CodeSetCache.java revision 608:7e06bf1dcb09 
1/*
2 * Copyright (c) 2001, 2004, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25package com.sun.corba.se.impl.encoding;
26
27import java.nio.charset.CharsetDecoder;
28import java.nio.charset.CharsetEncoder;
29import java.util.Map;
30import java.util.WeakHashMap;
31
32/**
33 * Thread local cache of sun.io code set converters for performance.
34 *
35 * The thread local class contains a single reference to a Map[]
36 * containing two WeakHashMaps.  One for CharsetEncoders and
37 * one for CharsetDecoders.  Constants are defined for indexing.
38 *
39 * This is used internally by CodeSetConversion.
40 */
41class CodeSetCache
42{
43    /**
44     * The ThreadLocal data is a 2 element Map array indexed
45     * by BTC_CACHE_MAP and CTB_CACHE_MAP.
46     */
47    private ThreadLocal converterCaches = new ThreadLocal() {
48        public java.lang.Object initialValue() {
49            return new Map[] { new WeakHashMap(), new WeakHashMap() };
50        }
51    };
52
53    /**
54     * Index in the thread local converterCaches array for
55     * the byte to char converter Map.  A key is the Java
56     * name corresponding to the desired code set.
57     */
58    private static final int BTC_CACHE_MAP = 0;
59
60    /**
61     * Index in the thread local converterCaches array for
62     * the char to byte converter Map.  A key is the Java
63     * name corresponding to the desired code set.
64     */
65    private static final int CTB_CACHE_MAP = 1;
66
67    /**
68     * Retrieve a CharsetDecoder from the Map using the given key.
69     */
70    CharsetDecoder getByteToCharConverter(Object key) {
71        Map btcMap = ((Map[])converterCaches.get())[BTC_CACHE_MAP];
72
73        return (CharsetDecoder)btcMap.get(key);
74    }
75
76    /**
77     * Retrieve a CharsetEncoder from the Map using the given key.
78     */
79    CharsetEncoder getCharToByteConverter(Object key) {
80        Map ctbMap = ((Map[])converterCaches.get())[CTB_CACHE_MAP];
81
82        return (CharsetEncoder)ctbMap.get(key);
83    }
84
85    /**
86     * Stores the given CharsetDecoder in the thread local cache,
87     * and returns the same converter.
88     */
89    CharsetDecoder setConverter(Object key, CharsetDecoder converter) {
90        Map btcMap = ((Map[])converterCaches.get())[BTC_CACHE_MAP];
91
92        btcMap.put(key, converter);
93
94        return converter;
95    }
96
97    /**
98     * Stores the given CharsetEncoder in the thread local cache,
99     * and returns the same converter.
100     */
101    CharsetEncoder setConverter(Object key, CharsetEncoder converter) {
102
103        Map ctbMap = ((Map[])converterCaches.get())[CTB_CACHE_MAP];
104
105        ctbMap.put(key, converter);
106
107        return converter;
108    }
109}
110