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

   1 /*
   2  * Sone - MemoryDatabase.java - Copyright © 2013 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 java.util.Collections.emptyList;
  25 import static net.pterodactylus.sone.data.Sone.LOCAL_SONE_FILTER;
  26
  27 import java.util.ArrayList;
  28 import java.util.Collection;
  29 import java.util.Collections;
  30 import java.util.Comparator;
  31 import java.util.HashMap;
  32 import java.util.HashSet;
  33 import java.util.List;
  34 import java.util.Map;
  35 import java.util.Set;
  36 import java.util.SortedSet;
  37 import java.util.TreeSet;
  38 import java.util.concurrent.locks.ReadWriteLock;
  39 import java.util.concurrent.locks.ReentrantReadWriteLock;
  40
  41 import net.pterodactylus.sone.data.Album;
  42 import net.pterodactylus.sone.data.Image;
  43 import net.pterodactylus.sone.data.Post;
  44 import net.pterodactylus.sone.data.PostReply;
  45 import net.pterodactylus.sone.data.Reply;
  46 import net.pterodactylus.sone.data.Sone;
  47 import net.pterodactylus.sone.database.Database;
  48 import net.pterodactylus.sone.database.DatabaseException;
  49 import net.pterodactylus.sone.database.PostBuilder;
  50 import net.pterodactylus.sone.database.PostDatabase;
  51 import net.pterodactylus.sone.database.PostReplyBuilder;
  52 import net.pterodactylus.sone.database.SoneBuilder;
  53 import net.pterodactylus.util.config.Configuration;
  54 import net.pterodactylus.util.config.ConfigurationException;
  55
  56 import com.google.common.base.Function;
  57 import com.google.common.base.Optional;
  58 import com.google.common.collect.ArrayListMultimap;
  59 import com.google.common.collect.ListMultimap;
  60 import com.google.common.collect.SortedSetMultimap;
  61 import com.google.common.collect.TreeMultimap;
  62 import com.google.common.util.concurrent.AbstractService;
  63 import com.google.inject.Inject;
  64
  65 /**
  66  * Memory-based {@link PostDatabase} implementation.
  67  *
  68  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  69  */
  70 public class MemoryDatabase extends AbstractService implements Database {
  71
  72         /** The lock. */
  73         private final ReadWriteLock lock = new ReentrantReadWriteLock();
  74
  75         /** The configuration. */
  76         private final Configuration configuration;
  77
  78         private final Map<String, Sone> sones = new HashMap<String, Sone>();
  79
  80         /** All posts by their ID. */
  81         private final Map<String, Post> allPosts = new HashMap<String, Post>();
  82
  83         /** All posts by their Sones. */
  84         private final Map<String, Collection<Post>> sonePosts = new HashMap<String, Collection<Post>>();
  85
  86         /** All posts by their recipient. */
  87         private final Map<String, Collection<Post>> recipientPosts = new HashMap<String, Collection<Post>>();
  88
  89         /** Whether posts are known. */
  90         private final Set<String> knownPosts = new HashSet<String>();
  91
  92         /** All post replies by their ID. */
  93         private final Map<String, PostReply> allPostReplies = new HashMap<String, PostReply>();
  94
  95         /** Replies sorted by Sone. */
  96         private final SortedSetMultimap<String, PostReply> sonePostReplies = TreeMultimap.create(new Comparator<String>() {
  97
  98                 @Override
  99                 public int compare(String leftString, String rightString) {
 100                         return leftString.compareTo(rightString);
 101                 }
 102         }, PostReply.TIME_COMPARATOR);
 103
 104         /** Replies by post. */
 105         private final Map<String, SortedSet<PostReply>> postReplies = new HashMap<String, SortedSet<PostReply>>();
 106
 107         /** Whether post replies are known. */
 108         private final Set<String> knownPostReplies = new HashSet<String>();
 109
 110         private final Map<String, Album> allAlbums = new HashMap<String, Album>();
 111         private final ListMultimap<String, String> albumChildren = ArrayListMultimap.create();
 112         private final ListMultimap<String, String> albumImages = ArrayListMultimap.create();
 113
 114         private final Map<String, Image> allImages = new HashMap<String, Image>();
 115
 116         /**
 117          * Creates a new memory database.
