annotate py/utils.py @ 253:0a1b642e3086

long polling config updates
author Matt Johnston <matt@ucc.asn.au>
date Mon, 08 Jun 2015 22:29:46 +0800
parents 185621f47040
children 26eee8591f61
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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 import logging
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7 import binascii
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8
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9 D = logging.debug
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10 L = logging.info
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11 W = logging.warning
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12 E = logging.error
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13
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14 DEFAULT_TRIES = 3
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15 READLINE_SELECT_TIMEOUT = 1
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16
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17 def EX(msg, *args, **kwargs):
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18 kwargs['exc_info'] = True
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19 logging.error(msg, *args, **kwargs)
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20
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21 clock_gettime = None
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22 no_clock_gettime = True
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23 def monotonic_time():
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24 global clock_gettime
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25 global no_clock_gettime
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26 if no_clock_gettime:
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27 return time.time()
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28
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29 class timespec(ctypes.Structure):
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30 _fields_ = [
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31 ('tv_sec', ctypes.c_long),
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32 ('tv_nsec', ctypes.c_long)
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33 ]
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34 if not clock_gettime:
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35 try:
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36 librt = ctypes.CDLL('librt.so.0', use_errno=True)
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37 clock_gettime = librt.clock_gettime
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38 clock_gettime.argtypes = [ctypes.c_int, ctypes.POINTER(timespec)]
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39 except:
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40 W("No clock_gettime(), using fake fallback.")
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41 no_clock_gettime = True
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42 return time.time()
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43
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44 t = timespec()
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45 CLOCK_MONOTONIC = 1 # see <linux/time.h>
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46
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47 if clock_gettime(CLOCK_MONOTONIC, ctypes.pointer(t)) != 0:
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48 errno_ = ctypes.get_errno()
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49 raise OSError(errno_, os.strerror(errno_))
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50 return t.tv_sec + t.tv_nsec * 1e-9
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51
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52 # decorator, tries a number of times, returns None on failure, sleeps between
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53 # Must be used as "@retry()" if arguments are defaulted
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54 def retry(retries=DEFAULT_TRIES, try_time = 1):
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55 def inner(func):
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56 def new_f(*args, **kwargs):
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57 for i in range(retries):
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58 d = func(*args, **kwargs)
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59 if d is not None:
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60 return d
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61 time.sleep(try_time)
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62 return None
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63
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64 new_f.__name__ = func.__name__
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65 return new_f
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66 return inner
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67
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68 def readline(sock):
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69 timeout = READLINE_SELECT_TIMEOUT
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70 buf = ''
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71 while True:
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72 (rlist, wlist, xlist) = select.select([sock], [], [], timeout)
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73 if sock not in rlist:
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74 # hit timeout
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75 return None
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76
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77 c = sock.recv(1)
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78 if c == '':
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79 # lightblue timeout
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80 return None
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81 if c == '\r':
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82 continue
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83
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84 buf += c
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85 if c == '\n':
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86 return buf
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87
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88 # from http://blog.stalkr.net/2011/04/pctf-2011-32-thats-no-bluetooth.html
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89 def crc16(buff, crc = 0, poly = 0x8408):
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90 l = len(buff)
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91 i = 0
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92 while i < l:
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93 ch = ord(buff[i])
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94 uc = 0
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95 while uc < 8:
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96 if (crc & 1) ^ (ch & 1):
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97 crc = (crc >> 1) ^ poly
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98 else:
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99 crc >>= 1
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100 ch >>= 1
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101 uc += 1
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102 i += 1
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103 return crc
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104
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105 def cheap_daemon():
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106 L("Daemonising.")
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107 sys.stdout.flush()
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108 sys.stderr.flush()
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109 out = file('/dev/null', 'a+')
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110 os.dup2(out.fileno(), sys.stdout.fileno())
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111 os.dup2(out.fileno(), sys.stderr.fileno())
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112
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113 try:
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114 pid = os.fork()
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115 if pid > 0:
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116 sys.exit(0)
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117 except OSError as e:
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118 E("Bad fork()")
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119 sys.exit(1)
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120
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121 os.setsid()
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122
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123 try:
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124 pid = os.fork()
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125 if pid > 0:
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126 sys.exit(0)
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127 except OSError as e:
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128 E("Bad fork()")
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129 sys.exit(1)
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130
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131 def uptime():
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132 try:
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133 return float(open('/proc/uptime', 'r').read().split(' ', 1)[0])
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134 except Exception as e:
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135 return -1
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136
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137 def hexnonce():
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138 return binascii.hexlify(os.urandom(120))