log4j-layout-jackson/src/main/java/org/apache/logging/log4j/jackson/AbstractJacksonLayout.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.jackson;

import java.io.IOException;
import java.io.Writer;
import java.nio.charset.Charset;
import java.util.LinkedHashMap;
import java.util.Map;

import com.fasterxml.jackson.annotation.JsonIgnore;
import org.apache.logging.log4j.Level;
import org.apache.logging.log4j.Marker;
import org.apache.logging.log4j.ThreadContext;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.config.Configuration;
import org.apache.logging.log4j.plugins.PluginBuilderAttribute;
import org.apache.logging.log4j.plugins.PluginElement;
import org.apache.logging.log4j.core.impl.ThrowableProxy;
import org.apache.logging.log4j.core.layout.AbstractStringLayout;
import org.apache.logging.log4j.core.lookup.StrSubstitutor;
import org.apache.logging.log4j.core.time.Instant;
import org.apache.logging.log4j.core.util.KeyValuePair;
import org.apache.logging.log4j.core.util.StringBuilderWriter;
import org.apache.logging.log4j.message.Message;
import org.apache.logging.log4j.util.ReadOnlyStringMap;
import org.apache.logging.log4j.util.Strings;

import com.fasterxml.jackson.databind.ObjectWriter;

public abstract class AbstractJacksonLayout extends AbstractStringLayout {

    public static abstract class Builder<B extends Builder<B>> extends AbstractStringLayout.Builder<B> {

        @PluginBuilderAttribute
        private boolean eventEol;

        @PluginBuilderAttribute
        private String endOfLine;

        @PluginBuilderAttribute
        private boolean compact;

        @PluginBuilderAttribute
        private boolean complete;

        @PluginBuilderAttribute
        private boolean locationInfo;

        @PluginBuilderAttribute
        private boolean properties;

        @PluginBuilderAttribute
        private boolean includeStacktrace = true;

        @PluginBuilderAttribute
        private boolean stacktraceAsString = false;

        @PluginBuilderAttribute
        private boolean includeNullDelimiter = false;

        @PluginBuilderAttribute
        private boolean includeTimeMillis = false;

        @PluginElement("AdditionalField")
        private KeyValuePair[] additionalFields;

        public KeyValuePair[] getAdditionalFields() {
            return additionalFields;
        }

        public boolean getEventEol() {
            return eventEol;
        }

        public String getEndOfLine() {
            return endOfLine;
        }

        public boolean isCompact() {
            return compact;
        }

        public boolean isComplete() {
            return complete;
        }

        public boolean isIncludeNullDelimiter() {
            return includeNullDelimiter;
        }

        public boolean isIncludeTimeMillis() {
            return includeTimeMillis;
        }

        /**
         * If "true", includes the stack trace of any Throwable in the generated data, defaults to "true".
         *
         * @return If "true", includes the stack trace of any Throwable in the generated data, defaults to "true".
         */
        public boolean isIncludeStacktrace() {
            return includeStacktrace;
        }

        public boolean isLocationInfo() {
            return locationInfo;
        }

        public boolean isProperties() {
            return properties;
        }

        public boolean isStacktraceAsString() {
            return stacktraceAsString;
        }

        /**
         * Additional fields to set on each log event.
         * @param additionalFields The additional Key/Value pairs to add.
         * @return this builder
         */
        public B setAdditionalFields(final KeyValuePair[] additionalFields) {
            this.additionalFields = additionalFields;
            return asBuilder();
        }

        public B setCompact(final boolean compact) {
            this.compact = compact;
            return asBuilder();
        }

        public B setComplete(final boolean complete) {
            this.complete = complete;
            return asBuilder();
        }

        public B setEventEol(final boolean eventEol) {
            this.eventEol = eventEol;
            return asBuilder();
        }

        public B setEndOfLine(final String endOfLine) {
            this.endOfLine = endOfLine;
            return asBuilder();
        }

        /**
         * Whether to include NULL byte as delimiter after each event (optional, default to false).
         * @param includeNullDelimiter true if a null delimiter should be included.
         * @return this builder
         */
        public B setIncludeNullDelimiter(final boolean includeNullDelimiter) {
            this.includeNullDelimiter = includeNullDelimiter;
            return asBuilder();
        }

        /**
         * Whether to include the timestamp (in addition to the Instant) (optional, default to false).
         *
         * @return this builder
         */
        public B setIncludeTimeMillis(final boolean includeTimeMillis) {
            this.includeTimeMillis = includeTimeMillis;
            return asBuilder();
        }

