1 files changed, 116 insertions, 0 deletions
diff --git a/buildbot/buildbot/changes/maildir.py b/buildbot/buildbot/changes/maildir.py
new file mode 100644
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+++ b/buildbot/buildbot/changes/maildir.py
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+
+# This is a class which watches a maildir for new messages. It uses the
+# linux dirwatcher API (if available) to look for new files. The
+# .messageReceived method is invoked with the filename of the new message,
+# relative to the top of the maildir (so it will look like "new/blahblah").
+
+import os
+from twisted.python import log
+from twisted.application import service, internet
+from twisted.internet import reactor
+dnotify = None
+try:
+    import dnotify
+except:
+    # I'm not actually sure this log message gets recorded
+    log.msg("unable to import dnotify, so Maildir will use polling instead")
+
+class NoSuchMaildir(Exception):
+    pass
+
+class MaildirService(service.MultiService):
+    """I watch a maildir for new messages. I should be placed as the service
+    child of some MultiService instance. When running, I use the linux
+    dirwatcher API (if available) or poll for new files in the 'new'
+    subdirectory of my maildir path. When I discover a new message, I invoke
+    my .messageReceived() method with the short filename of the new message,
+    so the full name of the new file can be obtained with
+    os.path.join(maildir, 'new', filename). messageReceived() should be
+    overridden by a subclass to do something useful. I will not move or
+    delete the file on my own: the subclass's messageReceived() should
+    probably do that.
+    """
+    pollinterval = 10  # only used if we don't have DNotify
+
+    def __init__(self, basedir=None):
+        """Create the Maildir watcher. BASEDIR is the maildir directory (the
+        one which contains new/ and tmp/)
+        """
+        service.MultiService.__init__(self)
+        self.basedir = basedir
+        self.files = []
+        self.dnotify = None
+
+    def setBasedir(self, basedir):
+        # some users of MaildirService (scheduler.Try_Jobdir, in particular)
+        # don't know their basedir until setServiceParent, since it is
+        # relative to the buildmaster's basedir. So let them set it late. We
+        # don't actually need it until our own startService.
+        self.basedir = basedir
+
+    def startService(self):
+        service.MultiService.startService(self)
+        self.newdir = os.path.join(self.basedir, "new")
+        if not os.path.isdir(self.basedir) or not os.path.isdir(self.newdir):
+            raise NoSuchMaildir("invalid maildir '%s'" % self.basedir)
+        try:
+            if dnotify:
+                # we must hold an fd open on the directory, so we can get
+                # notified when it changes.
+                self.dnotify = dnotify.DNotify(self.newdir,
+                                               self.dnotify_callback,
+                                               [dnotify.DNotify.DN_CREATE])
+        except (IOError, OverflowError):
+            # IOError is probably linux<2.4.19, which doesn't support
+            # dnotify. OverflowError will occur on some 64-bit machines
+            # because of a python bug
+            log.msg("DNotify failed, falling back to polling")
+        if not self.dnotify:
+            t = internet.TimerService(self.pollinterval, self.poll)
+            t.setServiceParent(self)
+        self.poll()
+
+    def dnotify_callback(self):
+        log.msg("dnotify noticed something, now polling")
+
+        # give it a moment. I found that qmail had problems when the message
+        # was removed from the maildir instantly. It shouldn't, that's what
+        # maildirs are made for. I wasn't able to eyeball any reason for the
+        # problem, and safecat didn't behave the same way, but qmail reports
+        # "Temporary_error_on_maildir_delivery" (qmail-local.c:165,
+        # maildir_child() process exited with rc not in 0,2,3,4). Not sure
+        # why, and I'd have to hack qmail to investigate further, so it's
+        # easier to just wait a second before yanking the message out of new/
+
+        reactor.callLater(0.1, self.poll)
+
+
+    def stopService(self):
+        if self.dnotify:
+            self.dnotify.remove()
+            self.dnotify = None
+        return service.MultiService.stopService(self)
+
+    def poll(self):
+        assert self.basedir
+        # see what's new
+        for f in self.files:
+            if not os.path.isfile(os.path.join(self.newdir, f)):
+                self.files.remove(f)
+        newfiles = []
+        for f in os.listdir(self.newdir):
+            if not f in self.files:
+                newfiles.append(f)
+        self.files.extend(newfiles)
+        # TODO: sort by ctime, then filename, since safecat uses a rather
+        # fine-grained timestamp in the filename
+        for n in newfiles:
+            # TODO: consider catching exceptions in messageReceived
+            self.messageReceived(n)
+
+    def messageReceived(self, filename):
+        """Called when a new file is noticed. Will call
+        self.parent.messageReceived() with a path relative to maildir/new.
+        Should probably be overridden in subclasses."""
+        self.parent.messageReceived(filename)
+