1 /*
   2  * Copyright (c) 2012, 2013, 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 /*
  27  * This file is available under and governed by the GNU General Public
  28  * License version 2 only, as published by the Free Software Foundation.
  29  * However, the following notice accompanied the original version of this
  30  * file:
  31  *
  32  * Copyright (c) 2009-2012, Stephen Colebourne & Michael Nascimento Santos
  33  *
  34  * All rights reserved.
  35  *
  36  * Redistribution and use in source and binary forms, with or without
  37  * modification, are permitted provided that the following conditions are met:
  38  *
  39  *  * Redistributions of source code must retain the above copyright notice,
  40  *    this list of conditions and the following disclaimer.
  41  *
  42  *  * Redistributions in binary form must reproduce the above copyright notice,
  43  *    this list of conditions and the following disclaimer in the documentation
  44  *    and/or other materials provided with the distribution.
  45  *
  46  *  * Neither the name of JSR-310 nor the names of its contributors
  47  *    may be used to endorse or promote products derived from this software
  48  *    without specific prior written permission.
  49  *
  50  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  51  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  52  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  53  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
  54  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
  55  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
  56  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
  57  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
  58  * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  59  * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  60  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  61  */
  62 package java.time.zone;
  63 
  64 import java.time.DateTimeException;

  65 import java.time.ZoneId;
  66 import java.time.ZonedDateTime;
  67 import java.util.ArrayList;
  68 import java.util.Collections;
  69 import java.util.HashSet;
  70 import java.util.Iterator;
  71 import java.util.List;
  72 import java.util.NavigableMap;
  73 import java.util.Objects;
  74 import java.util.ServiceConfigurationError;
  75 import java.util.ServiceLoader;
  76 import java.util.Set;
  77 import java.util.concurrent.ConcurrentHashMap;
  78 import java.util.concurrent.ConcurrentMap;
  79 import java.util.concurrent.CopyOnWriteArrayList;
  80 
  81 /**
  82  * Provider of time-zone rules to the system.
  83  * <p>
  84  * This class manages the configuration of time-zone rules.
  85  * The static methods provide the public API that can be used to manage the providers.
  86  * The abstract methods provide the SPI that allows rules to be provided.
  87  * <p>



















  88  * Rules are looked up primarily by zone ID, as used by {@link ZoneId}.
  89  * Only zone region IDs may be used, zone offset IDs are not used here.
  90  * <p>
  91  * Time-zone rules are political, thus the data can change at any time.
  92  * Each provider will provide the latest rules for each zone ID, but they
  93  * may also provide the history of how the rules changed.
  94  *
  95  * <h3>Specification for implementors</h3>
  96  * This interface is a service provider that can be called by multiple threads.
  97  * Implementations must be immutable and thread-safe.
  98  * <p>
  99  * Providers must ensure that once a rule has been seen by the application, the
 100  * rule must continue to be available.
 101  * <p>


 102  * Many systems would like to update time-zone rules dynamically without stopping the JVM.
 103  * When examined in detail, this is a complex problem.
 104  * Providers may choose to handle dynamic updates, however the default provider does not.
 105  *
 106  * @since 1.8
 107  */
 108 public abstract class ZoneRulesProvider {
 109 
 110     /**
 111      * The set of loaded providers.
 112      */
 113     private static final CopyOnWriteArrayList<ZoneRulesProvider> PROVIDERS = new CopyOnWriteArrayList<>();
 114     /**
 115      * The lookup from zone region ID to provider.
 116      */
 117     private static final ConcurrentMap<String, ZoneRulesProvider> ZONES = new ConcurrentHashMap<>(512, 0.75f, 2);

 118     static {
















 119         registerProvider(new TzdbZoneRulesProvider());





