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   /*
    * Copyright 2018 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:
    *
    *   https://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.socket.nio;
  
  import io.netty.channel.ChannelException;
  import io.netty.channel.ChannelOption;
  import io.netty.util.internal.SuppressJava6Requirement;
  
  import java.io.IOException;
  import java.nio.channels.Channel;
  import java.nio.channels.ServerSocketChannel;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Set;
  
  /**
   * Provides {@link ChannelOption} over a given {@link java.net.SocketOption} which is then passed through the underlying
   * {@link java.nio.channels.NetworkChannel}.
   */
  @SuppressJava6Requirement(reason = "Usage explicit by the user")
  public final class NioChannelOption<T> extends ChannelOption<T> {
  
      private final java.net.SocketOption<T> option;
  
      @SuppressWarnings("deprecation")
      private NioChannelOption(java.net.SocketOption<T> option) {
          super(option.name());
          this.option = option;
      }
  
      /**
       * Returns a {@link ChannelOption} for the given {@link java.net.SocketOption}.
       */
      public static <T> ChannelOption<T> of(java.net.SocketOption<T> option) {
          return new NioChannelOption<T>(option);
      }
  
      // It's important to not use java.nio.channels.NetworkChannel as otherwise the classes that sometimes call this
      // method may not be used on Java 6, as method linking can happen eagerly even if this method was not actually
      // called at runtime.
      //
      // See https://github.com/netty/netty/issues/8166
  
      // Internal helper methods to remove code duplication between Nio*Channel implementations.
      @SuppressJava6Requirement(reason = "Usage guarded by java version check")
      static <T> boolean setOption(Channel jdkChannel, NioChannelOption<T> option, T value) {
          java.nio.channels.NetworkChannel channel = (java.nio.channels.NetworkChannel) jdkChannel;
          if (!channel.supportedOptions().contains(option.option)) {
              return false;
          }
          if (channel instanceof ServerSocketChannel && option.option == java.net.StandardSocketOptions.IP_TOS) {
              // Skip IP_TOS as a workaround for a JDK bug:
              // See https://mail.openjdk.java.net/pipermail/nio-dev/2018-August/005365.html
              return false;
          }
          try {
              channel.setOption(option.option, value);
              return true;
          } catch (IOException e) {
              throw new ChannelException(e);
          }
      }
  
      @SuppressJava6Requirement(reason = "Usage guarded by java version check")
      static <T> T getOption(Channel jdkChannel, NioChannelOption<T> option) {
          java.nio.channels.NetworkChannel channel = (java.nio.channels.NetworkChannel) jdkChannel;
  
          if (!channel.supportedOptions().contains(option.option)) {
              return null;
          }
          if (channel instanceof ServerSocketChannel && option.option == java.net.StandardSocketOptions.IP_TOS) {
              // Skip IP_TOS as a workaround for a JDK bug:
              // See https://mail.openjdk.java.net/pipermail/nio-dev/2018-August/005365.html
              return null;
          }
          try {
              return channel.getOption(option.option);
          } catch (IOException e) {
              throw new ChannelException(e);
          }
      }
  
      @SuppressJava6Requirement(reason = "Usage guarded by java version check")
      @SuppressWarnings("unchecked")
      static ChannelOption[] getOptions(Channel jdkChannel) {
          java.nio.channels.NetworkChannel channel = (java.nio.channels.NetworkChannel) jdkChannel;
         Set<java.net.SocketOption<?>> supportedOpts = channel.supportedOptions();
 
         if (channel instanceof ServerSocketChannel) {
             List<ChannelOption<?>> extraOpts = new ArrayList<ChannelOption<?>>(supportedOpts.size());
             for (java.net.SocketOption<?> opt : supportedOpts) {
                 if (opt == java.net.StandardSocketOptions.IP_TOS) {
                     // Skip IP_TOS as a workaround for a JDK bug:
                     // See https://mail.openjdk.java.net/pipermail/nio-dev/2018-August/005365.html
                     continue;
                 }
                 extraOpts.add(new NioChannelOption(opt));
             }
             return extraOpts.toArray(new ChannelOption[0]);
         } else {
             ChannelOption<?>[] extraOpts = new ChannelOption[supportedOpts.size()];
 
             int i = 0;
             for (java.net.SocketOption<?> opt : supportedOpts) {
                 extraOpts[i++] = new NioChannelOption(opt);
             }
             return extraOpts;
         }
     }
 }