def loop(condition, timeout=None):
"""
Executes the main loop until condition is met.
This function may be called recursively, however two loops may not
run in parallel threads.
:param condition: a callable or object that is evaluated after each step
of the loop. If it evaluates False, the loop
terminates. (If condition is therefore ``True``, the
loop will run forever.)
:param timeout: number of seconds after which the loop will terminate
(regardless of the condition).
"""
_loop_lock.acquire()
if is_running() and not is_mainthread():
# race condition. Two threads started a mainloop and the other
# one is executed right now. Raise a RuntimeError
_loop_lock.release()
raise RuntimeError('loop running in a different thread')
initial_mainloop = False
if not is_running():
# no mainloop is running, set this thread as mainloop and
# set the internal running state.
initial_mainloop = True
set_as_mainthread()
_set_running(True)
# ok, that was the critical part
_loop_lock.release()
if not callable(condition):
condition = lambda: condition
abort = []
if timeout is not None:
# timeout handling to stop the mainloop after the given timeout
# even when the condition is still True.
sec = timeout
timeout = OneShotTimer(lambda: abort.append(True))
timeout.start(sec)
try:
while condition() and not abort:
try:
notifier.step()
signals['step'].emit()
except BaseException, e:
if signals['exception'].emit(*sys.exc_info()) != False:
# Either there are no global exception handlers, or none of
# them explicitly returned False to abort mainloop
# termination. So abort the main loop.
type, value, tb = sys.exc_info()
raise type, value, tb
finally:
# make sure we set mainloop status
if timeout is not None:
timeout.stop()
if initial_mainloop:
_set_running(False)
def delay(seconds):
"""
Returns an InProgress that finishes after the given time in seconds.
:param obj: object to represent as an InProgress.
:return: :class:`~kaa.InProgress`
"""
ip = InProgressCallback()
timer = OneShotTimer(ip)
# If the IP gets aborted, stop the timer. Otherwise the timer
# will fire and the IP would attempt to get finished a second
# time (and would therefore raise an exception).
ip.signals['abort'].connect_weak(lambda exc: timer.stop())
timer.start(seconds)
return ip
class EventManager(object):
"""
Class to manage Event and EventHandler objects.
Internal use only.
"""
def __init__(self):
self.queue = []
self.locked = False
self.timer = OneShotTimer(self.handle)
self.handler = []
def post(self, event):
"""
Add event to the queue.
"""
self.queue.append(event)
if not self.timer.active:
self.timer.start(0)
def handle(self):
"""
Handle the next event.
"""
if self.locked:
self.timer.start(0.01)
return
if not self.queue:
return
self.locked = True
event = self.queue[0]
self.queue = self.queue[1:]
try:
for handler in copy.copy(self.handler):
handler(event)
except Exception, e:
log.exception('event callback')
self.locked = False
if self.queue and not self.timer.active:
self.timer.start(0)
def __init__(self):
self.queue = []
self.locked = False
self.timer = OneShotTimer(self.handle)
self.handler = []
