src/main/java/net/pterodactylus/sone/database/memory/MemoryDatabase.java

   1 /*
   2  * Sone - MemoryDatabase.java - Copyright © 2013–2016 David Roden
   3  *
   4  * This program is free software: you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation, either version 3 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  16  */
  17
  18 package net.pterodactylus.sone.database.memory;
  19
  20 import static com.google.common.base.Optional.fromNullable;
  21 import static com.google.common.base.Preconditions.checkNotNull;
  22 import static com.google.common.base.Predicates.not;
  23 import static com.google.common.collect.FluentIterable.from;
  24 import static net.pterodactylus.sone.data.Reply.TIME_COMPARATOR;
  25 import static net.pterodactylus.sone.data.Sone.LOCAL_SONE_FILTER;
  26 import static net.pterodactylus.sone.data.Sone.toAllAlbums;
  27 import static net.pterodactylus.sone.data.Sone.toAllImages;
  28
  29 import java.util.Collection;
  30 import java.util.Collections;
  31 import java.util.Comparator;
  32 import java.util.HashMap;
  33 import java.util.HashSet;
  34 import java.util.List;
  35 import java.util.Map;
  36 import java.util.Set;
  37 import java.util.concurrent.locks.ReadWriteLock;
  38 import java.util.concurrent.locks.ReentrantReadWriteLock;
  39
  40 import javax.annotation.Nonnull;
  41
  42 import net.pterodactylus.sone.data.Album;
  43 import net.pterodactylus.sone.data.Image;
  44 import net.pterodactylus.sone.data.Post;
  45 import net.pterodactylus.sone.data.PostReply;
  46 import net.pterodactylus.sone.data.Sone;
  47 import net.pterodactylus.sone.data.impl.AlbumBuilderImpl;
  48 import net.pterodactylus.sone.data.impl.ImageBuilderImpl;
  49 import net.pterodactylus.sone.database.AlbumBuilder;
  50 import net.pterodactylus.sone.database.Database;
  51 import net.pterodactylus.sone.database.DatabaseException;
  52 import net.pterodactylus.sone.database.ImageBuilder;
  53 import net.pterodactylus.sone.database.PostBuilder;
  54 import net.pterodactylus.sone.database.PostDatabase;
  55 import net.pterodactylus.sone.database.PostReplyBuilder;
  56 import net.pterodactylus.sone.database.SoneBuilder;
  57 import net.pterodactylus.sone.database.SoneProvider;
  58 import net.pterodactylus.util.config.Configuration;
  59 import net.pterodactylus.util.config.ConfigurationException;
  60
  61 import com.google.common.base.Optional;
  62 import com.google.common.base.Predicate;
  63 import com.google.common.collect.HashMultimap;
  64 import com.google.common.collect.Multimap;
  65 import com.google.common.collect.SortedSetMultimap;
  66 import com.google.common.collect.TreeMultimap;
  67 import com.google.common.util.concurrent.AbstractService;
  68 import com.google.inject.Inject;
  69 import com.google.inject.Singleton;
  70 import kotlin.jvm.functions.Function1;
  71
  72 /**
  73  * Memory-based {@link PostDatabase} implementation.
  74  *
  75  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  76  */
  77 @Singleton
  78 public class MemoryDatabase extends AbstractService implements Database {
  79
  80         /** The lock. */
  81         private final ReadWriteLock lock = new ReentrantReadWriteLock();
  82
  83         /** The Sone provider. */
  84         private final SoneProvider soneProvider;
  85
  86         /** The configuration. */
  87         private final Configuration configuration;
  88         private final ConfigurationLoader configurationLoader;
  89
  90         private final Map<String, Sone> allSones = new HashMap<String, Sone>();
  91
  92         /** All posts by their ID. */
  93         private final Map<String, Post> allPosts = new HashMap<String, Post>();
  94
  95         /** All posts by their Sones. */
  96         private final Multimap<String, Post> sonePosts = HashMultimap.create();
  97
  98         /** Whether posts are known. */
  99         private final Set<String> knownPosts = new HashSet<String>();
 100
 101         /** All post replies by their ID. */
 102         private final Map<String, PostReply> allPostReplies = new HashMap<String, PostReply>();
 103
 104         /** Replies sorted by Sone. */
 105         private final SortedSetMultimap<String, PostReply> sonePostReplies = TreeMultimap.create(new Comparator<String>() {
 106
 107                 @Override
 108                 public int compare(String leftString, String rightString) {
 109                         return leftString.compareTo(rightString);
 110                 }
 111         }, TIME_COMPARATOR);
 112
 113         /** Whether post replies are known. */
 114         private final Set<String> knownPostReplies = new HashSet<String>();
 115
 116         private final Map<String, Album> allAlbums = new HashMap<String, Album>();
 117         private final Multimap<String, Album> soneAlbums = HashMultimap.create();
 118
 119         private final Map<String, Image> allImages = new HashMap<String, Image>();
 120         private final Multimap<String, Image> soneImages = HashMultimap.create();
 121
 122         private final MemoryBookmarkDatabase memoryBookmarkDatabase;
 123         private final MemoryFriendDatabase memoryFriendDatabase;
 124
 125         /**
 126          * Creates a new memory database.
