/*
* 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.spi;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import org.apache.logging.log4j.util.BiConsumer;
import org.apache.logging.log4j.util.ReadOnlyStringMap;
import org.apache.logging.log4j.util.PropertiesUtil;
import org.apache.logging.log4j.util.TriConsumer;
/**
* The actual ThreadContext Map. A new ThreadContext Map is created each time it is updated and the Map stored is always
* immutable. This means the Map can be passed to other threads without concern that it will be updated. Since it is
* expected that the Map will be passed to many more log events than the number of keys it contains the performance
* should be much better than if the Map was copied for each event.
*/
public class DefaultThreadContextMap implements ThreadContextMap, ReadOnlyStringMap {
/**
* Property name ({@value} ) for selecting {@code InheritableThreadLocal} (value "true") or plain
* {@code ThreadLocal} (value is not "true") in the implementation.
*/
public static final String INHERITABLE_MAP = "isThreadContextMapInheritable";
private final boolean useMap;
private final ThreadLocal<Map<String, String>> localMap;
public DefaultThreadContextMap() {
this(true);
}
public DefaultThreadContextMap(final boolean useMap) {
this.useMap = useMap;
this.localMap = createThreadLocalMap(useMap);
}
// LOG4J2-479: by default, use a plain ThreadLocal, only use InheritableThreadLocal if configured.
// (This method is package protected for JUnit tests.)
static ThreadLocal<Map<String, String>> createThreadLocalMap(final boolean isMapEnabled) {
final PropertiesUtil managerProps = PropertiesUtil.getProperties();
final boolean inheritable = managerProps.getBooleanProperty(INHERITABLE_MAP);
if (inheritable) {
return new InheritableThreadLocal<Map<String, String>>() {
@Override
protected Map<String, String> childValue(final Map<String, String> parentValue) {
return parentValue != null && isMapEnabled //
? Collections.unmodifiableMap(new HashMap<>(parentValue)) //
: null;
}
};
}
// if not inheritable, return plain ThreadLocal with null as initial value
return new ThreadLocal<>();
}
@Override
public void put(final String key, final String value) {
if (!useMap) {
return;
}
Map<String, String> map = localMap.get();
map = map == null ? new HashMap<String, String>(1) : new HashMap<>(map);
map.put(key, value);
localMap.set(Collections.unmodifiableMap(map));
}
public void putAll(final Map<String, String> m) {
if (!useMap) {
return;
}
Map<String, String> map = localMap.get();
map = map == null ? new HashMap<String, String>(m.size()) : new HashMap<>(map);
for (final Map.Entry<String, String> e : m.entrySet()) {
map.put(e.getKey(), e.getValue());
}
localMap.set(Collections.unmodifiableMap(map));
}
@Override
public String get(final String key) {
final Map<String, String> map = localMap.get();
return map == null ? null : map.get(key);
}
@Override
public void remove(final String key) {
final Map<String, String> map = localMap.get();
if (map != null) {
final Map<String, String> copy = new HashMap<>(map);
copy.remove(key);
localMap.set(Collections.unmodifiableMap(copy));
}
}
public void removeAll(final Iterable<String> keys) {
final Map<String, String> map = localMap.get();
if (map != null) {
final Map<String, String> copy = new HashMap<>(map);
for (final String key : keys) {
copy.remove(key);
}
localMap.set(Collections.unmodifiableMap(copy));
}
}
@Override
public void clear() {
localMap.remove();
}
@Override
public Map<String, String> toMap() {
return getCopy();
}
@Override
public boolean containsKey(final String key) {
final Map<String, String> map = localMap.get();
return map != null && map.containsKey(key);
}
@Override
public <V> void forEach(final BiConsumer<String, ? super V> action) {
final Map<String, String> map = localMap.get();
if (map == null) {
return;
}
for (final Map.Entry<String, String> entry : map.entrySet()) {
action.accept(entry.getKey(), (V) entry.getValue());
}
}
@Override
public <V, S> void forEach(final TriConsumer<String, ? super V, S> action, final S state) {
final Map<String, String> map = localMap.get();
if (map == null) {
return;
}
for (final Map.Entry<String, String> entry : map.entrySet()) {
action.accept(entry.getKey(), (V) entry.getValue(), state);
}
}
@SuppressWarnings("unchecked")
@Override
public <V> V getValue(final String key) {
final Map<String, String> map = localMap.get();
return (V) (map == null ? null : map.get(key));
}
@Override
public Map<String, String> getCopy() {
final Map<String, String> map = localMap.get();
return map == null ? new HashMap<String, String>() : new HashMap<>(map);
}
@Override
public Map<String, String> getImmutableMapOrNull() {
return localMap.get();
}
@Override
public boolean isEmpty() {
final Map<String, String> map = localMap.get();
return map == null || map.size() == 0;
}
@Override
public int size() {
final Map<String, String> map = localMap.get();
return map == null ? 0 : map.size();
}
@Override
public String toString() {
final Map<String, String> map = localMap.get();
return map == null ? "{}" : map.toString();
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
final Map<String, String> map = this.localMap.get();
result = prime * result + ((map == null) ? 0 : map.hashCode());
result = prime * result + Boolean.valueOf(this.useMap).hashCode();
return result;
}
@Override
public boolean equals(final Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (obj instanceof DefaultThreadContextMap) {
final DefaultThreadContextMap other = (DefaultThreadContextMap) obj;
if (this.useMap != other.useMap) {
return false;
}
}
if (!(obj instanceof ThreadContextMap)) {
return false;
}
final ThreadContextMap other = (ThreadContextMap) obj;
final Map<String, String> map = this.localMap.get();
final Map<String, String> otherMap = other.getImmutableMapOrNull();
if (map == null) {
if (otherMap != null) {
return false;
}
} else if (!map.equals(otherMap)) {
return false;
}
return true;
}
}