ChannelPool.java

/*
 *    Copyright (c) 2014-2024 AsyncHttpClient Project. 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.
 *    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.asynchttpclient.channel;

import io.netty.channel.Channel;
import org.jspecify.annotations.Nullable;

import java.util.Map;
import java.util.function.Predicate;

public interface ChannelPool {

    /**
     * Add a channel to the pool
     *
     * @param channel      an I/O channel
     * @param partitionKey a key used to retrieve the cached channel
     * @return true if added.
     */
    boolean offer(Channel channel, Object partitionKey);

    /**
     * Remove the channel associated with the uri.
     *
     * @param partitionKey the partition used when invoking offer
     * @return the channel associated with the uri
     */
    @Nullable
    Channel poll(Object partitionKey);

    /**
     * Remove all channels from the cache. A channel might have been associated
     * with several uri.
     *
     * @param channel a channel
     * @return the true if the channel has been removed
     */
    boolean removeAll(Channel channel);

    /**
     * Return true if a channel can be cached. An implementation can decide based
     * on some rules to allow caching Calling this method is equivalent of
     * checking the returned value of {@link ChannelPool#offer(Channel, Object)}
     *
     * @return true if a channel can be cached.
     */
    boolean isOpen();

    /**
     * Destroy all channels that has been cached by this instance.
     */
    void destroy();

    /**
     * Flush partitions based on a predicate
     *
     * @param predicate the predicate
     */
    void flushPartitions(Predicate<Object> predicate);

    /**
     * @return The number of idle channels per host.
     */
    Map<String, Long> getIdleChannelCountPerHost();
}