 127          *
 128          * @param soneProvider
 129          *              The Sone provider
 130          * @param configuration
 131          *              The configuration for loading and saving elements
 132          */
 133         @Inject
 134         public MemoryDatabase(SoneProvider soneProvider, Configuration configuration) {
 135                 this.soneProvider = soneProvider;
 136                 this.configuration = configuration;
 137                 this.configurationLoader = new ConfigurationLoader(configuration);
 138                 memoryBookmarkDatabase =
 139                                 new MemoryBookmarkDatabase(this, configurationLoader);
 140                 memoryFriendDatabase = new MemoryFriendDatabase(configurationLoader);
 141         }
 142
 143         //
 144         // DATABASE METHODS
 145         //
 146
 147         /**
 148          * Saves the database.
 149          *
 150          * @throws DatabaseException
 151          *              if an error occurs while saving
 152          */
 153         @Override
 154         public void save() throws DatabaseException {
 155                 saveKnownPosts();
 156                 saveKnownPostReplies();
 157         }
 158
 159         //
 160         // SERVICE METHODS
 161         //
 162
 163         /** {@inheritDocs} */
 164         @Override
 165         protected void doStart() {
 166                 memoryBookmarkDatabase.start();
 167                 loadKnownPosts();
 168                 loadKnownPostReplies();
 169                 notifyStarted();
 170         }
 171
 172         /** {@inheritDocs} */
 173         @Override
 174         protected void doStop() {
 175                 try {
 176                         memoryBookmarkDatabase.stop();
 177                         save();
 178                         notifyStopped();
 179                 } catch (DatabaseException de1) {
 180                         notifyFailed(de1);
 181                 }
 182         }
 183
 184         @Override
 185         public SoneBuilder newSoneBuilder() {
 186                 return new MemorySoneBuilder(this);
 187         }
 188
 189         @Override
 190         public void storeSone(Sone sone) {
 191                 lock.writeLock().lock();
 192                 try {
 193                         removeSone(sone);
 194
 195                         allSones.put(sone.getId(), sone);
 196                         sonePosts.putAll(sone.getId(), sone.getPosts());
 197                         for (Post post : sone.getPosts()) {
 198                                 allPosts.put(post.getId(), post);
 199                         }
 200                         sonePostReplies.putAll(sone.getId(), sone.getReplies());
 201                         for (PostReply postReply : sone.getReplies()) {
 202                                 allPostReplies.put(postReply.getId(), postReply);
 203                         }
 204                         soneAlbums.putAll(sone.getId(), toAllAlbums.apply(sone));
 205                         for (Album album : toAllAlbums.apply(sone)) {
 206                                 allAlbums.put(album.getId(), album);
 207                         }
 208                         soneImages.putAll(sone.getId(), toAllImages.apply(sone));
 209                         for (Image image : toAllImages.apply(sone)) {
 210                                 allImages.put(image.getId(), image);
 211                         }
 212                 } finally {
 213                         lock.writeLock().unlock();
 214                 }
 215         }
 216
 217         @Override
 218         public void removeSone(Sone sone) {
 219                 lock.writeLock().lock();
 220                 try {
 221                         allSones.remove(sone.getId());
 222                         Collection<Post> removedPosts = sonePosts.removeAll(sone.getId());
 223                         for (Post removedPost : removedPosts) {
 224                                 allPosts.remove(removedPost.getId());
 225                         }
 226                         Collection<PostReply> removedPostReplies =
 227                                         sonePostReplies.removeAll(sone.getId());
 228                         for (PostReply removedPostReply : removedPostReplies) {
 229                                 allPostReplies.remove(removedPostReply.getId());
 230                         }
 231                         Collection<Album> removedAlbums =
 232                                         soneAlbums.removeAll(sone.getId());
 233                         for (Album removedAlbum : removedAlbums) {
 234                                 allAlbums.remove(removedAlbum.getId());
 235                         }
