org.apache.logging.log4j.spi.CopyOnWriteSortedArrayThreadContextMap Maven / Gradle / Ivy
/*
* 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 java.util.Objects;
import org.apache.logging.log4j.util.ReadOnlyStringMap;
import org.apache.logging.log4j.util.SortedArrayStringMap;
import org.apache.logging.log4j.util.StringMap;
import org.apache.logging.log4j.util.PropertiesUtil;
/**
* {@code SortedArrayStringMap}-based implementation of the {@code ThreadContextMap} interface that creates a copy of
* the data structure on every modification. Any particular instance of the data structure is a snapshot of the
* ThreadContext at some point in time and can safely be passed off to other threads. 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.
*
* @since 2.7
*/
class CopyOnWriteSortedArrayThreadContextMap implements ReadOnlyThreadContextMap, ObjectThreadContextMap, CopyOnWrite {
/**
* 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";
/**
* The default initial capacity.
*/
protected static final int DEFAULT_INITIAL_CAPACITY = 16;
/**
* System property name that can be used to control the data structure's initial capacity.
*/
protected static final String PROPERTY_NAME_INITIAL_CAPACITY = "log4j2.ThreadContext.initial.capacity";
private static final StringMap EMPTY_CONTEXT_DATA = new SortedArrayStringMap(1);
private static volatile int initialCapacity;
private static volatile boolean inheritableMap;
/**
* Initializes static variables based on system properties. Normally called when this class is initialized by the VM
* and when Log4j is reconfigured.
*/
static void init() {
final PropertiesUtil properties = PropertiesUtil.getProperties();
initialCapacity = properties.getIntegerProperty(PROPERTY_NAME_INITIAL_CAPACITY, DEFAULT_INITIAL_CAPACITY);
inheritableMap = properties.getBooleanProperty(INHERITABLE_MAP);
}
static {
EMPTY_CONTEXT_DATA.freeze();
init();
}
private final ThreadLocal localMap;
public CopyOnWriteSortedArrayThreadContextMap() {
this.localMap = createThreadLocalMap();
}
// LOG4J2-479: by default, use a plain ThreadLocal, only use InheritableThreadLocal if configured.
// (This method is package protected for JUnit tests.)
private ThreadLocal createThreadLocalMap() {
if (inheritableMap) {
return new InheritableThreadLocal() {
@Override
protected StringMap childValue(final StringMap parentValue) {
if (parentValue == null) {
return null;
}
final StringMap stringMap = createStringMap(parentValue);
stringMap.freeze();
return stringMap;
}
};
}
// if not inheritable, return plain ThreadLocal with null as initial value
return new ThreadLocal<>();
}
/**
* Returns an implementation of the {@code StringMap} used to back this thread context map.
*
* Subclasses may override.
*
* @return an implementation of the {@code StringMap} used to back this thread context map
*/
protected StringMap createStringMap() {
return new SortedArrayStringMap(initialCapacity);
}
/**
* Returns an implementation of the {@code StringMap} used to back this thread context map, pre-populated
* with the contents of the specified context data.
*
* Subclasses may override.
*
* @param original the key-value pairs to initialize the returned context data with
* @return an implementation of the {@code StringMap} used to back this thread context map
*/
protected StringMap createStringMap(final ReadOnlyStringMap original) {
return new SortedArrayStringMap(original);
}
@Override
public void put(final String key, final String value) {
putValue(key, value);
}
@Override
public void putValue(final String key, final Object value) {
StringMap map = localMap.get();
map = map == null ? createStringMap() : createStringMap(map);
map.putValue(key, value);
map.freeze();
localMap.set(map);
}
@Override
public void putAll(final Map values) {
if (values == null || values.isEmpty()) {
return;
}
StringMap map = localMap.get();
map = map == null ? createStringMap() : createStringMap(map);
for (final Map.Entry entry : values.entrySet()) {
map.putValue(entry.getKey(), entry.getValue());
}
map.freeze();
localMap.set(map);
}
@Override
public void putAllValues(final Map values) {
if (values == null || values.isEmpty()) {
return;
}
StringMap map = localMap.get();
map = map == null ? createStringMap() : createStringMap(map);
for (final Map.Entry entry : values.entrySet()) {
map.putValue(entry.getKey(), entry.getValue());
}
map.freeze();
localMap.set(map);
}
@Override
public String get(final String key) {
return (String) getValue(key);
}
@Override
public V getValue(final String key) {
final StringMap map = localMap.get();
return map == null ? null : map.getValue(key);
}
@Override
public void remove(final String key) {
final StringMap map = localMap.get();
if (map != null) {
final StringMap copy = createStringMap(map);
copy.remove(key);
copy.freeze();
localMap.set(copy);
}
}
@Override
public void removeAll(final Iterable keys) {
final StringMap map = localMap.get();
if (map != null) {
final StringMap copy = createStringMap(map);
for (final String key : keys) {
copy.remove(key);
}
copy.freeze();
localMap.set(copy);
}
}
@Override
public void clear() {
localMap.remove();
}
@Override
public boolean containsKey(final String key) {
final StringMap map = localMap.get();
return map != null && map.containsKey(key);
}
@Override
public Map getCopy() {
final StringMap map = localMap.get();
return map == null ? new HashMap<>() : map.toMap();
}
/**
* {@inheritDoc}
*/
@Override
public StringMap getReadOnlyContextData() {
final StringMap map = localMap.get();
return map == null ? EMPTY_CONTEXT_DATA : map;
}
@Override
public Map getImmutableMapOrNull() {
final StringMap map = localMap.get();
return map == null ? null : Collections.unmodifiableMap(map.toMap());
}
@Override
public boolean isEmpty() {
final StringMap map = localMap.get();
return map == null || map.isEmpty();
}
@Override
public String toString() {
final StringMap map = localMap.get();
return map == null ? "{}" : map.toString();
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
final StringMap map = this.localMap.get();
result = prime * result + ((map == null) ? 0 : map.hashCode());
return result;
}
@Override
public boolean equals(final Object obj) {
if (this == obj) {
return true;
}
if (obj == null) {
return false;
}
if (!(obj instanceof ThreadContextMap)) {
return false;
}
final ThreadContextMap other = (ThreadContextMap) obj;
final Map map = this.getImmutableMapOrNull();
final Map otherMap = other.getImmutableMapOrNull();
return Objects.equals(map, otherMap);
}
}