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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * under the terms of the GNU General Public License version 2 only, as

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 * particular file as subject to the "Classpath" exception as provided

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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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 * accompanied this code).

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package java.util.logging;

import java.util.*;

import java.util.concurrent.CopyOnWriteArrayList;

import java.security.*;

import java.lang.ref.WeakReference;

/**

 * A Logger object is used to log messages for a specific

 * system or application component.  Loggers are normally named,

 * using a hierarchical dot-separated namespace.  Logger names

 * can be arbitrary strings, but they should normally be based on

 * the package name or class name of the logged component, such

 * as java.net or javax.swing.  In addition it is possible to create

 * "anonymous" Loggers that are not stored in the Logger namespace.

 * <p>

 * Logger objects may be obtained by calls on one of the getLogger

 * factory methods.  These will either create a new Logger or

 * return a suitable existing Logger. It is important to note that

 * the Logger returned by one of the {@code getLogger} factory methods

 * may be garbage collected at any time if a strong reference to the

 * Logger is not kept.

 * <p>

 * Logging messages will be forwarded to registered Handler

 * objects, which can forward the messages to a variety of

 * destinations, including consoles, files, OS logs, etc.

 * <p>

 * Each Logger keeps track of a "parent" Logger, which is its

 * nearest existing ancestor in the Logger namespace.

 * <p>

 * Each Logger has a "Level" associated with it.  This reflects

 * a minimum Level that this logger cares about.  If a Logger's

 * level is set to <tt>null</tt>, then its effective level is inherited

 * from its parent, which may in turn obtain it recursively from its

 * parent, and so on up the tree.

 * <p>

 * The log level can be configured based on the properties from the

 * logging configuration file, as described in the description

 * of the LogManager class.  However it may also be dynamically changed

 * by calls on the Logger.setLevel method.  If a logger's level is

 * changed the change may also affect child loggers, since any child

 * logger that has <tt>null</tt> as its level will inherit its

 * effective level from its parent.

 * <p>

 * On each logging call the Logger initially performs a cheap

 * check of the request level (e.g., SEVERE or FINE) against the

 * effective log level of the logger.  If the request level is

 * lower than the log level, the logging call returns immediately.

 * <p>

 * After passing this initial (cheap) test, the Logger will allocate

 * a LogRecord to describe the logging message.  It will then call a

 * Filter (if present) to do a more detailed check on whether the

 * record should be published.  If that passes it will then publish

 * the LogRecord to its output Handlers.  By default, loggers also

 * publish to their parent's Handlers, recursively up the tree.

 * <p>

 * Each Logger may have a ResourceBundle name associated with it.

 * The named bundle will be used for localizing logging messages.

 * If a Logger does not have its own ResourceBundle name, then

 * it will inherit the ResourceBundle name from its parent,

 * recursively up the tree.

 * <p>

 * Most of the logger output methods take a "msg" argument.  This

 * msg argument may be either a raw value or a localization key.

 * During formatting, if the logger has (or inherits) a localization

 * ResourceBundle and if the ResourceBundle has a mapping for the msg

 * string, then the msg string is replaced by the localized value.

 * Otherwise the original msg string is used.  Typically, formatters use

 * java.text.MessageFormat style formatting to format parameters, so

 * for example a format string "{0} {1}" would format two parameters

 * as strings.

 * <p>

 * When mapping ResourceBundle names to ResourceBundles, the Logger

 * will first try to use the Thread's ContextClassLoader.  If that

 * is null it will try the SystemClassLoader instead.  As a temporary

 * transition feature in the initial implementation, if the Logger is

 * unable to locate a ResourceBundle from the ContextClassLoader or

 * SystemClassLoader the Logger will also search up the class stack

 * and use successive calling ClassLoaders to try to locate a ResourceBundle.

 * (This call stack search is to allow containers to transition to

 * using ContextClassLoaders and is likely to be removed in future

 * versions.)

 * <p>

 * Formatting (including localization) is the responsibility of

 * the output Handler, which will typically call a Formatter.

 * <p>

 * Note that formatting need not occur synchronously.  It may be delayed

 * until a LogRecord is actually written to an external sink.

 * <p>

 * The logging methods are grouped in five main categories:

 * <ul>

 * <li><p>

 *     There are a set of "log" methods that take a log level, a message

 *     string, and optionally some parameters to the message string.

 * <li><p>

 *     There are a set of "logp" methods (for "log precise") that are

 *     like the "log" methods, but also take an explicit source class name

 *     and method name.