 236                         Collection<Image> removedImages =
 237                                         soneImages.removeAll(sone.getId());
 238                         for (Image removedImage : removedImages) {
 239                                 allImages.remove(removedImage.getId());
 240                         }
 241                 } finally {
 242                         lock.writeLock().unlock();
 243                 }
 244         }
 245
 246         @Nonnull
 247         @Override
 248         public Function1<String, Sone> getSoneLoader() {
 249                 return new Function1<String, Sone>() {
 250                         @Override
 251                         public Sone invoke(String soneId) {
 252                                 return getSone(soneId);
 253                         }
 254                 };
 255         }
 256
 257         @Override
 258         public Sone getSone(String soneId) {
 259                 lock.readLock().lock();
 260                 try {
 261                         return allSones.get(soneId);
 262                 } finally {
 263                         lock.readLock().unlock();
 264                 }
 265         }
 266
 267         @Override
 268         public Collection<Sone> getSones() {
 269                 lock.readLock().lock();
 270                 try {
 271                         return new HashSet<Sone>(allSones.values());
 272                 } finally {
 273                         lock.readLock().unlock();
 274                 }
 275         }
 276
 277         @Override
 278         public Collection<Sone> getLocalSones() {
 279                 lock.readLock().lock();
 280                 try {
 281                         return from(allSones.values()).filter(LOCAL_SONE_FILTER).toSet();
 282                 } finally {
 283                         lock.readLock().unlock();
 284                 }
 285         }
 286
 287         @Override
 288         public Collection<Sone> getRemoteSones() {
 289                 lock.readLock().lock();
 290                 try {
 291                         return from(allSones.values())
 292                                         .filter(not(LOCAL_SONE_FILTER)) .toSet();
 293                 } finally {
 294                         lock.readLock().unlock();
 295                 }
 296         }
 297
 298         @Override
 299         public Collection<String> getFriends(Sone localSone) {
 300                 if (!localSone.isLocal()) {
 301                         return Collections.emptySet();
 302                 }
 303                 return memoryFriendDatabase.getFriends(localSone.getId());
 304         }
 305
 306         @Override
 307         public boolean isFriend(Sone localSone, String friendSoneId) {
 308                 if (!localSone.isLocal()) {
 309                         return false;
 310                 }
 311                 return memoryFriendDatabase.isFriend(localSone.getId(), friendSoneId);
 312         }
 313
 314         @Override
 315         public void addFriend(Sone localSone, String friendSoneId) {
 316                 if (!localSone.isLocal()) {
 317                         return;
 318                 }
 319                 memoryFriendDatabase.addFriend(localSone.getId(), friendSoneId);
 320         }
 321
 322         @Override
 323         public void removeFriend(Sone localSone, String friendSoneId) {
 324                 if (!localSone.isLocal()) {
 325                         return;
 326                 }
 327                 memoryFriendDatabase.removeFriend(localSone.getId(), friendSoneId);
 328         }
 329
 330         //
 331         // POSTPROVIDER METHODS
 332         //
 333
 334         /** {@inheritDocs} */
 335         @Override
 336         public Optional<Post> getPost(String postId) {
 337                 lock.readLock().lock();
 338                 try {
 339                         return fromNullable(allPosts.get(postId));
 340                 } finally {
 341                         lock.readLock().unlock();
 342                 }
 343         }
 344
 345         /** {@inheritDocs} */
 346         @Override
 347         public Collection<Post> getPosts(String soneId) {
 348                 return new HashSet<Post>(getPostsFrom(soneId));
 349         }
 350
 351         /** {@inheritDocs} */
 352         @Override
 353         public Collection<Post> getDirectedPosts(final String recipientId) {
 354                 lock.readLock().lock();
 355                 try {
 356                         return from(sonePosts.values()).filter(new Predicate<Post>() {
 357                                 @Override
 358                                 public boolean apply(Post post) {
 359                                         return post.getRecipientId().asSet().contains(recipientId);
