logmanager.java

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/*
 * @(#)LogManager.java	1.28 04/06/08
 *
 * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */


package java.util.logging;

import java.io.*;
import java.util.*;
import java.security.*;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.net.URL;
import sun.security.action.GetPropertyAction;

/**
 * There is a single global LogManager object that is used to
 * maintain a set of shared state about Loggers and log services.
 * <p>
 * This LogManager object:
 * <ul>
 * <li> Manages a hierarchical namespace of Logger objects.  All
 *      named Loggers are stored in this namespace.
 * <li> Manages a set of logging control properties.  These are
 *      simple key-value pairs that can be used by Handlers and
 *      other logging objects to configure themselves.
 * </ul>
 * <p>
 * The global LogManager object can be retrieved using LogManager.getLogManager().
 * The LogManager object is created during class initialization and
 * cannot subsequently be changed.
 * <p>
 * At startup the LogManager class is located using the 
 * java.util.logging.manager system property.
 * <p>
 * By default, the LogManager reads its initial configuration from 
 * a properties file "lib/logging.properties" in the JRE directory.
 * If you edit that property file you can change the default logging
 * configuration for all uses of that JRE.
 * <p>
 * In addition, the LogManager uses two optional system properties that
 * allow more control over reading the initial configuration:
 * <ul>
 * <li>"java.util.logging.config.class"
 * <li>"java.util.logging.config.file"
 * </ul>
 * These two properties may be set via the Preferences API, or as
 * command line property definitions to the "java" command, or as
 * system property definitions passed to JNI_CreateJavaVM.
 * <p>
 * If the "java.util.logging.config.class" property is set, then the
 * property value is treated as a class name.  The given class will be
 * loaded, an object will be instantiated, and that object's constructor
 * is responsible for reading in the initial configuration.  (That object
 * may use other system properties to control its configuration.)  The
 * alternate configuration class can use <tt>readConfiguration(InputStream)</tt>
 * to define properties in the LogManager.
 * <p>
 * If "java.util.logging.config.class" property is <b>not</b> set,
 * then the "java.util.logging.config.file" system property can be used
 * to specify a properties file (in java.util.Properties format). The
 * initial logging configuration will be read from this file.
 * <p>
 * If neither of these properties is defined then, as described
 * above, the LogManager will read its initial configuration from 
 * a properties file "lib/logging.properties" in the JRE directory.
 * <p>
 * The properties for loggers and Handlers will have names starting
 * with the dot-separated name for the handler or logger.
 * <p>
 * The global logging properties may include:
 * <ul>
 * <li>A property "handlers".  This defines a whitespace separated
 * list of class names for handler classes to load and register as
 * handlers on the root Logger (the Logger named "").  Each class
 * name must be for a Handler class which has a default constructor.
 * Note that these Handlers may be created lazily, when they are
 * first used.
 *
 * <li>A property "config".  This property is intended to allow
 * arbitrary configuration code to be run.  The property defines a
 * whitespace separated list of class names.  A new instance will be
 * created for each named class.  The default constructor of each class
 * may execute arbitrary code to update the logging configuration, such as
 * setting logger levels, adding handlers, adding filters, etc.
 * </ul>
 * <p>
 * Note that all classes loaded during LogManager configuration must
 * be on the system class path.  That includes the LogManager class,
 * any config classes, and any handler classes.
 * <p>
 * Loggers are organized into a naming hierarchy based on their
 * dot separated names.  Thus "a.b.c" is a child of "a.b", but
 * "a.b1" and a.b2" are peers.
 * <p>
 * All properties whose names end with ".level" are assumed to define
 * log levels for Loggers.  Thus "foo.level" defines a log level for
 * the logger called "foo" and (recursively) for any of its children
 * in the naming hierarchy.  Log Levels are applied in the order they 
 * are defined in the properties file.  Thus level settings for child
 * nodes in the tree should come after settings for their parents.
 * The property name ".level" can be used to set the level for the
 * root of the tree.
 * <p> 
 * All methods on the LogManager object are multi-thread safe.
 *
 * @version 1.28, 06/08/04
 * @since 1.4
*/

public class LogManager {
    // The global LogManager object
    private static LogManager manager;

    private final static Handler[] emptyHandlers = { };
    private Properties props = new Properties();
    private PropertyChangeSupport changes
			 = new PropertyChangeSupport(LogManager.class);
    private final static Level defaultLevel = Level.INFO;

