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@@ -1,425 +1,425 b'' | |||
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1 | 1 | """ |
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2 | 2 | Module provides a class allowing to wrap communication over subprocess.Popen |
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3 | 3 | input, output, error streams into a meaningfull, non-blocking, concurrent |
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4 | 4 | stream processor exposing the output data as an iterator fitting to be a |
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5 | 5 | return value passed by a WSGI applicaiton to a WSGI server per PEP 3333. |
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6 | 6 | |
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7 | 7 | Copyright (c) 2011 Daniel Dotsenko <dotsa[at]hotmail.com> |
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8 | 8 | |
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9 | 9 | This file is part of git_http_backend.py Project. |
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10 | 10 | |
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11 | 11 | git_http_backend.py Project is free software: you can redistribute it and/or |
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12 | 12 | modify it under the terms of the GNU Lesser General Public License as |
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13 | 13 | published by the Free Software Foundation, either version 2.1 of the License, |
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14 | 14 | or (at your option) any later version. |
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15 | 15 | |
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16 | 16 | git_http_backend.py Project is distributed in the hope that it will be useful, |
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17 | 17 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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18 | 18 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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19 | 19 | GNU Lesser General Public License for more details. |
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20 | 20 | |
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21 | 21 | You should have received a copy of the GNU Lesser General Public License |
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22 | 22 | along with git_http_backend.py Project. |
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23 | 23 | If not, see <http://www.gnu.org/licenses/>. |
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24 | 24 | """ |
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25 | 25 | import os |
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26 | 26 | import subprocess |
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27 | 27 | from kallithea.lib.vcs.utils.compat import deque, Event, Thread, _bytes, _bytearray |
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28 | 28 | |
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29 | 29 | |
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30 | 30 | class StreamFeeder(Thread): |
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31 | 31 | """ |
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32 | 32 | Normal writing into pipe-like is blocking once the buffer is filled. |
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33 | 33 | This thread allows a thread to seep data from a file-like into a pipe |
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34 | 34 | without blocking the main thread. |
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35 | 35 | We close inpipe once the end of the source stream is reached. |
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36 | 36 | """ |
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37 | 37 | |
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38 | 38 | def __init__(self, source): |
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39 | 39 | super(StreamFeeder, self).__init__() |
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40 | 40 | self.daemon = True |
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41 | 41 | filelike = False |
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42 | 42 | self.bytes = _bytes() |
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43 | 43 | if type(source) in (type(''), _bytes, _bytearray): # string-like |
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44 | 44 | self.bytes = _bytes(source) |
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45 | 45 | else: # can be either file pointer or file-like |
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46 | 46 | if type(source) in (int, long): # file pointer it is |
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47 | 47 | ## converting file descriptor (int) stdin into file-like |
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48 | 48 | source = os.fdopen(source, 'rb', 16384) |
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49 | 49 | # let's see if source is file-like by now |
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50 | 50 | filelike = hasattr(source, 'read') |
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51 | 51 | if not filelike and not self.bytes: |
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52 | 52 | raise TypeError("StreamFeeder's source object must be a readable " |
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53 | 53 | "file-like, a file descriptor, or a string-like.") |
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54 | 54 | self.source = source |
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55 | 55 | self.readiface, self.writeiface = os.pipe() |
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56 | 56 | |
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57 | 57 | def run(self): |
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58 | 58 | t = self.writeiface |
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59 | 59 | if self.bytes: |
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60 | 60 | os.write(t, self.bytes) |
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61 | 61 | else: |
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62 | 62 | s = self.source |
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63 | 63 | b = s.read(4096) |
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64 | 64 | while b: |
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65 | 65 | os.write(t, b) |
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66 | 66 | b = s.read(4096) |
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67 | 67 | os.close(t) |
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68 | 68 | |
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69 | 69 | @property |
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70 | 70 | def output(self): |
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71 | 71 | return self.readiface |
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72 | 72 | |
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73 | 73 | |
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74 | 74 | class InputStreamChunker(Thread): |
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75 | 75 | def __init__(self, source, target, buffer_size, chunk_size): |
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76 | 76 | |
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77 | 77 | super(InputStreamChunker, self).__init__() |
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78 | 78 | |
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79 | 79 | self.daemon = True # die die die. |
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80 | 80 | |
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81 | 81 | self.source = source |
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82 | 82 | self.target = target |
