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596
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1 #!/usr/bin/env python
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2
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3 """
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4 multiprocessing/subprocess experiments
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5 """
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6
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7 import argparse
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8 import os
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9 import subprocess
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10 import sys
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11 import time
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12 import tempfile
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13
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606
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14 string = (str, unicode)
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15
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601
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16 class Process(subprocess.Popen):
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17 """why would you name a subprocess object Popen?"""
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18
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606
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19 # http://docs.python.org/2/library/subprocess.html#popen-constructor
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610
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20 defaults = {'bufsize': 1, # line buffered
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611
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21 'store_output': True, # store stdout
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603
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22 }
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23
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606
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24 def __init__(self, command, **kwargs):
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25
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26 # setup arguments
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27 self.command = command
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28 _kwargs = self.defaults.copy()
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29 _kwargs.update(kwargs)
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30
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607
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31 # on unix, ``shell={True|False}`` should always come from the
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32 # type of command (string or list)
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609
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33 if not subprocess.mswindows:
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607
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34 _kwargs['shell'] = isinstance(command, string)
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35
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606
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36 # output buffer
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611
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37 self.location = 0
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606
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38 self.output_buffer = tempfile.SpooledTemporaryFile()
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611
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39 self.output = '' if _kwargs.pop('store_output') else None
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606
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40 _kwargs['stdout'] = self.output_buffer
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41
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611
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42 # runtime
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43 self.start = time.time()
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44 self.end = None
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45
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606
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46 # launch subprocess
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607
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47 subprocess.Popen.__init__(self, command, **_kwargs)
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606
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48
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611
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49 def _finalize(self, process_output):
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50 """internal function to finalize"""
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51
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52 # read final output
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53 self.read(process_output)
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54
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614
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55 # reset output buffer location
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611
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56 self.output_buffer.seek(0)
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57
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58 # set end time
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59 self.end = time.time()
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60
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614
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61 def poll(self, process_output=None):
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62
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63 if process_output is not None:
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64 self.read(process_output) # read from output buffer
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65 poll = subprocess.Popen.poll(self)
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66 if poll is not None:
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67 self._finalize(process_output)
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68 return poll
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613
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69
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611
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70 def wait(self, maxtime=None, sleep=1., process_output=None):
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606
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71 """
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72 maxtime -- timeout in seconds
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73 sleep -- number of seconds to sleep between polling
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74 """
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614
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75 while self.poll(process_output) is None:
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606
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76
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77 # check for timeout
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78 curr_time = time.time()
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613
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79 run_time = self.runtime()
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612
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80 if maxtime is not None and run_time > maxtime:
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611
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81 self.kill()
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82 self._finalize(process_output)
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83 return
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606
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84
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85 # naptime
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86 if sleep:
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87 time.sleep(sleep)
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88
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611
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89 # finalize
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613
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90 self._finalize(process_output)
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608
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91
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92 return self.returncode # set by ``.poll()``
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606
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93
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611
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94 def read(self, process_output=None):
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610
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95 """read from the output buffer"""
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611
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96
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610
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97 self.output_buffer.seek(self.location)
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98 read = self.output_buffer.read()
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611
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99 if self.output is not None:
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100 self.output += read
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101 if process_output:
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102 process_output(read)
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610
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103 self.location += len(read)
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104 return read
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105
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606
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106 def commandline(self):
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107 """returns string of command line"""
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108
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109 if isinstance(self.command, string):
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110 return self.command
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111 return subprocess.list2cmdline(self.command)
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112
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113 __str__ = commandline
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114
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611
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115 def runtime(self):
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116 """returns time spent running or total runtime if completed"""
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117
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118 if self.end is None:
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613
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119 return time.time() - self.start
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120 return self.end - self.start
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611
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121
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596
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122
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123 def main(args=sys.argv[1:]):
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599
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124 """CLI"""
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596
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125
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615
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126 description = """demonstration of how to do things with subprocess"""
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127
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600
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128 # available programs
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129 progs = {'yes': ["yes"],
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130 'ping': ['ping', 'google.com']}
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131
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599
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132 # parse command line
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615
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133 parser = argparse.ArgumentParser(description=description)
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596
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134 parser.add_argument("-t", "--time", dest="time",
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599
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135 type=float, default=4.,
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614
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136 help="seconds to run for (or <= 0 for forever)")
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599
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137 parser.add_argument("-s", "--sleep", dest="sleep",
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596
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138 type=float, default=1.,
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600
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139 help="sleep this number of seconds between polling")
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140 parser.add_argument("-p", "--prog", dest='program',
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606
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141 choices=progs.keys(), default='ping',
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600
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142 help="subprocess to run")
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606
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143 parser.add_argument("--list-programs", dest='list_programs',
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144 action='store_true', default=False,
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145 help="list available programs")
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615
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146 parser.add_argument("--wait", dest='wait',
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147 action='store_true', default=False,
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148 help="run with ``.wait()`` and a callback")
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149 parser.add_argument("--callback", dest='callback',
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150 action='store_true', default=False,
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151 help="run with polling and a callback")
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596
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152 options = parser.parse_args(args)
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153
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608
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154 # list programs
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155 if options.list_programs:
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156 for key in sorted(progs.keys()):
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157 print ('{}: {}'.format(key, subprocess.list2cmdline(progs[key])))
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610
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158 sys.exit(0)
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599
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159
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160 # select program
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600
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161 prog = progs[options.program]
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599
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162
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611
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163 # start process
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608
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164 proc = Process(prog)
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596
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165
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615
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166 # demo function for processing output
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167 def output_processor(output):
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168 print ('[{}]:\n{}\n{}'.format(proc.runtime(),
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169 output.upper(),
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170 '-==-'*10))
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171 if options.callback:
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172 process_output = output_processor
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173 else:
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174 process_output = None
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613
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175
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615
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176 if options.wait:
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177 # wait for being done
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178 proc.wait(maxtime=options.time, sleep=options.sleep, process_output=output_processor)
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179 else:
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180 # start the main subprocess loop
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181 while proc.poll(process_output) is None:
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608
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182
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615
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183 if options.time > 0 and proc.runtime() > options.time:
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184 proc.kill()
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596
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185
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615
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186 if options.sleep:
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187 time.sleep(options.sleep)
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188
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189 if process_output is not None:
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190 # process the output with ``.read()`` call
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191 proc.read(output_processor)
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611
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192
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614
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193 # correctness tests
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194 assert proc.end is not None
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195
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196 # print summary
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611
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197 output = proc.output
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198 n_lines = len(output.splitlines())
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615
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199 print ("{}: {} lines, ran for {} seconds".format(subprocess.list2cmdline(prog), n_lines, proc.runtime()))
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596
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200
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201 if __name__ == '__main__':
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202 main()
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