    // Table of known loggers.  Maps names to Loggers.
    private Hashtable loggers = new Hashtable();
    // Tree of known loggers
    private LogNode root = new LogNode(null);
    private Logger rootLogger;

    // Have we done the primordial reading of the configuration file?
    // (Must be done after a suitable amount of java.lang.System
    // initialization has been done)
    private volatile boolean readPrimordialConfiguration;
    // Have we initialized global (root) handlers yet?
    // This gets set to false in readConfiguration
    private boolean initializedGlobalHandlers = true;
    // True if JVM death is imminent and the exit hook has been called.
    private boolean deathImminent;

    static {
	AccessController.doPrivileged(new PrivilegedAction() {
                public Object run() {
                    String cname = null;
		    String contextLoading = null;
                    try {
                        cname = System.getProperty("java.util.logging.manager");
                        if (cname != null) {
			    try {
                                Class clz = ClassLoader.getSystemClassLoader().loadClass(cname);
                                manager = (LogManager) clz.newInstance();
			    } catch (ClassNotFoundException ex) {
				contextLoading = System.getProperty("java.util.logging.manager.altclassloader");
				if (contextLoading != null) {
				    Class clz = Thread.currentThread().getContextClassLoader().loadClass(cname);
				    manager = (LogManager) clz.newInstance();
				} else {
				    throw ex;
				}
			    }
                        }
                    } catch (Exception ex) {
                        System.err.println("Could not load Logmanager \"" + cname + "\"");
                        ex.printStackTrace();
                    }
                    if (manager == null) {
                        manager = new LogManager();
                    }

                    // Create and retain Logger for the root of the namespace.
                    manager.rootLogger = manager.new RootLogger();
                    manager.addLogger(manager.rootLogger);

                    // We don't call readConfiguration() here, as we may be running
                    // very early in the JVM startup sequence.  Instead readConfiguration
                    // will be called lazily in getLogManager().
                    return null;
                }
            });
    }


    // This private class is used as a shutdown hook.
    // It does a "reset" to close all open handlers.
    private class Cleaner extends Thread {
	public void run() {
	    // If the global handlershaven't been initialized yet, we
	    // don't want to initialize them just so we can close them!
	    synchronized (LogManager.this) {
		// Note that death is imminent.
	        deathImminent = true;
		initializedGlobalHandlers = true;
	    }

	    // Do a reset to close all active handlers.
	    reset();
 	}
    }


    /**     
     * Protected constructor.  This is protected so that container applications
     * (such as J2EE containers) can subclass the object.  It is non-public as
     * it is intended that there only be one LogManager object, whose value is
     * retrieved by calling Logmanager.getLogManager.
     */
    protected LogManager() {
	// Add a shutdown hook to close the global handlers.
	try {
	    Runtime.getRuntime().addShutdownHook(new Cleaner());
	} catch(IllegalStateException e) {
	    // If the VM is already shutting down,
	    // We do not need to register shutdownHook.
	}
    }

    /**
     * Return the global LogManager object.
     */
    public static LogManager getLogManager() {
        if (manager != null) {
            manager.readPrimordialConfiguration();
        }
	return manager;
    }

    private void readPrimordialConfiguration() {
        if (!readPrimordialConfiguration) {
            synchronized (this) {
                if (!readPrimordialConfiguration) {
                    // If System.in/out/err are null, it's a good
                    // indication that we're still in the
                    // bootstrapping phase
                    if (System.out == null) {
                        return;
                    }
                    readPrimordialConfiguration = true;
                    try {
                        AccessController.doPrivileged(new PrivilegedExceptionAction() {
                                public Object run() throws Exception {
                                    readConfiguration();
                                    return null;
                                }
                            });
                    } catch (Exception ex) {
                        // System.err.println("Can't read logging configuration:");
                        // ex.printStackTrace();
                    }
                }
            }
        }
    }

    /**
     * Add an event listener to be invoked when the logging
     * properties are re-read.
     *
     * @param l  event listener
     * @exception  SecurityException  if a security manager exists and if
     *             the caller does not have LoggingPermission("control").
     */
    public void addPropertyChangeListener(PropertyChangeListener l) throws SecurityException {
	checkAccess();
	changes.addPropertyChangeListener(l);
    }

