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1   /*
2    * Copyright 2013 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  package io.netty.channel;
17  
18  /**
19   * Responsible to estimate the size of a message. The size represents approximately how much memory the message will
20   * reserve in memory.
21   */
22  public interface MessageSizeEstimator {
23  
24      /**
25       * Creates a new handle. The handle provides the actual operations.
26       */
27      Handle newHandle();
28  
29      interface Handle {
30  
31          /**
32           * Calculate the size of the given message.
33           *
34           * @param msg       The message for which the size should be calculated
35           * @return size     The size in bytes. The returned size must be >= 0
36           */
37          int size(Object msg);
38      }
39  }