/*
 * Copyright 2015 The Netty Project
 *
 * The Netty Project 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 io.netty.channel.pool;

import io.netty.channel.Channel;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.Promise;

import java.io.Closeable;

Allows to acquire and release Channel and so act as a pool of these. /**
 * Allows to acquire and release {@link Channel} and so act as a pool of these.
 */
public interface ChannelPool extends Closeable {

    
Acquire a Channel from this ChannelPool. The returned Future is notified once the acquire is successful and failed otherwise. Its important that an acquired is always released to the pool again, even if the Channel is explicitly closed..
/**
     * Acquire a {@link Channel} from this {@link ChannelPool}. The returned {@link Future} is notified once
     * the acquire is successful and failed otherwise.
     *
     * <strong>Its important that an acquired is always released to the pool again, even if the {@link Channel}
     * is explicitly closed..</strong>
     */
    Future<Channel> acquire();

    
Acquire a Channel from this ChannelPool. The given Promise is notified once the acquire is successful and failed otherwise. Its important that an acquired is always released to the pool again, even if the Channel is explicitly closed..
/**
     * Acquire a {@link Channel} from this {@link ChannelPool}. The given {@link Promise} is notified once
     * the acquire is successful and failed otherwise.
     *
     * <strong>Its important that an acquired is always released to the pool again, even if the {@link Channel}
     * is explicitly closed..</strong>
     */
    Future<Channel> acquire(Promise<Channel> promise);

    
Release a Channel back to this ChannelPool. The returned Future is notified once the release is successful and failed otherwise. When failed the Channel will automatically closed. /**
     * Release a {@link Channel} back to this {@link ChannelPool}. The returned {@link Future} is notified once
     * the release is successful and failed otherwise. When failed the {@link Channel} will automatically closed.
     */
    Future<Void> release(Channel channel);

    
Release a Channel back to this ChannelPool. The given Promise is notified once the release is successful and failed otherwise. When failed the Channel will automatically closed. /**
     * Release a {@link Channel} back to this {@link ChannelPool}. The given {@link Promise} is notified once
     * the release is successful and failed otherwise. When failed the {@link Channel} will automatically closed.
     */
    Future<Void> release(Channel channel, Promise<Void> promise);

    @Override
    void close();
}