 120         ServiceLoader<ZoneRulesProvider> sl = ServiceLoader.load(ZoneRulesProvider.class, ClassLoader.getSystemClassLoader());
 121         List<ZoneRulesProvider> loaded = new ArrayList<>();
 122         Iterator<ZoneRulesProvider> it = sl.iterator();
 123         while (it.hasNext()) {
 124             ZoneRulesProvider provider;
 125             try {
 126                 provider = it.next();
 127             } catch (ServiceConfigurationError ex) {
 128                 if (ex.getCause() instanceof SecurityException) {
 129                     continue;  // ignore the security exception, try the next provider
 130                 }
 131                 throw ex;
 132             }







 133             registerProvider0(provider);


 134         }
 135         // CopyOnWriteList could be slow if lots of providers and each added individually
 136         PROVIDERS.addAll(loaded);
 137     }
 138 
 139     //-------------------------------------------------------------------------
 140     /**
 141      * Gets the set of available zone IDs.
 142      * <p>
 143      * These zone IDs are loaded and available for use by {@code ZoneId}.
 144      *
 145      * @return a modifiable copy of the set of zone IDs, not null
 146      */
 147     public static Set<String> getAvailableZoneIds() {
 148         return new HashSet<>(ZONES.keySet());
 149     }
 150 
 151     /**
 152      * Gets the rules for the zone ID.
 153      * <p>
 154      * This returns the latest available rules for the zone ID.
 155      * <p>
 156      * This method relies on time-zone data provider files that are configured.
 157      * These are loaded using a {@code ServiceLoader}.
 158      *
 159      * @param zoneId  the zone region ID as used by {@code ZoneId}, not null
 160      * @return the rules for the ID, not null
 161      * @throws ZoneRulesException if the zone ID is unknown











 162      */
 163     public static ZoneRules getRules(String zoneId) {
 164         Objects.requireNonNull(zoneId, "zoneId");
 165         return getProvider(zoneId).provideRules(zoneId);
 166     }
 167 
 168     /**
 169      * Gets the history of rules for the zone ID.
 170      * <p>
 171      * Time-zones are defined by governments and change frequently.
 172      * This method allows applications to find the history of changes to the
 173      * rules for a single zone ID. The map is keyed by a string, which is the
 174      * version string associated with the rules.
 175      * <p>
 176      * The exact meaning and format of the version is provider specific.
 177      * The version must follow lexicographical order, thus the returned map will
 178      * be order from the oldest known rules to the newest available rules.
 179      * The default 'TZDB' group uses version numbering consisting of the year
 180      * followed by a letter, such as '2009e' or '2012f'.
 181      * <p>
 182      * Implementations must provide a result for each valid zone ID, however
 183      * they do not have to provide a history of rules.
 184      * Thus the map will always contain one element, and will only contain more
 185      * than one element if historical rule information is available.
 186      *
 187      * @param zoneId  the zone region ID as used by {@code ZoneId}, not null
 188      * @return a modifiable copy of the history of the rules for the ID, sorted
 189      *  from oldest to newest, not null
 190      * @throws ZoneRulesException if the zone ID is unknown
