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 * 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.
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package org.apache.commons.lang3.concurrent;


Definition of an interface for the thread-safe initialization of objects.

 The idea behind this interface is to provide access to an object in a thread-safe manner. A ConcurrentInitializer can be passed to multiple threads which can all access the object produced by the initializer. Through the get() method the object can be queried. 

Concrete implementations of this interface will use different strategies for
the creation of the managed object, e.g. lazy initialization or
initialization in a background thread. This is completely transparent to
client code, so it is possible to change the initialization strategy without
affecting clients.

Type parameters:
<T> – the type of the object managed by this initializer class
Since:
3.0/**
 * <p>
 * Definition of an interface for the thread-safe initialization of objects.
 * </p>
 * <p>
 * The idea behind this interface is to provide access to an object in a
 * thread-safe manner. A {@code ConcurrentInitializer} can be passed to multiple
 * threads which can all access the object produced by the initializer. Through
 * the {@link #get()} method the object can be queried.
 * </p>
 * <p>
 * Concrete implementations of this interface will use different strategies for
 * the creation of the managed object, e.g. lazy initialization or
 * initialization in a background thread. This is completely transparent to
 * client code, so it is possible to change the initialization strategy without
 * affecting clients.
 * </p>
 *
 * @since 3.0
 * @param <T> the type of the object managed by this initializer class
 */
public interface ConcurrentInitializer<T> {
    
Returns the fully initialized object produced by this 
ConcurrentInitializer. A concrete implementation here returns the results of the initialization process. This method may block until results are available. Typically, once created the result object is always the same. 
Throws:
ConcurrentException – if an error occurred during initialization of
the object
Returns:
the object created by this ConcurrentException/**
     * Returns the fully initialized object produced by this {@code
     * ConcurrentInitializer}. A concrete implementation here returns the
     * results of the initialization process. This method may block until
     * results are available. Typically, once created the result object is
     * always the same.
     *
     * @return the object created by this {@code ConcurrentException}
     * @throws ConcurrentException if an error occurred during initialization of
     * the object
     */
    T get() throws ConcurrentException;
}