Adding a blocking hash map to use while looking up data connections.

ProtocolLib/src/main/java/com/comphenix/protocol/concurrency/BlockingHashMap.java

@@ -0,0 +1,165 @@
+package com.comphenix.protocol.concurrency;
+
+import java.util.Collection;
+import java.util.Set;
+import java.util.concurrent.ConcurrentMap;
+import java.util.concurrent.TimeUnit;
+
+import com.google.common.collect.MapMaker;
+
+/**
+ * A map that supports blocking on read operations. Null keys are not supported.
+ * <p>
+ * Keys are stored as weak references, and will be automatically removed once they've all been dereferenced.
+ * <p>
+ * @author Kristian
+ *
+ * @param <TKey> - type of the key.
+ * @param <TValue> - type of the value.
+ */
+public class BlockingHashMap<TKey, TValue> {
+
+	// Map of values
+	private final ConcurrentMap<TKey, TValue> backingMap;
+
+	// Map of locked objects
+	private final ConcurrentMap<TKey, Object> locks;
+	
+	/**
+	 * Initialize a new map.
+	 */
+	public BlockingHashMap() {
+		backingMap = new MapMaker().weakKeys().makeMap();
+		locks = new MapMaker().weakKeys().makeMap();
+	}
+	
+	/**
+	 * Initialize a new map.
+	 * @return The created map.
+	 */
+	public static <TKey, TValue> BlockingHashMap<TKey, TValue> create() {
+		return new BlockingHashMap<TKey, TValue>();
+	}
+	
+	/**
+	 * Waits until a value has been associated with the given key, and then retrieves that value.
+	 * @param key - the key whose associated value is to be returned 
+	 * @return The value to which the specified key is mapped.
+	 * @throws InterruptedException If the current thread got interrupted while waiting.
+	 */
+	public TValue get(TKey key) throws InterruptedException {
+		if (key == null)
+			throw new IllegalArgumentException("key cannot be NULL.");
+		
+		TValue value = backingMap.get(key);
+		
+		// Only lock if no value is available
+		if (value == null) {
+			final Object lock = getLock(key);
+			
+			synchronized (lock) {
+				while (value == null) {
+					lock.wait();
+					value = backingMap.get(key);
+				}
+			}
+		}
+		
+		return value;
+	}
+	
+	/**
+	 * Waits until a value has been associated with the given key, and then retrieves that value.
+	 * @param key - the key whose associated value is to be returned 
+	 * @param timeout - the amount of time to wait until an association has been made.
+	 * @param unit - unit of timeout.
+	 * @return The value to which the specified key is mapped, or NULL if the timeout elapsed.
+	 * @throws InterruptedException If the current thread got interrupted while waiting.
+	 */
+	public TValue get(TKey key, long timeout, TimeUnit unit) throws InterruptedException {
+		if (key == null)
+			throw new IllegalArgumentException("key cannot be NULL.");
+		if (unit == null)
+			throw new IllegalArgumentException("Unit cannot be NULL.");
+		
+		TValue value = backingMap.get(key);
+		
+		// Only lock if no value is available
+		if (value == null) {
+			final Object lock = getLock(key);
+			final long stopTimeNS = System.nanoTime() + unit.toNanos(timeout);
+			
+			// Don't exceed the timeout
+			synchronized (lock) {
+				while (value == null) {
+					long remainingTime = stopTimeNS - System.nanoTime();
+					
+					if (remainingTime > 0) {
+						TimeUnit.NANOSECONDS.timedWait(lock, remainingTime);
+						value = backingMap.get(key);
+					} 
+				}
+			}
+		}
+		
+		return value;
+	}
+	
+	/**
+	 * Associate a given key with the given value.
+	 * <p>
+	 * Wakes up any blocking getters on this specific key.
+	 * 
+	 * @param key - the key to associate.
+	 * @param value - the value.
+	 * @return The previously associated value.
+	 */
+	public TValue put(TKey key, TValue value) {
+		if (value == null)
+			throw new IllegalArgumentException("This map doesn't support NULL values.");
+		
+		final TValue previous = backingMap.put(key, value);
+		final Object lock = getLock(key);
+		
+		// Inform our readers about this change
+		synchronized (lock) {
+			lock.notifyAll();
+			return previous;
+		}
+	}
+	
+	public int size() {
+		return backingMap.size();
+	}
+	
+	public Collection<TValue> values() {
+		return backingMap.values();
+	}
+	
+	public Set<TKey> keys() {
+		return backingMap.keySet();
+	}
+	
+	/**
+	 * Atomically retrieve the lock associated with a given key.
+	 * @param key - the current key.
+	 * @return An asssociated lock.
+	 */
+	private Object getLock(TKey key) {
+		Object lock = locks.get(key);
+		
+		if (lock == null) {
+			Object created = new Object();
+			
+			// Do this atomically
+			lock = locks.putIfAbsent(key, created);
+			
+			// If we succeeded, use the latch we created - otherwise, use the already inserted latch
+			if (lock == null) {
+				lock = created;
+			}
+		}
+		
+		return lock;
+	}
+}

