两个实用的 python 装饰器: timeout超时控制和 trace单步追踪

2017/05/24

timeout超时控制

通过设置时钟信号给函数添加超时终端功能, 不适用于通过 os.system() 调用外部程序的情形.

import signal
import functools
 
class TimeoutError(Exception):
  pass
 
def timeout(seconds, error_message='Function call timed out'):
  def decorated(func):
    def _handle_timeout(signum, frame):
      raise TimeoutError(error_message)
 
    def wrapper(*args, **kwargs):
      signal.signal(signal.SIGALRM, _handle_timeout)
      signal.alarm(seconds)
 
      try:
        result = func(*args, **kwargs)
      finally:
        signal.alarm(0)
 
      return result
    return functools.wraps(func)(wrapper)
  return decorated
 
  @timeout(3)
  def slowfunc(sleep_time):
    import time
    time.sleep(sleep_time)
 
  if '__main__' == __name__:
    slowfunc(1)
    print 'ok'
 
    try:
      slowfunc(5)
    except TimeoutError:
      print 'timeout'

import signal

import functools

class TimeoutError(Exception):

pass

def timeout(seconds, error_message='Function call timed out'):

def decorated(func):

def _handle_timeout(signum, frame):

raise TimeoutError(error_message)

def wrapper(*args, **kwargs):

signal.signal(signal.SIGALRM, _handle_timeout)

signal.alarm(seconds)

try:

result = func(*args, **kwargs)

finally:

signal.alarm(0)

return result

return functools.wraps(func)(wrapper)

return decorated

@timeout(3)

def slowfunc(sleep_time):

import time

time.sleep(sleep_time)

if '__main__' == __name__:

slowfunc(1)

print 'ok'

try:

slowfunc(5)

except TimeoutError:

print 'timeout'

trace单步追踪

提供类似 bash -x 调试功能, 打印执行的每一行代码.

import os
import sys
import linecache
 
def trace(f):
  def localtrace(frame, why, arg):
    if 'line' == why:
      # record the file name and line number of every trace 
      filepath = frame.f_code.co_filename
      lineno = frame.f_lineno
      print '{filepath}({lineno}): {line}'.format(
        filepath=filepath,
        lineno=lineno,
        line=linecache.getline(filepath, lineno).strip('\r\n'))
 
    return localtrace
 
  def globaltrace(frame, why, arg):
    if 'call' == why:
      return localtrace
    return None
 
  def _f(*args, **kwards):
    sys.settrace(globaltrace)
    result = f(*args, **kwards)
    sys.settrace(None)
    return result
 
  return _f
 
@trace
def xxx():
  print 1
 
  result = ''
  for i in ['1', '2', '3']:
    if i == '3':
      result += i
 
  print result
 
if '__main__' == __name__:
  xxx()

import os

import sys

import linecache

def trace(f):

def localtrace(frame, why, arg):

if 'line' == why:

# record the file name and line number of every trace

filepath = frame.f_code.co_filename

lineno = frame.f_lineno

print '{filepath}({lineno}): {line}'.format(

filepath=filepath,

lineno=lineno,

line=linecache.getline(filepath, lineno).strip('\r\n'))

return localtrace

def globaltrace(frame, why, arg):

if 'call' == why:

return localtrace

return None

def _f(*args, **kwards):

sys.settrace(globaltrace)

result = f(*args, **kwards)

sys.settrace(None)

return result

return _f

@trace

def xxx():

print 1

result = ''

for i in ['1', '2', '3']:

if i == '3':

result += i

print result

if '__main__' == __name__:

xxx()

输出示例：

python2 ./test/trace.py
./test/trace.py(34):   print 1
1
./test/trace.py(36):   result = ''
./test/trace.py(37):   for i in ['1', '2', '3']:
./test/trace.py(38):     if i == '3':
./test/trace.py(37):   for i in ['1', '2', '3']:
./test/trace.py(38):     if i == '3':
./test/trace.py(37):   for i in ['1', '2', '3']:
./test/trace.py(38):     if i == '3':
./test/trace.py(39):       result += i
./test/trace.py(37):   for i in ['1', '2', '3']:
./test/trace.py(41):   print result
3

python2 ./test/trace.py

./test/trace.py(34): print 1

./test/trace.py(36): result = ''

./test/trace.py(37): for i in ['1', '2', '3']:

./test/trace.py(38): if i == '3':

./test/trace.py(37): for i in ['1', '2', '3']:

./test/trace.py(38): if i == '3':

./test/trace.py(37): for i in ['1', '2', '3']:

./test/trace.py(38): if i == '3':

./test/trace.py(39): result += i

./test/trace.py(37): for i in ['1', '2', '3']:

./test/trace.py(41): print result

原文地址：http://www.logevery.com/python/python_two_decorate_timeout_and_trace.html

timeout超时控制

trace单步追踪

Blogroll