net.logstash.logback.pattern.PatternLayoutCompatibilityUtil Maven / Gradle / Ivy

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Logback encoder which will output events as Logstash-compatible JSON
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/*
 * Copyright 2013-2025 the original author or authors.
 *
 * 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.pattern;

import java.lang.reflect.Method;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.Map;
import java.util.function.Supplier;

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.pattern.DynamicConverter;
import ch.qos.logback.core.pattern.PatternLayoutBase;

/**
 * Utilities for working around backwards incompatibilities introduced in logback's
 * PatternLayout related classes to maintain support for multiple logback versions.
 *
 * This can be removed in a major version of logstash-logback-encoder,
 * which bumps the minimum logback version to >= 1.5.13.
 */
class PatternLayoutCompatibilityUtil {

    /**
     * Registers the given converter in the layout's {@link PatternLayoutBase#getInstanceConverterMap()}.
     *
     * @param layout the layout to which to add the converter
     * @param converterName the name of the converter
     * @param converterClass the class of the converter
     * @param converterSupplier a supplier of instances of the converter
     * @param  type of object converted by the converter
     * @param  type of converter
     */
    static > void registerConverter(
            PatternLayoutBase layout,
            String converterName,
            Class converterClass,
            Supplier converterSupplier) {

        try {
            Method method = PatternLayoutBase.class.getDeclaredMethod("getInstanceConverterMap");
            ParameterizedType type = (ParameterizedType) method.getGenericReturnType();
            Type valueType = type.getActualTypeArguments()[1];

            if (valueType.getTypeName().equals("java.lang.String")) {
                /*
                 * In logback <= 1.5.12, getInstanceConverterMap() is a Map.
                 *     key = converter name
                 *     value = name of converter class
                 */
                putUnchecked(layout.getInstanceConverterMap(), converterName, converterClass.getName());
            } else if (valueType.getTypeName().equals("java.util.function.Supplier")) {
                /*
                 * In logback >= 1.5.13, getInstanceConverterMap() is a Map.
                 *     key = converter name
                 *     value = supplier of converter instances
                 *
                 * Related issues:
                 *     https://github.com/qos-ch/logback/issues/803
                 *     https://github.com/qos-ch/logback/issues/931
                 *     https://github.com/qos-ch/logback/issues/932
                 */
                putUnchecked(layout.getInstanceConverterMap(), converterName, converterSupplier);
            } else {
                throw new IncompatibleClassChangeError(
                        "Unexpected return type found for PatternLayoutBase.getInstanceConverterMap(), logback-core dependency version is not compatible");
            }

        } catch (NoSuchMethodException e) {
            throw new IncompatibleClassChangeError(
                    "Method PatternLayoutBase.getInstanceConverterMap() not found, logback-core dependency version is not compatible");
        }
    }

    @SuppressWarnings({"rawtypes", "unchecked"})
    private static void putUnchecked(Map map, String key, Object value) {
        map.put(key, value);
    }

}