聊聊TraceIdPatternLogbackLayout

序

本文主要研究一下TraceIdPatternLogbackLayout

TraceIdPatternLogbackLayout

org/apache/skywalking/apm/toolkit/log/logback/v1/x/TraceIdPatternLogbackLayout.class

public class TraceIdPatternLogbackLayout extends PatternLayout {
    public TraceIdPatternLogbackLayout() {
    }

    static {
        defaultConverterMap.put("tid", LogbackPatternConverter.class.getName());
    }
}

skywalking的TraceIdPatternLogbackLayout继承了PatternLayout，其static方法往defaultConverterMap添加了tid，value为LogbackPatternConverter.class.getName()

PatternLayout

ch/qos/logback/classic/PatternLayout.java

public class PatternLayout extends PatternLayoutBase<ILoggingEvent> {

    public static final Map<String, String> defaultConverterMap = new HashMap<String, String>();
    public static final String HEADER_PREFIX = "#logback.classic pattern: ";

    static {
        defaultConverterMap.putAll(Parser.DEFAULT_COMPOSITE_CONVERTER_MAP);

        defaultConverterMap.put("d", DateConverter.class.getName());
        defaultConverterMap.put("date", DateConverter.class.getName());

        defaultConverterMap.put("r", RelativeTimeConverter.class.getName());
        defaultConverterMap.put("relative", RelativeTimeConverter.class.getName());

        defaultConverterMap.put("level", LevelConverter.class.getName());
        defaultConverterMap.put("le", LevelConverter.class.getName());
        defaultConverterMap.put("p", LevelConverter.class.getName());

        defaultConverterMap.put("t", ThreadConverter.class.getName());
        defaultConverterMap.put("thread", ThreadConverter.class.getName());

        defaultConverterMap.put("lo", LoggerConverter.class.getName());
        defaultConverterMap.put("logger", LoggerConverter.class.getName());
        defaultConverterMap.put("c", LoggerConverter.class.getName());

        defaultConverterMap.put("m", MessageConverter.class.getName());
        defaultConverterMap.put("msg", MessageConverter.class.getName());
        defaultConverterMap.put("message", MessageConverter.class.getName());

        defaultConverterMap.put("C", ClassOfCallerConverter.class.getName());
        defaultConverterMap.put("class", ClassOfCallerConverter.class.getName());

        defaultConverterMap.put("M", MethodOfCallerConverter.class.getName());
        defaultConverterMap.put("method", MethodOfCallerConverter.class.getName());

        defaultConverterMap.put("L", LineOfCallerConverter.class.getName());
        defaultConverterMap.put("line", LineOfCallerConverter.class.getName());

        defaultConverterMap.put("F", FileOfCallerConverter.class.getName());
        defaultConverterMap.put("file", FileOfCallerConverter.class.getName());

        defaultConverterMap.put("X", MDCConverter.class.getName());
        defaultConverterMap.put("mdc", MDCConverter.class.getName());

        defaultConverterMap.put("ex", ThrowableProxyConverter.class.getName());
        defaultConverterMap.put("exception", ThrowableProxyConverter.class.getName());
        defaultConverterMap.put("rEx", RootCauseFirstThrowableProxyConverter.class.getName());
        defaultConverterMap.put("rootException", RootCauseFirstThrowableProxyConverter.class.getName());
        defaultConverterMap.put("throwable", ThrowableProxyConverter.class.getName());

        defaultConverterMap.put("xEx", ExtendedThrowableProxyConverter.class.getName());
        defaultConverterMap.put("xException", ExtendedThrowableProxyConverter.class.getName());
        defaultConverterMap.put("xThrowable", ExtendedThrowableProxyConverter.class.getName());

        defaultConverterMap.put("nopex", NopThrowableInformationConverter.class.getName());
        defaultConverterMap.put("nopexception", NopThrowableInformationConverter.class.getName());

        defaultConverterMap.put("cn", ContextNameConverter.class.getName());
        defaultConverterMap.put("contextName", ContextNameConverter.class.getName());

        defaultConverterMap.put("caller", CallerDataConverter.class.getName());

        defaultConverterMap.put("marker", MarkerConverter.class.getName());

        defaultConverterMap.put("property", PropertyConverter.class.getName());

        defaultConverterMap.put("n", LineSeparatorConverter.class.getName());