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83 | 83 | self.chunk_count_max = int(buffer_size / chunk_size) + 1 |
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84 | 84 | self.chunk_size = chunk_size |
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85 | 85 | |
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86 | 86 | self.data_added = Event() |
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87 | 87 | self.data_added.clear() |
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88 | 88 | |
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89 | 89 | self.keep_reading = Event() |
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90 | 90 | self.keep_reading.set() |
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91 | 91 | |
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92 | 92 | self.EOF = Event() |
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93 | 93 | self.EOF.clear() |
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94 | 94 | |
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95 | 95 | self.go = Event() |
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96 | 96 | self.go.set() |
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97 | 97 | |
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98 | 98 | def stop(self): |
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99 | 99 | self.go.clear() |
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100 | 100 | self.EOF.set() |
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101 | 101 | try: |
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102 | 102 | # this is not proper, but is done to force the reader thread let |
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103 | 103 | # go of the input because, if successful, .close() will send EOF |
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104 | 104 | # down the pipe. |
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105 | 105 | self.source.close() |
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106 | 106 | except: |
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107 | 107 | pass |
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108 | 108 | |
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109 | 109 | def run(self): |
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110 | 110 | s = self.source |
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111 | 111 | t = self.target |
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112 | 112 | cs = self.chunk_size |
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113 | 113 | ccm = self.chunk_count_max |
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114 | 114 | kr = self.keep_reading |
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115 | 115 | da = self.data_added |
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116 | 116 | go = self.go |
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117 | 117 | |
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118 | 118 | try: |
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119 | 119 | b = s.read(cs) |
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120 | 120 | except ValueError: |
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121 | 121 | b = '' |
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122 | 122 | |
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123 | 123 | while b and go.is_set(): |
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124 | 124 | if len(t) > ccm: |
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125 | 125 | kr.clear() |
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126 | 126 | kr.wait(2) |
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127 | 127 | # # this only works on 2.7.x and up |
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128 | 128 | # if not kr.wait(10): |
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129 | 129 | # raise Exception("Timed out while waiting for input to be read.") |
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130 | 130 | # instead we'll use this |
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131 | 131 | if len(t) > ccm + 3: |
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132 | 132 | raise IOError( |
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133 | 133 | "Timed out while waiting for input from subprocess.") |
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134 | 134 | t.append(b) |
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135 | 135 | da.set() |
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136 | 136 | try: |
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137 | 137 | b = s.read(cs) |
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138 | 138 | except ValueError: # probably "I/O operation on closed file" |
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139 | 139 | b = '' |
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140 | 140 | |
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141 | 141 | self.EOF.set() |
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142 | 142 | da.set() # for cases when done but there was no input. |
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143 | 143 | |
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144 | 144 | |
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145 | 145 | class BufferedGenerator(object): |
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146 | 146 | """ |
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147 | 147 | Class behaves as a non-blocking, buffered pipe reader. |
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148 | 148 | Reads chunks of data (through a thread) |
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149 | 149 | from a blocking pipe, and attaches these to an array (Deque) of chunks. |
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150 | 150 | Reading is halted in the thread when max chunks is internally buffered. |
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151 | 151 | The .next() may operate in blocking or non-blocking fashion by yielding |
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152 | 152 | '' if no data is ready |
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153 | 153 | to be sent or by not returning until there is some data to send |
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154 | 154 | When we get EOF from underlying source pipe we raise the marker to raise |
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155 | 155 | StopIteration after the last chunk of data is yielded. |
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156 | 156 | """ |
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157 | 157 | |
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158 | 158 | def __init__(self, source, buffer_size=65536, chunk_size=4096, |
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159 | 159 | starting_values=None, bottomless=False): |
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160 | 160 | starting_values = starting_values or [] |
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161 | 161 | if bottomless: |
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162 | 162 | maxlen = int(buffer_size / chunk_size) |
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163 | 163 | else: |
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164 | 164 | maxlen = None |
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165 | 165 | |
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166 | 166 | self.data = deque(starting_values, maxlen) |
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167 | 167 | self.worker = InputStreamChunker(source, self.data, buffer_size, |
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168 | 168 | chunk_size) |
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169 | 169 | if starting_values: |
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170 | 170 | self.worker.data_added.set() |
