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   /*
    * Copyright 2012 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;
  
  import io.netty.buffer.ByteBuf;
  import io.netty.buffer.ByteBufAllocator;
  
  /**
   * Allocates a new receive buffer whose capacity is probably large enough to read all inbound data and small enough
   * not to waste its space.
   */
  public interface RecvByteBufAllocator {
  
      /**
       * Creates a new handle.  The handle provides the actual operations and keeps the internal information which is
       * required for predicting an optimal buffer capacity.
       */
      Handle newHandle();
  
      interface Handle {
          /**
           * Creates a new receive buffer whose capacity is probably large enough to read all inbound data and small
           * enough not to waste its space.
           */
          ByteBuf allocate(ByteBufAllocator alloc);
  
          /**
           * Similar to {@link #allocate(ByteBufAllocator)} except that it does not allocate anything but just tells the
           * capacity.
           */
          int guess();
  
          /**
           * Records the the actual number of read bytes in the previous read operation so that the allocator allocates
           * the buffer with potentially more correct capacity.
           *
           * @param actualReadBytes the actual number of read bytes in the previous read operation
           */
          void record(int actualReadBytes);
      }
  }