Natlink thread example

_natlink_thread_example.py

# Natlink doesn't usually work well with other threads because of how it
# works internally. This example command module demonstrates a workaround
# for this problem using a Dragonfly timer and Thread.join().
#
# This workaround can work using the natlink.setTimerCallback() function
# directly instead.
#
# Copy this file into the natlink MacroSystem folder to try it out.

import threading
import time

from dragonfly import get_engine


# Initialise and start a new thread that prints a message every five
# seconds.
shutdown_event = threading.Event()
def run():
    thread_name = threading.current_thread().name
    while not shutdown_event.is_set():
        print("Output from %s" % thread_name)
        time.sleep(5)
    print("%s exiting..." % thread_name)

thread = threading.Thread(target=run)
thread.start()

# Initialise a dragonfly timer to manually yield control to the thread.
def timer_func():
    thread.join(0.002)

timer = get_engine().create_timer(timer_func, 0.02)


def unload():  # Natlink unload() function.
    # Set the shutdown event and wait for the thread to finish.
    shutdown_event.set()
    thread.join()

    # Stop the timer now that the thread has finished.
    timer.stop()