 118          *
 119          * @param configuration
 120          *              The configuration for loading and saving elements
 121          */
 122         @Inject
 123         public MemoryDatabase(Configuration configuration) {
 124                 this.configuration = configuration;
 125         }
 126
 127         //
 128         // DATABASE METHODS
 129         //
 130
 131         /**
 132          * Saves the database.
 133          *
 134          * @throws DatabaseException
 135          *              if an error occurs while saving
 136          */
 137         @Override
 138         public void save() throws DatabaseException {
 139                 saveKnownPosts();
 140                 saveKnownPostReplies();
 141         }
 142
 143         //
 144         // SERVICE METHODS
 145         //
 146
 147         /** {@inheritDocs} */
 148         @Override
 149         protected void doStart() {
 150                 loadKnownPosts();
 151                 loadKnownPostReplies();
 152                 notifyStarted();
 153         }
 154
 155         /** {@inheritDocs} */
 156         @Override
 157         protected void doStop() {
 158                 try {
 159                         save();
 160                         notifyStopped();
 161                 } catch (DatabaseException de1) {
 162                         notifyFailed(de1);
 163                 }
 164         }
 165
 166         @Override
 167         public Optional<Sone> getSone(String soneId) {
 168                 lock.readLock().lock();
 169                 try {
 170                         return fromNullable(sones.get(soneId));
 171                 } finally {
 172                         lock.readLock().unlock();
 173                 }
 174         }
 175
 176         @Override
 177         public Collection<Sone> getSones() {
 178                 lock.readLock().lock();
 179                 try {
 180                         return Collections.unmodifiableCollection(sones.values());
 181                 } finally {
 182                         lock.readLock().unlock();
 183                 }
 184         }
 185
 186         @Override
 187         public Collection<Sone> getLocalSones() {
 188                 lock.readLock().lock();
 189                 try {
 190                         return from(getSones()).filter(LOCAL_SONE_FILTER).toSet();
 191                 } finally {
 192                         lock.readLock().unlock();
 193                 }
 194         }
 195
 196         @Override
 197         public Collection<Sone> getRemoteSones() {
 198                 lock.readLock().lock();
 199                 try {
 200                         return from(getSones()).filter(not(LOCAL_SONE_FILTER)).toSet();
 201                 } finally {
 202                         lock.readLock().unlock();
 203                 }
 204         }
 205
 206         @Override
 207         public SoneBuilder newSoneBuilder() {
 208                 return null;
 209         }
 210
 211         //
 212         // POSTPROVIDER METHODS
 213         //
 214
 215         /** {@inheritDocs} */
 216         @Override
 217         public Optional<Post> getPost(String postId) {
 218                 lock.readLock().lock();
 219                 try {
 220                         return fromNullable(allPosts.get(postId));
 221                 } finally {
 222                         lock.readLock().unlock();
 223                 }
 224         }
 225
 226         /** {@inheritDocs} */
 227         @Override
 228         public Collection<Post> getPosts(String soneId) {
 229                 return new HashSet<Post>(getPostsFrom(soneId));
 230         }
 231
 232         /** {@inheritDocs} */
 233         @Override
 234         public Collection<Post> getDirectedPosts(String recipientId) {
 235                 lock.readLock().lock();
 236                 try {
 237                         Collection<Post> posts = recipientPosts.get(recipientId);
 238                         return (posts == null) ? Collections.<Post>emptySet() : new HashSet<Post>(posts);
 239                 } finally {
 240                         lock.readLock().unlock();
 241                 }
 242         }
 243
 244         //
 245         // POSTBUILDERFACTORY METHODS
 246         //
 247
 248         /** {@inheritDocs} */
 249         @Override
 250         public PostBuilder newPostBuilder() {
 251                 return new MemoryPostBuilder(this);
 252         }
 253
 254         //
 255         // POSTSTORE METHODS
 256         //
 257
 258         /** {@inheritDocs} */
 259         @Override
 260         public void storePost(Post post) {
 261                 checkNotNull(post, "post must not be null");
 262                 lock.writeLock().lock();
 263                 try {
 264                         allPosts.put(post.getId(), post);
 265                         getPostsFrom(post.getSone().getId()).add(post);
 266                         if (post.getRecipientId().isPresent()) {
 267                                 getPostsTo(post.getRecipientId().get()).add(post);
 268                         }
 269                 } finally {
 270                         lock.writeLock().unlock();
 271                 }
