#!/usr/bin/python
import time
import functools
from threading import Thread
from Queue import Queue
import gobject
class Job:
"""Wrap a co-routines that yields asynchronous tasks (see Task class)."""
def __init__(self, generator):
self.generator = generator
task = generator.send(None)
self._start_task(task)
def _start_task(self, task):
return_cb = functools.partial(self._advance_task, "send")
exception_cb = functools.partial(self._advance_task, "throw")
task.config(return_cb, exception_cb)
task.run()
def _advance_task(self, method, result=None):
assert method in ("send", "throw")
try:
task = getattr(self.generator, method)(result)
except StopIteration:
return
self._start_task(task)
class Task:
"""Base class for asynchronous tasks."""
def config(self, return_cb, exception_cb):
"""Set return and exception callbacks."""
self.return_cb = return_cb
self.exception_cb = exception_cb
def run(self):
raise RuntimeError, "Run method must be overriden"
class ThreadedTask(Task):
"""Run a function in a new thread and return its output."""
def __init__(self, fun, *args, **kwargs):
self.function = (fun, args, kwargs)
def run(self):
"""Start thread and set callback to get the result value."""
queue = Queue()
thread = Thread(target=self._thread_manager, args=(self.function, queue))
thread.setDaemon(True)
thread.start()
self.source_id = gobject.timeout_add(50, self._thread_receiver, queue)
def _thread_receiver(self, queue):
if queue.empty():
return True
rtype, rvalue = queue.get()
if rtype == "return":
self.return_cb(rvalue)
else:
self.exception_cb(rvalue)
return False
def _thread_manager(self, function, queue):
fun, args, kwargs = function
try:
result = fun(*args, **kwargs)
except Exception, exc:
queue.put(("exception", Exception(exc)))
raise
queue.put(("return", result))
class SleepTask(Task):
"""Sleep for some time and return."""
def __init__(self, seconds):
self.seconds = seconds
def run(self):
def _return():
self.return_cb()
return False
self.source_id = gobject.timeout_add(int(self.seconds * 1000), _return)
# Example with PyGTK
def heavy_function(x, y):
time.sleep(1.0)
return int(x) + int(y)
def my_job(wait, a, b):
print "wait", wait
yield SleepTask(wait)
print "do sequential heavy work in a thread"
result1 = (yield ThreadedTask(heavy_function, a, b))
print "do more sequential work"
result2 = (yield ThreadedTask(heavy_function, result1, b))
print "done! result of work was", result2
def other_async_work():
import sys
sys.stderr.write(".")
return True
def on_start(button, entrya, entryb):
import random
job = Job(my_job(random.uniform(1, 5), entrya.get_text(), entryb.get_text()))
print "start job", job
def main(args):
import gtk
gobject.threads_init()
window = gtk.Window()
start = gtk.Button("start")
window.connect("delete-event", lambda *args: gtk.main_quit())
box = gtk.VBox()
entrya, entryb = gtk.Entry(), gtk.Entry()
entrya.set_text("1")
entryb.set_text("2")
start.connect("clicked", on_start, entrya, entryb)
for widget in (entrya, entryb, start):
box.pack_start(widget)
window.add(box)
start.set_flags(gtk.CAN_DEFAULT)
entrya.set_activates_default(True)
entryb.set_activates_default(True)
window.set_default(start)
window.show_all()
gobject.timeout_add(100, other_async_work)
gtk.main()
if __name__ == '__main__':
import sys
sys.exit(main(sys.argv[1:]))
Diff to Previous Revision
--- revision 1 2010-03-19 10:31:59
+++ revision 2 2010-03-19 12:01:17
@@ -64,8 +64,8 @@
fun, args, kwargs = function
try:
result = fun(*args, **kwargs)
- except Exception as exc:
- queue.put(("exception", exc))
+ except Exception, exc:
+ queue.put(("exception", Exception(exc)))
raise
queue.put(("return", result))