content: /*
   * 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.bookkeeper.util;
  
  import io.netty.channel.ChannelFutureListener;
  import io.netty.channel.ChannelOutboundInvoker;
  import io.netty.channel.VoidChannelPromise;
  
  /**
   * Contains utility methods for working with Netty Channels.
   */
  public final class NettyChannelUtil {
  
      private NettyChannelUtil() {
      }
  
      /**
       * Write and flush the message to the channel.
       *
       * The promise is an instance of {@link VoidChannelPromise} that properly propagates exceptions up to the pipeline.
       * Netty has many ad-hoc optimization if the promise is an instance of {@link VoidChannelPromise}.
       * Lastly, it reduces pollution of useless {@link io.netty.channel.ChannelPromise} objects created
       * by the default write and flush method {@link ChannelOutboundInvoker#writeAndFlush(Object)}.
       * See https://stackoverflow.com/q/54169262 and https://stackoverflow.com/a/9030420 for more details.
       *
       * @param ctx channel's context
       * @param msg buffer to write in the channel
       */
      public static void writeAndFlushWithVoidPromise(ChannelOutboundInvoker ctx, Object msg) {
          ctx.writeAndFlush(msg, ctx.voidPromise());
      }
  
      /**
       * Write and flush the message to the channel and the close the channel.
       *
       * This method is particularly helpful when the connection is in an invalid state
       * and therefore a new connection must be created to continue.
       *
       * @param ctx channel's context
       * @param msg buffer to write in the channel
       */
      public static void writeAndFlushWithClosePromise(ChannelOutboundInvoker ctx, Object msg) {
          ctx.writeAndFlush(msg).addListener(ChannelFutureListener.CLOSE);
      }
  
  }
  