Extract memory-backed post database into its own class.
[Sone.git] / src / main / java / net / pterodactylus / sone / database / memory / MemoryPostDatabase.java
diff --git a/src/main/java/net/pterodactylus/sone/database/memory/MemoryPostDatabase.java b/src/main/java/net/pterodactylus/sone/database/memory/MemoryPostDatabase.java
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+/*
+ * Sone - MemoryPostDatabase.java - Copyright © 2014 David Roden
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+package net.pterodactylus.sone.database.memory;
+
+import static com.google.common.base.Optional.fromNullable;
+import static com.google.common.base.Preconditions.checkNotNull;
+import static com.google.common.collect.FluentIterable.from;
+import static com.google.common.collect.HashMultimap.create;
+
+import java.util.Collection;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.locks.ReadWriteLock;
+
+import net.pterodactylus.sone.data.Post;
+import net.pterodactylus.sone.data.Sone;
+import net.pterodactylus.sone.database.DatabaseException;
+import net.pterodactylus.sone.database.PostDatabase;
+import net.pterodactylus.util.config.Configuration;
+import net.pterodactylus.util.config.ConfigurationException;
+
+import com.google.common.base.Function;
+import com.google.common.base.Optional;
+import com.google.common.collect.Multimap;
+import com.google.common.collect.SetMultimap;
+
+/**
+ * Memory-based {@link PostDatabase} implementation.
+ *
+ * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
+ */
+public class MemoryPostDatabase implements PostDatabase {
+
+       private final MemoryDatabase memoryDatabase;
+       private final ReadWriteLock readWriteLock;
+       private final Configuration configuration;
+       private final Map<String, Post> allPosts = new HashMap<String, Post>();
+       private final Multimap<String, Post> sonePosts = create();
+       private final SetMultimap<String, String> likedPostsBySone = create();
+       private final SetMultimap<String, String> postLikingSones = create();
+       private final Multimap<String, Post> recipientPosts = create();
+       private final Set<String> knownPosts = new HashSet<String>();
+
+       public MemoryPostDatabase(MemoryDatabase memoryDatabase, ReadWriteLock readWriteLock, Configuration configuration) {
+               this.memoryDatabase = memoryDatabase;
+               this.readWriteLock = readWriteLock;
+               this.configuration = configuration;
+       }
+
+       @Override
+       public Function<String, Optional<Post>> getPost() {
+               return new Function<String, Optional<Post>>() {
+                       @Override
+                       public Optional<Post> apply(String postId) {
+                               return (postId == null) ? Optional.<Post>absent() : getPost(postId);
+                       }
+               };
+       }
+
+       @Override
+       public Optional<Post> getPost(String postId) {
+               readWriteLock.readLock().lock();
+               try {
+                       return fromNullable(allPosts.get(postId));
+               } finally {
+                       readWriteLock.readLock().unlock();
+               }
+       }
+
+       @Override
+       public Collection<Post> getPosts(String soneId) {
+               readWriteLock.readLock().lock();
+               try {
+                       return new HashSet<Post>(sonePosts.get(soneId));
+               } finally {
+                       readWriteLock.readLock().unlock();
+               }
+       }
+
+       @Override
+       public Collection<Post> getDirectedPosts(String recipientId) {
+               readWriteLock.readLock().lock();
+               try {
+                       Collection<Post> posts = recipientPosts.get(recipientId);
+                       return (posts == null) ? Collections.<Post>emptySet() : new HashSet<Post>(posts);
+               } finally {
+                       readWriteLock.readLock().unlock();
+               }
+       }
+
+       /**
+        * Returns whether the given post is known.
+        *
+        * @param post
+        *              The post
+        * @return {@code true} if the post is known, {@code false} otherwise
+        */
+       @Override
+       public boolean isPostKnown(Post post) {
+               readWriteLock.readLock().lock();
+               try {
+                       return knownPosts.contains(post.getId());
+               } finally {
+                       readWriteLock.readLock().unlock();
+               }
+       }
+
+       /**
+        * Sets whether the given post is known.
