Logback: the reliable, generic, fast and flexible logging framework.
Copyright (C) 1999-2015, QOS.ch. All rights reserved.
This program and the accompanying materials are dual-licensed under
either the terms of the Eclipse Public License v1.0 as published by
the Eclipse Foundation
  or (per the licensee's choosing)
under the terms of the GNU Lesser General Public License version 2.1
as published by the Free Software Foundation.
/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.classic.pattern;

import java.net.InetAddress;
import java.net.UnknownHostException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;
import java.util.Locale;

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.classic.util.LevelToSyslogSeverity;
import ch.qos.logback.core.net.SyslogAppenderBase;

public class SyslogStartConverter extends ClassicConverter {

    long lastTimestamp = -1;
    String timesmapStr = null;
    SimpleDateFormat simpleMonthFormat;
    SimpleDateFormat simpleTimeFormat;
    private final Calendar calendar = Calendar.getInstance(Locale.US);

    String localHostName;
    int facility;

    public void start() {
        int errorCount = 0;

        String facilityStr = getFirstOption();
        if (facilityStr == null) {
            addError("was expecting a facility string as an option");
            return;
        }

        facility = SyslogAppenderBase.facilityStringToint(facilityStr);

        localHostName = getLocalHostname();
        try {
            // hours should be in 0-23, see also http://jira.qos.ch/browse/LBCLASSIC-48
            simpleMonthFormat = new SimpleDateFormat("MMM", Locale.US);
            simpleTimeFormat = new SimpleDateFormat("HH:mm:ss", Locale.US);
        } catch (IllegalArgumentException e) {
            addError("Could not instantiate SimpleDateFormat", e);
            errorCount++;
        }

        if (errorCount == 0) {
            super.start();
        }
    }

    public String convert(ILoggingEvent event) {
        StringBuilder sb = new StringBuilder();

        int pri = facility + LevelToSyslogSeverity.convert(event);

        sb.append("<");
        sb.append(pri);
        sb.append(">");
        sb.append(computeTimeStampString(event.getTimeStamp()));
        sb.append(' ');
        sb.append(localHostName);
        sb.append(' ');

        return sb.toString();
    }

    
This method gets the network name of the machine we are running on.
Returns "UNKNOWN_LOCALHOST" in the unlikely case where the host name 
cannot be found.
Returns:
String the name of the local host/**
     * This method gets the network name of the machine we are running on.
     * Returns "UNKNOWN_LOCALHOST" in the unlikely case where the host name 
     * cannot be found.
     * @return String the name of the local host
     */
    public String getLocalHostname() {
        try {
            InetAddress addr = InetAddress.getLocalHost();
            return addr.getHostName();
        } catch (UnknownHostException uhe) {
            addError("Could not determine local host name", uhe);
            return "UNKNOWN_LOCALHOST";
        }
    }

    String computeTimeStampString(long now) {
        synchronized (this) {
            // Since the formatted output is only precise to the second, we can use the same cached string if the
            // current
            // second is the same (stripping off the milliseconds).
            if ((now / 1000) != lastTimestamp) {
                lastTimestamp = now / 1000;
                Date nowDate = new Date(now);
                calendar.setTime(nowDate);
                timesmapStr = String.format("%s %2d %s", simpleMonthFormat.format(nowDate), calendar.get(Calendar.DAY_OF_MONTH),
                                simpleTimeFormat.format(nowDate));
            }
            return timesmapStr;
        }
    }
}