#3771: Make PluginManager methods thread safe

api/src/main/java/net/md_5/bungee/api/plugin/PluginManager.java

@@ -23,6 +23,10 @@ import java.util.Locale;
 import java.util.Map;
 import java.util.Set;
 import java.util.Stack;
+import java.util.concurrent.locks.Lock;
+import java.util.concurrent.locks.ReadWriteLock;
+import java.util.concurrent.locks.ReentrantLock;
+import java.util.concurrent.locks.ReentrantReadWriteLock;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
 import java.util.logging.Level;
@@ -59,6 +63,9 @@ public final class PluginManager
     private final Multimap<Plugin, Command> commandsByPlugin = ArrayListMultimap.create();
     private final Multimap<Plugin, Listener> listenersByPlugin = ArrayListMultimap.create();
 
+    private final ReadWriteLock commandsLock = new ReentrantReadWriteLock();
+    private final Lock listenersLock = new ReentrantLock();
+
     @SuppressWarnings("unchecked")
     public PluginManager(ProxyServer proxy)
     {
@@ -92,6 +99,9 @@ public final class PluginManager
      * @param command the command to register
      */
     public void registerCommand(Plugin plugin, Command command)
+    {
+        commandsLock.writeLock().lock();
+        try
         {
             commandMap.put( command.getName().toLowerCase( Locale.ROOT ), command );
             for ( String alias : command.getAliases() )
@@ -99,6 +109,10 @@ public final class PluginManager
                 commandMap.put( alias.toLowerCase( Locale.ROOT ), command );
             }
             commandsByPlugin.put( plugin, command );
+        } finally
+        {
+            commandsLock.writeLock().unlock();
+        }
     }
 
     /**
@@ -107,9 +121,16 @@ public final class PluginManager
      * @param command the command to unregister
      */
     public void unregisterCommand(Command command)
+    {
+        commandsLock.writeLock().lock();
+        try
         {
             while ( commandMap.values().remove( command ) );
             commandsByPlugin.values().remove( command );
+        } finally
+        {
+            commandsLock.writeLock().unlock();
+        }
     }
 
     /**
@@ -118,6 +139,9 @@ public final class PluginManager
      * @param plugin the plugin to register the commands of
      */
     public void unregisterCommands(Plugin plugin)
+    {
+        commandsLock.writeLock().lock();
+        try
         {
             for ( Iterator<Command> it = commandsByPlugin.get( plugin ).iterator(); it.hasNext(); )
             {
@@ -125,6 +149,10 @@ public final class PluginManager
                 while ( commandMap.values().remove( command ) );
                 it.remove();
             }
+        } finally
+        {
+            commandsLock.writeLock().unlock();
+        }
     }
 
     private Command getCommandIfEnabled(String commandName, CommandSender sender)
@@ -137,7 +165,14 @@ public final class PluginManager
             return null;
         }
 
+        commandsLock.readLock().lock();
+        try
+        {
             return commandMap.get( commandLower );
+        } finally
+        {
+            commandsLock.readLock().unlock();
+        }
     }
 
     /**
@@ -433,6 +468,9 @@ public final class PluginManager
      * @param listener the listener to register events for
      */
     public void registerListener(Plugin plugin, Listener listener)
+    {
+        listenersLock.lock();
+        try
         {
             for ( Method method : listener.getClass().getDeclaredMethods() )
             {
@@ -441,6 +479,10 @@ public final class PluginManager
             }
             eventBus.register( listener );
             listenersByPlugin.put( plugin, listener );
+        } finally
+        {
+            listenersLock.unlock();
+        }
     }
 
     /**
@@ -449,9 +491,16 @@ public final class PluginManager
      * @param listener the listener to unregister
      */
     public void unregisterListener(Listener listener)
+    {
+        listenersLock.lock();
+        try
         {
             eventBus.unregister( listener );
             listenersByPlugin.values().remove( listener );
+        } finally
+        {
+            listenersLock.unlock();
+        }
     }
 
     /**
@@ -460,12 +509,19 @@ public final class PluginManager
      * @param plugin target plugin
      */
     public void unregisterListeners(Plugin plugin)
+    {
+        listenersLock.lock();
+        try
         {
             for ( Iterator<Listener> it = listenersByPlugin.get( plugin ).iterator(); it.hasNext(); )
             {
                 eventBus.unregister( it.next() );
                 it.remove();
             }
+        } finally
+        {
+            listenersLock.unlock();
+        }
     }
 
     /**
@@ -474,8 +530,15 @@ public final class PluginManager
      * @return commands
      */
     public Collection<Map.Entry<String, Command>> getCommands()
+    {
+        commandsLock.readLock().lock();
+        try
         {
             return Collections.unmodifiableCollection( commandMap.entrySet() );
+        } finally
+        {
+            commandsLock.readLock().unlock();
+        }
     }
 
     boolean isTransitiveDepend(PluginDescription plugin, PluginDescription depend)