+        *
+        * @param post
+        *              The post
+        */
+       @Override
+       public void setPostKnown(Post post) {
+               readWriteLock.writeLock().lock();
+               try {
+                       knownPosts.add(post.getId());
+               } finally {
+                       readWriteLock.writeLock().unlock();
+               }
+       }
+
+       @Override
+       public void likePost(Post post, Sone localSone) {
+               readWriteLock.writeLock().lock();
+               try {
+                       likedPostsBySone.put(localSone.getId(), post.getId());
+                       postLikingSones.put(post.getId(), localSone.getId());
+               } finally {
+                       readWriteLock.writeLock().unlock();
+               }
+       }
+
+       @Override
+       public void unlikePost(Post post, Sone localSone) {
+               readWriteLock.writeLock().lock();
+               try {
+                       likedPostsBySone.remove(localSone.getId(), post.getId());
+                       postLikingSones.remove(post.getId(), localSone.getId());
+               } finally {
+                       readWriteLock.writeLock().unlock();
+               }
+       }
+
+       public boolean isLiked(Post post, Sone sone) {
+               readWriteLock.readLock().lock();
+               try {
+                       return likedPostsBySone.containsEntry(sone.getId(), post.getId());
+               } finally {
+                       readWriteLock.readLock().unlock();
+               }
+       }
+
+       @Override
+       public Set<Sone> getLikes(Post post) {
+               readWriteLock.readLock().lock();
+               try {
+                       return from(postLikingSones.get(post.getId())).transform(memoryDatabase.getSone()).transformAndConcat(MemoryDatabase.<Sone>unwrap()).toSet();
+               } finally {
+                       readWriteLock.readLock().unlock();
+               }
+       }
+
+       @Override
+       public void storePost(Post post) {
+               checkNotNull(post, "post must not be null");
+               readWriteLock.writeLock().lock();
+               try {
+                       allPosts.put(post.getId(), post);
+                       sonePosts.put(post.getSone().getId(), post);
+                       if (post.getRecipientId().isPresent()) {
+                               recipientPosts.put(post.getRecipientId().get(), post);
+                       }
+               } finally {
+                       readWriteLock.writeLock().unlock();
+               }
+       }
+
+       @Override
+       public void removePost(Post post) {
+               checkNotNull(post, "post must not be null");
+               readWriteLock.writeLock().lock();
+               try {
+                       allPosts.remove(post.getId());
+                       sonePosts.remove(post.getSone().getId(), post);
+                       if (post.getRecipientId().isPresent()) {
+                               recipientPosts.remove(post.getRecipientId().get(), post);
+                       }
+                       post.getSone().removePost(post);
+               } finally {
+                       readWriteLock.writeLock().unlock();
+               }
+       }
+
+       @Override
+       public void storePosts(Sone sone, Collection<Post> posts) throws IllegalArgumentException {
+               checkNotNull(sone, "sone must not be null");
+               /* verify that all posts are from the same Sone. */
+               for (Post post : posts) {
+                       if (!sone.equals(post.getSone())) {
+                               throw new IllegalArgumentException(String.format("Post from different Sone found: %s", post));
+                       }
+               }
+
+               readWriteLock.writeLock().lock();
+               try {
+                       /* remove all posts by the Sone. */
+                       sonePosts.removeAll(sone.getId());
+                       for (Post post : posts) {
+                               allPosts.remove(post.getId());
+                               if (post.getRecipientId().isPresent()) {
+                                       recipientPosts.remove(post.getRecipientId().get(), post);
+                               }
+                       }
+
+                       /* add new posts. */
+                       sonePosts.putAll(sone.getId(), posts);
+                       for (Post post : posts) {
+                               allPosts.put(post.getId(), post);
+                               if (post.getRecipientId().isPresent()) {
+                                       recipientPosts.put(post.getRecipientId().get(), post);
+                               }
+                       }
+               } finally {
+                       readWriteLock.writeLock().unlock();
+               }
+       }
+
+       @Override
+       public void removePosts(Sone sone) {
+               checkNotNull(sone, "sone must not be null");
+               readWriteLock.writeLock().lock();
+               try {
+                       /* remove all posts by the Sone. */
+                       sonePosts.removeAll(sone.getId());
+                       for (Post post : sone.getPosts()) {
+                               allPosts.remove(post.getId());
+                               if (post.getRecipientId().isPresent()) {
+                                       recipientPosts.remove(post.getRecipientId().get(), post);
+                               }
+                       }
+               } finally {
+                       readWriteLock.writeLock().unlock();
+               }
+       }
+
+       public void start() {
+               readWriteLock.writeLock().lock();
+               try {
+                       int postCounter = 0;
+                       while (true) {
+                               String knownPostId = configuration.getStringValue("KnownPosts/" + postCounter++ + "/ID").getValue(null);
+                               if (knownPostId == null) {
+                                       break;
+                               }
+                               knownPosts.add(knownPostId);
+                       }
+               } finally {
+                       readWriteLock.writeLock().unlock();
+               }
+       }
+
+       public void stop() throws DatabaseException {
+               save();
+       }
+
+       public void save() throws DatabaseException {
+               readWriteLock.readLock().lock();
+               try {
+                       int postCounter = 0;
+                       for (String knownPostId : knownPosts) {
+                               configuration.getStringValue("KnownPosts/" + postCounter++ + "/ID").setValue(knownPostId);
+                       }
+                       configuration.getStringValue("KnownPosts/" + postCounter + "/ID").setValue(null);
+               } catch (ConfigurationException ce1) {
+                       throw new DatabaseException("Could not save database.", ce1);
+               } finally {
+                       readWriteLock.readLock().unlock();
+               }
+       }
+
+}