        defaultConverterMap.put("black", BlackCompositeConverter.class.getName());
        defaultConverterMap.put("red", RedCompositeConverter.class.getName());
        defaultConverterMap.put("green", GreenCompositeConverter.class.getName());
        defaultConverterMap.put("yellow", YellowCompositeConverter.class.getName());
        defaultConverterMap.put("blue", BlueCompositeConverter.class.getName());
        defaultConverterMap.put("magenta", MagentaCompositeConverter.class.getName());
        defaultConverterMap.put("cyan", CyanCompositeConverter.class.getName());
        defaultConverterMap.put("white", WhiteCompositeConverter.class.getName());
        defaultConverterMap.put("gray", GrayCompositeConverter.class.getName());
        defaultConverterMap.put("boldRed", BoldRedCompositeConverter.class.getName());
        defaultConverterMap.put("boldGreen", BoldGreenCompositeConverter.class.getName());
        defaultConverterMap.put("boldYellow", BoldYellowCompositeConverter.class.getName());
        defaultConverterMap.put("boldBlue", BoldBlueCompositeConverter.class.getName());
        defaultConverterMap.put("boldMagenta", BoldMagentaCompositeConverter.class.getName());
        defaultConverterMap.put("boldCyan", BoldCyanCompositeConverter.class.getName());
        defaultConverterMap.put("boldWhite", BoldWhiteCompositeConverter.class.getName());
        defaultConverterMap.put("highlight", HighlightingCompositeConverter.class.getName());

        defaultConverterMap.put("lsn", LocalSequenceNumberConverter.class.getName());

    }

    public PatternLayout() {
        this.postCompileProcessor = new EnsureExceptionHandling();
    }

    public Map<String, String> getDefaultConverterMap() {
        return defaultConverterMap;
    }

    public String doLayout(ILoggingEvent event) {
        if (!isStarted()) {
            return CoreConstants.EMPTY_STRING;
        }
        return writeLoopOnConverters(event);
    }

    @Override
    protected String getPresentationHeaderPrefix() {
        return HEADER_PREFIX;
    }
}

PatternLayout继承了PatternLayoutBase，其static方法往defaultConverterMap添加了一系列的convert

PatternLayoutBase

ch/qos/logback/core/pattern/PatternLayoutBase.java

abstract public class PatternLayoutBase<E> extends LayoutBase<E> {

    static final int INTIAL_STRING_BUILDER_SIZE = 256;
    Converter<E> head;
    String pattern;
    protected PostCompileProcessor<E> postCompileProcessor;
    
    Map<String, String> instanceConverterMap = new HashMap<String, String>();
    protected boolean outputPatternAsHeader = false;

    //......

    /**
     * Concrete implementations of this class are responsible for elaborating the
     * mapping between pattern words and converters.
     * 
     * @return A map associating pattern words to the names of converter classes
     */
    abstract public Map<String, String> getDefaultConverterMap();

    /**
     * Returns a map where the default converter map is merged with the map
     * contained in the context.
     */
    public Map<String, String> getEffectiveConverterMap() {
        Map<String, String> effectiveMap = new HashMap<String, String>();

        // add the least specific map fist
        Map<String, String> defaultMap = getDefaultConverterMap();
        if (defaultMap != null) {
            effectiveMap.putAll(defaultMap);
        }

        // contextMap is more specific than the default map
        Context context = getContext();
        if (context != null) {
            @SuppressWarnings("unchecked")
            Map<String, String> contextMap = (Map<String, String>) context.getObject(CoreConstants.PATTERN_RULE_REGISTRY);
            if (contextMap != null) {
                effectiveMap.putAll(contextMap);
            }
        }
        // set the most specific map last
        effectiveMap.putAll(instanceConverterMap);
        return effectiveMap;
    }    
}    

PatternLayoutBase继承了LayoutBase，它定义了抽象类getDefaultConverterMap，而getEffectiveConverterMap方法返回的effectiveMap则包含了defaultConverterMap，它还包含了context中key为CoreConstants.PATTERN_RULE_REGISTRY注册的，以及本身定义的instanceConverterMap

LogbackPatternConverter

org/apache/skywalking/apm/toolkit/log/logback/v1/x/LogbackPatternConverter.class

public class LogbackPatternConverter extends ClassicConverter {
    public LogbackPatternConverter() {
    }

    public String convert(ILoggingEvent iLoggingEvent) {
        return "TID: N/A";
    }
}

LogbackPatternConverter继承了ClassicConverter，其convert方法返回TID: N/A

ClassicConverter

ch/qos/logback/classic/pattern/ClassicConverter.java

abstract public class ClassicConverter extends DynamicConverter<ILoggingEvent> {

}

ClassicConverter继承了DynamicConverter，其泛型为ILoggingEvent

DynamicConverter

ch/qos/logback/core/pattern/DynamicConverter.java

abstract public class DynamicConverter<E> extends FormattingConverter<E> implements LifeCycle, ContextAware {

