fb538ea532
Motivation: When Netty runs in a managed environment such as web application server, Netty needs to provide an explicit way to remove the thread-local variables it created to prevent class loader leaks. FastThreadLocal uses different execution paths for storing a thread-local variable depending on the type of the current thread. It increases the complexity of thread-local removal. Modifications: - Moved FastThreadLocal and FastThreadLocalThread out of the internal package so that a user can use it. - FastThreadLocal now keeps track of all thread local variables it has initialized, and calling FastThreadLocal.removeAll() will remove all thread-local variables of the caller thread. - Added FastThreadLocal.size() for diagnostics and tests - Introduce InternalThreadLocalMap which is a mixture of hard-wired thread local variable fields and extensible indexed variables - FastThreadLocal now uses InternalThreadLocalMap to implement a thread-local variable. - Added ThreadDeathWatcher.unwatch() so that PooledByteBufAllocator tells it to stop watching when its thread-local cache has been freed by FastThreadLocal.removeAll(). - Added FastThreadLocalTest to ensure that removeAll() works - Added microbenchmark for FastThreadLocal and JDK ThreadLocal - Upgraded to JMH 0.9 Result: - A user can remove all thread-local variables Netty created, as long as he or she did not exit from the current thread. (Note that there's no way to remove a thread-local variable from outside of the thread.) - FastThreadLocal exposes more useful operations such as isSet() because we always implement a thread local variable via InternalThreadLocalMap instead of falling back to JDK ThreadLocal. - FastThreadLocalBenchmark shows that this change improves the performance of FastThreadLocal even more.
118 lines
3.7 KiB
Java
118 lines
3.7 KiB
Java
/*
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* Copyright 2012 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.util;
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import io.netty.util.internal.InternalThreadLocalMap;
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import java.nio.charset.Charset;
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import java.nio.charset.CharsetDecoder;
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import java.nio.charset.CharsetEncoder;
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import java.nio.charset.CodingErrorAction;
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import java.util.Map;
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/**
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* A utility class that provides various common operations and constants
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* related with {@link Charset} and its relevant classes.
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*/
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public final class CharsetUtil {
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/**
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* 16-bit UTF (UCS Transformation Format) whose byte order is identified by
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* an optional byte-order mark
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*/
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public static final Charset UTF_16 = Charset.forName("UTF-16");
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/**
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* 16-bit UTF (UCS Transformation Format) whose byte order is big-endian
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*/
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public static final Charset UTF_16BE = Charset.forName("UTF-16BE");
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/**
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* 16-bit UTF (UCS Transformation Format) whose byte order is little-endian
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*/
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public static final Charset UTF_16LE = Charset.forName("UTF-16LE");
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/**
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* 8-bit UTF (UCS Transformation Format)
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*/
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public static final Charset UTF_8 = Charset.forName("UTF-8");
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/**
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* ISO Latin Alphabet No. 1, as known as <tt>ISO-LATIN-1</tt>
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*/
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public static final Charset ISO_8859_1 = Charset.forName("ISO-8859-1");
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/**
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* 7-bit ASCII, as known as ISO646-US or the Basic Latin block of the
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* Unicode character set
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*/
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public static final Charset US_ASCII = Charset.forName("US-ASCII");
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/**
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* Returns a cached thread-local {@link CharsetEncoder} for the specified
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* <tt>charset</tt>.
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*/
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public static CharsetEncoder getEncoder(Charset charset) {
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if (charset == null) {
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throw new NullPointerException("charset");
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}
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Map<Charset, CharsetEncoder> map = InternalThreadLocalMap.get().charsetEncoderCache();
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CharsetEncoder e = map.get(charset);
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if (e != null) {
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e.reset();
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e.onMalformedInput(CodingErrorAction.REPLACE);
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e.onUnmappableCharacter(CodingErrorAction.REPLACE);
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return e;
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}
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e = charset.newEncoder();
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e.onMalformedInput(CodingErrorAction.REPLACE);
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e.onUnmappableCharacter(CodingErrorAction.REPLACE);
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map.put(charset, e);
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return e;
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}
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/**
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* Returns a cached thread-local {@link CharsetDecoder} for the specified
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* <tt>charset</tt>.
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*/
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public static CharsetDecoder getDecoder(Charset charset) {
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if (charset == null) {
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throw new NullPointerException("charset");
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}
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Map<Charset, CharsetDecoder> map = InternalThreadLocalMap.get().charsetDecoderCache();
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CharsetDecoder d = map.get(charset);
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if (d != null) {
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d.reset();
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d.onMalformedInput(CodingErrorAction.REPLACE);
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d.onUnmappableCharacter(CodingErrorAction.REPLACE);
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return d;
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}
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d = charset.newDecoder();
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d.onMalformedInput(CodingErrorAction.REPLACE);
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d.onUnmappableCharacter(CodingErrorAction.REPLACE);
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map.put(charset, d);
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return d;
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}
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private CharsetUtil() {
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// Unused
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}
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}
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