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1   /*
2    * Copyright 2020 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    *   https://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.buffer;
17  
18  /**
19   * Expose metrics for an SizeClasses.
20   */
21  public interface SizeClassesMetric {
22  
23      /**
24       * Computes size from lookup table according to sizeIdx.
25       *
26       * @return size
27       */
28      int sizeIdx2size(int sizeIdx);
29  
30      /**
31       * Computes size according to sizeIdx.
32       *
33       * @return size
34       */
35      int sizeIdx2sizeCompute(int sizeIdx);
36  
37      /**
38       * Computes size from lookup table according to pageIdx.
39       *
40       * @return size which is multiples of pageSize.
41       */
42      long pageIdx2size(int pageIdx);
43  
44      /**
45       * Computes size according to pageIdx.
46       *
47       * @return size which is multiples of pageSize
48       */
49      long pageIdx2sizeCompute(int pageIdx);
50  
51      /**
52       * Normalizes request size up to the nearest size class.
53       *
54       * @param size request size
55       *
56       * @return sizeIdx of the size class
57       */
58      int size2SizeIdx(int size);
59  
60      /**
61       * Normalizes request size up to the nearest pageSize class.
62       *
63       * @param pages multiples of pageSizes
64       *
65       * @return pageIdx of the pageSize class
66       */
67      int pages2pageIdx(int pages);
68  
69      /**
70       * Normalizes request size down to the nearest pageSize class.
71       *
72       * @param pages multiples of pageSizes
73       *
74       * @return pageIdx of the pageSize class
75       */
76      int pages2pageIdxFloor(int pages);
77  
78      /**
79       * Normalizes usable size that would result from allocating an object with the
80       * specified size and alignment.
81       *
82       * @param size request size
83       *
84       * @return normalized size
85       */
86      int normalizeSize(int size);
87  }