        /**
         * If "true", includes the stacktrace of any Throwable in the generated JSON, defaults to "true".
         *
         * @param includeStacktrace
         *            If "true", includes the stacktrace of any Throwable in the generated JSON, defaults to "true".
         * @return this builder
         */
        public B setIncludeStacktrace(final boolean includeStacktrace) {
            this.includeStacktrace = includeStacktrace;
            return asBuilder();
        }

        public B setLocationInfo(final boolean locationInfo) {
            this.locationInfo = locationInfo;
            return asBuilder();
        }

        public B setProperties(final boolean properties) {
            this.properties = properties;
            return asBuilder();
        }

        /**
         * Whether to format the stacktrace as a string, and not a nested object (optional, defaults to false).
         * @param stacktraceAsString true if the stacktrace should be formatted as a String.
         * @return this builder
         */
        public B setStacktraceAsString(final boolean stacktraceAsString) {
            this.stacktraceAsString = stacktraceAsString;
            return asBuilder();
        }

        protected String toStringOrNull(final byte[] header) {
            return header == null ? null : new String(header, Charset.defaultCharset());
        }
    }
    /**
     * Subclasses can annotate with Jackson annotations for JSON example.
     */
    public static class LogEventWithAdditionalFields {

        private final LogEvent logEvent;
        private final Map<String, String> additionalFields;

        public LogEventWithAdditionalFields(final LogEvent logEvent, final Map<String, String> additionalFields) {
            this.logEvent = logEvent;
            this.additionalFields = additionalFields;
        }

        public Map<String, String> getAdditionalFields() {
            return additionalFields;
        }

        public LogEvent getLogEvent() {
            return logEvent;
        }
    }

    protected static class ResolvableKeyValuePair {

        final String key;
        final String value;
        final boolean valueNeedsLookup;

        ResolvableKeyValuePair(final KeyValuePair pair) {
            this.key = pair.getKey();
            this.value = pair.getValue();
            this.valueNeedsLookup = AbstractJacksonLayout.valueNeedsLookup(this.value);
        }
    }

    protected static final String DEFAULT_EOL = "\r\n";
    protected static final String COMPACT_EOL = Strings.EMPTY;

    private static ResolvableKeyValuePair[] prepareAdditionalFields(final Configuration config,
            final KeyValuePair[] additionalFields) {
        if (additionalFields == null || additionalFields.length == 0) {
            // No fields set
            return new ResolvableKeyValuePair[0];
        }

        // Convert to specific class which already determines whether values needs lookup during serialization
        final ResolvableKeyValuePair[] resolvableFields = new ResolvableKeyValuePair[additionalFields.length];

        for (int i = 0; i < additionalFields.length; i++) {
            final ResolvableKeyValuePair resolvable = resolvableFields[i] = new ResolvableKeyValuePair(additionalFields[i]);

            // Validate
            if (config == null && resolvable.valueNeedsLookup) {
                throw new IllegalArgumentException(
                        "configuration needs to be set when there are additional fields with variables");
            }
        }

        return resolvableFields;
    }
    protected static boolean valueNeedsLookup(final String value) {
        return value != null && value.contains("${");
    }
    protected final String eol;

    protected final ObjectWriter objectWriter;

    protected final boolean compact;

    protected final boolean complete;

    protected final boolean includeNullDelimiter;

    protected final ResolvableKeyValuePair[] additionalFields;

    protected AbstractJacksonLayout(final Configuration config, final ObjectWriter objectWriter, final Charset charset,
            final boolean compact, final boolean complete, final boolean eventEol, final Serializer headerSerializer,
            final Serializer footerSerializer, final boolean includeNullDelimiter,
            final KeyValuePair[] additionalFields) {
        this(config, objectWriter, charset, compact, complete, eventEol, null, headerSerializer, footerSerializer,
                includeNullDelimiter, additionalFields);
    }

    protected AbstractJacksonLayout(final Configuration config, final ObjectWriter objectWriter, final Charset charset,
            final boolean compact, final boolean complete, final boolean eventEol, final String endOfLine,
            final Serializer headerSerializer, final Serializer footerSerializer, final boolean includeNullDelimiter,
            final KeyValuePair[] additionalFields) {
        super(config, charset, headerSerializer, footerSerializer);
        this.objectWriter = objectWriter;
        this.compact = compact;
        this.complete = complete;
        this.eol = endOfLine != null ? endOfLine : compact && !eventEol ? COMPACT_EOL : DEFAULT_EOL;
        this.includeNullDelimiter = includeNullDelimiter;
        this.additionalFields = prepareAdditionalFields(config, additionalFields);
    }