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171 | 171 | self.worker.start() |
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172 | 172 | |
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173 | 173 | #################### |
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174 | 174 | # Generator's methods |
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175 | 175 | #################### |
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176 | 176 | |
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177 | 177 | def __iter__(self): |
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178 | 178 | return self |
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179 | 179 | |
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180 | 180 | def next(self): |
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181 | 181 | while not len(self.data) and not self.worker.EOF.is_set(): |
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182 | 182 | self.worker.data_added.clear() |
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183 | 183 | self.worker.data_added.wait(0.2) |
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184 | 184 | if len(self.data): |
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185 | 185 | self.worker.keep_reading.set() |
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186 | 186 | return _bytes(self.data.popleft()) |
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187 | 187 | elif self.worker.EOF.is_set(): |
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188 | 188 | raise StopIteration |
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189 | 189 | |
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190 | 190 | def throw(self, type, value=None, traceback=None): |
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191 | 191 | if not self.worker.EOF.is_set(): |
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192 | 192 | raise type(value) |
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193 | 193 | |
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194 | 194 | def start(self): |
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195 | 195 | self.worker.start() |
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196 | 196 | |
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197 | 197 | def stop(self): |
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198 | 198 | self.worker.stop() |
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199 | 199 | |
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200 | 200 | def close(self): |
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201 | 201 | try: |
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202 | 202 | self.worker.stop() |
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203 | 203 | self.throw(GeneratorExit) |
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204 | 204 | except (GeneratorExit, StopIteration): |
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205 | 205 | pass |
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206 | 206 | |
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207 | 207 | def __del__(self): |
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208 | 208 | self.close() |
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209 | 209 | |
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210 | 210 | #################### |
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211 | 211 | # Threaded reader's infrastructure. |
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212 | 212 | #################### |
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213 | 213 | @property |
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214 | 214 | def input(self): |
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215 | 215 | return self.worker.w |
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216 | 216 | |
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217 | 217 | @property |
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218 | 218 | def data_added_event(self): |
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219 | 219 | return self.worker.data_added |
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220 | 220 | |
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221 | 221 | @property |
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222 | 222 | def data_added(self): |
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223 | 223 | return self.worker.data_added.is_set() |
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224 | 224 | |
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225 | 225 | @property |
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226 | 226 | def reading_paused(self): |
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227 | 227 | return not self.worker.keep_reading.is_set() |
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228 | 228 | |
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229 | 229 | @property |
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230 | 230 | def done_reading_event(self): |
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231 | 231 | """ |
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232 | 232 | Done_reading does not mean that the iterator's buffer is empty. |
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233 | 233 | Iterator might have done reading from underlying source, but the read |
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234 | 234 | chunks might still be available for serving through .next() method. |
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235 | 235 | |
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236 | 236 | :returns: An Event class instance. |
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237 | 237 | """ |
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238 | 238 | return self.worker.EOF |
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239 | 239 | |
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240 | 240 | @property |
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241 | 241 | def done_reading(self): |
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242 | 242 | """ |
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243 | 243 | Done_reading does not mean that the iterator's buffer is empty. |
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244 | 244 | Iterator might have done reading from underlying source, but the read |
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245 | 245 | chunks might still be available for serving through .next() method. |
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246 | 246 | |
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247 | 247 | :returns: An Bool value. |
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248 | 248 | """ |
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249 | 249 | return self.worker.EOF.is_set() |
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250 | 250 | |
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251 | 251 | @property |
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252 | 252 | def length(self): |
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253 | 253 | """ |
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254 | 254 | returns int. |
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255 | 255 | |
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256 | 256 | This is the length of the queue of chunks, not the length of |
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257 | 257 | the combined contents in those chunks. |
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258 | 258 | |
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259 | 259 | __len__() cannot be meaningfully implemented because this |
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260 | 260 | reader is just flying through a bottomless pit content and |
