1 /*
   2  * Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package java.util.logging;
  27 
  28 import java.lang.ref.Reference;
  29 import java.lang.ref.ReferenceQueue;
  30 import java.lang.ref.WeakReference;
  31 import java.security.AccessController;
  32 import java.security.PrivilegedAction;
  33 import java.util.ArrayList;
  34 import java.util.Collections;
  35 import java.util.HashMap;
  36 import java.util.List;
  37 import java.util.Locale;
  38 import java.util.Map;
  39 import java.util.Optional;
  40 import java.util.ResourceBundle;
  41 import java.util.function.Function;
  42 import jdk.internal.loader.ClassLoaderValue;
  43 import jdk.internal.access.JavaUtilResourceBundleAccess;
  44 import jdk.internal.access.SharedSecrets;
  45 
  46 /**
  47  * The Level class defines a set of standard logging levels that
  48  * can be used to control logging output.  The logging Level objects
  49  * are ordered and are specified by ordered integers.  Enabling logging
  50  * at a given level also enables logging at all higher levels.
  51  * <p>
  52  * Clients should normally use the predefined Level constants such
  53  * as Level.SEVERE.
  54  * <p>
  55  * The levels in descending order are:
  56  * <ul>
  57  * <li>SEVERE (highest value)
  58  * <li>WARNING
  59  * <li>INFO
  60  * <li>CONFIG
  61  * <li>FINE
  62  * <li>FINER
  63  * <li>FINEST  (lowest value)
  64  * </ul>
  65  * In addition there is a level OFF that can be used to turn
  66  * off logging, and a level ALL that can be used to enable
  67  * logging of all messages.
  68  * <p>
  69  * It is possible for third parties to define additional logging
  70  * levels by subclassing Level.  In such cases subclasses should
  71  * take care to chose unique integer level values and to ensure that
  72  * they maintain the Object uniqueness property across serialization
  73  * by defining a suitable readResolve method.
  74  *
  75  * @since 1.4
  76  */
  77 
  78 public class Level implements java.io.Serializable {
  79     private static final String defaultBundle =
  80         "sun.util.logging.resources.logging";
  81 
  82     // Calling SharedSecrets.getJavaUtilResourceBundleAccess()
  83     // forces the initialization of ResourceBundle.class, which
  84     // can be too early if the VM has not finished booting yet.
  85     private static final class RbAccess {
  86         static final JavaUtilResourceBundleAccess RB_ACCESS =
  87             SharedSecrets.getJavaUtilResourceBundleAccess();
  88     }
  89 
  90     /**
  91      * @serial  The non-localized name of the level.
  92      */
  93     private final String name;
  94 
  95     /**
  96      * @serial  The integer value of the level.
  97      */
  98     private final int value;
  99 
 100     /**
 101      * @serial The resource bundle name to be used in localizing the level name.
 102      */
 103     private final String resourceBundleName;
 104 
 105     // localized level name
 106     private transient String localizedLevelName;
 107     private transient Locale cachedLocale;
 108 
 109     /**
 110      * OFF is a special level that can be used to turn off logging.
 111      * This level is initialized to <CODE>Integer.MAX_VALUE</CODE>.
 112      */
 113     public static final Level OFF = new Level("OFF",Integer.MAX_VALUE, defaultBundle);
 114 
 115     /**
 116      * SEVERE is a message level indicating a serious failure.
 117      * <p>
 118      * In general SEVERE messages should describe events that are
 119      * of considerable importance and which will prevent normal
 120      * program execution.   They should be reasonably intelligible
 121      * to end users and to system administrators.
 122      * This level is initialized to <CODE>1000</CODE>.
 123      */
 124     public static final Level SEVERE = new Level("SEVERE",1000, defaultBundle);
 125 
 126     /**
 127      * WARNING is a message level indicating a potential problem.
 128      * <p>
 129      * In general WARNING messages should describe events that will
 130      * be of interest to end users or system managers, or which
 131      * indicate potential problems.
 132      * This level is initialized to <CODE>900</CODE>.
 133      */
 134     public static final Level WARNING = new Level("WARNING", 900, defaultBundle);
 135 
 136     /**
 137      * INFO is a message level for informational messages.
 138      * <p>
 139      * Typically INFO messages will be written to the console
 140      * or its equivalent.  So the INFO level should only be
 141      * used for reasonably significant messages that will
 142      * make sense to end users and system administrators.
