/*
 * 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.channel.EventLoop;
import io.netty.util.concurrent.Future;
import io.netty.util.concurrent.Promise;

Called before a Channel will be returned via ChannelPool.acquire() or ChannelPool.acquire(Promise<Channel>). /**
 * Called before a {@link Channel} will be returned via {@link ChannelPool#acquire()} or
 * {@link ChannelPool#acquire(Promise)}.
 */
public interface ChannelHealthChecker {

    
ChannelHealthChecker implementation that checks if Channel.isActive() returns true. /**
     * {@link ChannelHealthChecker} implementation that checks if {@link Channel#isActive()} returns {@code true}.
     */
    ChannelHealthChecker ACTIVE = new ChannelHealthChecker() {
        @Override
        public Future<Boolean> isHealthy(Channel channel) {
            EventLoop loop = channel.eventLoop();
            return channel.isActive()? loop.newSucceededFuture(Boolean.TRUE) : loop.newSucceededFuture(Boolean.FALSE);
        }
    };

    
Check if the given channel is healthy which means it can be used. The returned Future is notified once the check is complete. If notified with Boolean.TRUE it can be used Boolean.FALSE otherwise. This method will be called by the EventLoop of the Channel. /**
     * Check if the given channel is healthy which means it can be used. The returned {@link Future} is notified once
     * the check is complete. If notified with {@link Boolean#TRUE} it can be used {@link Boolean#FALSE} otherwise.
     *
     * This method will be called by the {@link EventLoop} of the {@link Channel}.
     */
    Future<Boolean> isHealthy(Channel channel);
}