    ContextAwareBase cab = new ContextAwareBase(this);

    // Contains a list of option Strings.
    private List<String> optionList;

    /**
     * Is this component active?
     */
    protected boolean started = false;

    /**
     * Components that depend on options passed during configuration can override
     * this method in order to make appropriate use of those options. For simpler
     * components, the trivial implementation found in this abstract class will be
     * sufficient.
     */
    public void start() {
        started = true;
    }

    public void stop() {
        started = false;
    }

    public boolean isStarted() {
        return started;
    }

    public void setOptionList(List<String> optionList) {
        this.optionList = optionList;
    }

    /**
     * Return the first option passed to this component. The returned value may be
     * null if there are no options.
     * 
     * @return First option, may be null.
     */
    public String getFirstOption() {
        if (optionList == null || optionList.size() == 0) {
            return null;
        } else {
            return optionList.get(0);
        }
    }

    protected List<String> getOptionList() {
        return optionList;
    }

    public void setContext(Context context) {
        cab.setContext(context);
    }

    public Context getContext() {
        return cab.getContext();
    }

    public void addStatus(Status status) {
        cab.addStatus(status);
    }

    public void addInfo(String msg) {
        cab.addInfo(msg);
    }

    public void addInfo(String msg, Throwable ex) {
        cab.addInfo(msg, ex);
    }

    public void addWarn(String msg) {
        cab.addWarn(msg);
    }

    public void addWarn(String msg, Throwable ex) {
        cab.addWarn(msg, ex);
    }

    public void addError(String msg) {
        cab.addError(msg);
    }

    public void addError(String msg, Throwable ex) {
        cab.addError(msg, ex);
    }
}

DynamicConverter继承了FormattingConverter，声明实现LifeCycle, ContextAware接口

FormattingConverter

ch/qos/logback/core/pattern/FormattingConverter.java

abstract public class FormattingConverter<E> extends Converter<E> {

    static final int INITIAL_BUF_SIZE = 256;
    static final int MAX_CAPACITY = 1024;

    FormatInfo formattingInfo;

    final public FormatInfo getFormattingInfo() {
        return formattingInfo;
    }

    final public void setFormattingInfo(FormatInfo formattingInfo) {
        if (this.formattingInfo != null) {
            throw new IllegalStateException("FormattingInfo has been already set");
        }
        this.formattingInfo = formattingInfo;
    }

    @Override
    final public void write(StringBuilder buf, E event) {
        String s = convert(event);

        if (formattingInfo == null) {
            buf.append(s);
            return;
        }

        int min = formattingInfo.getMin();
        int max = formattingInfo.getMax();

        if (s == null) {
            if (0 < min)
                SpacePadder.spacePad(buf, min);
            return;
        }

        int len = s.length();

        if (len > max) {
            if (formattingInfo.isLeftTruncate()) {
                buf.append(s.substring(len - max));
            } else {
                buf.append(s.substring(0, max));
            }
        } else if (len < min) {
            if (formattingInfo.isLeftPad()) {
                SpacePadder.leftPad(buf, s, min);
            } else {
                SpacePadder.rightPad(buf, s, min);
            }
        } else {
            buf.append(s);
        }
    }
}

FormattingConverter继承了Converter，它定义了formattingInfo属性，其write方法根据formattingInfo信息进行append

示例

    <property name="PATTERN_DEFAULT" value="%d{${LOG_DATEFORMAT_PATTERN:-yyyy-MM-dd HH:mm:ss.SSS}} ${LOG_LEVEL_PATTERN:-%5p} ${PID:- } --- [%thread] [%tid] %-40.40logger{39} : %m%n${LOG_EXCEPTION_CONVERSION_WORD:-%wEx}"/>

    <appender name="STDOUT" class="ch.qos.logback.core.ConsoleAppender">　　　　　
        <encoder class="ch.qos.logback.core.encoder.LayoutWrappingEncoder">
            <layout class="org.apache.skywalking.apm.toolkit.log.logback.v1.x.TraceIdPatternLogbackLayout">
                <pattern>${PATTERN_DEFAULT}</pattern>
            </layout>
        </encoder>
    </appender>    

这里采用了TraceIdPatternLogbackLayout，并在pattern中使用了tid

小结

skywalking的apm-toolkit-logback-1.x组件提供了TraceIdPatternLogbackLayout，可以在日志中打印tid。