 143      * This level is initialized to <CODE>800</CODE>.
 144      */
 145     public static final Level INFO = new Level("INFO", 800, defaultBundle);
 146 
 147     /**
 148      * CONFIG is a message level for static configuration messages.
 149      * <p>
 150      * CONFIG messages are intended to provide a variety of static
 151      * configuration information, to assist in debugging problems
 152      * that may be associated with particular configurations.
 153      * For example, CONFIG message might include the CPU type,
 154      * the graphics depth, the GUI look-and-feel, etc.
 155      * This level is initialized to <CODE>700</CODE>.
 156      */
 157     public static final Level CONFIG = new Level("CONFIG", 700, defaultBundle);
 158 
 159     /**
 160      * FINE is a message level providing tracing information.
 161      * <p>
 162      * All of FINE, FINER, and FINEST are intended for relatively
 163      * detailed tracing.  The exact meaning of the three levels will
 164      * vary between subsystems, but in general, FINEST should be used
 165      * for the most voluminous detailed output, FINER for somewhat
 166      * less detailed output, and FINE for the  lowest volume (and
 167      * most important) messages.
 168      * <p>
 169      * In general the FINE level should be used for information
 170      * that will be broadly interesting to developers who do not have
 171      * a specialized interest in the specific subsystem.
 172      * <p>
 173      * FINE messages might include things like minor (recoverable)
 174      * failures.  Issues indicating potential performance problems
 175      * are also worth logging as FINE.
 176      * This level is initialized to <CODE>500</CODE>.
 177      */
 178     public static final Level FINE = new Level("FINE", 500, defaultBundle);
 179 
 180     /**
 181      * FINER indicates a fairly detailed tracing message.
 182      * By default logging calls for entering, returning, or throwing
 183      * an exception are traced at this level.
 184      * This level is initialized to <CODE>400</CODE>.
 185      */
 186     public static final Level FINER = new Level("FINER", 400, defaultBundle);
 187 
 188     /**
 189      * FINEST indicates a highly detailed tracing message.
 190      * This level is initialized to <CODE>300</CODE>.
 191      */
 192     public static final Level FINEST = new Level("FINEST", 300, defaultBundle);
 193 
 194     /**
 195      * ALL indicates that all messages should be logged.
 196      * This level is initialized to <CODE>Integer.MIN_VALUE</CODE>.
 197      */
 198     public static final Level ALL = new Level("ALL", Integer.MIN_VALUE, defaultBundle);
 199 
 200     private static final Level[] standardLevels = {
 201         OFF, SEVERE, WARNING, INFO, CONFIG, FINE, FINER, FINEST, ALL
 202     };
 203 
 204     /**
 205      * Create a named Level with a given integer value.
 206      * <p>
 207      * Note that this constructor is "protected" to allow subclassing.
 208      * In general clients of logging should use one of the constant Level
 209      * objects such as SEVERE or FINEST.  However, if clients need to
 210      * add new logging levels, they may subclass Level and define new
 211      * constants.
 212      * @param name  the name of the Level, for example "SEVERE".
 213      * @param value an integer value for the level.
 214      * @throws NullPointerException if the name is null
 215      */
 216     protected Level(String name, int value) {
 217         this(name, value, null);
 218     }
 219 
 220     /**
 221      * Create a named Level with a given integer value and a
 222      * given localization resource name.
 223      *
 224      * @param name  the name of the Level, for example "SEVERE".
 225      * @param value an integer value for the level.
 226      * @param resourceBundleName name of a resource bundle to use in
 227      *    localizing the given name. If the resourceBundleName is null
 228      *    or an empty string, it is ignored.
 229      * @throws NullPointerException if the name is null
 230      */
 231     protected Level(String name, int value, String resourceBundleName) {
 232         this(name, value, resourceBundleName, true);
 233     }
 234 
 235     // private constructor to specify whether this instance should be added
 236     // to the KnownLevel list from which Level.parse method does its look up
 237     private Level(String name, int value, String resourceBundleName, boolean visible) {
 238         if (name == null) {
 239             throw new NullPointerException();
 240         }
 241         this.name = name;
 242         this.value = value;
 243         this.resourceBundleName = resourceBundleName;
 244         this.localizedLevelName = resourceBundleName == null ? name : null;
 245         this.cachedLocale = null;
 246         if (visible) {
 247             KnownLevel.add(this);
 248         }
 249     }
 250 
 251     /**
 252      * Return the level's localization resource bundle name, or
 253      * null if no localization bundle is defined.