    /**
     * Remove an event listener for property change events.
     * <P>
     * Returns silently if the given listener is not found.
     * 
     * @param l  event listener 
     * @exception  SecurityException  if a security manager exists and if
     *             the caller does not have LoggingPermission("control").
     */
    public void removePropertyChangeListener(PropertyChangeListener l) throws SecurityException {
	checkAccess();
	changes.removePropertyChangeListener(l);
    }

    /**
     * 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) {
	String name = logger.getName();
	if (name == null) {
	    throw new NullPointerException();
	}

	Logger old = (Logger) loggers.get(name);
	if (old != null) {
	    // We already have a registered logger with the given name.
	    return false;
	}

	// We're adding a new logger.
	// Note that we are creating a strong reference here that will
	// keep the Logger in existence indefinitely.
	loggers.put(name, logger);

	// Apply any initial level defined for the new logger.
	Level level = getLevelProperty(name+".level", null);
	if (level != null) {
	    doSetLevel(logger, level);
	}

	// If any of the logger's parents have levels defined,
	// make sure they are instantiated.
	int ix = 1;
	for (;;) {
	    int ix2 = name.indexOf(".", ix);
	    if (ix2 < 0) {
		break;
	    }
	    String pname = name.substring(0,ix2);
	    if (getProperty(pname+".level") != null) {
		// This pname has a level definition.  Make sure it exists.
		Logger plogger = Logger.getLogger(pname);
	    }
	    ix = ix2+1;
	}

	// Find the new node and its parent.
	LogNode node = findNode(name);
	node.logger = logger;
	Logger parent = null;
	LogNode nodep = node.parent;
	while (nodep != null) {
	    if (nodep.logger != null) {
		parent = nodep.logger;
		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);

	return true;
    }


    // Private method to set a level on a logger.
    // If necessary, we raise privilege before doing the call.
    private static void doSetLevel(final Logger logger, final Level level) {
	SecurityManager sm = System.getSecurityManager();
	if (sm == null) {
	    // There is no security manager, so things are easy.
	    logger.setLevel(level);
	    return;
	} 
	// There is a security manager.  Raise privilege before
	// calling setLevel.
	AccessController.doPrivileged(new PrivilegedAction() {
	    public Object run() {
	        logger.setLevel(level);
		return null;
	    }});
    }



    // Private method to set a parent on a logger.
    // If necessary, we raise privilege before doing the setParent call.
    private static void doSetParent(final Logger logger, final Logger parent) {
	SecurityManager sm = System.getSecurityManager();
	if (sm == null) {
	    // There is no security manager, so things are easy.
	    logger.setParent(parent);
	    return;
	} 
	// There is a security manager.  Raise privilege before
	// calling setParent.
	AccessController.doPrivileged(new PrivilegedAction() {
	    public Object run() {
		logger.setParent(parent);
		return null;
	    }});
    }

    // Find a node in our tree of logger nodes.
    // If necessary, create it.
    private LogNode findNode(String name) {
	if (name == null || name.equals("")) {
	    return root;
	}
	LogNode node = root;
	while (name.length() > 0) {
	    int ix = name.indexOf(".");
	    String head;
	    if (ix > 0) {
		head = name.substring(0,ix);
		name = name.substring(ix+1);
	    } else {
		head = name;
		name = "";
	    }
	    if (node.children == null) {
		node.children = new HashMap();
	    }
	    LogNode child = (LogNode)node.children.get(head);
	    if (child == null) {
		child = new LogNode(node);
		node.children.put(head, child);
	    }
	    node = child;
	}
	return node;
    }

    /**
     * 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.
     * <p>
     * @param name name of the logger 
     * @return  matching logger or null if none is found
     */
    public synchronized Logger getLogger(String name) {
	return (Logger) loggers.get(name);
    }

    /**
     * Get an enumeration of known logger names.
     * <p>
     * Note:  Loggers may be added dynamically as new classes are loaded.
     * This method only reports on the loggers that are currently registered.
     * <p>
     * @return  enumeration of logger name strings
     */
    public synchronized Enumeration getLoggerNames() {
	return loggers.keys();
    }

    /**
     * Reinitialize the logging properties and reread the logging configuration.
     * <p>
     * The same rules are used for locating the configuration properties
     * as are used at startup.  So normally the logging properties will
     * be re-read from the same file that was used at startup.