/*
* 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.core.impl;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.logging.log4j.ThreadContext;
import org.apache.logging.log4j.core.ContextDataInjector;
import org.apache.logging.log4j.core.config.Property;
import org.apache.logging.log4j.spi.ReadOnlyThreadContextMap;
import org.apache.logging.log4j.util.ReadOnlyStringMap;
import org.apache.logging.log4j.util.StringMap;
/**
* {@code ThreadContextDataInjector} contains a number of strategies for copying key-value pairs from the various
* {@code ThreadContext} map implementations into a {@code StringMap}. In the case of duplicate keys,
* thread context values overwrite configuration {@code Property} values.
* <p>
* These are the default {@code ContextDataInjector} objects returned by the {@link ContextDataInjectorFactory}.
* </p>
*
* @see org.apache.logging.log4j.ThreadContext
* @see Property
* @see ReadOnlyStringMap
* @see ContextDataInjector
* @see ContextDataInjectorFactory
* @since 2.7
*/
public class ThreadContextDataInjector {
/**
* Default {@code ContextDataInjector} for the legacy {@code Map<String, String>}-based ThreadContext (which is
* also the ThreadContext implementation used for web applications).
* <p>
* This injector always puts key-value pairs into the specified reusable StringMap.
*/
public static class ForDefaultThreadContextMap implements ContextDataInjector {
/**
* Puts key-value pairs from both the specified list of properties as well as the thread context into the
* specified reusable StringMap.
*
* @param props list of configuration properties, may be {@code null}
* @param ignore a {@code StringMap} instance from the log event
* @return a {@code StringMap} combining configuration properties with thread context data
*/
@Override
public StringMap injectContextData(final List<Property> props, final StringMap ignore) {
final Map<String, String> copy = ThreadContext.getImmutableContext();
// The DefaultThreadContextMap stores context data in a Map<String, String>.
// This is a copy-on-write data structure so we are sure ThreadContext changes will not affect our copy.
// If there are no configuration properties returning a thin wrapper around the copy
// is faster than copying the elements into the LogEvent's reusable StringMap.
if (props == null || props.isEmpty()) {
// this will replace the LogEvent's context data with the returned instance.
// NOTE: must mark as frozen or downstream components may attempt to modify (UnsupportedOperationEx)
return copy.isEmpty() ? ContextDataFactory.emptyFrozenContextData() : frozenStringMap(copy);
}
// If the list of Properties is non-empty we need to combine the properties and the ThreadContext
// data. Note that we cannot reuse the specified StringMap: some Loggers may have properties defined
// and others not, so the LogEvent's context data may have been replaced with an immutable copy from
// the ThreadContext - this will throw an UnsupportedOperationException if we try to modify it.
final StringMap result = new JdkMapAdapterStringMap(new HashMap<>(copy));
for (int i = 0; i < props.size(); i++) {
final Property prop = props.get(i);
if (!copy.containsKey(prop.getName())) {
result.putValue(prop.getName(), prop.getValue());
}
}
result.freeze();
return result;
}
private static JdkMapAdapterStringMap frozenStringMap(final Map<String, String> copy) {
final JdkMapAdapterStringMap result = new JdkMapAdapterStringMap(copy);
result.freeze();
return result;
}
@Override
public ReadOnlyStringMap rawContextData() {
final ReadOnlyThreadContextMap map = ThreadContext.getThreadContextMap();
if (map instanceof ReadOnlyStringMap) {
return (ReadOnlyStringMap) map;
}
// note: default ThreadContextMap is null
final Map<String, String> copy = ThreadContext.getImmutableContext();
return copy.isEmpty() ? ContextDataFactory.emptyFrozenContextData() : new JdkMapAdapterStringMap(copy);
}
}
/**
* The {@code ContextDataInjector} used when the ThreadContextMap implementation is a garbage-free
* StringMap-based data structure.
* <p>
* This injector always puts key-value pairs into the specified reusable StringMap.
*/
public static class ForGarbageFreeThreadContextMap implements ContextDataInjector {
/**
* Puts key-value pairs from both the specified list of properties as well as the thread context into the
* specified reusable StringMap.
*
* @param props list of configuration properties, may be {@code null}
* @param reusable a {@code StringMap} instance that may be reused to avoid creating temporary objects
* @return a {@code StringMap} combining configuration properties with thread context data
*/
@Override
public StringMap injectContextData(final List<Property> props, final StringMap reusable) {
// When the ThreadContext is garbage-free, we must copy its key-value pairs into the specified reusable
// StringMap. We cannot return the ThreadContext's internal data structure because it may be modified later
// and such modifications should not be reflected in the log event.
copyProperties(props, reusable);
final ReadOnlyStringMap immutableCopy = ThreadContext.getThreadContextMap().getReadOnlyContextData();
reusable.putAll(immutableCopy);
return reusable;
}
@Override
public ReadOnlyStringMap rawContextData() {
return ThreadContext.getThreadContextMap().getReadOnlyContextData();
}
}
/**
* The {@code ContextDataInjector} used when the ThreadContextMap implementation is a copy-on-write
* StringMap-based data structure.
* <p>
* If there are no configuration properties, this injector will return the thread context's internal data
* structure. Otherwise the configuration properties are combined with the thread context key-value pairs into the
* specified reusable StringMap.
*/
public static class ForCopyOnWriteThreadContextMap implements ContextDataInjector {
/**
* If there are no configuration properties, this injector will return the thread context's internal data
* structure. Otherwise the configuration properties are combined with the thread context key-value pairs into the
* specified reusable StringMap.
*
* @param props list of configuration properties, may be {@code null}
* @param ignore a {@code StringMap} instance from the log event
* @return a {@code StringMap} combining configuration properties with thread context data
*/
@Override
public StringMap injectContextData(final List<Property> props, final StringMap ignore) {
// If there are no configuration properties we want to just return the ThreadContext's StringMap:
// it is a copy-on-write data structure so we are sure ThreadContext changes will not affect our copy.
final StringMap immutableCopy = ThreadContext.getThreadContextMap().getReadOnlyContextData();
if (props == null || props.isEmpty()) {
return immutableCopy; // this will replace the LogEvent's context data with the returned instance
}
// However, if the list of Properties is non-empty we need to combine the properties and the ThreadContext
// data. Note that we cannot reuse the specified StringMap: some Loggers may have properties defined
// and others not, so the LogEvent's context data may have been replaced with an immutable copy from
// the ThreadContext - this will throw an UnsupportedOperationException if we try to modify it.
final StringMap result = ContextDataFactory.createContextData(props.size() + immutableCopy.size());
copyProperties(props, result);
result.putAll(immutableCopy);
return result;
}
@Override
public ReadOnlyStringMap rawContextData() {
return ThreadContext.getThreadContextMap().getReadOnlyContextData();
}
}
/**
* Copies key-value pairs from the specified property list into the specified {@code StringMap}.
*
* @param properties list of configuration properties, may be {@code null}
* @param result the {@code StringMap} object to add the key-values to. Must be non-{@code null}.
*/
public static void copyProperties(final List<Property> properties, final StringMap result) {
if (properties != null) {
for (int i = 0; i < properties.size(); i++) {
final Property prop = properties.get(i);
result.putValue(prop.getName(), prop.getValue());
}
}
}
}