net.logstash.logback.marker.ObjectFieldsAppendingMarker Maven / Gradle / Ivy

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Logback encoder which will output events as Logstash-compatible JSON
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/**
 * Licensed 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 net.logstash.logback.marker;

import java.io.IOException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import net.logstash.logback.argument.StructuredArgument;
import net.logstash.logback.argument.StructuredArguments;
import net.logstash.logback.composite.loggingevent.ArgumentsJsonProvider;
import net.logstash.logback.composite.loggingevent.LogstashMarkersJsonProvider;

import org.apache.commons.lang.ObjectUtils;
import org.slf4j.Marker;

import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.JsonMappingException;
import com.fasterxml.jackson.databind.JsonSerializer;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.databind.SerializationConfig;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.DefaultSerializerProvider;
import com.fasterxml.jackson.databind.ser.ResolvableSerializer;
import com.fasterxml.jackson.databind.util.NameTransformer;

/**
 * A {@link Marker} OR {@link StructuredArgument} that 
 * that "unwraps" the given object into the logstash event.
 * 
 * 
 * When writing to the JSON data (via {@link ArgumentsJsonProvider} or {@link LogstashMarkersJsonProvider}),
 * the fields of the object are written inline into the JSON event
 * similar to how the {@link com.fasterxml.jackson.annotation.JsonUnwrapped} annotation works.
 * 

 * 
 * When writing to a String (when used as a {@link StructuredArgument} to the event's formatted message),
 * {@link StructuredArguments#toString(Object)} is used to convert the object to a string.
 * 

 * 
 * For example, if the message is "mymessage {}", and the object argument is:
 * 
 * 
 * {
 *     name1 : "value1",
 *     name2 : 5,
 *     name3 : [1, 2, 3],
 *     name4 : {
 *         name5 : 6
 *     }
 * }
 * 
 * 
 * Then the message, name1, name2, name3, name4 fields will be added to the json for the logstash event.
 * 

 * For example:
 * 
 * 
 * {
 *     "message" : "mymessage objectsToStringValue",
 *     "name1" : "value1",
 *     "name2" : 5,
 *     "name3" : [1, 2, 3],
 *     "name4" : { "name5" : 6 }
 * }
 * 
 * 
 * Note that if the object cannot be unwrapped, then nothing will be written.
 */
@SuppressWarnings("serial")
public class ObjectFieldsAppendingMarker extends LogstashMarker implements StructuredArgument {
    
    public static final String MARKER_NAME = LogstashMarker.MARKER_NAME_PREFIX + "OBJECT_FIELDS";
    
    private final Object object;
    
    /*
     * Would really like to use Guava's Cache for these two, with expiring entries, soft reference, etc.
     * But didn't want to introduce a dependency on Guava.
     * 
     * Since apps will typically serialize the same types of objects repeatedly, they shouldn't grow too much.
     */
    private static final ConcurrentHashMap, JsonSerializer