 254      *
 255      * @return localization resource bundle name
 256      */
 257     public String getResourceBundleName() {
 258         return resourceBundleName;
 259     }
 260 
 261     /**
 262      * Return the non-localized string name of the Level.
 263      *
 264      * @return non-localized name
 265      */
 266     public String getName() {
 267         return name;
 268     }
 269 
 270     /**
 271      * Return the localized string name of the Level, for
 272      * the current default locale.
 273      * <p>
 274      * If no localization information is available, the
 275      * non-localized name is returned.
 276      *
 277      * @return localized name
 278      */
 279     public String getLocalizedName() {
 280         return getLocalizedLevelName();
 281     }
 282 
 283     // package-private getLevelName() is used by the implementation
 284     // instead of getName() to avoid calling the subclass's version
 285     final String getLevelName() {
 286         return this.name;
 287     }
 288 
 289     private String computeLocalizedLevelName(Locale newLocale) {
 290         // Resource bundle should be loaded from the defining module
 291         // or its defining class loader, if it's unnamed module,
 292         // of this Level instance that can be a custom Level subclass;
 293         Module module = this.getClass().getModule();
 294         ResourceBundle rb = RbAccess.RB_ACCESS.getBundle(resourceBundleName,
 295                 newLocale, module);
 296 
 297         final String localizedName = rb.getString(name);
 298         final boolean isDefaultBundle = defaultBundle.equals(resourceBundleName);
 299         if (!isDefaultBundle) return localizedName;
 300 
 301         // This is a trick to determine whether the name has been translated
 302         // or not. If it has not been translated, we need to use Locale.ROOT
 303         // when calling toUpperCase().
 304         final Locale rbLocale = rb.getLocale();
 305         final Locale locale =
 306                 Locale.ROOT.equals(rbLocale)
 307                 || name.equals(localizedName.toUpperCase(Locale.ROOT))
 308                 ? Locale.ROOT : rbLocale;
 309 
 310         // ALL CAPS in a resource bundle's message indicates no translation
 311         // needed per Oracle translation guideline.  To workaround this
 312         // in Oracle JDK implementation, convert the localized level name
 313         // to uppercase for compatibility reason.
 314         return Locale.ROOT.equals(locale) ? name : localizedName.toUpperCase(locale);
 315     }
 316 
 317     // Avoid looking up the localizedLevelName twice if we already
 318     // have it.
 319     final String getCachedLocalizedLevelName() {
 320 
 321         if (localizedLevelName != null) {
 322             if (cachedLocale != null) {
 323                 if (cachedLocale.equals(Locale.getDefault())) {
 324                     // OK: our cached value was looked up with the same
 325                     //     locale. We can use it.
 326                     return localizedLevelName;
 327                 }
 328             }
 329         }
 330 
 331         if (resourceBundleName == null) {
 332             // No resource bundle: just use the name.
 333             return name;
 334         }
 335 
 336         // We need to compute the localized name.
 337         // Either because it's the first time, or because our cached
 338         // value is for a different locale. Just return null.
 339         return null;
 340     }
 341 
 342     final synchronized String getLocalizedLevelName() {
 343 
 344         // See if we have a cached localized name
 345         final String cachedLocalizedName = getCachedLocalizedLevelName();
 346         if (cachedLocalizedName != null) {
 347             return cachedLocalizedName;
 348         }
 349 
 350         // No cached localized name or cache invalid.
 351         // Need to compute the localized name.
 352         final Locale newLocale = Locale.getDefault();
 353         try {
 354             localizedLevelName = computeLocalizedLevelName(newLocale);
 355         } catch (Exception ex) {
 356             localizedLevelName = name;
 357         }
 358         cachedLocale = newLocale;
 359         return localizedLevelName;
 360     }
 361 
 362     // Returns a mirrored Level object that matches the given name as
 363     // specified in the Level.parse method.  Returns null if not found.
 364     //
 365     // It returns the same Level object as the one returned by Level.parse
 366     // method if the given name is a non-localized name or integer.
