alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (ThreadLocalCoders.java)

This example Java source code file (ThreadLocalCoders.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

cache, cache_size, charset, charsetdecoder, charsetencoder, object, string, threadlocal, threadlocalcoders

The ThreadLocalCoders.java Java example source code

/*
 * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */


package sun.nio.cs;

import java.nio.charset.*;


/**
 * Utility class for caching per-thread decoders and encoders.
 */

public class ThreadLocalCoders {

    private static final int CACHE_SIZE = 3;

    private static abstract class Cache {

        // Thread-local reference to array of cached objects, in LRU order
        private ThreadLocal<Object[]> cache = new ThreadLocal<>();
        private final int size;

        Cache(int size) {
            this.size = size;
        }

        abstract Object create(Object name);

        private void moveToFront(Object[] oa, int i) {
            Object ob = oa[i];
            for (int j = i; j > 0; j--)
                oa[j] = oa[j - 1];
            oa[0] = ob;
        }

        abstract boolean hasName(Object ob, Object name);

        Object forName(Object name) {
            Object[] oa = cache.get();
            if (oa == null) {
                oa = new Object[size];
                cache.set(oa);
            } else {
                for (int i = 0; i < oa.length; i++) {
                    Object ob = oa[i];
                    if (ob == null)
                        continue;
                    if (hasName(ob, name)) {
                        if (i > 0)
                            moveToFront(oa, i);
                        return ob;
                    }
                }
            }

            // Create a new object
            Object ob = create(name);
            oa[oa.length - 1] = ob;
            moveToFront(oa, oa.length - 1);
            return ob;
        }

    }

    private static Cache decoderCache = new Cache(CACHE_SIZE) {
            boolean hasName(Object ob, Object name) {
                if (name instanceof String)
                    return (((CharsetDecoder)ob).charset().name().equals(name));
                if (name instanceof Charset)
                    return ((CharsetDecoder)ob).charset().equals(name);
                return false;
            }
            Object create(Object name) {
                if (name instanceof String)
                    return Charset.forName((String)name).newDecoder();
                if (name instanceof Charset)
                    return ((Charset)name).newDecoder();
                assert false;
                return null;
            }
        };

    public static CharsetDecoder decoderFor(Object name) {
        CharsetDecoder cd = (CharsetDecoder)decoderCache.forName(name);
        cd.reset();
        return cd;
    }

    private static Cache encoderCache = new Cache(CACHE_SIZE) {
            boolean hasName(Object ob, Object name) {
                if (name instanceof String)
                    return (((CharsetEncoder)ob).charset().name().equals(name));
                if (name instanceof Charset)
                    return ((CharsetEncoder)ob).charset().equals(name);
                return false;
            }
            Object create(Object name) {
                if (name instanceof String)
                    return Charset.forName((String)name).newEncoder();
                if (name instanceof Charset)
                    return ((Charset)name).newEncoder();
                assert false;
                return null;
            }
        };

    public static CharsetEncoder encoderFor(Object name) {
        CharsetEncoder ce = (CharsetEncoder)encoderCache.forName(name);
        ce.reset();
        return ce;
    }

}

Other Java examples (source code examples)

Here is a short list of links related to this Java ThreadLocalCoders.java source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.