streaming/src/main/java/org/apache/gearpump/streaming/refactor/coder/ElementByteSizeObservableIterable.java

/*
 * 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 org.apache.gearpump.streaming.refactor.coder;

import java.util.ArrayList;
import java.util.List;
import java.util.Observer;

public abstract class ElementByteSizeObservableIterable<
        V, InputT extends ElementByteSizeObservableIterator<V>>
        implements Iterable<V> {
    private List<Observer> observers = new ArrayList<>();

    protected abstract InputT createIterator();

    public void addObserver(Observer observer) {
        observers.add(observer);
    }

    @Override
    public InputT iterator() {
        InputT iterator = createIterator();
        for (Observer observer : observers) {
            iterator.addObserver(observer);
        }
        observers.clear();
        return iterator;
    }
}