 360                                 }
 361                         }).toSet();
 362                 } finally {
 363                         lock.readLock().unlock();
 364                 }
 365         }
 366
 367         //
 368         // POSTBUILDERFACTORY METHODS
 369         //
 370
 371         /** {@inheritDocs} */
 372         @Override
 373         public PostBuilder newPostBuilder() {
 374                 return new MemoryPostBuilder(this, soneProvider);
 375         }
 376
 377         //
 378         // POSTSTORE METHODS
 379         //
 380
 381         /** {@inheritDocs} */
 382         @Override
 383         public void storePost(Post post) {
 384                 checkNotNull(post, "post must not be null");
 385                 lock.writeLock().lock();
 386                 try {
 387                         allPosts.put(post.getId(), post);
 388                         getPostsFrom(post.getSone().getId()).add(post);
 389                 } finally {
 390                         lock.writeLock().unlock();
 391                 }
 392         }
 393
 394         /** {@inheritDocs} */
 395         @Override
 396         public void removePost(Post post) {
 397                 checkNotNull(post, "post must not be null");
 398                 lock.writeLock().lock();
 399                 try {
 400                         allPosts.remove(post.getId());
 401                         getPostsFrom(post.getSone().getId()).remove(post);
 402                         post.getSone().removePost(post);
 403                 } finally {
 404                         lock.writeLock().unlock();
 405                 }
 406         }
 407
 408         //
 409         // POSTREPLYPROVIDER METHODS
 410         //
 411
 412         /** {@inheritDocs} */
 413         @Override
 414         public Optional<PostReply> getPostReply(String id) {
 415                 lock.readLock().lock();
 416                 try {
 417                         return fromNullable(allPostReplies.get(id));
 418                 } finally {
 419                         lock.readLock().unlock();
 420                 }
 421         }
 422
 423         /** {@inheritDocs} */
 424         @Override
 425         public List<PostReply> getReplies(final String postId) {
 426                 lock.readLock().lock();
 427                 try {
 428                         return from(allPostReplies.values())
 429                                         .filter(new Predicate<PostReply>() {
 430                                                 @Override
 431                                                 public boolean apply(PostReply postReply) {
 432                                                         return postReply.getPostId().equals(postId);
 433                                                 }
 434                                         }).toSortedList(TIME_COMPARATOR);
 435                 } finally {
 436                         lock.readLock().unlock();
 437                 }
 438         }
 439
 440         //
 441         // POSTREPLYBUILDERFACTORY METHODS
 442         //
 443
 444         /** {@inheritDocs} */
 445         @Override
 446         public PostReplyBuilder newPostReplyBuilder() {
 447                 return new MemoryPostReplyBuilder(this, soneProvider);
 448         }
 449
 450         //
 451         // POSTREPLYSTORE METHODS
 452         //
 453
 454         /** {@inheritDocs} */
 455         @Override
 456         public void storePostReply(PostReply postReply) {
 457                 lock.writeLock().lock();
 458                 try {
 459                         allPostReplies.put(postReply.getId(), postReply);
 460                 } finally {
 461                         lock.writeLock().unlock();
 462                 }
 463         }
 464
 465         /** {@inheritDocs} */
 466         @Override
 467         public void removePostReply(PostReply postReply) {
 468                 lock.writeLock().lock();
 469                 try {
 470                         allPostReplies.remove(postReply.getId());
 471                 } finally {
 472                         lock.writeLock().unlock();
 473                 }
 474         }
 475
 476         //
 477         // ALBUMPROVDER METHODS
 478         //
 479
 480         @Override
 481         public Optional<Album> getAlbum(String albumId) {
 482                 lock.readLock().lock();
 483                 try {
 484                         return fromNullable(allAlbums.get(albumId));
 485                 } finally {
 486                         lock.readLock().unlock();
 487                 }
 488         }
 489
 490         //
 491         // ALBUMBUILDERFACTORY METHODS
 492         //
 493
 494         @Override
 495         public AlbumBuilder newAlbumBuilder() {