 191      */
 192     public static NavigableMap<String, ZoneRules> getVersions(String zoneId) {
 193         Objects.requireNonNull(zoneId, "zoneId");
 194         return getProvider(zoneId).provideVersions(zoneId);
 195     }
 196 
 197     /**
 198      * Gets the provider for the zone ID.
 199      *
 200      * @param zoneId  the zone region ID as used by {@code ZoneId}, not null
 201      * @return the provider, not null
 202      * @throws ZoneRulesException if the zone ID is unknown
 203      */
 204     private static ZoneRulesProvider getProvider(String zoneId) {
 205         ZoneRulesProvider provider = ZONES.get(zoneId);
 206         if (provider == null) {
 207             if (ZONES.isEmpty()) {
 208                 throw new ZoneRulesException("No time-zone data files registered");
 209             }
 210             throw new ZoneRulesException("Unknown time-zone ID: " + zoneId);
 211         }
 212         return provider;
 213     }
 214 
 215     //-------------------------------------------------------------------------
 216     /**
 217      * Registers a zone rules provider.
 218      * <p>
 219      * This adds a new provider to those currently available.
 220      * A provider supplies rules for one or more zone IDs.
 221      * A provider cannot be registered if it supplies a zone ID that has already been
 222      * registered. See the notes on time-zone IDs in {@link ZoneId}, especially
 223      * the section on using the concept of a "group" to make IDs unique.
 224      * <p>
 225      * To ensure the integrity of time-zones already created, there is no way
 226      * to deregister providers.
 227      *
 228      * @param provider  the provider to register, not null
 229      * @throws ZoneRulesException if a region is already registered
 230      */
 231     public static void registerProvider(ZoneRulesProvider provider) {
 232         Objects.requireNonNull(provider, "provider");
 233         registerProvider0(provider);
 234         PROVIDERS.add(provider);
 235     }
 236 
 237     /**
 238      * Registers the provider.
 239      *
 240      * @param provider  the provider to register, not null
 241      * @throws ZoneRulesException if unable to complete the registration
 242      */
 243     private static void registerProvider0(ZoneRulesProvider provider) {
 244         for (String zoneId : provider.provideZoneIds()) {
 245             Objects.requireNonNull(zoneId, "zoneId");
 246             ZoneRulesProvider old = ZONES.putIfAbsent(zoneId, provider.provideBind(zoneId));
 247             if (old != null) {
 248                 throw new ZoneRulesException(
 249                     "Unable to register zone as one already registered with that ID: " + zoneId +
 250                     ", currently loading from provider: " + provider);
 251             }
 252         }
 253     }
 254 
 255     //-------------------------------------------------------------------------
 256     /**
 257      * Refreshes the rules from the underlying data provider.
 258      * <p>
 259      * This method is an extension point that allows providers to refresh their
 260      * rules dynamically at a time of the applications choosing.
 261      * After calling this method, the offset stored in any {@link ZonedDateTime}
 262      * may be invalid for the zone ID.
 263      * <p>
 264      * Dynamic behavior is entirely optional and most providers, including the
 265      * default provider, do not support it.









