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.HashMap;
   5 import java.util.Map;
   6 import java.util.concurrent.locks.ReadWriteLock;
   7 import java.util.concurrent.locks.ReentrantReadWriteLock;
   8
   9 import com.google.common.base.Optional;
  10 import com.google.common.collect.HashMultimap;
  11 import com.google.common.collect.Multimap;
  12
  13 /**
  14  * In-memory implementation of friend-related functionality.
  15  *
  16  * @author <a href="mailto:bombe@pterodactylus.net">David ‘Bombe’ Roden</a>
  17  */
  18 class MemoryFriendDatabase {
  19
  20         private final ReadWriteLock lock = new ReentrantReadWriteLock();
  21         private final ConfigurationLoader configurationLoader;
  22         private final Multimap<String, String> soneFriends = HashMultimap.create();
  23         private final Map<String, Long> soneFollowingTimes = new HashMap<String, Long>();
  24
  25         MemoryFriendDatabase(ConfigurationLoader configurationLoader) {
  26                 this.configurationLoader = configurationLoader;
  27         }
  28
  29         void start() {
  30                 loadSoneFollowingTimes();
  31         }
  32
  33         private void loadSoneFollowingTimes() {
  34                 Map<String, Long> soneFollowingTimes = configurationLoader.loadSoneFollowingTimes();
  35                 lock.writeLock().lock();
  36                 try {
  37                         this.soneFollowingTimes.clear();
  38                         this.soneFollowingTimes.putAll(soneFollowingTimes);
  39                 } finally {
  40                         lock.writeLock().unlock();
  41                 }
  42         }
  43
  44         void stop() {
  45                 saveSoneFollowingTimes();
  46         }
  47
  48         private void saveSoneFollowingTimes() {
  49                 lock.readLock().lock();
  50                 try {
  51                         configurationLoader.saveSoneFollowingTimes(soneFollowingTimes);
  52                 } finally {
  53                         lock.readLock().unlock();
  54                 }
  55         }
  56
  57         Collection<String> getFriends(String localSoneId) {
  58                 loadFriends(localSoneId);
  59                 lock.readLock().lock();
  60                 try {
  61                         return soneFriends.get(localSoneId);
  62                 } finally {
  63                         lock.readLock().unlock();
  64                 }
  65         }
  66
  67         Optional<Long> getSoneFollowingTime(String soneId) {
  68                 lock.readLock().lock();
  69                 try {
  70                         return Optional.fromNullable(soneFollowingTimes.get(soneId));
  71                 } finally {
  72                         lock.readLock().unlock();
  73                 }
  74         }
  75
  76         boolean isFriend(String localSoneId, String friendSoneId) {
  77                 loadFriends(localSoneId);
  78                 lock.readLock().lock();
  79                 try {
  80                         return soneFriends.containsEntry(localSoneId, friendSoneId);
  81                 } finally {
  82                         lock.readLock().unlock();
  83                 }
  84         }
  85
  86         void addFriend(String localSoneId, String friendSoneId) {
  87                 loadFriends(localSoneId);
  88                 lock.writeLock().lock();
  89                 try {
  90                         if (!soneFollowingTimes.containsKey(friendSoneId)) {
  91                                 soneFollowingTimes.put(friendSoneId, System.currentTimeMillis());
  92                                 saveSoneFollowingTimes();
  93                         }
  94                         if (soneFriends.put(localSoneId, friendSoneId)) {
  95                                 configurationLoader.saveFriends(localSoneId, soneFriends.get(localSoneId));
  96                         }
  97                 } finally {
  98                         lock.writeLock().unlock();
  99                 }
 100         }
 101
 102         void removeFriend(String localSoneId, String friendSoneId) {
 103                 loadFriends(localSoneId);
 104                 lock.writeLock().lock();
 105                 try {
 106                         if (soneFriends.remove(localSoneId, friendSoneId)) {
 107                                 if (!soneFriends.containsValue(friendSoneId)) {
 108                                         soneFollowingTimes.remove(friendSoneId);
 109                                         saveSoneFollowingTimes();
 110                                 }
 111                                 configurationLoader.saveFriends(localSoneId, soneFriends.get(localSoneId));
 112                         }
 113                 } finally {
 114                         lock.writeLock().unlock();
 115                 }
 116         }
 117
 118         private void loadFriends(String localSoneId) {
 119                 lock.writeLock().lock();
 120                 try {
 121                         if (soneFriends.containsKey(localSoneId)) {
 122                                 return;
 123                         }
 124                         soneFriends.putAll(localSoneId, configurationLoader.loadFriends(localSoneId));
 125                 } finally {
 126                         lock.writeLock().unlock();
 127                 }
 128         }
 129
 130 }