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The Apache Log4j Implementation
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache license, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the license for the specific language governing permissions and
* limitations under the license.
*/
package org.apache.logging.log4j.core.layout;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CodingErrorAction;
import java.util.Objects;
import org.apache.logging.log4j.core.util.Constants;
import org.apache.logging.log4j.status.StatusLogger;
/**
* Encoder for StringBuilders that uses ThreadLocals to avoid locking as much as possible.
*/
public class StringBuilderEncoder implements Encoder {
private static final int DEFAULT_BYTE_BUFFER_SIZE = 8 * 1024;
/**
* This ThreadLocal uses raw and inconvenient Object[] to store three heterogeneous objects (CharEncoder, CharBuffer
* and ByteBuffer) instead of a custom class, because it needs to contain JDK classes, no custom (Log4j) classes.
* Where possible putting only JDK classes in ThreadLocals is preferable to avoid memory leaks in web containers:
* the Log4j classes may be loaded by a separate class loader which cannot be garbage collected if a thread pool
* threadlocal still has a reference to it.
*
* Using just one ThreadLocal instead of three separate ones is an optimization: {@link ThreadLocal.ThreadLocalMap}
* is polluted less, {@link ThreadLocal.ThreadLocalMap#get()} is called only once on each call to {@link #encode}
* instead of three times.
*/
private final ThreadLocal