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PyGtk threading example
# Demo application showing how once can combine the python
# threading module with GObject signals to make a simple thread
# manager class which can be used to stop horrible blocking GUIs.
#
# (c) 2008, John Stowers <john.stowers@gmail.com>
#
# This program serves as an example, and can be freely used, copied, derived
# and redistributed by anyone. No warranty is implied or given.
import gtk
import gobject
gobject.threads_init()
import threading
import time
import random
class _IdleObject(gobject.GObject):
"""
Override gobject.GObject to always emit signals in the main thread
by emmitting on an idle handler
"""
def __init__(self):
gobject.GObject.__init__(self)
def emit(self, *args):
gobject.idle_add(gobject.GObject.emit,self,*args)
class _FooThread(threading.Thread, _IdleObject):
"""
Cancellable thread which uses gobject signals to return information
to the GUI.
"""
__gsignals__ = {
"completed": (
gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE, []),
"progress": (
gobject.SIGNAL_RUN_LAST, gobject.TYPE_NONE, [
gobject.TYPE_FLOAT]) #percent complete
}
def __init__(self, *args):
threading.Thread.__init__(self)
_IdleObject.__init__(self)
self.cancelled = False
self.data = args[0]
self.name = args[1]
self.setName("%s" % self.name)
def cancel(self):
"""
Threads in python are not cancellable, so we implement our own
cancellation logic
"""
self.cancelled = True
def run(self):
print "Running %s" % str(self)
for i in range(self.data):
if self.cancelled:
break
time.sleep(0.1)
self.emit("progress", i/float(self.data)*100)
self.emit("completed")
class FooThreadManager:
"""
Manages many FooThreads. This involves starting and stopping
said threads, and respecting a maximum num of concurrent threads limit
"""
def __init__(self, maxConcurrentThreads):
self.maxConcurrentThreads = maxConcurrentThreads
#stores all threads, running or stopped
self.fooThreads = {}
#the pending thread args are used as an index for the stopped threads
self.pendingFooThreadArgs = []
def _register_thread_completed(self, thread, *args):
"""
Decrements the count of concurrent threads and starts any
pending threads if there is space
"""
del(self.fooThreads[args])
running = len(self.fooThreads) - len(self.pendingFooThreadArgs)
print "%s completed. %s running, %s pending" % (
thread, running, len(self.pendingFooThreadArgs))
if running < self.maxConcurrentThreads:
try:
args = self.pendingFooThreadArgs.pop()
print "Starting pending %s" % self.fooThreads[args]
self.fooThreads[args].start()
except IndexError: pass
def make_thread(self, completedCb, progressCb, userData, *args):
"""
Makes a thread with args. The thread will be started when there is
a free slot
"""
running = len(self.fooThreads) - len(self.pendingFooThreadArgs)
if args not in self.fooThreads:
thread = _FooThread(*args)
#signals run in the order connected. Connect the user completed
#callback first incase they wish to do something
#before we delete the thread
thread.connect("completed", completedCb, userData)
thread.connect("completed", self._register_thread_completed, *args)
thread.connect("progress", progressCb, userData)
#This is why we use args, not kwargs, because args are hashable
self.fooThreads[args] = thread
if running < self.maxConcurrentThreads:
print "Starting %s" % thread
self.fooThreads[args].start()
else:
print "Queing %s" % thread
self.pendingFooThreadArgs.append(args)
def stop_all_threads(self, block=False):
"""
Stops all threads. If block is True then actually wait for the thread
to finish (may block the UI)
"""
for thread in self.fooThreads.values():
thread.cancel()
if block:
if thread.isAlive():
thread.join()
class Demo:
def __init__(self):
#build the GUI
win = gtk.Window()
win.connect("delete_event", self.quit)
box = gtk.VBox(False,4)
win.add(box)
addButton = gtk.Button("Add Thread")
addButton.connect("clicked",self.add_thread)
box.pack_start(addButton,False,False)
stopButton = gtk.Button("Stop All Threads")
stopButton.connect("clicked",self.stop_threads)
box.pack_start(stopButton,False,False)
#display threads in a treeview
self.pendingModel = gtk.ListStore(gobject.TYPE_STRING,gobject.TYPE_INT)
self.completeModel = gtk.ListStore(gobject.TYPE_STRING)
self._make_view(self.pendingModel, "Pending Threads", True, box)
self._make_view(self.completeModel,"Completed Threads", False, box)
#THE ACTUAL THREAD BIT
self.manager = FooThreadManager(3)
#Start the demo
win.show_all()
gtk.main()
def _make_view(self, model, title, showProgress, vbox):
view = gtk.TreeView(model)
view.append_column(gtk.TreeViewColumn(title, gtk.CellRendererText(), text=0))
if showProgress:
view.append_column(gtk.TreeViewColumn("Progress", gtk.CellRendererProgress(), value=1))
vbox.pack_start(view)
def quit(self, sender, event):
self.manager.stop_all_threads(block=True)
gtk.main_quit()
def stop_threads(self, *args):
#THE ACTUAL THREAD BIT
self.manager.stop_all_threads()
def add_thread(self, sender):
#make a thread and start it
data = random.randint(20,60)
name = "Thread #%s" % random.randint(0,1000)
rowref = self.pendingModel.insert(0,(name,0))
#THE ACTUAL THREAD BIT
self.manager.make_thread(
self.thread_finished,
self.thread_progress,
rowref,data,name)
def thread_finished(self, thread, rowref):
self.pendingModel.remove(rowref)
self.completeModel.insert(0,(thread.name,))
def thread_progress(self, thread, progress, rowref):
self.pendingModel.set_value(rowref,1,int(progress))
if __name__ == "__main__":
demo = Demo()
@bossjones

Posted an update to this FYI in case anyone is looking for an implementation using PyGObject/PyGI and GTK+3 here: https://gist.github.com/bossjones/e21b53c6dff04e8fdb3d

Thanks for the original @nzjrs !

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