Source code

001/*
002 * Licensed to the Apache Software Foundation (ASF) under one or more
003 * contributor license agreements. See the NOTICE file distributed with
004 * this work for additional information regarding copyright ownership.
005 * The ASF licenses this file to You under the Apache license, Version 2.0
006 * (the "License"); you may not use this file except in compliance with
007 * the License. You may obtain a copy of the License at
008 *
009 *      http://www.apache.org/licenses/LICENSE-2.0
010 *
011 * Unless required by applicable law or agreed to in writing, software
012 * distributed under the License is distributed on an "AS IS" BASIS,
013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014 * See the license for the specific language governing permissions and
015 * limitations under the license.
016 */
017package org.apache.logging.log4j.core.impl;
018
019import java.util.ArrayList;
020import java.util.Collection;
021import java.util.HashMap;
022import java.util.List;
023import java.util.Map;
024import java.util.ServiceLoader;
025import java.util.concurrent.ConcurrentLinkedDeque;
026import java.util.concurrent.locks.Lock;
027import java.util.concurrent.locks.ReentrantLock;
028
029import org.apache.logging.log4j.Logger;
030import org.apache.logging.log4j.ThreadContext;
031import org.apache.logging.log4j.core.ContextDataInjector;
032import org.apache.logging.log4j.core.config.Property;
033import org.apache.logging.log4j.core.util.ContextDataProvider;
034import org.apache.logging.log4j.spi.ReadOnlyThreadContextMap;
035import org.apache.logging.log4j.status.StatusLogger;
036import org.apache.logging.log4j.util.LoaderUtil;
037import org.apache.logging.log4j.util.ReadOnlyStringMap;
038import org.apache.logging.log4j.util.StringMap;
039
040/**
041 * {@code ThreadContextDataInjector} contains a number of strategies for copying key-value pairs from the various
042 * {@code ThreadContext} map implementations into a {@code StringMap}. In the case of duplicate keys,
043 * thread context values overwrite configuration {@code Property} values.
044 * <p>
045 * These are the default {@code ContextDataInjector} objects returned by the {@link ContextDataInjectorFactory}.
046 * </p>
047 *
048 * @see org.apache.logging.log4j.ThreadContext
049 * @see Property
050 * @see ReadOnlyStringMap
051 * @see ContextDataInjector
052 * @see ContextDataInjectorFactory
053 * @since 2.7
054 */
055public class ThreadContextDataInjector {
056
057    private static final Logger LOGGER = StatusLogger.getLogger();
058
059    /**
060     * ContextDataProviders loaded via OSGi.
061     */
062    public static Collection<ContextDataProvider> contextDataProviders =
063            new ConcurrentLinkedDeque<>();
064
065    private static volatile List<ContextDataProvider> serviceProviders = null;
066    private static final Lock providerLock = new ReentrantLock();
067
068    public static void initServiceProviders() {
069        if (serviceProviders == null) {
070            providerLock.lock();
071            try {
072                if (serviceProviders == null) {
073                    serviceProviders = getServiceProviders();
074                }
075            } finally {
076                providerLock.unlock();
077            }
078        }
079    }
080
081    private static List<ContextDataProvider> getServiceProviders() {
082        List<ContextDataProvider> providers = new ArrayList<>();
083        for (final ClassLoader classLoader : LoaderUtil.getClassLoaders()) {
084            try {
085                for (final ContextDataProvider provider : ServiceLoader.load(ContextDataProvider.class, classLoader)) {
086                    if (providers.stream().noneMatch(p -> p.getClass().isAssignableFrom(provider.getClass()))) {
087                        providers.add(provider);
088                    }
089                }
090            } catch (final Throwable ex) {
091                LOGGER.debug("Unable to access Context Data Providers {}", ex.getMessage());
092            }
093        }
094        return providers;
095    }
096
097    /**
098     * Default {@code ContextDataInjector} for the legacy {@code Map<String, String>}-based ThreadContext (which is
099     * also the ThreadContext implementation used for web applications).