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261 | 261 | can only know the length of what it already saw. |
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262 | 262 | |
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263 | 263 | If __len__() on WSGI server per PEP 3333 returns a value, |
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264 | 264 | the response's length will be set to that. In order not to |
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265 | 265 | confuse WSGI PEP3333 servers, we will not implement __len__ |
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266 | 266 | at all. |
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267 | 267 | """ |
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268 | 268 | return len(self.data) |
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269 | 269 | |
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270 | 270 | def prepend(self, x): |
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271 | 271 | self.data.appendleft(x) |
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272 | 272 | |
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273 | 273 | def append(self, x): |
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274 | 274 | self.data.append(x) |
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275 | 275 | |
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276 | 276 | def extend(self, o): |
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277 | 277 | self.data.extend(o) |
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278 | 278 | |
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279 | 279 | def __getitem__(self, i): |
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280 | 280 | return self.data[i] |
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281 | 281 | |
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282 | 282 | |
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283 | 283 | class SubprocessIOChunker(object): |
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284 | 284 | """ |
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285 | 285 | Processor class wrapping handling of subprocess IO. |
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286 | 286 | |
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287 | 287 | In a way, this is a "communicate()" replacement with a twist. |
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288 | 288 | |
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289 | 289 | - We are multithreaded. Writing in and reading out, err are all sep threads. |
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290 | 290 | - We support concurrent (in and out) stream processing. |
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291 | 291 | - The output is not a stream. It's a queue of read string (bytes, not unicode) |
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292 | 292 | chunks. The object behaves as an iterable. You can "for chunk in obj:" us. |
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293 | 293 | - We are non-blocking in more respects than communicate() |
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294 | 294 | (reading from subprocess out pauses when internal buffer is full, but |
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295 | 295 | does not block the parent calling code. On the flip side, reading from |
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296 | 296 | slow-yielding subprocess may block the iteration until data shows up. This |
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297 | 297 | does not block the parallel inpipe reading occurring parallel thread.) |
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298 | 298 | |
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299 | 299 | The purpose of the object is to allow us to wrap subprocess interactions into |
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300 | 300 | an iterable that can be passed to a WSGI server as the application's return |
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301 | 301 | value. Because of stream-processing-ability, WSGI does not have to read ALL |
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302 | 302 | of the subprocess's output and buffer it, before handing it to WSGI server for |
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303 | 303 | HTTP response. Instead, the class initializer reads just a bit of the stream |
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304 | 304 | to figure out if error occurred or likely to occur and if not, just hands the |
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305 | 305 | further iteration over subprocess output to the server for completion of HTTP |
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306 | 306 | response. |
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307 | 307 | |
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308 | 308 | The real or perceived subprocess error is trapped and raised as one of |
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309 | 309 | EnvironmentError family of exceptions |
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310 | 310 | |
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311 | 311 | Example usage: |
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312 | 312 | # try: |
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313 | 313 | # answer = SubprocessIOChunker( |
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314 | 314 | # cmd, |
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315 | 315 | # input, |
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316 | 316 | # buffer_size = 65536, |
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317 | 317 | # chunk_size = 4096 |
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318 | 318 | # ) |
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319 | 319 | # except (EnvironmentError) as e: |
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320 | 320 | # print str(e) |
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321 | 321 | # raise e |
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322 | 322 | # |
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323 | 323 | # return answer |
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324 | 324 | |
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325 | 325 | |
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326 | 326 | """ |
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327 | 327 | |
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328 | 328 | def __init__(self, cmd, inputstream=None, buffer_size=65536, |
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329 | 329 | chunk_size=4096, starting_values=None, **kwargs): |
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330 | 330 | """ |
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331 | 331 | Initializes SubprocessIOChunker |
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332 | 332 | |
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333 | 333 | :param cmd: A Subprocess.Popen style "cmd". Can be string or array of strings |
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334 | 334 | :param inputstream: (Default: None) A file-like, string, or file pointer. |
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335 | 335 | :param buffer_size: (Default: 65536) A size of total buffer per stream in bytes. |
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336 | 336 | :param chunk_size: (Default: 4096) A max size of a chunk. Actual chunk may be smaller. |
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337 | 337 | :param starting_values: (Default: []) An array of strings to put in front of output que. |
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338 | 338 | """ |
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339 | 339 | starting_values = starting_values or [] |
