update

Author: windard

README.md

@@ -183,7 +183,7 @@ python的强大之处有很大的一方面在于它有各种各样非常强大
 
 ## [csv](content/csv.md)
 
-## [] [signal](content/signal.md)
+## [signal](content/signal.md)
 
 ## [asyncore](content/asyncore.md)
 

code/signal_alarm.py

@@ -0,0 +1,22 @@
+# -*- coding: utf-8 -*-
+
+import time
+import signal
+
+
+# After finish alarm
+def receive_alarm(signum, stack):
+    print 'Alarm :', time.ctime()
+
+
+# Call receive_alarm with 2 seconds
+signal.signal(signal.SIGALRM, receive_alarm)
+print 'Before:', time.ctime()
+
+# Unix only
+signal.alarm(2)
+print 'After alarm :', time.ctime()
+
+# Alarm will finish sleep
+time.sleep(3)
+print 'After sleep :', time.ctime()

code/signal_demo.py

@@ -1,18 +1,24 @@
-# coding=utf-8
+# -*- coding: utf-8 -*-
 
-import time
 import signal
+import os
+import time
+
 
-def handle(signo, frame):
-	print "Got Signal",signo
+def receive_signal(signum, stack):
+    print 'Received:', signum
 
-signal.signal(signal.SIGINT, handle)
 
-# Unix Only
-signal.alarm(2)
+if __name__ == '__main__':
 
-now = time.now()
+    # Register signal handlers
+    signal.signal(signal.SIGUSR1, receive_signal)
+    signal.signal(signal.SIGUSR2, receive_signal)
 
-time.sleep(200)
+    # Print the process ID so it can be used with 'kill'
+    # to send this program signals.
+    print 'My PID is:', os.getpid()
 
-print "sleep for",time.time() - now," seconds "
+    while True:
+        print 'Waiting...'
+        time.sleep(3)

code/signal_exit.py

@@ -0,0 +1,17 @@
+# -*- coding: utf-8 -*-
+
+import signal
+import os
+
+
+def do_exit(sig, stack):
+    raise SystemExit('Exiting')
+
+
+signal.signal(signal.SIGINT, signal.SIG_IGN)
+signal.signal(signal.SIGUSR1, do_exit)
+
+print 'My PID:', os.getpid()
+
+signal.pause()  # 当接受到键盘的时候，signal.SIG_IGN给忽略了
+print 'End of Exit'

code/signal_official.py

@@ -0,0 +1,18 @@
+# -*- coding: utf-8 -*-
+
+import os
+import signal
+
+# 定义一个信号处理函数，该函数打印收到的信号，然后raise IOError
+def handler(signum, frame):
+    print 'Signal handler called with signal', signum
+    raise IOError("Couldn't open device!")
+
+# 对SIGALRM(终止)设置处理的handler, 然后设置定时器，5秒后触发SIGALRM信号
+signal.signal(signal.SIGALRM, handler)
+signal.alarm(5)
+
+# open 操作可能异常等待
+fd = os.open('/dev/ttys0', os.O_RDWR)
+
+signal.alarm(0)          # 关闭定时器

code/signal_show.py

@@ -0,0 +1,31 @@
+# -*- coding: utf-8 -*-
+
+import signal
+import os
+import time
+
+
+def receive_signal(signum, stack):
+    print 'Received:', signum
+
+
+def receive_exit(signum, stack):
+    print 'Exit'
+    raise SystemExit('Exiting')
+
+
+if __name__ == '__main__':
+
+    # Register signal handlers
+    signal.signal(signal.SIGINT, receive_signal)
+    signal.signal(signal.SIGQUIT, receive_signal)
+
+    # SIGSTOP, SIGKILL can't received message
+    # signal.signal(signal.SIGSTOP, receive_signal)
+    # signal.signal(signal.SIGKILL, receive_exit)
+
+    print 'My PID is:', os.getpid()
+
+    while True:
+        print 'Waiting...'
+        time.sleep(3)

code/signal_timeout.py

@@ -0,0 +1,31 @@
+# -*- coding: utf-8 -*-
+
+import signal
+import requests
+
+
+def timeoutFn(func, args=(), kwargs={}, timeout_duration=5, default=None):
+
+    class TimeoutError(Exception):
+        pass
+
+    def handler(signum, frame):
+        raise TimeoutError()
+
+    # set the timeout handler
+    signal.signal(signal.SIGALRM, handler)
+    signal.alarm(timeout_duration)
+    try:
+        result = func(*args, **kwargs)
+    except TimeoutError as exc:
+        result = default
+    finally:
+
+        signal.alarm(0)
+        signal.signal(signal.SIGALRM, signal.SIG_DFL)
+    return result
+
+
+if __name__ == '__main__':
+    print timeoutFn(requests.get, ("https://baidu.com", ), default='failed')
+    print timeoutFn(requests.get, ("https://google.com", ), default='failed')

code/signal_traverse.py

@@ -0,0 +1,31 @@
+# -*- coding: utf-8 -*-
+
+import signal
+
+
+def alarm_received(n, stack):
+    return
+
+
+signal.signal(signal.SIGALRM, alarm_received)
+
+
+# SIG_ING 如果信号被忽略
+# SIG_DFL 如果使用默认行为
+# SIG_IGN -- if the signal is being ignored
+# SIG_DFL -- if the default action for the signal is in effect
+# None -- if an unknown handler is in effect
+# anything else -- the callable Python object used as a handler
+signals_to_names = dict(
+    (getattr(signal, n), n)
+    for n in dir(signal)
+    if n.startswith('SIG') and '_' not in n
+)
+
+for s, name in sorted(signals_to_names.items()):
+    handler = signal.getsignal(s)
+    if handler is signal.SIG_DFL:
+        handler = 'SIG_DFL'
+    elif handler is signal.SIG_IGN:
+        handler = 'SIG_IGN'
+    print '%-10s (%2d):' % (name, s), handler