Fix removing webcams in OSX hanging (#713)

CameraSource stopAsync on remove (OSX only)

Author: SamCarlberg

core/src/main/java/edu/wpi/grip/core/sources/CameraSource.java

@@ -350,7 +350,23 @@ public void onSourceRemovedEvent(SourceRemovedEvent event) throws InterruptedExc
         // a new camera source is added. For webcam sources, this means that the video stream
         // won't be freed and new sources won't be able to connect to the webcam until the
         // application is closed.
-        this.stopAndAwait();
+        if (StandardSystemProperty.OS_NAME.value().toLowerCase().contains("mac")) {
+          // Workaround for #716. This affects webcams as well as IP camera sources.
+          // Use only stopAsync() to avoid blocking. Since we have no way of knowing when
+          // the capture has actually been freed, we use a dumb delay to try to make sure it's
+          // freed before returning. THIS IS NOT A GOOD SOLUTION. But it's the best one we have
+          // until the bug is fixed.
+          stopAsync();
+          try {
+            // Wait a bit to try to make sure the capture is actually freed before returning
+            Thread.sleep(100);
+          } catch (InterruptedException ignore) {
+            // We did our best. Hopefully, the webcam has been freed at this point.
+            Thread.currentThread().interrupt();
+          }
+        } else {
+          this.stopAndAwait();
+        }
       } finally {
         this.eventBus.unregister(this);
       }