    protected LogEventWithAdditionalFields createLogEventWithAdditionalFields(final LogEvent event,
            final Map<String, String> additionalFieldsMap) {
        return new LogEventWithAdditionalFields(event, additionalFieldsMap);
    }

    private Map<String, String> resolveAdditionalFields(final LogEvent logEvent) {
        // Note: LinkedHashMap retains order
        final Map<String, String> additionalFieldsMap = new LinkedHashMap<>(additionalFields.length);
        final StrSubstitutor strSubstitutor = configuration.getStrSubstitutor();

        // Go over each field
        for (final ResolvableKeyValuePair pair : additionalFields) {
            if (pair.valueNeedsLookup) {
                // Resolve value
                additionalFieldsMap.put(pair.key, strSubstitutor.replace(logEvent, pair.value));
            } else {
                // Plain text value
                additionalFieldsMap.put(pair.key, pair.value);
            }
        }

        return additionalFieldsMap;
    }

    /**
     * Formats a {@link org.apache.logging.log4j.core.LogEvent}.
     *
     * @param event
     *            The LogEvent.
     * @return The XML representation of the LogEvent.
     */
    @Override
    public String toSerializable(final LogEvent event) {
        try (final StringBuilderWriter writer = new StringBuilderWriter()) {
            toSerializable(event, writer);
            return writer.toString();
        } catch (final IOException e) {
            // Should this be an ISE or IAE?
            LOGGER.error(e);
            return Strings.EMPTY;
        }
    }

    public void toSerializable(final LogEvent event, final Writer writer) throws IOException {
        objectWriter.writeValue(writer, wrapLogEvent(event));
        writer.write(eol);
        if (includeNullDelimiter) {
            writer.write('\0');
        }
        markEvent();
    }

    protected Object wrapLogEvent(final LogEvent event) {
        if (additionalFields.length > 0) {
            // Construct map for serialization - note that we are intentionally using original LogEvent
            final Map<String, String> additionalFieldsMap = resolveAdditionalFields(event);
            // This class combines LogEvent with AdditionalFields during serialization
            return createLogEventWithAdditionalFields(event, additionalFieldsMap);
        } else if (event instanceof Message) {
            // If the LogEvent implements the Message interface Jackson will not treat is as a LogEvent.
            return new ReadOnlyLogEventWrapper(event);
            // No additional fields, return original object
        }
        return event;
    }
    private static class ReadOnlyLogEventWrapper implements LogEvent {

        @JsonIgnore
        private final LogEvent event;

        public ReadOnlyLogEventWrapper(LogEvent event) {
            this.event = event;
        }

        @Override
        public LogEvent toImmutable() {
            return event.toImmutable();
        }

        @Override
        public ReadOnlyStringMap getContextData() {
            return event.getContextData();
        }

        @Override
        public ThreadContext.ContextStack getContextStack() {
            return event.getContextStack();
        }

        @Override
        public String getLoggerFqcn() {
            return event.getLoggerFqcn();
        }

        @Override
        public Level getLevel() {
            return event.getLevel();
        }

        @Override
        public String getLoggerName() {
            return event.getLoggerName();
        }

        @Override
        public Marker getMarker() {
            return event.getMarker();
        }

        @Override
        public Message getMessage() {
            return event.getMessage();
        }

        @Override
        public long getTimeMillis() {
            return event.getTimeMillis();
        }

        @Override
        public Instant getInstant() {
            return event.getInstant();
        }

        @Override
        public StackTraceElement getSource() {
            return event.getSource();
        }

        @Override
        public String getThreadName() {
            return event.getThreadName();
        }

        @Override
        public long getThreadId() {
            return event.getThreadId();
        }

        @Override
        public int getThreadPriority() {
            return event.getThreadPriority();
        }

        @Override
        public Throwable getThrown() {
            return event.getThrown();
        }

        @Override
        public ThrowableProxy getThrownProxy() {
            return event.getThrownProxy();
        }

        @Override
        public boolean isEndOfBatch() {
            return event.isEndOfBatch();
        }

        @Override
        public boolean isIncludeLocation() {
            return event.isIncludeLocation();
        }

        @Override
        public void setEndOfBatch(boolean endOfBatch) {

        }

        @Override
        public void setIncludeLocation(boolean locationRequired) {

        }

        @Override
        public long getNanoTime() {
            return event.getNanoTime();
        }
    }
}