 496                 return new AlbumBuilderImpl();
 497         }
 498
 499         //
 500         // ALBUMSTORE METHODS
 501         //
 502
 503         @Override
 504         public void storeAlbum(Album album) {
 505                 lock.writeLock().lock();
 506                 try {
 507                         allAlbums.put(album.getId(), album);
 508                         soneAlbums.put(album.getSone().getId(), album);
 509                 } finally {
 510                         lock.writeLock().unlock();
 511                 }
 512         }
 513
 514         @Override
 515         public void removeAlbum(Album album) {
 516                 lock.writeLock().lock();
 517                 try {
 518                         allAlbums.remove(album.getId());
 519                         soneAlbums.remove(album.getSone().getId(), album);
 520                 } finally {
 521                         lock.writeLock().unlock();
 522                 }
 523         }
 524
 525         //
 526         // IMAGEPROVIDER METHODS
 527         //
 528
 529         @Override
 530         public Optional<Image> getImage(String imageId) {
 531                 lock.readLock().lock();
 532                 try {
 533                         return fromNullable(allImages.get(imageId));
 534                 } finally {
 535                         lock.readLock().unlock();
 536                 }
 537         }
 538
 539         //
 540         // IMAGEBUILDERFACTORY METHODS
 541         //
 542
 543         @Override
 544         public ImageBuilder newImageBuilder() {
 545                 return new ImageBuilderImpl();
 546         }
 547
 548         //
 549         // IMAGESTORE METHODS
 550         //
 551
 552         @Override
 553         public void storeImage(Image image) {
 554                 lock.writeLock().lock();
 555                 try {
 556                         allImages.put(image.getId(), image);
 557                         soneImages.put(image.getSone().getId(), image);
 558                 } finally {
 559                         lock.writeLock().unlock();
 560                 }
 561         }
 562
 563         @Override
 564         public void removeImage(Image image) {
 565                 lock.writeLock().lock();
 566                 try {
 567                         allImages.remove(image.getId());
 568                         soneImages.remove(image.getSone().getId(), image);
 569                 } finally {
 570                         lock.writeLock().unlock();
 571                 }
 572         }
 573
 574         @Override
 575         public void bookmarkPost(Post post) {
 576                 memoryBookmarkDatabase.bookmarkPost(post);
 577         }
 578
 579         @Override
 580         public void unbookmarkPost(Post post) {
 581                 memoryBookmarkDatabase.unbookmarkPost(post);
 582         }
 583
 584         @Override
 585         public boolean isPostBookmarked(Post post) {
 586                 return memoryBookmarkDatabase.isPostBookmarked(post);
 587         }
 588
 589         @Override
 590         public Set<Post> getBookmarkedPosts() {
 591                 return memoryBookmarkDatabase.getBookmarkedPosts();
 592         }
 593
 594         //
 595         // PACKAGE-PRIVATE METHODS
 596         //
 597
 598         /**
 599          * Returns whether the given post is known.
 600          *
 601          * @param post
 602          *              The post
 603          * @return {@code true} if the post is known, {@code false} otherwise
 604          */
 605         boolean isPostKnown(Post post) {
 606                 lock.readLock().lock();
 607                 try {
 608                         return knownPosts.contains(post.getId());
 609                 } finally {
 610                         lock.readLock().unlock();
 611                 }
 612         }
 613
 614         /**
 615          * Sets whether the given post is known.
 616          *
 617          * @param post
 618          *              The post
 619          * @param known
 620          *              {@code true} if the post is known, {@code false} otherwise
 621          */
 622         void setPostKnown(Post post, boolean known) {
 623                 lock.writeLock().lock();
 624                 try {
 625                         if (known) {
 626                                 knownPosts.add(post.getId());
 627                         } else {
 628                                 knownPosts.remove(post.getId());
 629                         }
 630                 } finally {
 631                         lock.writeLock().unlock();
 632                 }
 633         }
 634
 635         /**
 636          * Returns whether the given post reply is known.