 * <li><p>

 *     There are a set of "logrb" method (for "log with resource bundle")

 *     that are like the "logp" method, but also take an explicit resource

 *     bundle name for use in localizing the log message.

 * <li><p>

 *     There are convenience methods for tracing method entries (the

 *     "entering" methods), method returns (the "exiting" methods) and

 *     throwing exceptions (the "throwing" methods).

 * <li><p>

 *     Finally, there are a set of convenience methods for use in the

 *     very simplest cases, when a developer simply wants to log a

 *     simple string at a given log level.  These methods are named

 *     after the standard Level names ("severe", "warning", "info", etc.)

 *     and take a single argument, a message string.

 * </ul>

 * <p>

 * For the methods that do not take an explicit source name and

 * method name, the Logging framework will make a "best effort"

 * to determine which class and method called into the logging method.

 * However, it is important to realize that this automatically inferred

 * information may only be approximate (or may even be quite wrong!).

 * Virtual machines are allowed to do extensive optimizations when

 * JITing and may entirely remove stack frames, making it impossible

 * to reliably locate the calling class and method.

 * <P>

 * All methods on Logger are multi-thread safe.

 * <p>

 * <b>Subclassing Information:</b> Note that a LogManager class may

 * provide its own implementation of named Loggers for any point in

 * the namespace.  Therefore, any subclasses of Logger (unless they

 * are implemented in conjunction with a new LogManager class) should

 * take care to obtain a Logger instance from the LogManager class and

 * should delegate operations such as "isLoggable" and "log(LogRecord)"

 * to that instance.  Note that in order to intercept all logging

 * output, subclasses need only override the log(LogRecord) method.

 * All the other logging methods are implemented as calls on this

 * log(LogRecord) method.

 *

 * @since 1.4

 */

public class Logger {

    private static final Handler emptyHandlers[] = new Handler[0];

    private static final int offValue = Level.OFF.intValue();

    private LogManager manager;

    private String name;

    private final CopyOnWriteArrayList<Handler> handlers =

        new CopyOnWriteArrayList<>();

    private String resourceBundleName;

    private volatile boolean useParentHandlers = true;

    private volatile Filter filter;

    private boolean anonymous;

    private ResourceBundle catalog;     // Cached resource bundle

    private String catalogName;         // name associated with catalog

    private Locale catalogLocale;       // locale associated with catalog

    // The fields relating to parent-child relationships and levels

    // are managed under a separate lock, the treeLock.

    private static Object treeLock = new Object();

    // We keep weak references from parents to children, but strong

    // references from children to parents.

    private volatile Logger parent;    // our nearest parent.

    private ArrayList<LogManager.LoggerWeakRef> kids;   // WeakReferences to loggers that have us as parent

    private volatile Level levelObject;

    private volatile int levelValue;  // current effective level value

    /**

     * GLOBAL_LOGGER_NAME is a name for the global logger.

     *

     * @since 1.6

     */

    public static final String GLOBAL_LOGGER_NAME = "global";

    /**

     * Return global logger object with the name Logger.GLOBAL_LOGGER_NAME.

     *

     * @return global logger object

     * @since 1.7

     */

    public static final Logger getGlobal() {

        return global;

    }

    /**

     * The "global" Logger object is provided as a convenience to developers

     * who are making casual use of the Logging package.  Developers

     * who are making serious use of the logging package (for example

     * in products) should create and use their own Logger objects,

     * with appropriate names, so that logging can be controlled on a

     * suitable per-Logger granularity. Developers also need to keep a

     * strong reference to their Logger objects to prevent them from

     * being garbage collected.

     * <p>

     * @deprecated Initialization of this field is prone to deadlocks.

     * The field must be initialized by the Logger class initialization

     * which may cause deadlocks with the LogManager class initialization.

     * In such cases two class initialization wait for each other to complete.

     * The preferred way to get the global logger object is via the call

     * <code>Logger.getGlobal()</code>.

     * For compatibility with old JDK versions where the

     * <code>Logger.getGlobal()</code> is not available use the call

     * <code>Logger.getLogger(Logger.GLOBAL_LOGGER_NAME)</code>

     * or <code>Logger.getLogger("global")</code>.

     */

    @Deprecated

    public static final Logger global = new Logger(GLOBAL_LOGGER_NAME);

    /**

     * Protected method to construct a logger for a named subsystem.

     * <p>

     * The logger will be initially configured with a null Level

     * and with useParentHandlers set to true.

     *

     * @param   name    A name for the logger.  This should

     *                          be a dot-separated name and should normally

     *                          be based on the package name or class name

     *                          of the subsystem, such as java.net

     *                          or javax.swing.  It may be null for anonymous Loggers.