100     * <p>
101     * This injector always puts key-value pairs into the specified reusable StringMap.
102     */
103    public static class ForDefaultThreadContextMap implements ContextDataInjector {
104
105        private final List<ContextDataProvider> providers;
106
107        public ForDefaultThreadContextMap() {
108            providers = getProviders();
109        }
110
111        /**
112         * Puts key-value pairs from both the specified list of properties as well as the thread context into the
113         * specified reusable StringMap.
114         *
115         * @param props list of configuration properties, may be {@code null}
116         * @param contextData a {@code StringMap} instance from the log event
117         * @return a {@code StringMap} combining configuration properties with thread context data
118         */
119        @Override
120        public StringMap injectContextData(final List<Property> props, final StringMap contextData) {
121
122            final Map<String, String> copy;
123
124            if (providers.size() == 1) {
125                copy = providers.get(0).supplyContextData();
126            } else {
127                copy = new HashMap<>();
128                for (ContextDataProvider provider : providers) {
129                    copy.putAll(provider.supplyContextData());
130                }
131            }
132
133            // The DefaultThreadContextMap stores context data in a Map<String, String>.
134            // This is a copy-on-write data structure so we are sure ThreadContext changes will not affect our copy.
135            // If there are no configuration properties or providers returning a thin wrapper around the copy
136            // is faster than copying the elements into the LogEvent's reusable StringMap.
137            if ((props == null || props.isEmpty())) {
138                // this will replace the LogEvent's context data with the returned instance.
139                // NOTE: must mark as frozen or downstream components may attempt to modify (UnsupportedOperationEx)
140                return copy.isEmpty() ? ContextDataFactory.emptyFrozenContextData() : frozenStringMap(copy);
141            }
142            // If the list of Properties is non-empty we need to combine the properties and the ThreadContext
143            // data. Note that we cannot reuse the specified StringMap: some Loggers may have properties defined
144            // and others not, so the LogEvent's context data may have been replaced with an immutable copy from
145            // the ThreadContext - this will throw an UnsupportedOperationException if we try to modify it.
146            final StringMap result = new JdkMapAdapterStringMap(new HashMap<>(copy));
147            for (int i = 0; i < props.size(); i++) {
148                final Property prop = props.get(i);
149                if (!copy.containsKey(prop.getName())) {
150                    result.putValue(prop.getName(), prop.getValue());
151                }
152            }
153            result.freeze();
154            return result;
155        }
156
157        private static JdkMapAdapterStringMap frozenStringMap(final Map<String, String> copy) {
158            final JdkMapAdapterStringMap result = new JdkMapAdapterStringMap(copy);
159            result.freeze();
160            return result;
161        }
162
163        @Override
164        public ReadOnlyStringMap rawContextData() {
165            final ReadOnlyThreadContextMap map = ThreadContext.getThreadContextMap();
166            if (map instanceof ReadOnlyStringMap) {
167                return (ReadOnlyStringMap) map;
168            }
169            // note: default ThreadContextMap is null
170            final Map<String, String> copy = ThreadContext.getImmutableContext();
171            return copy.isEmpty() ? ContextDataFactory.emptyFrozenContextData() : new JdkMapAdapterStringMap(copy);
172        }
173    }
174
175    /**
176     * The {@code ContextDataInjector} used when the ThreadContextMap implementation is a garbage-free
177     * StringMap-based data structure.
178     * <p>
179     * This injector always puts key-value pairs into the specified reusable StringMap.
180     */
181    public static class ForGarbageFreeThreadContextMap implements ContextDataInjector {
182        private final List<ContextDataProvider> providers;
183
184        public ForGarbageFreeThreadContextMap() {
185            this.providers = getProviders();
186        }
187
188        /**
189         * Puts key-value pairs from both the specified list of properties as well as the thread context into the
190         * specified reusable StringMap.
