private boolean dispatchFirstVisit() {
        BooleanSupplier operation = visitOperations.poll();
        if (operation == null)
            return false;

        if (operation.getAsBoolean())
            return true;

        visitOperations.push(operation);
        return false;
    }
Attempts to dispatch the first enqueued visit operations, and returns whether this was successful.
vespaclient-container-plugin/src/main/java/com/yahoo/document/restapi/resource/DocumentV1ApiHandler.java