 637          *
 638          * @param postReply
 639          *              The post reply
 640          * @return {@code true} if the given post reply is known, {@code false}
 641          *         otherwise
 642          */
 643         boolean isPostReplyKnown(PostReply postReply) {
 644                 lock.readLock().lock();
 645                 try {
 646                         return knownPostReplies.contains(postReply.getId());
 647                 } finally {
 648                         lock.readLock().unlock();
 649                 }
 650         }
 651
 652         /**
 653          * Sets whether the given post reply is known.
 654          *
 655          * @param postReply
 656          *              The post reply
 657          * @param known
 658          *              {@code true} if the post reply is known, {@code false} otherwise
 659          */
 660         void setPostReplyKnown(PostReply postReply, boolean known) {
 661                 lock.writeLock().lock();
 662                 try {
 663                         if (known) {
 664                                 knownPostReplies.add(postReply.getId());
 665                         } else {
 666                                 knownPostReplies.remove(postReply.getId());
 667                         }
 668                 } finally {
 669                         lock.writeLock().unlock();
 670                 }
 671         }
 672
 673         //
 674         // PRIVATE METHODS
 675         //
 676
 677         /**
 678          * Gets all posts for the given Sone, creating a new collection if there is
 679          * none yet.
 680          *
 681          * @param soneId
 682          *              The ID of the Sone to get the posts for
 683          * @return All posts
 684          */
 685         private Collection<Post> getPostsFrom(String soneId) {
 686                 lock.readLock().lock();
 687                 try {
 688                         return sonePosts.get(soneId);
 689                 } finally {
 690                         lock.readLock().unlock();
 691                 }
 692         }
 693
 694         /** Loads the known posts. */
 695         private void loadKnownPosts() {
 696                 Set<String> knownPosts = configurationLoader.loadKnownPosts();
 697                 lock.writeLock().lock();
 698                 try {
 699                         this.knownPosts.clear();
 700                         this.knownPosts.addAll(knownPosts);
 701                 } finally {
 702                         lock.writeLock().unlock();
 703                 }
 704         }
 705
 706         /**
 707          * Saves the known posts to the configuration.
 708          *
 709          * @throws DatabaseException
 710          *              if a configuration error occurs
 711          */
 712         private void saveKnownPosts() throws DatabaseException {
 713                 lock.readLock().lock();
 714                 try {
 715                         int postCounter = 0;
 716                         for (String knownPostId : knownPosts) {
 717                                 configuration.getStringValue("KnownPosts/" + postCounter++ + "/ID").setValue(knownPostId);
 718                         }
 719                         configuration.getStringValue("KnownPosts/" + postCounter + "/ID").setValue(null);
 720                 } catch (ConfigurationException ce1) {
 721                         throw new DatabaseException("Could not save database.", ce1);
 722                 } finally {
 723                         lock.readLock().unlock();
 724                 }
 725         }
 726
 727         /** Loads the known post replies. */
 728         private void loadKnownPostReplies() {
 729                 Set<String> knownPostReplies = configurationLoader.loadKnownPostReplies();
 730                 lock.writeLock().lock();
 731                 try {
 732                         this.knownPostReplies.clear();
 733                         this.knownPostReplies.addAll(knownPostReplies);
 734                 } finally {
 735                         lock.writeLock().unlock();
 736                 }
 737         }
 738
 739         /**
 740          * Saves the known post replies to the configuration.
 741          *
 742          * @throws DatabaseException
 743          *              if a configuration error occurs
 744          */
 745         private void saveKnownPostReplies() throws DatabaseException {
 746                 lock.readLock().lock();
 747                 try {
 748                         int replyCounter = 0;
 749                         for (String knownReplyId : knownPostReplies) {
 750                                 configuration.getStringValue("KnownReplies/" + replyCounter++ + "/ID").setValue(knownReplyId);
 751                         }
 752                         configuration.getStringValue("KnownReplies/" + replyCounter + "/ID").setValue(null);
 753                 } catch (ConfigurationException ce1) {
 754                         throw new DatabaseException("Could not save database.", ce1);
 755                 } finally {
 756                         lock.readLock().unlock();
 757                 }
 758         }
 759
 760 }