tahoe-lafs/src/allmydata/test/test_runner.py

# -*- coding: utf-8 -*-

from twisted.trial import unittest

from twisted.python import usage, runtime
from twisted.internet import utils
import os.path, re, sys
from cStringIO import StringIO
from allmydata.util import fileutil, pollmixin
from allmydata.scripts import runner

from allmydata.test import common_util
import allmydata

bintahoe = os.path.join(os.path.dirname(os.path.dirname(os.path.dirname(allmydata.__file__))), 'bin', 'tahoe')
if sys.platform == "win32":  # TODO: should this include cygwin?
    bintahoe += ".exe"


class SkipMixin:
    def skip_if_cannot_run_bintahoe(self):
        if "cygwin" in sys.platform.lower():
            raise unittest.SkipTest("We don't know how to make this test work on cygwin: spawnProcess seems to hang forever. We don't know if 'bin/tahoe start' can be run on cygwin.")
        if not os.path.exists(bintahoe):
            raise unittest.SkipTest("The bin/tahoe script isn't to be found in the expected location (%s), and I don't want to test a 'tahoe' executable that I find somewhere else, in case it isn't the right executable for this version of Tahoe. Perhaps running 'setup.py build' again will help." % (bintahoe,))

    def skip_if_cannot_daemonize(self):
        self.skip_if_cannot_run_bintahoe()
        if runtime.platformType == "win32":
            # twistd on windows doesn't daemonize. cygwin should work normally.
            raise unittest.SkipTest("twistd does not fork under windows")


class TheRightCode(common_util.SignalMixin, unittest.TestCase, SkipMixin):
    def test_path(self):
        self.skip_if_cannot_run_bintahoe()
        d = utils.getProcessOutputAndValue(bintahoe, args=["--version-and-path"], env=os.environ)
        def _cb(res):
            out, err, rc_or_sig = res
            self.failUnlessEqual(rc_or_sig, 0)

            # Fail unless the allmydata-tahoe package is *this* version *and*
            # was loaded from *this* source directory.
            ad = os.path.dirname(os.path.dirname(os.path.realpath(allmydata.__file__)))
            required_ver_and_path = "allmydata-tahoe: %s (%s)" % (allmydata.__version__, ad)
            self.failUnless(out.startswith(required_ver_and_path),
                            (out, err, rc_or_sig, required_ver_and_path))
        d.addCallback(_cb)
        return d


class CreateNode(unittest.TestCase):
    # exercise "tahoe create-node", create-introducer,
    # create-key-generator, and create-stats-gatherer, by calling the
    # corresponding code as a subroutine.

    def workdir(self, name):
        basedir = os.path.join("test_runner", "CreateNode", name)
        fileutil.make_dirs(basedir)
        return basedir

    def run_tahoe(self, argv):
        out,err = StringIO(), StringIO()
        rc = runner.runner(argv, stdout=out, stderr=err)
        return rc, out.getvalue(), err.getvalue()

    def do_create(self, command, basedir):
        c1 = os.path.join(basedir, command + "-c1")
        argv = ["--quiet", command, "--basedir", c1]
        rc, out, err = self.run_tahoe(argv)
        self.failUnlessEqual(err, "")
        self.failUnlessEqual(out, "")
        self.failUnlessEqual(rc, 0)
        self.failUnless(os.path.exists(c1))
        self.failUnless(os.path.exists(os.path.join(c1, "tahoe-client.tac")))

        # tahoe.cfg should exist, and should have storage enabled for
        # 'create-node', and disabled for 'create-client'.
        tahoe_cfg = os.path.join(c1, "tahoe.cfg")
        self.failUnless(os.path.exists(tahoe_cfg))
        content = open(tahoe_cfg).read()
        if command == "create-client":
            self.failUnless("\n[storage]\nenabled = false\n" in content)
        else:
            self.failUnless("\n[storage]\nenabled = true\n" in content)

