import futurist
import futurist.waiters
import six
import subprocess
import sys
import time

EXECUTOR = futurist.ThreadPoolExecutor()
TIMEOUT = 5
WORK_AMOUNT = 10

def cancel():
    print('\ncancel succeeded:')
    print(future.cancel())
    print(EXECUTOR.statistics)

def cb(*args, **kwargs):
    print('done callback called, but thread remains running (check with ps -T)')
    subprocess.run(['ps', '-Tf', '-C', 'python3'])
    cancel()

def work(*args, **kwargs):
    time.sleep(WORK_AMOUNT)
    #sys.exit(1)
    return 42

try:
    future = EXECUTOR.submit(work)
    future.add_done_callback(cb)
    # Can't be cancelled when running or done (c)
    cancel()
    # Raises TimeoutError, but never CancelledError :(
    # returns no result here, when TIMEOUT is shorter than WORK_AMOUNT
    print('Result: %s' % future.result(TIMEOUT))
except Exception as e:
    print('caught exception %s' % six.text_type(e))
    # And can never be cancelled...
    cancel()
    #raise e

while True:
    print(futurist.waiters.wait_for_all([future], timeout=1))
    if not future.done():
        print(EXECUTOR.statistics)
        cancel()
    else:
        print(future.result())
        print('done, but thread remains running')
        break

time.sleep(3)
# never...
cancel()
print('thread remains running (check with ps -T)')
subprocess.run(['ps', '-Tf', '-C', 'python3'])