annotate server/utils.py @ 22:885532437100

A bit of work on the server python
author Matt Johnston <matt@ucc.asn.au>
date Sat, 26 May 2012 10:17:27 +0800
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children b5925cb4f264
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1 import os
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2 import sys
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3 import ctypes
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4 import time
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5 import select
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6
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7 DEFAULT_TRIES = 3
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8
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9 __all__ = ('monotonic_time', 'retry')
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10
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11 clock_gettime = None
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12 no_clock_gettime = False
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13 def monotonic_time():
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14 global clock_gettime
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15 global no_clock_gettime
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16 if no_clock_gettime:
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17 return time.time()
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18
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19 class timespec(ctypes.Structure):
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20 _fields_ = [
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21 ('tv_sec', ctypes.c_long),
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22 ('tv_nsec', ctypes.c_long)
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23 ]
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24 if not clock_gettime:
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25 try:
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26 librt = ctypes.CDLL('librt.so.0', use_errno=True)
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27 clock_gettime = librt.clock_gettime
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28 clock_gettime.argtypes = [ctypes.c_int, ctypes.POINTER(timespec)]
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29 except:
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30 print>>sys.stderr, "No clock_gettime(), using fake fallback."
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31 no_clock_gettime = True
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32 return time.time()
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33
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34 t = timespec()
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35 CLOCK_MONOTONIC = 1 # see <linux/time.h>
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36
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37 if clock_gettime(CLOCK_MONOTONIC, ctypes.pointer(t)) != 0:
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38 errno_ = ctypes.get_errno()
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39 raise OSError(errno_, os.strerror(errno_))
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40 return t.tv_sec + t.tv_nsec * 1e-9
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41
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42 # decorator, tries a number of times, returns None on failure, sleeps between
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43 # Must be used as "@retry()" if arguments are defaulted
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44 def retry(retries=DEFAULT_TRIES, try_time = 1):
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45 def inner(func):
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46 print "inner"
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47 def new_f(*args, **kwargs):
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48 print "newf"
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49 for i in range(retries):
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50 print "retry %d" % i
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51 d = func(*args, **kwargs)
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52 if d:
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53 return d
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54 time.sleep(try_time)
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55 new_f.func_name = func.func_name
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56 return new_f
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57 return inner
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58
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59 def readline(sock):
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60 timeout = READLINE_SELECT_TIMEOUT
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61 buf = ''
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62 while true:
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63 (rlist, wlist, xlist) = select.select([sock], [], [], timeout)
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64 if sock not in rlist:
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65 # hit timeout
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66 return None
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67
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68 c = sock.recv(1)
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69 if c == '\r':
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70 continue
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71
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72 buf.append(c)
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73 if c == '\n':
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74 return buf
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75