 272         }
 273
 274         /** {@inheritDocs} */
 275         @Override
 276         public void removePost(Post post) {
 277                 checkNotNull(post, "post must not be null");
 278                 lock.writeLock().lock();
 279                 try {
 280                         allPosts.remove(post.getId());
 281                         getPostsFrom(post.getSone().getId()).remove(post);
 282                         if (post.getRecipientId().isPresent()) {
 283                                 getPostsTo(post.getRecipientId().get()).remove(post);
 284                         }
 285                         post.getSone().removePost(post);
 286                 } finally {
 287                         lock.writeLock().unlock();
 288                 }
 289         }
 290
 291         /** {@inheritDocs} */
 292         @Override
 293         public void storePosts(Sone sone, Collection<Post> posts) throws IllegalArgumentException {
 294                 checkNotNull(sone, "sone must not be null");
 295                 /* verify that all posts are from the same Sone. */
 296                 for (Post post : posts) {
 297                         if (!sone.equals(post.getSone())) {
 298                                 throw new IllegalArgumentException(String.format("Post from different Sone found: %s", post));
 299                         }
 300                 }
 301
 302                 lock.writeLock().lock();
 303                 try {
 304                         /* remove all posts by the Sone. */
 305                         getPostsFrom(sone.getId()).clear();
 306                         for (Post post : posts) {
 307                                 allPosts.remove(post.getId());
 308                                 if (post.getRecipientId().isPresent()) {
 309                                         getPostsTo(post.getRecipientId().get()).remove(post);
 310                                 }
 311                         }
 312
 313                         /* add new posts. */
 314                         getPostsFrom(sone.getId()).addAll(posts);
 315                         for (Post post : posts) {
 316                                 allPosts.put(post.getId(), post);
 317                                 if (post.getRecipientId().isPresent()) {
 318                                         getPostsTo(post.getRecipientId().get()).add(post);
 319                                 }
 320                         }
 321                 } finally {
 322                         lock.writeLock().unlock();
 323                 }
 324         }
 325
 326         /** {@inheritDocs} */
 327         @Override
 328         public void removePosts(Sone sone) {
 329                 checkNotNull(sone, "sone must not be null");
 330                 lock.writeLock().lock();
 331                 try {
 332                         /* remove all posts by the Sone. */
 333                         getPostsFrom(sone.getId()).clear();
 334                         for (Post post : sone.getPosts()) {
 335                                 allPosts.remove(post.getId());
 336                                 if (post.getRecipientId().isPresent()) {
 337                                         getPostsTo(post.getRecipientId().get()).remove(post);
 338                                 }
 339                         }
 340                 } finally {
 341                         lock.writeLock().unlock();
 342                 }
 343         }
 344
 345         //
 346         // POSTREPLYPROVIDER METHODS
 347         //
 348
 349         /** {@inheritDocs} */
 350         @Override
 351         public Optional<PostReply> getPostReply(String id) {
 352                 lock.readLock().lock();
 353                 try {
 354                         return fromNullable(allPostReplies.get(id));
 355                 } finally {
 356                         lock.readLock().unlock();
 357                 }
 358         }
 359
 360         /** {@inheritDocs} */
 361         @Override
 362         public List<PostReply> getReplies(String postId) {
 363                 lock.readLock().lock();
 364                 try {
 365                         if (!postReplies.containsKey(postId)) {
 366                                 return emptyList();
 367                         }
 368                         return new ArrayList<PostReply>(postReplies.get(postId));
 369                 } finally {
 370                         lock.readLock().unlock();
 371                 }
 372         }
 373
 374         //
 375         // POSTREPLYBUILDERFACTORY METHODS
 376         //
 377
 378         /** {@inheritDocs} */
 379         @Override
 380         public PostReplyBuilder newPostReplyBuilder() {
 381                 return new MemoryPostReplyBuilder(this, this);
 382         }
 383
 384         //
 385         // POSTREPLYSTORE METHODS
 386         //
 387
 388         /** {@inheritDocs} */
 389         @Override
 390         public void storePostReply(PostReply postReply) {
 391                 lock.writeLock().lock();
 392                 try {
 393                         allPostReplies.put(postReply.getId(), postReply);
 394                         if (postReplies.containsKey(postReply.getPostId())) {
