https://eclipse.org/jetty/jetty-server: The core jetty server artifact. (Webtide) 
//
// ========================================================================
// Copyright (c) 1995-2020 Mort Bay Consulting Pty Ltd and others.
//
// This program and the accompanying materials are made available under
// the terms of the Eclipse Public License 2.0 which is available at
// https://www.eclipse.org/legal/epl-2.0
//
// This Source Code may also be made available under the following
// Secondary Licenses when the conditions for such availability set
// forth in the Eclipse Public License, v. 2.0 are satisfied:
// the Apache License v2.0 which is available at
// https://www.apache.org/licenses/LICENSE-2.0
//
// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
// ========================================================================
//

package org.eclipse.jetty.server;

import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.util.TimeZone;

import org.eclipse.jetty.util.RolloverFileOutputStream;
import org.eclipse.jetty.util.annotation.ManagedAttribute;
import org.eclipse.jetty.util.annotation.ManagedObject;
import org.eclipse.jetty.util.component.AbstractLifeCycle;
import org.eclipse.jetty.util.thread.AutoLock;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;


Writer which outputs pre-formatted request log strings to a file using RolloverFileOutputStream. 
/**
 * Writer which outputs pre-formatted request log strings to a file using {@link RolloverFileOutputStream}.
 */
@ManagedObject("Request Log writer which writes to file")
public class RequestLogWriter extends AbstractLifeCycle implements RequestLog.Writer
{
    private static final Logger LOG = LoggerFactory.getLogger(RequestLogWriter.class);

    private final AutoLock _lock = new AutoLock();
    private String _filename;
    private boolean _append;
    private int _retainDays;
    private boolean _closeOut;
    private String _timeZone = "GMT";
    private String _filenameDateFormat = null;
    private transient OutputStream _out;
    private transient OutputStream _fileOut;
    private transient Writer _writer;

    public RequestLogWriter()
    {
        this(null);
    }

    public RequestLogWriter(String filename)
    {
        setAppend(true);
        setRetainDays(31);

        if (filename != null)
            setFilename(filename);
    }

    
Set the output file name of the request log. The file name may be in the format expected by RolloverFileOutputStream. 
Params:
  • filename – file name of the request log
/**
     * Set the output file name of the request log.
     * The file name may be in the format expected by
     * {@link RolloverFileOutputStream}.
     *
     * @param filename file name of the request log
     */
    public void setFilename(String filename)
    {
        if (filename != null)
        {
            filename = filename.trim();
            if (filename.length() == 0)
                filename = null;
        }
        _filename = filename;
    }

    
Retrieve the output file name of the request log.

Returns:file name of the request log
/**
     * Retrieve the output file name of the request log.
     *
     * @return file name of the request log
     */
    @ManagedAttribute("filename")
    public String getFileName()
    {
        return _filename;
    }

    
Retrieve the file name of the request log with the expanded date wildcard if the output is written to the disk using RolloverFileOutputStream. 
Returns:file name of the request log, or null if not applicable
/**
     * Retrieve the file name of the request log with the expanded
     * date wildcard if the output is written to the disk using
     * {@link RolloverFileOutputStream}.
     *
     * @return file name of the request log, or null if not applicable
     */
    @ManagedAttribute("dated filename")
    public String getDatedFilename()
    {
        if (_fileOut instanceof RolloverFileOutputStream)
            return ((RolloverFileOutputStream)_fileOut).getDatedFilename();
        return null;
    }

    
Set the number of days before rotated log files are deleted.

Params:
  • retainDays – number of days to keep a log file
/**
     * Set the number of days before rotated log files are deleted.
     *
     * @param retainDays number of days to keep a log file
     */
    public void setRetainDays(int retainDays)
    {
        _retainDays = retainDays;
    }

    
Retrieve the number of days before rotated log files are deleted.

Returns:number of days to keep a log file
/**
     * Retrieve the number of days before rotated log files are deleted.
     *
     * @return number of days to keep a log file
     */
    @ManagedAttribute("number of days to keep a log file")
    public int getRetainDays()
    {
        return _retainDays;
    }

    
Set append to log flag.

Params:
  • append – true - request log file will be appended after restart,
false - request log file will be overwritten after restart
/**
     * Set append to log flag.
     *
     * @param append true - request log file will be appended after restart,
     * false - request log file will be overwritten after restart
     */
    public void setAppend(boolean append)
    {
        _append = append;
    }

    
Retrieve append to log flag.

Returns:value of the flag
/**
     * Retrieve append to log flag.
     *
     * @return value of the flag
     */
    @ManagedAttribute("if request log file will be appended after restart")
    public boolean isAppend()
    {
        return _append;
    }

    
Set the log file name date format.

Params:
See Also:
/**
     * Set the log file name date format.
     *
     * @param logFileDateFormat format string that is passed to {@link RolloverFileOutputStream}
     * @see RolloverFileOutputStream#RolloverFileOutputStream(String, boolean, int, TimeZone, String, String)
     */
    public void setFilenameDateFormat(String logFileDateFormat)
    {
        _filenameDateFormat = logFileDateFormat;
    }

    
Retrieve the file name date format string.

Returns:the log File Date Format
/**
     * Retrieve the file name date format string.
     *
     * @return the log File Date Format
     */
    @ManagedAttribute("log file name date format")
    public String getFilenameDateFormat()
    {
        return _filenameDateFormat;
    }

    @Override
    public void write(String requestEntry) throws IOException
    {
        try (AutoLock l = _lock.lock())
        {
            if (_writer == null)
                return;
            _writer.write(requestEntry);
            _writer.write(System.lineSeparator());
            _writer.flush();
        }
    }

    @Override
    protected void doStart() throws Exception
    {
        try (AutoLock l = _lock.lock())
        {
            if (_filename != null)
            {
                _fileOut = new RolloverFileOutputStream(_filename, _append, _retainDays, TimeZone.getTimeZone(getTimeZone()), _filenameDateFormat, null);
                _closeOut = true;
                LOG.info("Opened {}", getDatedFilename());
            }
            else
            {
                _fileOut = System.err;
            }
            _out = _fileOut;
            _writer = new OutputStreamWriter(_out);
            super.doStart();
        }
    }

    public void setTimeZone(String timeZone)
    {
        _timeZone = timeZone;
    }

    @ManagedAttribute("timezone of the log")
    public String getTimeZone()
    {
        return _timeZone;
    }

    @Override
    protected void doStop() throws Exception
    {
        try (AutoLock ignored = _lock.lock())
        {
            super.doStop();
            try
            {
                if (_writer != null)
                    _writer.flush();
            }
            catch (IOException e)
            {
                LOG.trace("IGNORED", e);
            }
            if (_out != null && _closeOut)
            {
                try
                {
                    _out.close();
                }
                catch (IOException e)
                {
                    LOG.trace("IGNORED", e);
                }
            }

            _out = null;
            _fileOut = null;
            _closeOut = false;
            _writer = null;
        }
    }
}