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

   1 package net.pterodactylus.sone.database.memory;
   2
   3 import java.util.Collection;
   4 import java.util.concurrent.locks.ReadWriteLock;
   5 import java.util.concurrent.locks.ReentrantReadWriteLock;
   6
   7 import com.google.common.collect.HashMultimap;
   8 import com.google.common.collect.Multimap;
   9
  10 /**
  11  * In-memory implementation of friend-related functionality.
  12  *
  13  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  14  */
  15 class MemoryFriendDatabase {
  16
  17         private final ReadWriteLock lock = new ReentrantReadWriteLock();
  18         private final ConfigurationLoader configurationLoader;
  19         private final Multimap<String, String> soneFriends = HashMultimap.create();
  20
  21         MemoryFriendDatabase(ConfigurationLoader configurationLoader) {
  22                 this.configurationLoader = configurationLoader;
  23         }
  24
  25         Collection<String> getFriends(String localSoneId) {
  26                 loadFriends(localSoneId);
  27                 lock.readLock().lock();
  28                 try {
  29                         return soneFriends.get(localSoneId);
  30                 } finally {
  31                         lock.readLock().unlock();
  32                 }
  33         }
  34
  35         boolean isFriend(String localSoneId, String friendSoneId) {
  36                 loadFriends(localSoneId);
  37                 lock.readLock().lock();
  38                 try {
  39                         return soneFriends.containsEntry(localSoneId, friendSoneId);
  40                 } finally {
  41                         lock.readLock().unlock();
  42                 }
  43         }
  44
  45         void addFriend(String localSoneId, String friendSoneId) {
  46                 lock.writeLock().lock();
  47                 try {
  48                         if (soneFriends.put(localSoneId, friendSoneId)) {
  49                                 configurationLoader.saveFriends(localSoneId, soneFriends.get(localSoneId));
  50                         }
  51                 } finally {
  52                         lock.writeLock().unlock();
  53                 }
  54         }
  55
  56         void removeFriend(String localSoneId, String friendSoneId) {
  57                 lock.writeLock().lock();
  58                 try {
  59                         if (soneFriends.remove(localSoneId, friendSoneId)) {
  60                                 configurationLoader.saveFriends(localSoneId, soneFriends.get(localSoneId));
  61                         }
  62                 } finally {
  63                         lock.writeLock().unlock();
  64                 }
  65         }
  66
  67         private void loadFriends(String localSoneId) {
  68                 lock.writeLock().lock();
  69                 try {
  70                         if (soneFriends.containsKey(localSoneId)) {
  71                                 return;
  72                         }
  73                         soneFriends.putAll(localSoneId, configurationLoader.loadFriends(localSoneId));
  74                 } finally {
  75                         lock.writeLock().unlock();
  76                 }
  77         }
  78
  79 }