 367     //
 368     // If the name is a localized name, findLevel and parse method may
 369     // return a different level value if there is a custom Level subclass
 370     // that overrides Level.getLocalizedName() to return a different string
 371     // than what's returned by the default implementation.
 372     //
 373     static Level findLevel(String name) {
 374         if (name == null) {
 375             throw new NullPointerException();
 376         }
 377 
 378         Optional<Level> level;
 379 
 380         // Look for a known Level with the given non-localized name.
 381         level = KnownLevel.findByName(name, KnownLevel::mirrored);
 382         if (level.isPresent()) {
 383             return level.get();
 384         }
 385 
 386         // Now, check if the given name is an integer.  If so,
 387         // first look for a Level with the given value and then
 388         // if necessary create one.
 389         try {
 390             int x = Integer.parseInt(name);
 391             level = KnownLevel.findByValue(x, KnownLevel::mirrored);
 392             if (level.isPresent()) {
 393                 return level.get();
 394             }
 395             // add new Level
 396             Level levelObject = new Level(name, x);
 397             // There's no need to use a reachability fence here because
 398             // KnownLevel keeps a strong reference on the level when
 399             // level.getClass() == Level.class.
 400             return KnownLevel.findByValue(x, KnownLevel::mirrored).get();
 401         } catch (NumberFormatException ex) {
 402             // Not an integer.
 403             // Drop through.
 404         }
 405 
 406         level = KnownLevel.findByLocalizedLevelName(name,
 407                 KnownLevel::mirrored);
 408         if (level.isPresent()) {
 409             return level.get();
 410         }
 411 
 412         return null;
 413     }
 414 
 415     /**
 416      * Returns a string representation of this Level.
 417      *
 418      * @return the non-localized name of the Level, for example "INFO".
 419      */
 420     @Override
 421     public final String toString() {
 422         return name;
 423     }
 424 
 425     /**
 426      * Get the integer value for this level.  This integer value
 427      * can be used for efficient ordering comparisons between
 428      * Level objects.
 429      * @return the integer value for this level.
 430      */
 431     public final int intValue() {
 432         return value;
 433     }
 434 
 435     private static final long serialVersionUID = -8176160795706313070L;
 436 
 437     // Serialization magic to prevent "doppelgangers".
 438     // This is a performance optimization.
 439     private Object readResolve() {
 440         Optional<Level> level = KnownLevel.matches(this);
 441         if (level.isPresent()) {
 442             return level.get();
 443         }
 444         // Woops.  Whoever sent us this object knows
 445         // about a new log level.  Add it to our list.
 446         return new Level(this.name, this.value, this.resourceBundleName);
 447     }
 448 
 449     /**
 450      * Parse a level name string into a Level.
 451      * <p>
 452      * The argument string may consist of either a level name
 453      * or an integer value.
 454      * <p>
 455      * For example:
 456      * <ul>
 457      * <li>     "SEVERE"
 458      * <li>     "1000"
 459      * </ul>
 460      *
 461      * @param  name   string to be parsed
 462      * @throws NullPointerException if the name is null
 463      * @throws IllegalArgumentException if the value is not valid.
 464      * Valid values are integers between <CODE>Integer.MIN_VALUE</CODE>
 465      * and <CODE>Integer.MAX_VALUE</CODE>, and all known level names.
 466      * Known names are the levels defined by this class (e.g., <CODE>FINE</CODE>,
 467      * <CODE>FINER</CODE>, <CODE>FINEST</CODE>), or created by this class with
 468      * appropriate package access, or new levels defined or created
 469      * by subclasses.
 470      *
 471      * @return The parsed value. Passing an integer that corresponds to a known name
 472      * (e.g., 700) will return the associated name (e.g., <CODE>CONFIG</CODE>).
 473      * Passing an integer that does not (e.g., 1) will return a new level name
 474      * initialized to that value.
 475      */
 476     public static synchronized Level parse(String name) throws IllegalArgumentException {
 477         // Check that name is not null.
 478         name.length();
 479 
 480         Optional<Level> level;
 481 
 482         // Look for a known Level with the given non-localized name.
 483         level = KnownLevel.findByName(name, KnownLevel::referent);
 484         if (level.isPresent()) {
 485             return level.get();
 486         }
 487 
 488         // Now, check if the given name is an integer.  If so,
 489         // first look for a Level with the given value and then
 490         // if necessary create one.
