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A single bundled dependency that includes all service and dependent JARs with third-party libraries relocated to different namespaces.

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/*
 * Copyright 2010-2018 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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 software.amazon.awssdk.http.nio.netty.internal;

import static software.amazon.awssdk.utils.Validate.paramNotNull;

import io.netty.channel.pool.ChannelPool;
import io.netty.channel.pool.ChannelPoolMap;
import java.io.Closeable;
import java.util.Iterator;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
import software.amazon.awssdk.annotations.SdkInternalApi;

/**
 * Replacement for {@link io.netty.channel.pool.AbstractChannelPoolMap}. This implementation guarantees
 * only one instance of a {@link ChannelPool} is created for each key.
 */
// TODO do we need to use this for H2?
@SdkInternalApi
public abstract class SdkChannelPoolMap
        implements ChannelPoolMap, Iterable>, Closeable {

    private final ConcurrentMap map = new ConcurrentHashMap<>();

    @Override
    public final P get(K key) {
        return map.computeIfAbsent(key, this::newPool);
    }

    /**
     * Remove the {@link ChannelPool} from this {@link io.netty.channel.pool.AbstractChannelPoolMap}. Returns {@code true} if
     * removed, {@code false} otherwise.
     *
     * Please note that {@code null} keys are not allowed.
     */
    public final boolean remove(K key) {
        P pool = map.remove(paramNotNull(key, "key"));
        if (pool != null) {
            pool.close();
            return true;
        }
        return false;
    }

    @Override
    public final Iterator> iterator() {
        return new ReadOnlyIterator<>(map.entrySet().iterator());
    }

    /**
     * Returns the number of {@link ChannelPool}s currently in this {@link io.netty.channel.pool.AbstractChannelPoolMap}.
     */
    public final int size() {
        return map.size();
    }

    /**
     * Returns {@code true} if the {@link io.netty.channel.pool.AbstractChannelPoolMap} is empty, otherwise {@code false}.
     */
    public final boolean isEmpty() {
        return map.isEmpty();
    }

    @Override
    public final boolean contains(K key) {
        return map.containsKey(paramNotNull(key, "key"));
    }

    /**
     * Called once a new {@link ChannelPool} needs to be created as non exists yet for the {@code key}.
     */
    protected abstract P newPool(K key);

    @Override
    public final void close() {
        map.keySet().forEach(this::remove);
    }

    /**
     * {@link Iterator} that prevents removal.
     *
     * @param  Type of object being iterated.
     */
    private final class ReadOnlyIterator implements Iterator {
        private final Iterator iterator;

        private ReadOnlyIterator(Iterator iterator) {
            this.iterator = paramNotNull(iterator, "iterator");
        }

        public boolean hasNext() {
            return this.iterator.hasNext();
        }

        public T next() {
            return this.iterator.next();
        }

        public void remove() {
            throw new UnsupportedOperationException("Read-only iterator doesn't support removal.");
        }
    }
}