CodeSetCache


1   /*
2    * @(#)CodeSetCache.java    1.8 04/03/01
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   package com.sun.corba.se.impl.encoding;
8   
9   import java.nio.charset.CharsetDecoder  ;
10  import java.nio.charset.CharsetEncoder  ;
11  import java.util.Map  ;
12  import java.util.WeakHashMap  ;
13  
14  /**
15   * Thread local cache of sun.io code set converters for performance.
16   *
17   * The thread local class contains a single reference to a Map[]
18   * containing two WeakHashMaps.  One for CharsetEncoders and
19   * one for CharsetDecoders.  Constants are defined for indexing.
20   *
21   * This is used internally by CodeSetConversion.
22   */
23  class CodeSetCache
24  {
25      /**
26       * The ThreadLocal data is a 2 element Map array indexed
27       * by BTC_CACHE_MAP and CTB_CACHE_MAP.
28       */
29      private ThreadLocal   converterCaches = new ThreadLocal  () {
30          public java.lang.Object   initialValue() {
31              return new Map  [] { new WeakHashMap  (), new WeakHashMap  () };
32          }
33      };
34  
35      /**
36       * Index in the thread local converterCaches array for
37       * the byte to char converter Map.  A key is the Java
38       * name corresponding to the desired code set.
39       */
40      private static final int BTC_CACHE_MAP = 0;
41  
42      /** 
43       * Index in the thread local converterCaches array for
44       * the char to byte converter Map.  A key is the Java
45       * name corresponding to the desired code set.
46       */
47      private static final int CTB_CACHE_MAP = 1;
48  
49      /**
50       * Retrieve a CharsetDecoder from the Map using the given key.
51       */
52      CharsetDecoder   getByteToCharConverter(Object   key) {
53          Map   btcMap = ((Map  [])converterCaches.get())[BTC_CACHE_MAP];
54          
55          return (CharsetDecoder  )btcMap.get(key);
56      }
57  
58      /**
59       * Retrieve a CharsetEncoder from the Map using the given key.
60       */
61      CharsetEncoder   getCharToByteConverter(Object   key) {
62          Map   ctbMap = ((Map  [])converterCaches.get())[CTB_CACHE_MAP];
63  
64          return (CharsetEncoder  )ctbMap.get(key);
65      }
66  
67      /**
68       * Stores the given CharsetDecoder in the thread local cache,
69       * and returns the same converter.
70       */
71      CharsetDecoder   setConverter(Object   key, CharsetDecoder   converter) {
72          Map   btcMap = ((Map  [])converterCaches.get())[BTC_CACHE_MAP];
73  
74          btcMap.put(key, converter);
75  
76          return converter;
77      }
78  
79      /**
80       * Stores the given CharsetEncoder in the thread local cache,
81       * and returns the same converter.
82       */
83      CharsetEncoder   setConverter(Object   key, CharsetEncoder   converter) {
84  
85          Map   ctbMap = ((Map  [])converterCaches.get())[CTB_CACHE_MAP];
86  
87          ctbMap.put(key, converter);
88  
89          return converter;
90      }
91  }
92
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