ch.qos.logback.classic.util.LogbackMDCAdapterSimple Maven / Gradle / Ivy
/**
* Logback: the reliable, generic, fast and flexible logging framework.
* Copyright (C) 1999-2015, QOS.ch. All rights reserved.
*
* This program and the accompanying materials are dual-licensed under
* either the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation
*
* or (per the licensee's choosing)
*
* under the terms of the GNU Lesser General Public License version 2.1
* as published by the Free Software Foundation.
*/
package ch.qos.logback.classic.util;
import java.util.Collections;
import java.util.Deque;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
import org.slf4j.helpers.ThreadLocalMapOfStacks;
import org.slf4j.spi.MDCAdapter;
/**
* A Mapped Diagnostic Context, or MDC in short, is an instrument for
* distinguishing interleaved log output from different sources. Log output is
* typically interleaved when a server handles multiple clients
* near-simultaneously.
*
* The MDC is managed on a per thread basis. Note that a child
* thread does not inherit the mapped diagnostic context of its parent.
*
*
* For more information about MDC, please refer to the online manual at
* http://logback.qos.ch/manual/mdc.html
*
* @author Ceki Gülcü
*/
public class LogbackMDCAdapterSimple implements MDCAdapter {
// We wish to avoid unnecessarily copying of the map. To ensure
// efficient/timely copying, we have a variable keeping track of the previous
// operation. A copy is necessary on 'put' or 'remove' but only if the last
// operation was a 'get'. Get operations never necessitate a copy nor
// successive 'put/remove' operations, only a get followed by a 'put/remove'
// requires copying the map.
// See http://jira.qos.ch/browse/LOGBACK-620 for the original discussion.
// We no longer use CopyOnInheritThreadLocal in order to solve LBCLASSIC-183
// Initially the contents of the thread local in parent and child threads
// reference the same map. However, as soon as a thread invokes the put()
// method, the maps diverge as they should.
// final ThreadLocal> modifiableMap = new ThreadLocal>();
final ThreadLocal> threadLocalUnmodifiableMap = new ThreadLocal>();
// private static final int WRITE_OPERATION = 1;
// private static final int MAP_COPY_OPERATION = 2;
// keeps track of the previous operation performed
// final ThreadLocal previousOperation = new ThreadLocal();
private final ThreadLocalMapOfStacks threadLocalMapOfDeques = new ThreadLocalMapOfStacks();
// private Integer getAndSetPreviousOperation(int op) {
// Integer penultimateOp = previousOperation.get();
// previousOperation.set(op);
// return penultimateOp;
// }
// private boolean wasPreviousOpReadOrNull(Integer lastOp) {
// return lastOp == null || lastOp.intValue() == MAP_COPY_OPERATION;
// }
// private Map duplicateAndInsertNewMap(Map oldMap) {
// Map newMap = duplicateOldMap(oldMap);
// modifiableMap.set(newMap);
// return newMap;
// }
private Map duplicateMap(Map oldMap) {
if(oldMap != null)
return new HashMap<>(oldMap);
else
return new HashMap<>();
}
/**
* Put a context value (the val parameter) as identified with the
* key parameter into the current thread's context map. Note that
* contrary to log4j, the val parameter can be null.
*
*
* If the current thread does not have a context map it is created as a side
* effect of this call.
*
* @throws IllegalArgumentException in case the "key" parameter is null
*/
public void put(String key, String val) throws IllegalArgumentException {
if (key == null) {
throw new IllegalArgumentException("key cannot be null");
}
Map oldMap = threadLocalUnmodifiableMap.get();
Map newMap = duplicateMap(oldMap);
newMap.put(key, val);
makeUnmodifiableAndThreadLocalSet(newMap);
}
private void makeUnmodifiableAndThreadLocalSet(Map aMap) {
Map unmodifiable = Collections.unmodifiableMap(aMap);
threadLocalUnmodifiableMap.set(unmodifiable);
}
/**
* Remove the context identified by the key parameter.
*
*/
public void remove(String key) {
if (key == null) {
return;
}
Map oldMap = threadLocalUnmodifiableMap.get();
if (oldMap == null)
return;
Map newMap = duplicateMap(oldMap);
newMap.remove(key);
makeUnmodifiableAndThreadLocalSet(newMap);
}
/**
* Clear all entries in the MDC.
*/
public void clear() {
threadLocalUnmodifiableMap.remove();
}
/**
* Get the context identified by the key parameter.
*
*/
public String get(String key) {
final Map map = threadLocalUnmodifiableMap.get();
if ((map != null) && (key != null)) {
return map.get(key);
} else {
return null;
}
}
/**
* Get the current thread's MDC as a map. This method is intended to be used
* internally.
*/
public Map getPropertyMap() {
return threadLocalUnmodifiableMap.get();
}
/**
* Returns the keys in the MDC as a {@link Set}. The returned value can be null.
*/
public Set getKeys() {
Map map = getPropertyMap();
if (map != null) {
return map.keySet();
} else {
return null;
}
}
/**
* Return a copy of the current thread's context map. Returned value may be
* null.
*/
public Map getCopyOfContextMap() {
Map hashMap = threadLocalUnmodifiableMap.get();
return duplicateMap(hashMap);
}
/**
* Set the MDC map to the map passed as parameter.
*
* @param contextMap the new map
*/
public void setContextMap(Map contextMap) {
duplicateMap(contextMap);
}
@Override
public void pushByKey(String key, String value) {
threadLocalMapOfDeques.pushByKey(key, value);
}
@Override
public String popByKey(String key) {
return threadLocalMapOfDeques.popByKey(key);
}
@Override
public Deque getCopyOfDequeByKey(String key) {
return threadLocalMapOfDeques.getCopyOfDequeByKey(key);
}
@Override
public void clearDequeByKey(String key) {
threadLocalMapOfDeques.clearDequeByKey(key);
}
}