getting a thread out of sleep

On Feb 22, 12:08 pm, mark <rkmr...@gmail. comwrote:

On 21 Feb 2007 16:10:51 -0800, placid <Bul...@gmail.c omwrote:

On Feb 22, 10:20 am, mark <rkmr...@gmail. comwrote:

On 21 Feb 2007 14:47:50 -0800, placid <Bul...@gmail.c omwrote:

On Feb 22, 3:23 am, mark <rkmr...@gmail. comwrote:
On 20 Feb 2007 21:26:18 -0800, placid <Bul...@gmail.c omwrote:

On Feb 21, 4:21 pm, "placid" <Bul...@gmail.c omwrote:
On Feb 21, 4:12 pm, mark <rkmr...@gmail. comwrote:
On 20 Feb 2007 20:47:57 -0800, placid <Bul...@gmail.c omwrote:
On Feb 21, 3:08 pm, mark <rkmr...@gmail. comwrote:
Right now I have a thread that sleeps for sometime and check if an
event has happened and go back to sleep. Now instead I want the thread
to sleep until the event has occured process the event and go back to sleep

class eventhndler(thr eading.Thread):
def __init__(self):
threading.Threa d.__init__(self )
def run(self):
while True:
time.sleep(SLEE PTIME)
''''do event stuff'''

The way i would do this is by using an threading.Event (
>http://docs.python.org/lib/event-objects.html)

<code>

class eventhandler(th reading.Thread) :
def __init__(self):
threading.Threa d.__init__(self )
self.event = threading.Event ()
def run:
while True:
# block until some event happens
self.event.wait ()
""" do stuff here """
self.event.clea r()
</code>

the way to use this is to get the main/separate thread to set() the
event object.

Can you give an example of how to get the main threead to set teh event object?
this is exactly what i wanted to do!
thanks a lot!
mark>
oops I've miss-typed the thread variable name the following should
work

<code>
if __name__ == "__main__":
evtHandlerThrea d = eventhandler()
evtHandlerThrea d.start()

# do something here #
evtHandlerThrea d.event.set()

# do more stuff here #
evtHandlerThrea d.event.set()

</code>

Can I have the same thread process two or more events? Can you tell
how to do this? The code you gave is waiting on one event right. How
can I do it for more events?
thanks a lot!
mark

I don't think a thread can block on more than one event at a time. But
you can make it block on more then one event one at a time.

<code>

class eventhandler(th reading.Thread) :
def __init__(self):
threading.Threa d.__init__(self )
self.events = [threading.Event (), threading.Event ()]
self.currentEve nt = None
def run:
while True:
for event in self.events:
self.currentEve nt = event
# block until some event happens
self.currentEve nt.wait()
""" do stuff here """
self.currentEve nt.clear()

if __name__ == "__main__":
evtHandlerThrea d = eventhandler()
evtHandlerThrea d.start()

# do something here #
evtHandlerThrea d.currentEvent. set()

# do more stuff here #
evtHandlerThrea d.currentEvent. set()

</code>

what the thread does is sequentially waits for two events to happen
and then execute the same code. You could change this code to perform
different functions for different event objects.

Once the thread starts it is going to wait on the event that is the
first element of the list right? This would mean :

This is correct.

evtHandlerThrea d.currentEvent. set(): that I have only one event right?

this means that the current event occurred.

Can you explain how I can have different event objects. I dont see how
I can do different functinos for same event.

Thanks a lot!

mark

To run different functions for the same event is easy, just write a
wrapper class around threading.event () and include some method that
you will run and assign this to different functions for each
EventWrapper.

<code>

class EventWrapper():
def __init__(self,w ork ):
self.event = threading.Event ()
self.eventWork = work

def wait(self):
self.event.wait ()

def clear(self)
self.event.clea r()

def eventWork(self) :
print "no work"

class eventhandler(th reading.Thread) :
def __init__(self, events = None):
threading.Threa d.__init__(self )
self.events = events
self.currentEve nt = None
def run:
while True:
if self.events:
for event in self.events:
self.currentEve nt = event
# block until the current event happens
self.currentEve nt.wait()
self.currentEve nt.eventWork()
self.currentEve nt.clear()

def eventOneWork():
# do some event 1 specific work here

def eventTwoWork():
# do some event 2 specific work here

if __name__ == "__main__":
events = [EventWrapper(ev entOneWork),Eve ntWrapper(event TwoWork)]

evtHandlerThrea d = eventhandler(ev ents)
evtHandlerThrea d.start()

# do something here #
evtHandlerThrea d.currentEvent. set()
# do more stuff here #
evtHandlerThrea d.currentEvent. set()

</code>

So you have a EventWrapper class that now contains the Event object
and a workEvent() method which is assigned to a function you create.

THanks a lot! Does this have to have event1 and event2 occur in
sequence? Will this still work even if only event2 occurs and event1
never occurs?
thanks
mark

well if event1 never occurs then it will block/wait until forever and
even if event2 has occurred you never know about it until event1
occurs. You can introduce a timeout to the wait() call on the event
object which says, "block X seconds or until event happens (someone
calls the set method)" so even if event1 doesnt occur you will execute
event1.eventWor k() because the timeout occurred. The way to fix this
is before you call the eventWork() method check if the event has
occurred via the isSet() method of Event objects.

http://docs.python.org/lib/event-objects.html

Cheers

placid wrote:

On Feb 22, 12:08 pm, mark <rkmr...@gmail. comwrote:

>On 21 Feb 2007 16:10:51 -0800, placid <Bul...@gmail.c omwrote:

>>On Feb 22, 10:20 am, mark <rkmr...@gmail. comwrote:
On 21 Feb 2007 14:47:50 -0800, placid <Bul...@gmail.c omwrote:
On Feb 22, 3:23 am, mark <rkmr...@gmail. comwrote:
>On 20 Feb 2007 21:26:18 -0800, placid <Bul...@gmail.c omwrote:
>>On Feb 21, 4:21 pm, "placid" <Bul...@gmail.c omwrote:
>>>On Feb 21, 4:12 pm, mark <rkmr...@gmail. comwrote:
>>>>On 20 Feb 2007 20:47:57 -0800, placid <Bul...@gmail.c omwrote:
>>>>>On Feb 21, 3:08 pm, mark <rkmr...@gmail. comwrote:
>>>>>>Rig ht now I have a thread that sleeps for sometime and check if an

[...]
Perhaps in future we can avoid quoting the whole preceding thread except
when strictly necessary?

regards
Steve
--
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