Fix synchronization

pom.xml

@@ -4,7 +4,7 @@
     <groupId>it.cavallium</groupId>
     <artifactId>filequeue</artifactId>
     <name>file queue project</name>
-    <version>3.1.3</version>
+    <version>3.1.4</version>
     <packaging>jar</packaging>
     <description>Light weight, high performance, simple, reliable and persistent queue</description>
     <modelVersion>4.0.0</modelVersion>

src/main/java/it/cavallium/filequeue/LMDBQueueToConsumer.java

@@ -22,23 +22,17 @@ public final class LMDBQueueToConsumer<T> implements IQueueToConsumer<T> {
 
 	@Override
 	public void add(T value) {
-		synchronized (queue) {
-			queue.add(value);
-		}
+		queue.add(value);
 	}
 
 	@Override
 	public void close() {
-		synchronized (queue) {
-			queue.close();
-			queueLMDB.close();
-		}
+		queue.close();
+		queueLMDB.close();
 	}
 
 	@Override
 	public void startQueue() {
-		synchronized (queue) {
-			queue.startQueue();
-		}
+		queue.startQueue();
 	}
 }

src/main/java/it/cavallium/filequeue/QueueToConsumer.java

@@ -42,9 +42,7 @@ class QueueToConsumer<T> implements IQueueToConsumer<T> {
 			}
 		}
 		if (shouldAdd && !closed) {
-			synchronized (queue) {
-				queue.add(value);
-			}
+			queue.add(value);
 			semaphore.release();
 		}
 	}
@@ -71,9 +69,7 @@ class QueueToConsumer<T> implements IQueueToConsumer<T> {
 					}
 					semaphore.acquire();
 					if (!closed && shouldRemove) {
-						synchronized (queue) {
-							element = queue.remove();
-						}
+						element = queue.remove();
 						long nextDelay = BACKOFF_NS;
 						while (!closed && !consumer.tryConsume(element)) {
 							LockSupport.parkNanos(nextDelay);

src/main/java/it/cavallium/filequeue/SimpleQueue.java

@@ -1,5 +1,8 @@
 package it.cavallium.filequeue;
 
+/**
+ * The queue must be thread-safe
+ */
 interface SimpleQueue<T> {
 
 	void add(T element);

src/main/java/it/cavallium/filequeue/SimpleQueueFile.java

@@ -17,7 +17,7 @@ class SimpleQueueFile<T> implements SimpleQueue<T> {
 	}
 
 	@Override
-	public void add(T element) {
+	public synchronized void add(T element) {
 		try {
 			queueFile.add(ser.serialize(element));
 		} catch (IOException e) {
@@ -26,7 +26,7 @@ class SimpleQueueFile<T> implements SimpleQueue<T> {
 	}
 
 	@Override
-	public T remove() {
+	public synchronized T remove() {
 		try {
 			byte[] element = queueFile.peek();
 			if (element == null) {
@@ -41,7 +41,7 @@ class SimpleQueueFile<T> implements SimpleQueue<T> {
 	}
 
 	@Override
-	public int size() {
+	public synchronized int size() {
 		return queueFile.size();
 	}
 }

src/main/java/it/cavallium/filequeue/SimpleQueueJava.java

@@ -2,10 +2,16 @@ package it.cavallium.filequeue;
 
 import java.util.Queue;
 
+/**
+ * Thread safe queue
+ */
 class SimpleQueueJava<T> implements SimpleQueue<T> {
 
 	private final Queue<T> queue;
 
+	/**
+	 * @param queue the queue must be thread-safe
+	 */
 	public SimpleQueueJava(Queue<T> queue) {
 		this.queue = queue;
 	}

src/main/java/it/cavallium/filequeue/SimpleQueueLMDB.java

@@ -13,6 +13,9 @@ import org.lmdbjava.DbiFlags;
 import org.lmdbjava.Env;
 import org.lmdbjava.Txn;
 
+/**
+ * Thread safe queue
+ */
 public class SimpleQueueLMDB<T> implements SimpleQueue<T>, Closeable {
 
 	private static final Set<String> REGISTRY = new HashSet<>();