最近更新: 2012-08-07

Python - GObject event, Threading, and Signal

示範如何在 Python 中使用 GObject event 、Python threading 與 Signal 進行非同步工作。

#!/usr/bin/python

# coding: utf-8

import os, sys, time
import gobject      # need for gobject event timeout

import signal       # need for system signal.

import threading    # need for python thread.

#from dbus.mainloop.glib import DBusGMainLoop

reload(sys)
sys.setdefaultencoding('utf-8')

def g_event_timer(*args):
    # for gobject.timeout_add(). it's gobject-style thread.

    # note: there are three kind of basic event source.

    print("1. g_event_timer tick.")
    return True  # keep interval


def sys_signal_timer(*args):
    # for system Signal

    print("2. sys_signal_timer tick.")

def thread_timer_func(*args):
    # for threading.Timer

    while True:
        print("3. thread_timer tick.")
        time.sleep(2)

def terminate_gobject_loop(signum, func):
    loop.quit()

signal.signal(signal.SIGINT,  terminate_gobject_loop)

gobject.threads_init()            # required for gobject collaborate with python thread.

#DBusGMainLoop(set_as_default=True) # if you use DBus.

#dbus.mainloop.glib.threads_init() # required for dbus collaborate with python thread.

loop = gobject.MainLoop()

# enable g_event_timer tick.

gobject.timeout_add(2000, g_event_timer)

# enable sys_signal_timer tick.

signal.signal(signal.SIGALRM, sys_signal_timer)
signal.setitimer(signal.ITIMER_REAL, 2, 2)
signal.siginterrupt(signal.SIGALRM, False)  # not really work.


# enable thread_timer tick.

thread_timer = threading.Timer(2, thread_timer_func)
thread_timer.start()

print("PID: %d" % os.getpid())
print("Press Ctrl+C will quit g_event_timer.")
try:
    loop.run()
except:
    print("Unknown error. It breaks eventloop.")

signal.signal(signal.SIGALRM, signal.SIG_IGN)  # cancel signal_timer.


print("Wait 5 seconds.")
print("Quit g_event_timer.")
print("Ignore signal_timer.")
print("Only thread_timer tick.")
time.sleep(5)
# 1. g_event_timer will not tick.

# 2. if I don't cancel signal_timer, signal_timer will tick and interrupt sleep.

# 3. thread_timer will still tick.


print("End")
os._exit(0)

基於 GObject 事件機制的程式類型,例如 GTK 或 DBus ,若要配合 Python 內部的 threading 機制,則必須在使用前先調用 gobject.threads_init() 。 而 DBus 程式則還要再調用 dbus.mainloop.glib.threads_init()。 才可以讓 Python threading 正常運作。

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