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.kafka.common.network;
  
  import java.io.IOException;
  import java.nio.channels.FileChannel;
  import java.nio.channels.GatheringByteChannel;
  
  /**
   * Extends GatheringByteChannel with the minimal set of methods required by the Send interface. Supporting TLS and
   * efficient zero copy transfers are the main reasons for the additional methods.
   * 
   * @see SslTransportLayer
   */
  public interface TransferableChannel extends GatheringByteChannel {
  
      /**
       * @return true if there are any pending writes. false if the implementation directly write all data to output.
       */
      boolean hasPendingWrites();
  
      /**
       * Transfers bytes from `fileChannel` to this `TransferableChannel`.
       *
       * This method will delegate to {@link FileChannel#transferTo(long, long, java.nio.channels.WritableByteChannel)},
       * but it will unwrap the destination channel, if possible, in order to benefit from zero copy. This is required
       * because the fast path of `transferTo` is only executed if the destination buffer inherits from an internal JDK
       * class.
       *
       * @param fileChannel The source channel
       * @param position The position within the file at which the transfer is to begin; must be non-negative
       * @param count The maximum number of bytes to be transferred; must be non-negative
       * @return The number of bytes, possibly zero, that were actually transferred
       * @see FileChannel#transferTo(long, long, java.nio.channels.WritableByteChannel)
       */
      long transferFrom(FileChannel fileChannel, long position, long count) throws IOException;
  }
  