Reduce lock contention in concurrent queue poll and peek

Author: tomcashman

core/src/main/java/org/mini2Dx/miniscript/core/util/AbstractConcurrentQueue.java

@@ -157,6 +157,13 @@ public E remove() {
 
 	@Override
 	public E poll() {
+		lock.lockRead();
+		if(internalQueue.isEmpty()) {
+			lock.unlockRead();
+			return null;
+		}
+		lock.unlockRead();
+
 		lock.lockWrite();
 		try {
 			return internalQueue.poll();
@@ -177,6 +184,13 @@ public E element() {
 
 	@Override
 	public E peek() {
+		lock.lockRead();
+		if(internalQueue.isEmpty()) {
+			lock.unlockRead();
+			return null;
+		}
+		lock.unlockRead();
+
 		lock.lockRead();
 		try {
 			return internalQueue.peek();