Apache Log4j Core Implementation provides the functional components of the logging system. Users are free to create their own plugins and include them in the logging configuration. Apache Log4j Core is a required module to use Apache Log4j.

Bytecode (Java 8) for Apache Log4j Core Implementation is provided in a separate JAR file like log4j-core-2.14.1.jar.

Source Code files for Apache Log4j API are provided in both binary packge like apache-log4j-2.14.1-bin.zip and source package like apache-log4j-2.14.1-src.zip. You can download them at Apache Log4j Website.

You can also browse Source Code files for Apache Log4j Core Implementation 2.14.1 below.

⏎ org/apache/logging/log4j/core/appender/OutputStreamManager.java

/*
 * 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.appender;

import java.io.IOException;
import java.io.OutputStream;
import java.io.Serializable;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.util.Objects;
import java.util.concurrent.TimeUnit;

import org.apache.logging.log4j.core.Layout;
import org.apache.logging.log4j.core.LoggerContext;
import org.apache.logging.log4j.core.layout.ByteBufferDestination;
import org.apache.logging.log4j.core.layout.ByteBufferDestinationHelper;
import org.apache.logging.log4j.core.util.Constants;

/**
 * Manages an OutputStream so that it can be shared by multiple Appenders and will
 * allow appenders to reconfigure without requiring a new stream.
 */
public class OutputStreamManager extends AbstractManager implements ByteBufferDestination {
    protected final Layout<?> layout;
    protected ByteBuffer byteBuffer;
    private volatile OutputStream outputStream;
    private boolean skipFooter;

    protected OutputStreamManager(final OutputStream os, final String streamName, final Layout<?> layout,
            final boolean writeHeader) {
        this(os, streamName, layout, writeHeader, Constants.ENCODER_BYTE_BUFFER_SIZE);
    }

    protected OutputStreamManager(final OutputStream os, final String streamName, final Layout<?> layout,
            final boolean writeHeader, final int bufferSize) {
        this(os, streamName, layout, writeHeader, ByteBuffer.wrap(new byte[bufferSize]));
    }

    /**
     * @since 2.6
     * @deprecated
     */
    @Deprecated
    protected OutputStreamManager(final OutputStream os, final String streamName, final Layout<?> layout,
            final boolean writeHeader, final ByteBuffer byteBuffer) {
        super(null, streamName);
        this.outputStream = os;
        this.layout = layout;
        if (writeHeader) {
            writeHeader(os);
        }
        this.byteBuffer = Objects.requireNonNull(byteBuffer, "byteBuffer");
    }

    /**
     * @since 2.7
     */
    protected OutputStreamManager(final LoggerContext loggerContext, final OutputStream os, final String streamName,
            final boolean createOnDemand, final Layout<? extends Serializable> layout, final boolean writeHeader,
            final ByteBuffer byteBuffer) {
        super(loggerContext, streamName);
        if (createOnDemand && os != null) {
            LOGGER.error(
                    "Invalid OutputStreamManager configuration for '{}': You cannot both set the OutputStream and request on-demand.",
                    streamName);
        }
        this.layout = layout;
        this.byteBuffer = Objects.requireNonNull(byteBuffer, "byteBuffer");
        this.outputStream = os;
        if (writeHeader) {
            writeHeader(os);
        }
    }

    /**
     * Creates a Manager.
     *
     * @param name The name of the stream to manage.
     * @param data The data to pass to the Manager.
     * @param factory The factory to use to create the Manager.
     * @param <T> The type of the OutputStreamManager.
     * @return An OutputStreamManager.
     */
    public static <T> OutputStreamManager getManager(final String name, final T data,
                                                 final ManagerFactory<? extends OutputStreamManager, T> factory) {
        return AbstractManager.getManager(name, factory, data);
    }

    @SuppressWarnings("unused")
    protected OutputStream createOutputStream() throws IOException {
        throw new IllegalStateException(getClass().getCanonicalName() + " must implement createOutputStream()");
    }

    /**
     * Indicate whether the footer should be skipped or not.
     * @param skipFooter true if the footer should be skipped.
     */
    public void skipFooter(final boolean skipFooter) {
        this.skipFooter = skipFooter;
    }

    /**
     * Default hook to write footer during close.
     */
    @Override
    public boolean releaseSub(final long timeout, final TimeUnit timeUnit) {
        writeFooter();
        return closeOutputStream();
    }

    protected void writeHeader(OutputStream os) {
        if (layout != null && os != null) {
            final byte[] header = layout.getHeader();
            if (header != null) {
                try {
                    os.write(header, 0, header.length);
                } catch (final IOException e) {
                    logError("Unable to write header", e);
                }
            }
        }
    }

    /**
     * Writes the footer.
     */
    protected void writeFooter() {
        if (layout == null || skipFooter) {
            return;
        }
        final byte[] footer = layout.getFooter();
        if (footer != null) {
            write(footer);
        }
    }

    /**
     * Returns the status of the stream.
     * @return true if the stream is open, false if it is not.
     */
    public boolean isOpen() {
        return getCount() > 0;
    }

    public boolean hasOutputStream() {
        return outputStream != null;
    }

    protected OutputStream getOutputStream() throws IOException {
        if (outputStream == null) {
            outputStream = createOutputStream();
        }
        return outputStream;
    }

    protected void setOutputStream(final OutputStream os) {
        this.outputStream = os;
    }

    /**
     * Some output streams synchronize writes while others do not.
     * @param bytes The serialized Log event.
     * @throws AppenderLoggingException if an error occurs.
     */
    protected void write(final byte[] bytes)  {
        write(bytes, 0, bytes.length, false);
    }