 395                                 postReplies.get(postReply.getPostId()).add(postReply);
 396                         } else {
 397                                 TreeSet<PostReply> replies = new TreeSet<PostReply>(Reply.TIME_COMPARATOR);
 398                                 replies.add(postReply);
 399                                 postReplies.put(postReply.getPostId(), replies);
 400                         }
 401                 } finally {
 402                         lock.writeLock().unlock();
 403                 }
 404         }
 405
 406         /** {@inheritDocs} */
 407         @Override
 408         public void storePostReplies(Sone sone, Collection<PostReply> postReplies) {
 409                 checkNotNull(sone, "sone must not be null");
 410                 /* verify that all posts are from the same Sone. */
 411                 for (PostReply postReply : postReplies) {
 412                         if (!sone.equals(postReply.getSone())) {
 413                                 throw new IllegalArgumentException(String.format("PostReply from different Sone found: %s", postReply));
 414                         }
 415                 }
 416
 417                 lock.writeLock().lock();
 418                 try {
 419                         /* remove all post replies of the Sone. */
 420                         for (PostReply postReply : getRepliesFrom(sone.getId())) {
 421                                 removePostReply(postReply);
 422                         }
 423                         for (PostReply postReply : postReplies) {
 424                                 allPostReplies.put(postReply.getId(), postReply);
 425                                 sonePostReplies.put(postReply.getSone().getId(), postReply);
 426                                 if (this.postReplies.containsKey(postReply.getPostId())) {
 427                                         this.postReplies.get(postReply.getPostId()).add(postReply);
 428                                 } else {
 429                                         TreeSet<PostReply> replies = new TreeSet<PostReply>(Reply.TIME_COMPARATOR);
 430                                         replies.add(postReply);
 431                                         this.postReplies.put(postReply.getPostId(), replies);
 432                                 }
 433                         }
 434                 } finally {
 435                         lock.writeLock().unlock();
 436                 }
 437         }
 438
 439         /** {@inheritDocs} */
 440         @Override
 441         public void removePostReply(PostReply postReply) {
 442                 lock.writeLock().lock();
 443                 try {
 444                         allPostReplies.remove(postReply.getId());
 445                         if (postReplies.containsKey(postReply.getPostId())) {
 446                                 postReplies.get(postReply.getPostId()).remove(postReply);
 447                                 if (postReplies.get(postReply.getPostId()).isEmpty()) {
 448                                         postReplies.remove(postReply.getPostId());
 449                                 }
 450                         }
 451                 } finally {
 452                         lock.writeLock().unlock();
 453                 }
 454         }
 455
 456         /** {@inheritDocs} */
 457         @Override
 458         public void removePostReplies(Sone sone) {
 459                 checkNotNull(sone, "sone must not be null");
 460
 461                 lock.writeLock().lock();
 462                 try {
 463                         for (PostReply postReply : sone.getReplies()) {
 464                                 removePostReply(postReply);
 465                         }
 466                 } finally {
 467                         lock.writeLock().unlock();
 468                 }
 469         }
 470
 471         //
 472         // ALBUMPROVDER METHODS
 473         //
 474
 475         @Override
 476         public Optional<Album> getAlbum(String albumId) {
 477                 lock.readLock().lock();
 478                 try {
 479                         return fromNullable(allAlbums.get(albumId));
 480                 } finally {
 481                         lock.readLock().unlock();
 482                 }
 483         }
 484
 485         @Override
 486         public List<Album> getAlbums(Album parent) {
 487                 lock.readLock().lock();
 488                 try {
 489                         return from(albumChildren.get(parent.getId())).transformAndConcat(getAlbum()).toList();
 490                 } finally {
 491                         lock.readLock().unlock();
 492                 }
 493         }
 494
 495         @Override
 496         public void moveUp(Album album) {
 497                 lock.writeLock().lock();
 498                 try {
 499                         List<String> albums = albumChildren.get(album.getParent().getId());
 500                         int currentIndex = albums.indexOf(album.getId());
 501                         if (currentIndex == 0) {
 502                                 return;
 503                         }
 504                         albums.remove(album.getId());
