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/*
* 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.ArrayList;
import java.util.Collection;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.ServiceLoader;
import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;
import org.apache.logging.log4j.Logger;
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.core.util.ContextDataProvider;
import org.apache.logging.log4j.spi.ReadOnlyThreadContextMap;
import org.apache.logging.log4j.status.StatusLogger;
import org.apache.logging.log4j.util.LoaderUtil;
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.
*
* These are the default {@code ContextDataInjector} objects returned by the {@link ContextDataInjectorFactory}.
*
*
* @see org.apache.logging.log4j.ThreadContext
* @see Property
* @see ReadOnlyStringMap
* @see ContextDataInjector
* @see ContextDataInjectorFactory
* @since 2.7
*/
public class ThreadContextDataInjector {
private static final Logger LOGGER = StatusLogger.getLogger();
/**
* ContextDataProviders loaded via OSGi.
*/
public static Collection contextDataProviders =
new ConcurrentLinkedDeque<>();
private static volatile List serviceProviders = null;
private static final Lock providerLock = new ReentrantLock();
public static void initServiceProviders() {
if (serviceProviders == null) {
providerLock.lock();
try {
if (serviceProviders == null) {
serviceProviders = getServiceProviders();
}
} finally {
providerLock.unlock();
}
}
}
private static List getServiceProviders() {
List providers = new ArrayList<>();
for (final ClassLoader classLoader : LoaderUtil.getClassLoaders()) {
try {
for (final ContextDataProvider provider : ServiceLoader.load(ContextDataProvider.class, classLoader)) {
if (providers.stream().noneMatch(p -> p.getClass().isAssignableFrom(provider.getClass()))) {
providers.add(provider);
}
}
} catch (final Throwable ex) {
LOGGER.debug("Unable to access Context Data Providers {}", ex.getMessage());
}
}
return providers;
}
/**
* Default {@code ContextDataInjector} for the legacy {@code Map}-based ThreadContext (which is
* also the ThreadContext implementation used for web applications).
*
* This injector always puts key-value pairs into the specified reusable StringMap.
*/
public static class ForDefaultThreadContextMap implements ContextDataInjector {
private final List providers;
public ForDefaultThreadContextMap() {
providers = getProviders();
}
/**
* 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 contextData 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 props, final StringMap contextData) {
final Map copy;
if (providers.size() == 1) {
copy = providers.get(0).supplyContextData();
} else {
copy = new HashMap<>();
for (ContextDataProvider provider : providers) {
copy.putAll(provider.supplyContextData());
}
}
// The DefaultThreadContextMap stores context data in a Map.
// 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 or providers 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 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 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.
*
* This injector always puts key-value pairs into the specified reusable StringMap.
*/
public static class ForGarbageFreeThreadContextMap implements ContextDataInjector {
private final List providers;
public ForGarbageFreeThreadContextMap() {
this.providers = getProviders();
}
/**
* 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 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);
for (int i = 0; i < providers.size(); ++i) {
reusable.putAll(providers.get(i).supplyStringMap());
}
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.
*
* 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 {
private final List providers;
public ForCopyOnWriteThreadContextMap() {
this.providers = getProviders();
}
/**
* 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 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.
if (providers.size() == 1 && (props == null || props.isEmpty())) {
// this will replace the LogEvent's context data with the returned instance
return providers.get(0).supplyStringMap();
}
int count = props == null ? 0 : props.size();
StringMap[] maps = new StringMap[providers.size()];
for (int i = 0; i < providers.size(); ++i) {
maps[i] = providers.get(i).supplyStringMap();
count += maps[i].size();
}
// 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(count);
copyProperties(props, result);
for (StringMap map : maps) {
result.putAll(map);
}
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 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());
}
}
}
private static List getProviders() {
initServiceProviders();
final List providers = new ArrayList<>(contextDataProviders);
if (serviceProviders != null) {
providers.addAll(serviceProviders);
}
return providers;
}
}