    /**
     * Some output streams synchronize writes while others do not.
     * @param bytes The serialized Log event.
     * @param immediateFlush If true, flushes after writing.
     * @throws AppenderLoggingException if an error occurs.
     */
    protected void write(final byte[] bytes, final boolean immediateFlush)  {
        write(bytes, 0, bytes.length, immediateFlush);
    }

    @Override
    public void writeBytes(final byte[] data, final int offset, final int length) {
        write(data, offset, length, false);
    }

    /**
     * Some output streams synchronize writes while others do not. Synchronizing here insures that
     * log events won't be intertwined.
     * @param bytes The serialized Log event.
     * @param offset The offset into the byte array.
     * @param length The number of bytes to write.
     * @throws AppenderLoggingException if an error occurs.
     */
    protected void write(final byte[] bytes, final int offset, final int length) {
        writeBytes(bytes, offset, length);
    }

    /**
     * Some output streams synchronize writes while others do not. Synchronizing here insures that
     * log events won't be intertwined.
     * @param bytes The serialized Log event.
     * @param offset The offset into the byte array.
     * @param length The number of bytes to write.
     * @param immediateFlush flushes immediately after writing.
     * @throws AppenderLoggingException if an error occurs.
     */
    protected synchronized void write(final byte[] bytes, final int offset, final int length, final boolean immediateFlush) {
        if (immediateFlush && byteBuffer.position() == 0) {
            writeToDestination(bytes, offset, length);
            flushDestination();
            return;
        }
        if (length >= byteBuffer.capacity()) {
            // if request length exceeds buffer capacity, flush the buffer and write the data directly
            flush();
            writeToDestination(bytes, offset, length);
        } else {
            if (length > byteBuffer.remaining()) {
                flush();
            }
            byteBuffer.put(bytes, offset, length);
        }
        if (immediateFlush) {
            flush();
        }
    }

    /**
     * Writes the specified section of the specified byte array to the stream.
     *
     * @param bytes the array containing data
     * @param offset from where to write
     * @param length how many bytes to write
     * @since 2.6
     */
    protected synchronized void writeToDestination(final byte[] bytes, final int offset, final int length) {
        try {
            getOutputStream().write(bytes, offset, length);
        } catch (final IOException ex) {
            throw new AppenderLoggingException("Error writing to stream " + getName(), ex);
        }
    }

    /**
     * Calls {@code flush()} on the underlying output stream.
     * @since 2.6
     */
    protected synchronized void flushDestination() {
        final OutputStream stream = outputStream; // access volatile field only once per method
        if (stream != null) {
            try {
                stream.flush();
            } catch (final IOException ex) {
                throw new AppenderLoggingException("Error flushing stream " + getName(), ex);
            }
        }
    }

    /**
     * Drains the ByteBufferDestination's buffer into the destination. By default this calls
     * {@link OutputStreamManager#write(byte[], int, int, boolean)} with the buffer contents.
     * The underlying stream is not {@linkplain OutputStream#flush() flushed}.
     *
     * @see #flushDestination()
     * @since 2.6
     */
    protected synchronized void flushBuffer(final ByteBuffer buf) {
        ((Buffer) buf).flip();
        try {
            if (buf.remaining() > 0) {
                writeToDestination(buf.array(), buf.arrayOffset() + buf.position(), buf.remaining());
            }
        } finally {
            buf.clear();
        }
    }

    /**
     * Flushes any buffers.
     */
    public synchronized void flush() {
        flushBuffer(byteBuffer);
        flushDestination();
    }

    protected synchronized boolean closeOutputStream() {
        flush();
        final OutputStream stream = outputStream; // access volatile field only once per method
        if (stream == null || stream == System.out || stream == System.err) {
            return true;
        }
        try {
            stream.close();
            LOGGER.debug("OutputStream closed");
        } catch (final IOException ex) {
            logError("Unable to close stream", ex);
            return false;
        }
        return true;
    }

    /**
     * Returns this {@code ByteBufferDestination}'s buffer.
     * @return the buffer
     * @since 2.6
     */
    @Override
    public ByteBuffer getByteBuffer() {
        return byteBuffer;
    }

    /**
     * Drains the ByteBufferDestination's buffer into the destination. By default this calls
     * {@link #flushBuffer(ByteBuffer)} with the specified buffer. Subclasses may override.
     * <p>
     * Do not call this method lightly! For some subclasses this is a very expensive operation. For example,
     * {@link MemoryMappedFileManager} will assume this method was called because the end of the mapped region
     * was reached during a text encoding operation and will {@linkplain MemoryMappedFileManager#remap() remap} its
     * buffer.
     * </p><p>
     * To just flush the buffered contents to the underlying stream, call
     * {@link #flushBuffer(ByteBuffer)} directly instead.
     * </p>
     *
     * @param buf the buffer whose contents to write the destination
     * @return the specified buffer
     * @since 2.6
     */
    @Override
    public ByteBuffer drain(final ByteBuffer buf) {
        flushBuffer(buf);
        return buf;
    }

    @Override
    public void writeBytes(final ByteBuffer data) {
        if (data.remaining() == 0) {
          return;
        }
        synchronized (this) {
          ByteBufferDestinationHelper.writeToUnsynchronized(data, this);
        }
    }
}

⏎ org/apache/logging/log4j/core/appender/OutputStreamManager.java

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File name: log4j-core-2.14.1-sources.jar
File size: 1281358 bytes
Release date: 2021-03-06
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