Reduce lock contention when interactive script queue is empty

Author: tomcashman

CHANGES

@@ -1,5 +1,6 @@
 [1.7.1]
 - Fix interactive script running flag always being set to true. Update unit test.
+- Reduce lock contention when interactive script queue is empty
 
 [1.7.0]
 - Prevent game future execution by checking for script skipping in constructor

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

@@ -37,11 +37,15 @@ public ScriptInvocation poll() {
 	private ScriptInvocation pollInteractiveScript() {
 		interactiveScriptLock.lockRead();
 		boolean scriptRunning = interactiveScriptRunning.get();
+		boolean queueEmpty = interactiveScriptQueue.isEmpty();
 		interactiveScriptLock.unlockRead();
 
 		if(scriptRunning) {
 			return null;
 		}
+		if(queueEmpty) {
+			return null;
+		}
 
 		ScriptInvocation result = null;
 		interactiveScriptLock.lockWrite();

core/src/test/java/org/mini2Dx/miniscript/core/util/ScriptInvocationQueueTest.java

@@ -41,6 +41,7 @@ public void testOnlyOneInteractiveScriptPolled() {
 					}
 					if(scriptInvocation.isInteractive()) {
 						interactiveScriptsRunning.incrementAndGet();
+						Assert.assertTrue(invocationQueue.isInteractiveScriptRunnung());
 					}
 					try {
 						Thread.sleep(10);