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340 | 340 | if inputstream: |
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341 | 341 | input_streamer = StreamFeeder(inputstream) |
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342 | 342 | input_streamer.start() |
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343 | 343 | inputstream = input_streamer.output |
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344 | 344 | |
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345 | 345 | # Note: fragile cmd mangling has been removed for use in Kallithea |
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346 | 346 | assert isinstance(cmd, list), cmd |
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347 | 347 | |
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348 | 348 | _p = subprocess.Popen(cmd, bufsize=-1, |
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349 | 349 | stdin=inputstream, |
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350 | 350 | stdout=subprocess.PIPE, |
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351 | 351 | stderr=subprocess.PIPE, |
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352 | 352 | **kwargs) |
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353 | 353 | |
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354 | 354 | bg_out = BufferedGenerator(_p.stdout, buffer_size, chunk_size, |
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355 | 355 | starting_values) |
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356 | 356 | bg_err = BufferedGenerator(_p.stderr, 16000, 1, bottomless=True) |
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357 | 357 | |
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358 |
while not bg_out.done_reading and not bg_out.reading_paused |
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358 | while not bg_out.done_reading and not bg_out.reading_paused: | |
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359 | 359 | # doing this until we reach either end of file, or end of buffer. |
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360 | 360 | bg_out.data_added_event.wait(1) |
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361 | 361 | bg_out.data_added_event.clear() |
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362 | 362 | |
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363 | 363 | # at this point it's still ambiguous if we are done reading or just full buffer. |
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364 | 364 | # Either way, if error (returned by ended process, or implied based on |
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365 | 365 | # presence of stuff in stderr output) we error out. |
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366 | 366 | # Else, we are happy. |
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367 | 367 | _returncode = _p.poll() |
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368 | 368 | if _returncode or (_returncode is None and bg_err.length): |
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369 | 369 | try: |
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370 | 370 | _p.terminate() |
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371 | 371 | except Exception: |
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372 | 372 | pass |
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373 | 373 | bg_out.stop() |
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374 | 374 | out = ''.join(bg_out) |
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375 | 375 | bg_err.stop() |
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376 | 376 | err = ''.join(bg_err) |
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377 | 377 | if (err.strip() == 'fatal: The remote end hung up unexpectedly' and |
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378 | 378 | out.startswith('0034shallow ')): |
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379 | 379 | # hack inspired by https://github.com/schacon/grack/pull/7 |
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380 | 380 | bg_out = iter([out]) |
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381 | 381 | _p = None |
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382 | 382 | elif err: |
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383 | 383 | raise EnvironmentError( |
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384 | 384 | "Subprocess exited due to an error:\n" + err) |
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385 | 385 | else: |
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386 | 386 | raise EnvironmentError( |
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387 | 387 | "Subprocess exited with non 0 ret code:%s" % _returncode) |
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388 | 388 | self.process = _p |
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389 | 389 | self.output = bg_out |
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390 | 390 | self.error = bg_err |
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391 | 391 | self.inputstream = inputstream |
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392 | 392 | |
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393 | 393 | def __iter__(self): |
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394 | 394 | return self |
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395 | 395 | |
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396 | 396 | def next(self): |
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397 | 397 | if self.process and self.process.poll(): |
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398 | 398 | err = ''.join(self.error) |
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399 | 399 | raise EnvironmentError("Subprocess exited due to an error:\n" + err) |
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400 | 400 | return self.output.next() |
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401 | 401 | |
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402 | 402 | def throw(self, type, value=None, traceback=None): |
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403 | 403 | if self.output.length or not self.output.done_reading: |
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404 | 404 | raise type(value) |
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405 | 405 | |
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406 | 406 | def close(self): |
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407 | 407 | try: |
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408 | 408 | self.process.terminate() |
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409 | 409 | except: |
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410 | 410 | pass |
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411 | 411 | try: |
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412 | 412 | self.output.close() |
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413 | 413 | except: |
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414 | 414 | pass |
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415 | 415 | try: |
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416 | 416 | self.error.close() |
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417 | 417 | except: |
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418 | 418 | pass |
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419 | 419 | try: |
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420 | 420 | os.close(self.inputstream) |
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421 | 421 | except: |
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422 | 422 | pass |
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423 | 423 | |
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424 | 424 | def __del__(self): |
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425 | 425 | self.close() |
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