 491         try {
 492             int x = Integer.parseInt(name);
 493             level = KnownLevel.findByValue(x, KnownLevel::referent);
 494             if (level.isPresent()) {
 495                 return level.get();
 496             }
 497             // add new Level.
 498             Level levelObject = new Level(name, x);
 499             // There's no need to use a reachability fence here because
 500             // KnownLevel keeps a strong reference on the level when
 501             // level.getClass() == Level.class.
 502             return KnownLevel.findByValue(x, KnownLevel::referent).get();
 503         } catch (NumberFormatException ex) {
 504             // Not an integer.
 505             // Drop through.
 506         }
 507 
 508         // Finally, look for a known level with the given localized name,
 509         // in the current default locale.
 510         // This is relatively expensive, but not excessively so.
 511         level = KnownLevel.findByLocalizedLevelName(name, KnownLevel::referent);
 512         if (level .isPresent()) {
 513             return level.get();
 514         }
 515 
 516         // OK, we've tried everything and failed
 517         throw new IllegalArgumentException("Bad level \"" + name + "\"");
 518     }
 519 
 520     /**
 521      * Compare two objects for value equality.
 522      * @return true if and only if the two objects have the same level value.
 523      */
 524     @Override
 525     public boolean equals(Object ox) {
 526         try {
 527             Level lx = (Level)ox;
 528             return (lx.value == this.value);
 529         } catch (Exception ex) {
 530             return false;
 531         }
 532     }
 533 
 534     /**
 535      * Generate a hashcode.
 536      * @return a hashcode based on the level value
 537      */
 538     @Override
 539     public int hashCode() {
 540         return this.value;
 541     }
 542 
 543     // KnownLevel class maintains the global list of all known levels.
 544     // The API allows multiple custom Level instances of the same name/value
 545     // be created. This class provides convenient methods to find a level
 546     // by a given name, by a given value, or by a given localized name.
 547     //
 548     // KnownLevel wraps the following Level objects:
 549     // 1. levelObject:   standard Level object or custom Level object
 550     // 2. mirroredLevel: Level object representing the level specified in the
 551     //                   logging configuration.
 552     //
 553     // Level.getName, Level.getLocalizedName, Level.getResourceBundleName methods
 554     // are non-final but the name and resource bundle name are parameters to
 555     // the Level constructor.  Use the mirroredLevel object instead of the
 556     // levelObject to prevent the logging framework to execute foreign code
 557     // implemented by untrusted Level subclass.
 558     //
 559     // Implementation Notes:
 560     // If Level.getName, Level.getLocalizedName, Level.getResourceBundleName methods
 561     // were final, the following KnownLevel implementation can be removed.
 562     // Future API change should take this into consideration.
 563     static final class KnownLevel extends WeakReference<Level> {
 564         private static Map<String, List<KnownLevel>> nameToLevels = new HashMap<>();
 565         private static Map<Integer, List<KnownLevel>> intToLevels = new HashMap<>();
 566         private static final ReferenceQueue<Level> QUEUE = new ReferenceQueue<>();
 567 
 568         // CUSTOM_LEVEL_CLV is used to register custom level instances with
 569         // their defining class loader, so that they are garbage collected
 570         // if and only if their class loader is no longer strongly
 571         // referenced.