 266      *
 267      * @return true if the rules were updated
 268      * @throws ZoneRulesException if an error occurs during the refresh
 269      */
 270     public static boolean refresh() {
 271         boolean changed = false;
 272         for (ZoneRulesProvider provider : PROVIDERS) {
 273             changed |= provider.provideRefresh();
 274         }
 275         return changed;
 276     }
 277 
 278     //-----------------------------------------------------------------------
 279     /**
 280      * Constructor.
 281      */
 282     protected ZoneRulesProvider() {
 283     }
 284 
 285     //-----------------------------------------------------------------------
 286     /**
 287      * SPI method to get the available zone IDs.
 288      * <p>
 289      * This obtains the IDs that this {@code ZoneRulesProvider} provides.
 290      * A provider should provide data for at least one region.
 291      * <p>
 292      * The returned regions remain available and valid for the lifetime of the application.
 293      * A dynamic provider may increase the set of regions as more data becomes available.
 294      *
 295      * @return the unmodifiable set of region IDs being provided, not null

 296      */
 297     protected abstract Set<String> provideZoneIds();
 298 
 299     /**
 300      * SPI method to bind to the specified zone ID.
 301      * <p>
 302      * {@code ZoneRulesProvider} has a lookup from zone ID to provider.
 303      * This method is used when building that lookup, allowing providers
 304      * to insert a derived provider that is precisely tuned to the zone ID.
 305      * This replaces two hash map lookups by one, enhancing performance.
 306      * <p>
 307      * This optimization is optional. Returning {@code this} is acceptable.
 308      * <p>
 309      * This implementation creates a bound provider that caches the
 310      * rules from the underlying provider. The request to version history
 311      * is forward on to the underlying. This is suitable for providers that
 312      * cannot change their contents during the lifetime of the JVM.
 313      *
 314      * @param zoneId  the zone region ID as used by {@code ZoneId}, not null
 315      * @return the resolved provider for the ID, not null
 316      * @throws DateTimeException if there is no provider for the specified group
 317      */
 318     protected ZoneRulesProvider provideBind(String zoneId) {
 319         return new BoundProvider(this, zoneId);
 320     }
 321 
 322     /**
 323      * SPI method to get the rules for the zone ID.
 324      * <p>
 325      * This loads the rules for the region and version specified.
 326      * The version may be null to indicate the "latest" version.
 327      *
 328      * @param regionId  the time-zone region ID, not null
 329      * @return the rules, not null
 330      * @throws DateTimeException if rules cannot be obtained
















 331      */
 332     protected abstract ZoneRules provideRules(String regionId);
 333 
 334     /**
 335      * SPI method to get the history of rules for the zone ID.
 336      * <p>
 337      * This returns a map of historical rules keyed by a version string.
 338      * The exact meaning and format of the version is provider specific.
 339      * The version must follow lexicographical order, thus the returned map will
 340      * be order from the oldest known rules to the newest available rules.
 341      * The default 'TZDB' group uses version numbering consisting of the year
 342      * followed by a letter, such as '2009e' or '2012f'.
 343      * <p>
 344      * Implementations must provide a result for each valid zone ID, however
 345      * they do not have to provide a history of rules.
 346      * Thus the map will always contain one element, and will only contain more
 347      * than one element if historical rule information is available.
 348      * <p>
 349      * The returned versions remain available and valid for the lifetime of the application.
 350      * A dynamic provider may increase the set of versions as more data becomes available.
 351      *
 352      * @param zoneId  the zone region ID as used by {@code ZoneId}, not null
 353      * @return a modifiable copy of the history of the rules for the ID, sorted
 354      *  from oldest to newest, not null
 355      * @throws ZoneRulesException if the zone ID is unknown
 356      */
 357     protected abstract NavigableMap<String, ZoneRules> provideVersions(String zoneId);
 358 
 359     /**
 360      * SPI method to refresh the rules from the underlying data provider.
 361      * <p>
 362      * This method provides the opportunity for a provider to dynamically
 363      * recheck the underlying data provider to find the latest rules.
 364      * This could be used to load new rules without stopping the JVM.
 365      * Dynamic behavior is entirely optional and most providers do not support it.
 366      * <p>
 367      * This implementation returns false.
 368      *
 369      * @return true if the rules were updated
 370      * @throws DateTimeException if an error occurs during the refresh
 371      */
 372     protected boolean provideRefresh() {
 373         return false;
 374     }
 375 
 376     //-------------------------------------------------------------------------
 377     /**
 378      * A provider bound to a single zone ID.
 379      */
 380     private static class BoundProvider extends ZoneRulesProvider {
 381         private final ZoneRulesProvider provider;
 382         private final String zoneId;
 383         private final ZoneRules rules;
 384 
 385         private BoundProvider(ZoneRulesProvider provider, String zoneId) {
 386             this.provider = provider;
 387             this.zoneId = zoneId;
 388             this.rules = provider.provideRules(zoneId);
 389         }
 390 
 391         @Override
 392         protected Set<String> provideZoneIds() {
 393             return new HashSet<>(Collections.singleton(zoneId));
 394         }
 395 
 396         @Override
 397         protected ZoneRules provideRules(String regionId) {
 398             return rules;
 399         }
 400 
 401         @Override
 402         protected NavigableMap<String, ZoneRules> provideVersions(String zoneId) {
 403             return provider.provideVersions(zoneId);
 404         }
 405 
 406         @Override
 407         public String toString() {
 408             return zoneId;
 409         }
 410     }
 411 
 412 }
--- EOF ---