 505                         albums.add(currentIndex - 1, album.getId());
 506                 } finally {
 507                         lock.writeLock().unlock();
 508                 }
 509         }
 510
 511         @Override
 512         public void moveDown(Album album) {
 513                 lock.writeLock().lock();
 514                 try {
 515                         List<String> albums = albumChildren.get(album.getParent().getId());
 516                         int currentIndex = albums.indexOf(album.getId());
 517                         if (currentIndex == (albums.size() - 1)) {
 518                                 return;
 519                         }
 520                         albums.remove(album.getId());
 521                         albums.add(currentIndex + 1, album.getId());
 522                 } finally {
 523                         lock.writeLock().unlock();
 524                 }
 525         }
 526
 527         //
 528         // ALBUMSTORE METHODS
 529         //
 530
 531         @Override
 532         public void storeAlbum(Album album) {
 533                 lock.writeLock().lock();
 534                 try {
 535                         allAlbums.put(album.getId(), album);
 536                         albumChildren.put(album.getParent().getId(), album.getId());
 537                 } finally {
 538                         lock.writeLock().unlock();
 539                 }
 540         }
 541
 542         @Override
 543         public void removeAlbum(Album album) {
 544                 lock.writeLock().lock();
 545                 try {
 546                         allAlbums.remove(album.getId());
 547                         albumChildren.remove(album.getParent().getId(), album.getId());
 548                 } finally {
 549                         lock.writeLock().unlock();
 550                 }
 551         }
 552
 553         //
 554         // IMAGEPROVIDER METHODS
 555         //
 556
 557         @Override
 558         public Optional<Image> getImage(String imageId) {
 559                 lock.readLock().lock();
 560                 try {
 561                         return fromNullable(allImages.get(imageId));
 562                 } finally {
 563                         lock.readLock().unlock();
 564                 }
 565         }
 566
 567         @Override
 568         public List<Image> getImages(Album parent) {
 569                 lock.readLock().lock();
 570                 try {
 571                         return from(albumImages.get(parent.getId())).transformAndConcat(getImage()).toList();
 572                 } finally {
 573                         lock.readLock().unlock();
 574                 }
 575         }
 576
 577         @Override
 578         public void moveUp(Image image) {
 579                 lock.writeLock().lock();
 580                 try {
 581                         List<String> images = albumImages.get(image.getAlbum().getId());
 582                         int currentIndex = images.indexOf(image.getId());
 583                         if (currentIndex == 0) {
 584                                 return;
 585                         }
 586                         images.remove(image.getId());
 587                         images.add(currentIndex - 1, image.getId());
 588                 } finally {
 589                         lock.writeLock().unlock();
 590                 }
 591         }
 592
 593         @Override
 594         public void moveDown(Image image) {
 595                 lock.writeLock().lock();
 596                 try {
 597                         List<String> images = albumChildren.get(image.getAlbum().getId());
 598                         int currentIndex = images.indexOf(image.getId());
 599                         if (currentIndex == (images.size() - 1)) {
 600                                 return;
 601                         }
 602                         images.remove(image.getId());
 603                         images.add(currentIndex + 1, image.getId());
 604                 } finally {
 605                         lock.writeLock().unlock();
 606                 }
 607         }
 608
 609         //
 610         // IMAGESTORE METHODS
 611         //
 612
 613         @Override
 614         public void storeImage(Image image) {
 615                 lock.writeLock().lock();
 616                 try {
 617                         allImages.put(image.getId(), image);
 618                         albumImages.put(image.getAlbum().getId(), image.getId());
 619                 } finally {
 620                         lock.writeLock().unlock();
 621                 }
 622         }
 623
 624         @Override
 625         public void removeImage(Image image) {
 626                 lock.writeLock().lock();
 627                 try {
 628                         allImages.remove(image.getId());
 629                         albumImages.remove(image.getAlbum().getId(), image.getId());
 630                 } finally {
 631                         lock.writeLock().unlock();
 632                 }
 633         }
 634
 635         //
 636         // PACKAGE-PRIVATE METHODS
 637         //
 638
 639         /**
 640          * Returns whether the given post is known.