191         *
192         * @param props list of configuration properties, may be {@code null}
193         * @param reusable a {@code StringMap} instance that may be reused to avoid creating temporary objects
194         * @return a {@code StringMap} combining configuration properties with thread context data
195         */
196        @Override
197        public StringMap injectContextData(final List<Property> props, final StringMap reusable) {
198            // When the ThreadContext is garbage-free, we must copy its key-value pairs into the specified reusable
199            // StringMap. We cannot return the ThreadContext's internal data structure because it may be modified later
200            // and such modifications should not be reflected in the log event.
201            copyProperties(props, reusable);
202            for (int i = 0; i < providers.size(); ++i) {
203                reusable.putAll(providers.get(i).supplyStringMap());
204            }
205            return reusable;
206        }
207
208        @Override
209        public ReadOnlyStringMap rawContextData() {
210            return ThreadContext.getThreadContextMap().getReadOnlyContextData();
211        }
212    }
213
214    /**
215     * The {@code ContextDataInjector} used when the ThreadContextMap implementation is a copy-on-write
216     * StringMap-based data structure.
217     * <p>
218     * If there are no configuration properties, this injector will return the thread context's internal data
219     * structure. Otherwise the configuration properties are combined with the thread context key-value pairs into the
220     * specified reusable StringMap.
221     */
222    public static class ForCopyOnWriteThreadContextMap implements ContextDataInjector {
223        private final List<ContextDataProvider> providers;
224
225        public ForCopyOnWriteThreadContextMap() {
226            this.providers = getProviders();
227        }
228        /**
229         * If there are no configuration properties, this injector will return the thread context's internal data
230         * structure. Otherwise the configuration properties are combined with the thread context key-value pairs into the
231         * specified reusable StringMap.
232         *
233         * @param props list of configuration properties, may be {@code null}
234         * @param ignore a {@code StringMap} instance from the log event
235         * @return a {@code StringMap} combining configuration properties with thread context data
236         */
237        @Override
238        public StringMap injectContextData(final List<Property> props, final StringMap ignore) {
239            // If there are no configuration properties we want to just return the ThreadContext's StringMap:
240            // it is a copy-on-write data structure so we are sure ThreadContext changes will not affect our copy.
241            if (providers.size() == 1 && (props == null || props.isEmpty())) {
242                // this will replace the LogEvent's context data with the returned instance
243                return providers.get(0).supplyStringMap();
244            }
245            int count = props == null ? 0 : props.size();
246            StringMap[] maps = new StringMap[providers.size()];
247            for (int i = 0; i < providers.size(); ++i) {
248                maps[i] = providers.get(i).supplyStringMap();
249                count += maps[i].size();
250            }
251            // However, if the list of Properties is non-empty we need to combine the properties and the ThreadContext
252            // data. Note that we cannot reuse the specified StringMap: some Loggers may have properties defined
253            // and others not, so the LogEvent's context data may have been replaced with an immutable copy from
254            // the ThreadContext - this will throw an UnsupportedOperationException if we try to modify it.
255            final StringMap result = ContextDataFactory.createContextData(count);
256            copyProperties(props, result);
257            for (StringMap map : maps) {
258                result.putAll(map);
259            }
260            return result;
261        }
262
263        @Override
264        public ReadOnlyStringMap rawContextData() {
265            return ThreadContext.getThreadContextMap().getReadOnlyContextData();
266        }
267    }
268
269    /**
270     * Copies key-value pairs from the specified property list into the specified {@code StringMap}.
271     *
272     * @param properties list of configuration properties, may be {@code null}
273     * @param result the {@code StringMap} object to add the key-values to. Must be non-{@code null}.
274     */
275    public static void copyProperties(final List<Property> properties, final StringMap result) {
276        if (properties != null) {
277            for (int i = 0; i < properties.size(); i++) {
278                final Property prop = properties.get(i);
279                result.putValue(prop.getName(), prop.getValue());
280            }
281        }
282    }
283
284    private static List<ContextDataProvider> getProviders() {
285        initServiceProviders();
286        final List<ContextDataProvider> providers = new ArrayList<>(contextDataProviders);
287        if (serviceProviders != null) {
288            providers.addAll(serviceProviders);
289        }
290        return providers;
291    }
292}