     * @param   resourceBundleName  name of ResourceBundle to be used for localizing

     *                          messages for this logger.  May be null if none

     *                          of the messages require localization.

     * @throws MissingResourceException if the resourceBundleName is non-null and

     *             no corresponding resource can be found.

     */

    protected Logger(String name, String resourceBundleName) {

        this.manager = LogManager.getLogManager();

        if (resourceBundleName != null) {

            setupResourceInfo(resourceBundleName);

        }

        this.name = name;

        levelValue = Level.INFO.intValue();

    }

    // This constructor is used only to create the global Logger.

    // It is needed to break a cyclic dependence between the LogManager

    // and Logger static initializers causing deadlocks.

    private Logger(String name) {

        // The manager field is not initialized here.

        this.name = name;

        levelValue = Level.INFO.intValue();

    }

    // It is called from the LogManager.<clinit> to complete

    // initialization of the global Logger.

    void setLogManager(LogManager manager) {

        this.manager = manager;

    }

    private void checkAccess() throws SecurityException {

        if (!anonymous) {

            if (manager == null) {

                // Complete initialization of the global Logger.

                manager = LogManager.getLogManager();

            }

            manager.checkAccess();

        }

    }

    /**

     * Find or create a logger for a named subsystem.  If a logger has

     * already been created with the given name it is returned.  Otherwise

     * a new logger is created.

     * <p>

     * If a new logger is created its log level will be configured

     * based on the LogManager configuration and it will configured

     * to also send logging output to its parent's Handlers.  It will

     * be registered in the LogManager global namespace.

     * <p>

     * Note: The LogManager may only retain a weak reference to the newly

     * created Logger. It is important to understand that a previously

     * created Logger with the given name may be garbage collected at any

     * time if there is no strong reference to the Logger. In particular,

     * this means that two back-to-back calls like

     * {@code getLogger("MyLogger").log(...)} may use different Logger

     * objects named "MyLogger" if there is no strong reference to the

     * Logger named "MyLogger" elsewhere in the program.

     *

     * @param   name            A name for the logger.  This should

     *                          be a dot-separated name and should normally

     *                          be based on the package name or class name

     *                          of the subsystem, such as java.net

     *                          or javax.swing

     * @return a suitable Logger

     * @throws NullPointerException if the name is null.

     */

    // Synchronization is not required here. All synchronization for

    // adding a new Logger object is handled by LogManager.addLogger().

    public static Logger getLogger(String name) {

        // This method is intentionally not a wrapper around a call

        // to getLogger(name, resourceBundleName). If it were then

        // this sequence:

        //

        //     getLogger("Foo", "resourceBundleForFoo");

        //     getLogger("Foo");

        //

        // would throw an IllegalArgumentException in the second call

        // because the wrapper would result in an attempt to replace

        // the existing "resourceBundleForFoo" with null.

        LogManager manager = LogManager.getLogManager();

        return manager.demandLogger(name);

    }

    /**

     * Find or create a logger for a named subsystem.  If a logger has

     * already been created with the given name it is returned.  Otherwise

     * a new logger is created.

     * <p>

     * If a new logger is created its log level will be configured

     * based on the LogManager and it will configured to also send logging

     * output to its parent's Handlers.  It will be registered in

     * the LogManager global namespace.

     * <p>

     * Note: The LogManager may only retain a weak reference to the newly

     * created Logger. It is important to understand that a previously

     * created Logger with the given name may be garbage collected at any

     * time if there is no strong reference to the Logger. In particular,

     * this means that two back-to-back calls like

     * {@code getLogger("MyLogger", ...).log(...)} may use different Logger

     * objects named "MyLogger" if there is no strong reference to the

     * Logger named "MyLogger" elsewhere in the program.

     * <p>

     * If the named Logger already exists and does not yet have a

     * localization resource bundle then the given resource bundle

     * name is used.  If the named Logger already exists and has

     * a different resource bundle name then an IllegalArgumentException

     * is thrown.

     * <p>

     * @param   name    A name for the logger.  This should

     *                          be a dot-separated name and should normally

     *                          be based on the package name or class name

     *                          of the subsystem, such as java.net

     *                          or javax.swing

     * @param   resourceBundleName  name of ResourceBundle to be used for localizing

     *                          messages for this logger. May be <CODE>null</CODE> if none of

     *                          the messages require localization.

     * @return a suitable Logger

     * @throws MissingResourceException if the resourceBundleName is non-null and

     *             no corresponding resource can be found.

