timeout.py

#!/usr/local/cdat/bin/python

# timeout by function decoration.  based on recipe in
# http://code.activestate.com/recipes/307871-timing-out-function/

import signal, time

class TimedOutExc(Exception):
    def __init__(self, value = "Timed Out"):
        self.value = value
    def __str__(self):
        return repr(self.value)

def timed_out(timeout):
    def decorate(f):
        def handler(signum, frame):
            raise TimedOutExc()
        
        def new_f(*args, **kwargs):
            old = signal.signal(signal.SIGALRM, handler)
            signal.alarm(timeout)
            try:
                result = f(*args, **kwargs)
            finally:
                signal.signal(signal.SIGALRM, old)
            signal.alarm(0)
            return result
        
        new_f.func_name = f.func_name
        return new_f

    return decorate

# # test examples:
# 
# def fn_1(secs):
#     time.sleep(secs)
#     return "Finished"
# @timed_out(4)
# def fn_2(secs):
#     time.sleep(secs)
#     return("Finished")
# @timed_out(2)
# def fn_3(secs):
#     time.sleep(secs)
#     return "Finished"
# @timed_out(2)
# def fn_4(secs):
#     try:
#         time.sleep(secs)
#         return "Finished"
#     except TimedOutExc:
#         print "(Caught TimedOutExc, so cleaining up, and re-raising it) - ",
#         raise TimedOutExc
# 
# if __name__ == '__main__':
# 
#     try:
#         print "fn_2 (sleep 2, timeout 4): ",
#         print fn_2(2)
#     except TimedOutExc:
#         print "took too long"
# 
#     try:
#         print "fn_3 (sleep 4, timeout 2): ",
#         print fn_3(4)
#     except TimedOutExc:
#         print "took too long"
# 
#     try:
#         print "fn_4 (sleep 4, timeout 2): ",
#         print fn_4(4)
#     except TimedOutExc:
#         print "took too long"