add method to get remaining ThreadPoolTaskExecutor's queue capacity (#20

)

Co-authored-by: Stephen Tobayiwa <stephen.tobayiwa@unite.eu>

src/main/java/com/mercateo/sqs/utils/message/handling/LongRunningMessageHandler.java

@@ -205,5 +205,19 @@ public void shutdown() {
  messageProcessingExecutor.getThreadPoolExecutor().awaitTermination(10, TimeUnit.SECONDS);
  }
  }
+ /**
+ * Returns the number of elements that the {@link #messageProcessingExecutor} can accept
+ * <p>
+ * This method should only be used in a single threaded environment, since it is possible that
+ * in a multi-threaded environment the number of free slots changes between the call to this method
+ *
+ * @return Remaining queue capacity
+ */
+ public int getRemainingCapacity() {
+ return messageProcessingExecutor
+ .getThreadPoolExecutor()
+ .getQueue()
+ .remainingCapacity();
+ }
 
 }