Source Code for Module buildbot.monkeypatches.bug4881

  1  # coding=utf-8 
  2  # This file is part of Buildbot.  Buildbot is free software: you can 
  3  # redistribute it and/or modify it under the terms of the GNU General Public 
  4  # License as published by the Free Software Foundation, version 2. 
  5  # 
  6  # This program is distributed in the hope that it will be useful, but WITHOUT 
  7  # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 
  8  # FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more 
  9  # details. 
 10  # 
 11  # You should have received a copy of the GNU General Public License along with 
 12  # this program; if not, write to the Free Software Foundation, Inc., 51 
 13  # Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. 
 14  # 
 15  # Copyright Buildbot Team Members 
 16   
 17  import os 
 18  from twisted.internet import process 
 19  from twisted.python import log 
 20   
 21 -def patch(): 
 22      log.msg("Applying patch for http://twistedmatrix.com/trac/ticket/4881") 
 23      process._listOpenFDs = _listOpenFDs 
 24   
 25  ############################################################################# 
 26  # Everything below this line was taken verbatim from Twisted, except as 
 27  # annotated. 
 28   
 29  ######## 
 30  # r31474:trunk/LICENSE 
 31   
 32  # Copyright (c) 2001-2010 
 33  # Allen Short 
 34  # Andy Gayton 
 35  # Andrew Bennetts 
 36  # Antoine Pitrou 
 37  # Apple Computer, Inc. 
 38  # Benjamin Bruheim 
 39  # Bob Ippolito 
 40  # Canonical Limited 
 41  # Christopher Armstrong 
 42  # David Reid 
 43  # Donovan Preston 
 44  # Eric Mangold 
 45  # Eyal Lotem 
 46  # Itamar Shtull-Trauring 
 47  # James Knight 
 48  # Jason A. Mobarak 
 49  # Jean-Paul Calderone 
 50  # Jessica McKellar 
 51  # Jonathan Jacobs 
 52  # Jonathan Lange 
 53  # Jonathan D. Simms 
 54  # Jürgen Hermann 
 55  # Kevin Horn 
 56  # Kevin Turner 
 57  # Mary Gardiner 
 58  # Matthew Lefkowitz 
 59  # Massachusetts Institute of Technology 
 60  # Moshe Zadka 
 61  # Paul Swartz 
 62  # Pavel Pergamenshchik 
 63  # Ralph Meijer 
 64  # Sean Riley 
 65  # Software Freedom Conservancy 
 66  # Travis B. Hartwell 
 67  # Thijs Triemstra 
 68  # Thomas Herve 
 69  # Timothy Allen 
 70  #  
 71  # Permission is hereby granted, free of charge, to any person obtaining 
 72  # a copy of this software and associated documentation files (the 
 73  # "Software"), to deal in the Software without restriction, including 
 74  # without limitation the rights to use, copy, modify, merge, publish, 
 75  # distribute, sublicense, and/or sell copies of the Software, and to 
 76  # permit persons to whom the Software is furnished to do so, subject to 
 77  # the following conditions: 
 78  #  
 79  #     The above copyright notice and this permission notice shall be 
 80  #     included in all copies or substantial portions of the Software. 
 81  #  
 82  #     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 
 83  #     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 
 84  #     MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 
 85  #     NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE 
 86  #     LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 
 87  #     OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION 
 88  #     WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 
 89   
 90  ######## 
 91  # r31474:trunk/twisted/internet/process.py 
 92   
 93  # Copyright (c) Twisted Matrix Laboratories. 
 94  # See LICENSE for details. 
 95   
 96 -class _FDDetector(object): 
 97      """ 
 98      This class contains the logic necessary to decide which of the available 
 99      system techniques should be used to detect the open file descriptors for 
100      the current process. The chosen technique gets monkey-patched into the 
101      _listOpenFDs method of this class so that the detection only needs to occur 
102      once. 
103   
104      @ivars listdir: The implementation of listdir to use. This gets overwritten 
105          by the test cases. 
106      @ivars getpid: The implementation of getpid to use, returns the PID of the 
107          running process. 
108      @ivars openfile: The implementation of open() to use, by default the Python 
109          builtin. 
110      """ 
111      # So that we can unit test this 
112      listdir = os.listdir 
113      getpid = os.getpid 
114      openfile = open 
115   
116   
117 -    def _listOpenFDs(self): 
118          """ 
119          Figure out which implementation to use, then run it. 
120          """ 
121          self._listOpenFDs = self._getImplementation() 
122          return self._listOpenFDs() 
123   
124   
125 -    def _getImplementation(self): 
126          """ 
127          Check if /dev/fd works, if so, use that.  Otherwise, check if 
128          /proc/%d/fd exists, if so use that. 
129           
130          Otherwise, ask resource.getrlimit, if that throws an exception, then 
131          fallback to _fallbackFDImplementation. 
132          """ 
133          try: 
134              self.listdir("/dev/fd") 
135              if self._checkDevFDSanity(): # FreeBSD support :-) 
136                  return self._devFDImplementation 
137              else: 
138                  return self._fallbackFDImplementation 
139          except: 
140              try: 
141                  self.listdir("/proc/%d/fd" % (self.getpid(),)) 
142                  return self._procFDImplementation 
143              except: 
144                  try: 
145                      self._resourceFDImplementation() # Imports resource 
146                      return self._resourceFDImplementation 
147                  except: 
148                      return self._fallbackFDImplementation 
149   
150   
151 -    def _checkDevFDSanity(self): 
152          """ 
153          Returns true iff opening a file modifies the fds visible 
154          in /dev/fd, as it should on a sane platform. 
155          """ 
156          start = self.listdir("/dev/fd") 
157          self.openfile("/dev/null", "r") # changed in Buildbot to hush pyflakes 
158          end = self.listdir("/dev/fd") 
159          return start != end 
160   
161   
162 -    def _devFDImplementation(self): 
163          """ 
164          Simple implementation for systems where /dev/fd actually works. 
165          See: http://www.freebsd.org/cgi/man.cgi?fdescfs 
166          """ 
167          dname = "/dev/fd" 
168          result = [int(fd) for fd in os.listdir(dname)] 
169          return result 
170   
171   
172 -    def _procFDImplementation(self): 
173          """ 
174          Simple implementation for systems where /proc/pid/fd exists (we assume 
175          it works). 
176          """ 
177          dname = "/proc/%d/fd" % (os.getpid(),) 
178          return [int(fd) for fd in os.listdir(dname)] 
179   
180   
181 -    def _resourceFDImplementation(self): 
182          """ 
183          Fallback implementation where the resource module can inform us about 
184          how many FDs we can expect. 
185   
186          Note that on OS-X we expect to be using the /dev/fd implementation. 
187          """ 
188          import resource 
189          maxfds = resource.getrlimit(resource.RLIMIT_NOFILE)[1] + 1 
190          # OS-X reports 9223372036854775808. That's a lot of fds 
191          # to close 
192          if maxfds > 1024: 
193              maxfds = 1024 
194          return xrange(maxfds) 
195   
196   
197 -    def _fallbackFDImplementation(self): 
198          """ 
199          Fallback-fallback implementation where we just assume that we need to 
200          close 256 FDs. 
201          """ 
202          maxfds = 256 
203          return xrange(maxfds) 
204   
205   
206  detector = _FDDetector() 
207   
208 -def _listOpenFDs(): 
209      """ 
210      Use the global detector object to figure out which FD implementation to 
211      use. 
212      """ 
213      return detector._listOpenFDs() 
214