 641          *
 642          * @param post
 643          *              The post
 644          * @return {@code true} if the post is known, {@code false} otherwise
 645          */
 646         boolean isPostKnown(Post post) {
 647                 lock.readLock().lock();
 648                 try {
 649                         return knownPosts.contains(post.getId());
 650                 } finally {
 651                         lock.readLock().unlock();
 652                 }
 653         }
 654
 655         /**
 656          * Sets whether the given post is known.
 657          *
 658          * @param post
 659          *              The post
 660          * @param known
 661          *              {@code true} if the post is known, {@code false} otherwise
 662          */
 663         void setPostKnown(Post post, boolean known) {
 664                 lock.writeLock().lock();
 665                 try {
 666                         if (known) {
 667                                 knownPosts.add(post.getId());
 668                         } else {
 669                                 knownPosts.remove(post.getId());
 670                         }
 671                 } finally {
 672                         lock.writeLock().unlock();
 673                 }
 674         }
 675
 676         /**
 677          * Returns whether the given post reply is known.
 678          *
 679          * @param postReply
 680          *              The post reply
 681          * @return {@code true} if the given post reply is known, {@code false}
 682          *         otherwise
 683          */
 684         boolean isPostReplyKnown(PostReply postReply) {
 685                 lock.readLock().lock();
 686                 try {
 687                         return knownPostReplies.contains(postReply.getId());
 688                 } finally {
 689                         lock.readLock().unlock();
 690                 }
 691         }
 692
 693         /**
 694          * Sets whether the given post reply is known.
 695          *
 696          * @param postReply
 697          *              The post reply
 698          * @param known
 699          *              {@code true} if the post reply is known, {@code false} otherwise
 700          */
 701         void setPostReplyKnown(PostReply postReply, boolean known) {
 702                 lock.writeLock().lock();
 703                 try {
 704                         if (known) {
 705                                 knownPostReplies.add(postReply.getId());
 706                         } else {
 707                                 knownPostReplies.remove(postReply.getId());
 708                         }
 709                 } finally {
 710                         lock.writeLock().unlock();
 711                 }
 712         }
 713
 714         //
 715         // PRIVATE METHODS
 716         //
 717
 718         /**
 719          * Gets all posts for the given Sone, creating a new collection if there is
 720          * none yet.
 721          *
 722          * @param soneId
 723          *              The ID of the Sone to get the posts for
 724          * @return All posts
 725          */
 726         private Collection<Post> getPostsFrom(String soneId) {
 727                 Collection<Post> posts = null;
 728                 lock.readLock().lock();
 729                 try {
 730                         posts = sonePosts.get(soneId);
 731                 } finally {
 732                         lock.readLock().unlock();
 733                 }
 734                 if (posts != null) {
 735                         return posts;
 736                 }
 737
 738                 posts = new HashSet<Post>();
 739                 lock.writeLock().lock();
 740                 try {
 741                         sonePosts.put(soneId, posts);
 742                 } finally {
 743                         lock.writeLock().unlock();
 744                 }
 745
 746                 return posts;
 747         }
 748
 749         /**
 750          * Gets all posts that are directed the given Sone, creating a new collection
 751          * if there is none yet.
 752          *
 753          * @param recipientId
 754          *              The ID of the Sone to get the posts for
 755          * @return All posts
 756          */
 757         private Collection<Post> getPostsTo(String recipientId) {
 758                 Collection<Post> posts = null;
 759                 lock.readLock().lock();
 760                 try {
 761                         posts = recipientPosts.get(recipientId);
 762                 } finally {
 763                         lock.readLock().unlock();
 764                 }
 765                 if (posts != null) {
 766                         return posts;
 767                 }
 768
 769                 posts = new HashSet<Post>();
 770                 lock.writeLock().lock();
 771                 try {
 772                         recipientPosts.put(recipientId, posts);
 773                 } finally {
 774                         lock.writeLock().unlock();
 775                 }
 776
 777                 return posts;
 778         }
 779
 780         /** Loads the known posts. */
 781         private void loadKnownPosts() {
 782                 lock.writeLock().lock();
 783                 try {
 784                         int postCounter = 0;
 785                         while (true) {
 786                                 String knownPostId = configuration.getStringValue("KnownPosts/" + postCounter++ + "/ID").getValue(null);
 787                                 if (knownPostId == null) {
 788                                         break;
 789                                 }
 790                                 knownPosts.add(knownPostId);
 791                         }
 792                 } finally {
 793                         lock.writeLock().unlock();
 794                 }
 795         }
 796
 797         /**
 798          * Saves the known posts to the configuration.