 572         private static final ClassLoaderValue<List<Level>> CUSTOM_LEVEL_CLV =
 573                     new ClassLoaderValue<>();
 574 
 575         final Level mirroredLevel;   // mirror of the custom Level
 576         KnownLevel(Level l) {
 577             super(l, QUEUE);
 578             if (l.getClass() == Level.class) {
 579                 this.mirroredLevel = l;
 580             } else {
 581                 // this mirrored level object is hidden
 582                 this.mirroredLevel = new Level(l.name, l.value,
 583                         l.resourceBundleName, false);
 584             }
 585         }
 586 
 587         Optional<Level> mirrored() {
 588             return Optional.of(mirroredLevel);
 589         }
 590 
 591         Optional<Level> referent() {
 592             return Optional.ofNullable(get());
 593         }
 594 
 595         private void remove() {
 596             Optional.ofNullable(nameToLevels.get(mirroredLevel.name))
 597                     .ifPresent((x) -> x.remove(this));
 598             Optional.ofNullable(intToLevels.get(mirroredLevel.value))
 599                     .ifPresent((x) -> x.remove(this));
 600         }
 601 
 602         // Remove all stale KnownLevel instances
 603         static synchronized void purge() {
 604             Reference<? extends Level> ref;
 605             while ((ref = QUEUE.poll()) != null) {
 606                 if (ref instanceof KnownLevel) {
 607                     ((KnownLevel)ref).remove();
 608                 }
 609             }
 610         }
 611 
 612         private static void registerWithClassLoader(Level customLevel) {
 613             PrivilegedAction<ClassLoader> pa =
 614                   () -> customLevel.getClass().getClassLoader();
 615             PrivilegedAction<String> pn =  customLevel.getClass()::getName;
 616             final String name = AccessController.doPrivileged(pn);
 617             final ClassLoader cl = AccessController.doPrivileged(pa);
 618             CUSTOM_LEVEL_CLV.computeIfAbsent(cl, (c, v) -> new ArrayList<>())
 619                 .add(customLevel);
 620         }
 621 
 622         static synchronized void add(Level l) {
 623             purge();
 624             // the mirroredLevel object is always added to the list
 625             // before the custom Level instance
 626             KnownLevel o = new KnownLevel(l);
 627             List<KnownLevel> list = nameToLevels.get(l.name);
 628             if (list == null) {
 629                 list = new ArrayList<>();
 630                 nameToLevels.put(l.name, list);
 631             }
 632             list.add(o);
 633 
 634             list = intToLevels.get(l.value);
 635             if (list == null) {
 636                 list = new ArrayList<>();
 637                 intToLevels.put(l.value, list);
 638             }
 639             list.add(o);
 640 
 641             // keep the custom level reachable from its class loader
 642             // This will ensure that custom level values are not GC'ed
 643             // until there class loader is GC'ed.
 644             if (o.mirroredLevel != l) {
 645                 registerWithClassLoader(l);
 646             }
 647 
 648         }
 649 
 650         // Returns a KnownLevel with the given non-localized name.
 651         static synchronized Optional<Level> findByName(String name,
 652                 Function<KnownLevel, Optional<Level>> selector) {
 653             purge();
 654             return nameToLevels.getOrDefault(name, Collections.emptyList())
 655                         .stream()
 656                         .map(selector)
 657                         .flatMap(Optional::stream)
 658                         .findFirst();
 659         }
 660 
 661         // Returns a KnownLevel with the given value.
 662         static synchronized Optional<Level> findByValue(int value,
 663                 Function<KnownLevel, Optional<Level>> selector) {
 664             purge();
 665             return intToLevels.getOrDefault(value, Collections.emptyList())
 666                         .stream()
 667                         .map(selector)
 668                         .flatMap(Optional::stream)
 669                         .findFirst();
 670         }
 671 
 672         // Returns a KnownLevel with the given localized name matching
 673         // by calling the Level.getLocalizedLevelName() method (i.e. found
 674         // from the resourceBundle associated with the Level object).
 675         // This method does not call Level.getLocalizedName() that may
 676         // be overridden in a subclass implementation
 677         static synchronized Optional<Level> findByLocalizedLevelName(String name,
 678                 Function<KnownLevel, Optional<Level>> selector) {
 679             purge();
 680             return nameToLevels.values().stream()
 681                          .flatMap(List::stream)
 682                          .map(selector)
 683                          .flatMap(Optional::stream)
 684                          .filter(l -> name.equals(l.getLocalizedLevelName()))
 685                          .findFirst();
 686         }
 687 
 688         static synchronized Optional<Level> matches(Level l) {
 689             purge();
 690             List<KnownLevel> list = nameToLevels.get(l.name);
 691             if (list != null) {
 692                 for (KnownLevel ref : list) {
 693                     Level levelObject = ref.get();
 694                     if (levelObject == null) continue;
 695                     Level other = ref.mirroredLevel;
 696                     Class<? extends Level> type = levelObject.getClass();
 697                     if (l.value == other.value &&
 698                            (l.resourceBundleName == other.resourceBundleName ||
 699                                (l.resourceBundleName != null &&
 700                                 l.resourceBundleName.equals(other.resourceBundleName)))) {
 701                         if (type == l.getClass()) {
 702                             return Optional.of(levelObject);
 703                         }
 704                     }
 705                 }
 706             }
 707             return Optional.empty();
 708         }
 709     }
 710 
 711 }