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 */ 017 package org.apache.logging.log4j.spi; 018 019 import java.util.Collections; 020 import java.util.HashMap; 021 import java.util.Map; 022 023 import org.apache.logging.log4j.util.PropertiesUtil; 024 025 /** 026 * The actual ThreadContext Map. A new ThreadContext Map is created each time it is updated and the Map stored 027 * is always immutable. This means the Map can be passed to other threads without concern that it will be updated. 028 * Since it is expected that the Map will be passed to many more log events than the number of keys it contains 029 * the performance should be much better than if the Map was copied for each event. 030 */ 031 public class DefaultThreadContextMap implements ThreadContextMap { 032 /** 033 * Property name ({@value}) for selecting {@code InheritableThreadLocal} (value "true") 034 * or plain {@code ThreadLocal} (value is not "true") in the implementation. 035 */ 036 public static final String INHERITABLE_MAP = "isThreadContextMapInheritable"; 037 038 private final boolean useMap; 039 private final ThreadLocal<Map<String, String>> localMap; 040 041 public DefaultThreadContextMap(final boolean useMap) { 042 this.useMap = useMap; 043 this.localMap = createThreadLocalMap(useMap); 044 } 045 046 // LOG4J2-479: by default, use a plain ThreadLocal, only use InheritableThreadLocal if configured. 047 // (This method is package protected for JUnit tests.) 048 static ThreadLocal<Map<String, String>> createThreadLocalMap(final boolean isMapEnabled) { 049 final PropertiesUtil managerProps = PropertiesUtil.getProperties(); 050 final boolean inheritable = managerProps.getBooleanProperty(INHERITABLE_MAP); 051 if (inheritable) { 052 return new InheritableThreadLocal<Map<String, String>>() { 053 @Override 054 protected Map<String, String> childValue(final Map<String, String> parentValue) { 055 return parentValue != null && isMapEnabled // 056 ? Collections.unmodifiableMap(new HashMap<String, String>(parentValue)) // 057 : null; 058 } 059 }; 060 } 061 // if not inheritable, return plain ThreadLocal with null as initial value 062 return new ThreadLocal<Map<String, String>>(); 063 } 064 065 /** 066 * Put a context value (the <code>o</code> parameter) as identified 067 * with the <code>key</code> parameter into the current thread's 068 * context map. 069 * <p/> 070 * <p>If the current thread does not have a context map it is 071 * created as a side effect. 072 * @param key The key name. 073 * @param value The key value. 074 */ 075 @Override 076 public void put(final String key, final String value) { 077 if (!useMap) { 078 return; 079 } 080 Map<String, String> map = localMap.get(); 081 map = map == null ? new HashMap<String, String>() : new HashMap<String, String>(map); 082 map.put(key, value); 083 localMap.set(Collections.unmodifiableMap(map)); 084 } 085 086 /** 087 * Get the context identified by the <code>key</code> parameter. 088 * <p/> 089 * <p>This method has no side effects. 090 * @param key The key to locate. 091 * @return The value associated with the key or null. 092 */ 093 @Override 094 public String get(final String key) { 095 final Map<String, String> map = localMap.get(); 096 return map == null ? null : map.get(key); 097 } 098 099 /** 100 * Remove the the context identified by the <code>key</code> 101 * parameter. 102 * @param key The key to remove. 103 */ 104 @Override 105 public void remove(final String key) { 106 final Map<String, String> map = localMap.get(); 107 if (map != null) { 108 final Map<String, String> copy = new HashMap<String, String>(map); 109 copy.remove(key); 110 localMap.set(Collections.unmodifiableMap(copy)); 111 } 112 } 113 114 /** 115 * Clear the context. 116 */ 117 @Override 118 public void clear() { 119 localMap.remove(); 120 } 121 122 /** 123 * Determine if the key is in the context. 124 * @param key The key to locate. 125 * @return True if the key is in the context, false otherwise. 126 */ 127 @Override 128 public boolean containsKey(final String key) { 129 final Map<String, String> map = localMap.get(); 130 return map != null && map.containsKey(key); 131 } 132 133 /** 134 * Returns a non-{@code null} mutable copy of the ThreadContext Map. 135 * @return a non-{@code null} mutable copy of the context. 136 */ 137 @Override 138 public Map<String, String> getCopy() { 139 final Map<String, String> map = localMap.get(); 140 return map == null ? new HashMap<String, String>() : new HashMap<String, String>(map); 141 } 142 143 /** 144 * Returns either {@code null} or an immutable view of the context Map. 145 * @return the Context Map. 146 */ 147 @Override 148 public Map<String, String> getImmutableMapOrNull() { 149 return localMap.get(); 150 } 151 152 /** 153 * Returns true if the Map is empty. 154 * @return true if the Map is empty, false otherwise. 155 */ 156 @Override 157 public boolean isEmpty() { 158 final Map<String, String> map = localMap.get(); 159 return map == null || map.size() == 0; 160 } 161 162 @Override 163 public String toString() { 164 Map<String, String> map = localMap.get(); 165 return map == null ? "{}" : map.toString(); 166 } 167 168 @Override 169 public int hashCode() { 170 final int prime = 31; 171 int result = 1; 172 Map<String, String> map = this.localMap.get(); 173 result = prime * result + ((map == null) ? 0 : map.hashCode()); 174 result = prime * result + (this.useMap ? 1231 : 1237); 175 return result; 176 } 177 178 @Override 179 public boolean equals(Object obj) { 180 if (this == obj) { 181 return true; 182 } 183 if (obj == null) { 184 return false; 185 } 186 if (obj instanceof DefaultThreadContextMap) { 187 DefaultThreadContextMap other = (DefaultThreadContextMap) obj; 188 if (this.useMap != other.useMap) { 189 return false; 190 } 191 } 192 if (!(obj instanceof ThreadContextMap)) { 193 return false; 194 } 195 ThreadContextMap other = (ThreadContextMap) obj; 196 Map<String, String> map = this.localMap.get(); 197 Map<String, String> otherMap = other.getImmutableMapOrNull(); 198 if (map == null) { 199 if (otherMap != null) { 200 return false; 201 } 202 } else if (!map.equals(otherMap)) { 203 return false; 204 } 205 return true; 206 } 207 }