/**
* Method to find a named logger.
*
* <p>Note that since untrusted code may create loggers with arbitrary names this method should
* not be relied on to find Loggers for security sensitive logging. It is also important to note
* that the Logger associated with the String {@code name} may be garbage collected at any time if
* there is no strong reference to the Logger. The caller of this method must check the return
* value for null in order to properly handle the case where the Logger has been garbage
* collected.
*
* <p>
*
* @param name name of the logger
* @return matching logger or null if none is found
*/
public synchronized Logger getLogger(String name) {
LoggerWeakRef ref = namedLoggers.get(name);
if (ref == null) {
return null;
}
Logger logger = ref.get();
if (logger == null) {
// Hashtable holds stale weak reference
// to a logger which has been GC-ed.
namedLoggers.remove(name);
}
return logger;
}
// Recursive method to walk the tree below a node and set
// a new parent logger.
void walkAndSetParent(Logger parent) {
if (children == null) {
return;
}
Iterator<LogNode> values = children.values().iterator();
while (values.hasNext()) {
LogNode node = values.next();
LoggerWeakRef ref = node.loggerRef;
Logger logger = (ref == null) ? null : ref.get();
if (logger == null) {
node.walkAndSetParent(parent);
} else {
doSetParent(logger, parent);
}
}
}
/**
* Add a named logger. This does nothing and returns false if a logger with the same name is
* already registered.
*
* <p>The Logger factory methods call this method to register each newly created Logger.
*
* <p>The application should retain its own reference to the Logger object to avoid it being
* garbage collected. The LogManager may only retain a weak reference.
*
* @param logger the new logger.
* @return true if the argument logger was registered successfully, false if a logger of that name
* already exists.
* @exception NullPointerException if the logger name is null.
*/
public synchronized boolean addLogger(Logger logger) {
final String name = logger.getName();
if (name == null) {
throw new NullPointerException();
}
// cleanup some Loggers that have been GC'ed
drainLoggerRefQueueBounded();
LoggerWeakRef ref = namedLoggers.get(name);
if (ref != null) {
if (ref.get() == null) {
// It's possible that the Logger was GC'ed after the
// drainLoggerRefQueueBounded() call above so allow
// a new one to be registered.
namedLoggers.remove(name);
} else {
// We already have a registered logger with the given name.
return false;
}
}
// We're adding a new logger.
// Note that we are creating a weak reference here.
ref = new LoggerWeakRef(logger);
namedLoggers.put(name, ref);
// Apply any initial level defined for the new logger.
Level level = getLevelProperty(name + ".level", null);
if (level != null) {
doSetLevel(logger, level);
}
// Do we have a per logger handler too?
// Note: this will add a 200ms penalty
loadLoggerHandlers(logger, name, name + ".handlers");
processParentHandlers(logger, name);
// Find the new node and its parent.
LogNode node = findNode(name);
node.loggerRef = ref;
Logger parent = null;
LogNode nodep = node.parent;
while (nodep != null) {
LoggerWeakRef nodeRef = nodep.loggerRef;
if (nodeRef != null) {
parent = nodeRef.get();
if (parent != null) {
break;
}
}
nodep = nodep.parent;
}
if (parent != null) {
doSetParent(logger, parent);
}
// Walk over the children and tell them we are their new parent.
node.walkAndSetParent(logger);
// new LogNode is ready so tell the LoggerWeakRef about it
ref.setNode(node);
return true;
}