decRef must be called in a try/finally
* block to release the object again ie.:
*
* inst.incRef();
* try {
* // use the inst...
*
* } finally {
* inst.decRef();
* }
*
*/
public interface RefCounted {
/**
* Increments the refCount of this instance.
*
* @see #decRef
* @see #tryIncRef()
* @throws org.apache.lucene.store.AlreadyClosedException iff the reference counter can not be incremented.
*/
void incRef();
/**
* Tries to increment the refCount of this instance. This method will return true iff the refCount was
*
* @see #decRef()
* @see #incRef()
*/
boolean tryIncRef();
/**
* Decreases the refCount of this instance. If the refCount drops to 0, then this
* instance is considered as closed and should not be used anymore.
*
* @see #incRef
*/
void decRef();
}
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