 799          *
 800          * @throws DatabaseException
 801          *              if a configuration error occurs
 802          */
 803         private void saveKnownPosts() throws DatabaseException {
 804                 lock.readLock().lock();
 805                 try {
 806                         int postCounter = 0;
 807                         for (String knownPostId : knownPosts) {
 808                                 configuration.getStringValue("KnownPosts/" + postCounter++ + "/ID").setValue(knownPostId);
 809                         }
 810                         configuration.getStringValue("KnownPosts/" + postCounter + "/ID").setValue(null);
 811                 } catch (ConfigurationException ce1) {
 812                         throw new DatabaseException("Could not save database.", ce1);
 813                 } finally {
 814                         lock.readLock().unlock();
 815                 }
 816         }
 817
 818         /**
 819          * Returns all replies by the given Sone.
 820          *
 821          * @param id
 822          *              The ID of the Sone
 823          * @return The post replies of the Sone, sorted by time (newest first)
 824          */
 825         private Collection<PostReply> getRepliesFrom(String id) {
 826                 lock.readLock().lock();
 827                 try {
 828                         if (sonePostReplies.containsKey(id)) {
 829                                 return Collections.unmodifiableCollection(sonePostReplies.get(id));
 830                         }
 831                         return Collections.emptySet();
 832                 } finally {
 833                         lock.readLock().unlock();
 834                 }
 835         }
 836
 837         /** Loads the known post replies. */
 838         private void loadKnownPostReplies() {
 839                 lock.writeLock().lock();
 840                 try {
 841                         int replyCounter = 0;
 842                         while (true) {
 843                                 String knownReplyId = configuration.getStringValue("KnownReplies/" + replyCounter++ + "/ID").getValue(null);
 844                                 if (knownReplyId == null) {
 845                                         break;
 846                                 }
 847                                 knownPostReplies.add(knownReplyId);
 848                         }
 849                 } finally {
 850                         lock.writeLock().unlock();
 851                 }
 852         }
 853
 854         /**
 855          * Saves the known post replies to the configuration.
 856          *
 857          * @throws DatabaseException
 858          *              if a configuration error occurs
 859          */
 860         private void saveKnownPostReplies() throws DatabaseException {
 861                 lock.readLock().lock();
 862                 try {
 863                         int replyCounter = 0;
 864                         for (String knownReplyId : knownPostReplies) {
 865                                 configuration.getStringValue("KnownReplies/" + replyCounter++ + "/ID").setValue(knownReplyId);
 866                         }
 867                         configuration.getStringValue("KnownReplies/" + replyCounter + "/ID").setValue(null);
 868                 } catch (ConfigurationException ce1) {
 869                         throw new DatabaseException("Could not save database.", ce1);
 870                 } finally {
 871                         lock.readLock().unlock();
 872                 }
 873         }
 874
 875         private Function<String, Iterable<Album>> getAlbum() {
 876                 return new Function<String, Iterable<Album>>() {
 877                         @Override
 878                         public Iterable<Album> apply(String input) {
 879                                 return (input == null) ? Collections.<Album>emptyList() : getAlbum(input).asSet();
 880                         }
 881                 };
 882         }
 883
 884         private Function<String, Iterable<Image>> getImage() {
 885                 return new Function<String, Iterable<Image>>() {
 886                         @Override
 887                         public Iterable<Image> apply(String input) {
 888                                 return (input == null) ? Collections.<Image>emptyList() : getImage(input).asSet();
 889                         }
 890                 };
 891         }
 892
 893 }