org.apache.gobblin.util.request_allocation.GreedyAllocator.java Source code

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Here is the source code for org.apache.gobblin.util.request_allocation.GreedyAllocator.java

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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.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.gobblin.util.request_allocation;

import java.util.Iterator;
import java.util.concurrent.Callable;

import com.google.common.base.Function;
import com.google.common.collect.Iterators;

import org.apache.gobblin.util.iterators.InterruptibleIterator;

import javax.annotation.Nullable;
import lombok.extern.slf4j.Slf4j;

/**
 * A {@link RequestAllocator} that selects {@link Request}s without any order guarantees until the {@link ResourcePool}
 * is full, then stops. This allocator will mostly ignore the prioritizer.
 *
 * <p>
 *   This allocator is useful when there is no prioritization or fairness required. It is generally the fastest and least
 *   memory intensive implementation.
 * </p>
 */
@Slf4j
public class GreedyAllocator<T extends Request<T>> extends PriorityIterableBasedRequestAllocator<T> {

    public static class Factory implements RequestAllocator.Factory {
        @Override
        public <T extends Request<T>> RequestAllocator<T> createRequestAllocator(
                RequestAllocatorConfig<T> configuration) {
            return new GreedyAllocator<>(configuration);
        }
    }

    public GreedyAllocator(RequestAllocatorConfig<T> configuration) {
        super(log, configuration);
    }

    @Override
    protected Iterator<T> getJoinIterator(Iterator<? extends Requestor<T>> requestors,
            final ConcurrentBoundedPriorityIterable<T> requestIterable) {
        Iterator<T> unionIterator = Iterators
                .concat(Iterators.transform(requestors, new Function<Requestor<T>, Iterator<T>>() {
                    @Nullable
                    @Override
                    public Iterator<T> apply(Requestor<T> input) {
                        return input.iterator();
                    }
                }));

        return new InterruptibleIterator<>(unionIterator, new Callable<Boolean>() {
            @Override
            public Boolean call() throws Exception {
                return requestIterable.isFull();
            }
        });
    }
}