ProtocolLib/src/main/java/com/comphenix/protocol/injector/PacketInjector.java

@@ -202,13 +202,19 @@ class PacketInjector {
 	
 	// Called from the ReadPacketModified monitor
 	PacketEvent packetRecieved(PacketContainer packet, DataInputStream input) {
-		Player client = playerInjection.getPlayerByConnection(input);
+		try {
+			Player client = playerInjection.getPlayerByConnection(input);
 			
-		// Never invoke a event if we don't know where it's from
+			// Never invoke a event if we don't know where it's from
-		if (client != null)
+			if (client != null)
-			return packetRecieved(packet, client);
+				return packetRecieved(packet, client);
-		else
+			else
+				return null;
+			
+		} catch (InterruptedException e) {
+			reporter.reportDetailed(this, "Thread was interrupted.", e, packet, input);
 			return null;
+		}
 	}
 	
 	/**

ProtocolLib/src/main/java/com/comphenix/protocol/injector/player/PlayerInjectionHandler.java

@@ -24,12 +24,14 @@ import java.net.Socket;
 import java.net.SocketAddress;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.TimeUnit;
 
 import net.minecraft.server.Packet;
 
 import org.bukkit.Server;
 import org.bukkit.entity.Player;
 
+import com.comphenix.protocol.concurrency.BlockingHashMap;
 import com.comphenix.protocol.error.ErrorReporter;
 import com.comphenix.protocol.events.PacketAdapter;
 import com.comphenix.protocol.events.PacketContainer;
@@ -47,6 +49,10 @@ import com.google.common.collect.Maps;
  * @author Kristian
  */
 public class PlayerInjectionHandler {
+	/**
+	 * The maximum number of milliseconds to wait until a player can be looked up by connection.
+	 */
+	private static final long TIMEOUT_PLAYER_LOOKUP = 1000; // ms
 	
 	/**
 	 * The highest possible packet ID. It's unlikely that this value will ever change.
@@ -64,9 +70,11 @@ public class PlayerInjectionHandler {
 	
 	// Player injection
 	private Map<SocketAddress, PlayerInjector> addressLookup = Maps.newConcurrentMap();
-	private Map<DataInputStream, PlayerInjector> dataInputLookup = Maps.newConcurrentMap();
 	private Map<Player, PlayerInjector> playerInjection = Maps.newConcurrentMap();
 	
+	// Lookup player by connection
+	private BlockingHashMap<DataInputStream, PlayerInjector> dataInputLookup = BlockingHashMap.create();
+	
 	// Player injection types
 	private volatile PlayerInjectHooks loginPlayerHook = PlayerInjectHooks.NETWORK_SERVER_OBJECT;
 	private volatile PlayerInjectHooks playingPlayerHook = PlayerInjectHooks.NETWORK_SERVER_OBJECT;
@@ -193,26 +201,37 @@ public class PlayerInjectionHandler {
 	 * Retrieve a player by its DataInput connection.
 	 * @param inputStream - the associated DataInput connection.
 	 * @return The player.
+	 * @throws InterruptedException If the thread was interrupted during the wait.
 	 */
-	public Player getPlayerByConnection(DataInputStream inputStream) {
+	public Player getPlayerByConnection(DataInputStream inputStream) throws InterruptedException {
-		try {
+		return getPlayerByConnection(inputStream, TIMEOUT_PLAYER_LOOKUP, TimeUnit.MILLISECONDS);
-			// Concurrency issue!
+	}
-			netLoginInjector.getReadLock().lock();
 	