     * @throws IllegalArgumentException if the Logger already exists and uses

     *             a different resource bundle name.

     * @throws NullPointerException if the name is null.

     */

    // Synchronization is not required here. All synchronization for

    // adding a new Logger object is handled by LogManager.addLogger().

    public static Logger getLogger(String name, String resourceBundleName) {

        LogManager manager = LogManager.getLogManager();

        Logger result = manager.demandLogger(name);

        return result;

    }

    /**

     * Create an anonymous Logger.  The newly created Logger is not

     * registered in the LogManager namespace.  There will be no

     * access checks on updates to the logger.

     * <p>

     * This factory method is primarily intended for use from applets.

     * Because the resulting Logger is anonymous it can be kept private

     * by the creating class.  This removes the need for normal security

     * checks, which in turn allows untrusted applet code to update

     * the control state of the Logger.  For example an applet can do

     * a setLevel or an addHandler on an anonymous Logger.

     * <p>

     * Even although the new logger is anonymous, it is configured

     * to have the root logger ("") as its parent.  This means that

     * by default it inherits its effective level and handlers

     * from the root logger.

     * <p>

     *

     * @return a newly created private Logger

     */

    public static Logger getAnonymousLogger() {

        return getAnonymousLogger(null);

    }

    /**

     * Create an anonymous Logger.  The newly created Logger is not

     * registered in the LogManager namespace.  There will be no

     * access checks on updates to the logger.

     * <p>

     * This factory method is primarily intended for use from applets.

     * Because the resulting Logger is anonymous it can be kept private

     * by the creating class.  This removes the need for normal security

     * checks, which in turn allows untrusted applet code to update

     * the control state of the Logger.  For example an applet can do

     * a setLevel or an addHandler on an anonymous Logger.

     * <p>

     * Even although the new logger is anonymous, it is configured

     * to have the root logger ("") as its parent.  This means that

     * by default it inherits its effective level and handlers

     * from the root logger.

     * <p>

     * @param   resourceBundleName  name of ResourceBundle to be used for localizing

     *                          messages for this logger.

     *          May be null if none of the messages require localization.

     * @return a newly created private Logger

     * @throws MissingResourceException if the resourceBundleName is non-null and

     *             no corresponding resource can be found.

     */

    // Synchronization is not required here. All synchronization for

    // adding a new anonymous Logger object is handled by doSetParent().

    public static Logger getAnonymousLogger(String resourceBundleName) {

        LogManager manager = LogManager.getLogManager();

        // cleanup some Loggers that have been GC'ed

        manager.drainLoggerRefQueueBounded();

        Logger result = new Logger(null, resourceBundleName);

        result.anonymous = true;

        Logger root = manager.getLogger("");

        result.doSetParent(root);

        return result;

    }

    /**

     * Retrieve the localization resource bundle for this

     * logger for the current default locale.  Note that if

     * the result is null, then the Logger will use a resource

     * bundle inherited from its parent.

     *

     * @return localization bundle (may be null)

     */

    public ResourceBundle getResourceBundle() {

        return findResourceBundle(getResourceBundleName());

    }

    /**

     * Retrieve the localization resource bundle name for this

     * logger.  Note that if the result is null, then the Logger

     * will use a resource bundle name inherited from its parent.

     *

     * @return localization bundle name (may be null)

     */

    public String getResourceBundleName() {

        return resourceBundleName;

    }

    /**

     * Set a filter to control output on this Logger.

     * <P>

     * After passing the initial "level" check, the Logger will

     * call this Filter to check if a log record should really

     * be published.

     *

     * @param   newFilter  a filter object (may be null)

     * @exception  SecurityException  if a security manager exists and if

     *             the caller does not have LoggingPermission("control").

     */

    public void setFilter(Filter newFilter) throws SecurityException {

        checkAccess();

        filter = newFilter;

    }

    /**

     * Get the current filter for this Logger.

     *

     * @return  a filter object (may be null)

     */

    public Filter getFilter() {

        return filter;

    }

    /**

     * Log a LogRecord.

     * <p>

     * All the other logging methods in this class call through

     * this method to actually perform any logging.  Subclasses can

     * override this single method to capture all log activity.

     *

     * @param record the LogRecord to be published

     */

    public void log(LogRecord record) {

        if (record.getLevel().intValue() < levelValue || levelValue == offValue) {

            return;

        }

        Filter theFilter = filter;

        if (theFilter != null && !theFilter.isLoggable(record)) {

            return;

        }

        // Post the LogRecord to all our Handlers, and then to

        // our parents' handlers, all the way up the tree.

        Logger logger = this;