buildbot/changes/maildir.py

   1 #! /usr/bin/python
   2
   3 # This is a class which watches a maildir for new messages. It uses the
   4 # linux dirwatcher API (if available) to look for new files. The
   5 # .messageReceived method is invoked with the filename of the new message,
   6 # relative to the 'new' directory of the maildir.
   7
   8 # this is an abstract base class. It must be subclassed by something to
   9 # provide a delay function (which polls in the case that DNotify isn't
  10 # available) and a way to safely schedule code to run after a signal handler
  11 # has fired. See maildirgtk.py and maildirtwisted.py for forms that use the
  12 # event loops provided by Gtk+ and Twisted.
  13
  14 try:
  15     from dnotify import DNotify
  16     have_dnotify = 1
  17 except:
  18     have_dnotify = 0
  19 import os
  20
  21 class Maildir:
  22     """This is a class which watches a maildir for new messages. Once
  23     started, it will run its .messageReceived method when a message is
  24     available.
  25     """
  26     def __init__(self, basedir=None):
  27         """Create the Maildir watcher. BASEDIR is the maildir directory (the
  28         one which contains new/ and tmp/)
  29         """
  30         self.basedir = basedir
  31         self.files = []
  32         self.pollinterval = 10  # only used if we don't have DNotify
  33         self.running = 0
  34         self.dnotify = None
  35
  36     def setBasedir(self, basedir):
  37         self.basedir = basedir
  38
  39     def start(self):
  40         """You must run start to receive any messages."""
  41         assert self.basedir
  42         self.newdir = os.path.join(self.basedir, "new")
  43         if self.running:
  44             return
  45         self.running = 1
  46         if not os.path.isdir(self.basedir) or not os.path.isdir(self.newdir):
  47             raise "invalid maildir '%s'" % self.basedir
  48         # we must hold an fd open on the directory, so we can get notified
  49         # when it changes.
  50         global have_dnotify
  51         if have_dnotify:
  52             try:
  53                 self.dnotify = DNotify(self.newdir, self.dnotify_callback,
  54                                        [DNotify.DN_CREATE])
  55             except (IOError, OverflowError):
  56                 # IOError is probably linux<2.4.19, which doesn't support
  57                 # dnotify. OverflowError will occur on some 64-bit machines
  58                 # because of a python bug
  59                 print "DNotify failed, falling back to polling"
  60                 have_dnotify = 0
  61
  62         self.poll()
  63
  64     def startTimeout(self):
  65         raise NotImplemented
  66     def stopTimeout(self):
  67         raise NotImplemented
  68     def dnotify_callback(self):
  69         print "callback"
  70         self.poll()
  71         raise NotImplemented
  72
  73     def stop(self):
  74         if self.dnotify:
  75             self.dnotify.remove()
  76             self.dnotify = None
  77         else:
  78             self.stopTimeout()
  79         self.running = 0
  80
  81     def poll(self):
  82         assert self.basedir
  83         # see what's new
  84         for f in self.files:
  85             if not os.path.isfile(os.path.join(self.newdir, f)):
  86                 self.files.remove(f)
  87         newfiles = []
  88         for f in os.listdir(self.newdir):
  89             if not f in self.files:
  90                 newfiles.append(f)
  91         self.files.extend(newfiles)
  92         # TODO: sort by ctime, then filename, since safecat uses a rather
  93         # fine-grained timestamp in the filename
  94         for n in newfiles:
  95             # TODO: consider catching exceptions in messageReceived
  96             self.messageReceived(n)
  97         if not have_dnotify:
  98             self.startTimeout()
  99
 100     def messageReceived(self, filename):
 101         """Called when a new file is noticed. Override it in subclasses.
 102         Will receive path relative to maildir/new."""
 103         print filename
 104
 105
 106 def test1():
 107     m = Maildir("ddir")
 108     m.start()
 109     import signal
 110     while 1:
 111         signal.pause()
 112
 113 if __name__ == '__main__':
 114     test1()
 115