-			PlayerInjector injector = dataInputLookup.get(inputStream);
+	/**
+	 * Retrieve a player by its DataInput connection.
+	 * @param inputStream - the associated DataInput connection.
+	 * @param playerTimeout - the amount of time to wait for a result.
+	 * @param unit - unit of playerTimeout.
+	 * @return The player. 
+	 * @throws InterruptedException If the thread was interrupted during the wait.
+	 */
+	public Player getPlayerByConnection(DataInputStream inputStream, long playerTimeout, TimeUnit unit) throws InterruptedException {
 		
-			if (injector != null) {
+		PlayerInjector injector = dataInputLookup.get(inputStream, playerTimeout, unit);
-				return injector.getPlayer();
-			} else {
-				reporter.reportWarning(this, "Unable to find stream: " + inputStream);
-				return null;
-			}
 		
-		} finally {
+		if (injector != null) {
-			netLoginInjector.getReadLock().unlock();
+			return injector.getPlayer();
+		} else {
+			reporter.reportWarning(this, "Unable to find stream: " + inputStream);
+			return null;
 		}
 	}
 	
+	/**
+	 * Helper function that retrieves the injector type of a given player injector.
+	 * @param injector - injector type.
+	 * @return The injector type.
+	 */
 	private PlayerInjectHooks getInjectorType(PlayerInjector injector) {
 		return injector != null ? injector.getHookType() : PlayerInjectHooks.NONE;
 	}
@@ -404,7 +423,6 @@ public class PlayerInjectionHandler {
 			PlayerInjector injector = playerInjection.remove(player);
 
 			if (injector != null) {
-				DataInputStream input = injector.getInputStream(true);
 				InetSocketAddress address = player.getAddress();
 				injector.cleanupAll();
 				
@@ -423,8 +441,7 @@ public class PlayerInjectionHandler {
 				
 				// Clean up
 				if (removeAuxiliary) {
-					if (input != null) 
+					// Note that the dataInputLookup will clean itself
-						dataInputLookup.remove(input);
 					if (address != null) 
 						addressLookup.remove(address);
 				}
@@ -571,7 +588,6 @@ public class PlayerInjectionHandler {
 	}
 	
 	public void close() {
-		
 		// Guard
 		if (hasClosed || playerInjection == null)
 			return;
@@ -593,7 +609,6 @@ public class PlayerInjectionHandler {
 		hasClosed = true;
 		
 		playerInjection.clear();
-		dataInputLookup.clear();
 		addressLookup.clear();
 		invoker = null;
 	}
@@ -607,12 +622,9 @@ public class PlayerInjectionHandler {
 
 		// Update the DataInputStream
 		if (injector != null) {
-			final DataInputStream old = injector.getInputStream(true);
-
 			injector.scheduleAction(new Runnable() {
 				@Override
 				public void run() {
-					dataInputLookup.remove(old);
 					dataInputLookup.put(injector.getInputStream(false), injector);
 				}
 			});

ProtocolLib/src/main/resources/plugin.yml

@@ -1,5 +1,5 @@
 name: ProtocolLib
-version: 1.7.0
+version: 1.7.1-SNAPSHOT
 description: Provides read/write access to the Minecraft protocol.
 author: Comphenix
 website: http://www.comphenix.net/ProtocolLib

ProtocolLib/src/test/java/com/comphenix/protocol/concurrency/BlockingHashMapTest.java

@@ -0,0 +1,42 @@
+package com.comphenix.protocol.concurrency;
+
+import static org.junit.Assert.*;
+
+import java.util.concurrent.Callable;
+import java.util.concurrent.ExecutionException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
+
+import org.junit.Test;
+
+public class BlockingHashMapTest {
+
+	@Test
+	public void test() throws InterruptedException, ExecutionException {
+
+		final BlockingHashMap<Integer, String> map = BlockingHashMap.create();
+
+		ExecutorService service = Executors.newSingleThreadExecutor();
+		
+		// Create a reader
+		Future<String> future = service.submit(new Callable<String>() {
+			@Override
+			public String call() throws Exception {
+				// Combine for easy reading
+				return map.get(0) + map.get(1);
+			}
+		});
+
+		// Wait a bit
+		Thread.sleep(50);
+		
+		// Insert values
+		map.put(0, "hello ");
+		map.put(1, "world");
+		
+		// Wait for the other thread to complete
+		assertEquals(future.get(), "hello world");
+	}
+
+}