        # creating the client a second time should be rejected
        rc, out, err = self.run_tahoe(argv)
        self.failIfEqual(rc, 0, str((out, err, rc)))
        self.failUnlessEqual(out, "")
        self.failUnless("is not empty." in err)

        # Fail if there is a non-empty line that doesn't end with a
        # punctuation mark.
        for line in err.splitlines():
            self.failIf(re.search("[\S][^\.!?]$", line), (line,))

        # test that the non --basedir form works too
        c2 = os.path.join(basedir, command + "c2")
        argv = ["--quiet", command, c2]
        rc, out, err = self.run_tahoe(argv)
        self.failUnless(os.path.exists(c2))
        self.failUnless(os.path.exists(os.path.join(c2, "tahoe-client.tac")))

        # make sure it rejects too many arguments
        argv = [command, "basedir", "extraarg"]
        self.failUnlessRaises(usage.UsageError,
                              runner.runner, argv,
                              run_by_human=False)

    def test_node(self):
        basedir = self.workdir("test_node")
        self.do_create("create-node", basedir)

    def test_client(self):
        # create-client should behave like create-node --no-storage.
        basedir = self.workdir("test_client")
        self.do_create("create-client", basedir)

    def test_introducer(self):
        basedir = self.workdir("test_introducer")
        c1 = os.path.join(basedir, "c1")
        argv = ["--quiet", "create-introducer", "--basedir", c1]
        rc, out, err = self.run_tahoe(argv)
        self.failUnlessEqual(err, "", err)
        self.failUnlessEqual(out, "")
        self.failUnlessEqual(rc, 0)
        self.failUnless(os.path.exists(c1))
        self.failUnless(os.path.exists(os.path.join(c1,"tahoe-introducer.tac")))

        # creating the introducer a second time should be rejected
        rc, out, err = self.run_tahoe(argv)
        self.failIfEqual(rc, 0)
        self.failUnlessEqual(out, "")
        self.failUnless("is not empty" in err)

        # Fail if there is a non-empty line that doesn't end with a
        # punctuation mark.
        for line in err.splitlines():
            self.failIf(re.search("[\S][^\.!?]$", line), (line,))

        # test the non --basedir form
        c2 = os.path.join(basedir, "c2")
        argv = ["--quiet", "create-introducer", c2]
        rc, out, err = self.run_tahoe(argv)
        self.failUnlessEqual(err, "", err)
        self.failUnlessEqual(out, "")
        self.failUnlessEqual(rc, 0)
        self.failUnless(os.path.exists(c2))
        self.failUnless(os.path.exists(os.path.join(c2,"tahoe-introducer.tac")))

        # reject extra arguments
        argv = ["create-introducer", "basedir", "extraarg"]
        self.failUnlessRaises(usage.UsageError,
                              runner.runner, argv,
                              run_by_human=False)
        # and require basedir to be provided in some form
        argv = ["create-introducer"]
        self.failUnlessRaises(usage.UsageError,
                              runner.runner, argv,
                              run_by_human=False)

    def test_key_generator(self):
        basedir = self.workdir("test_key_generator")
        kg1 = os.path.join(basedir, "kg1")
        argv = ["--quiet", "create-key-generator", "--basedir", kg1]
        rc, out, err = self.run_tahoe(argv)
        self.failUnlessEqual(err, "")
        self.failUnlessEqual(out, "")
        self.failUnlessEqual(rc, 0)
        self.failUnless(os.path.exists(kg1))
        self.failUnless(os.path.exists(os.path.join(kg1, "tahoe-key-generator.tac")))

        # creating it a second time should be rejected
        rc, out, err = self.run_tahoe(argv)
        self.failIfEqual(rc, 0, str((out, err, rc)))
        self.failUnlessEqual(out, "")
        self.failUnless("is not empty." in err)

        # make sure it rejects too many arguments
        argv = ["create-key-generator", "basedir", "extraarg"]
        self.failUnlessRaises(usage.UsageError,
                              runner.runner, argv,
                              run_by_human=False)

        # make sure it rejects a missing basedir specification
        argv = ["create-key-generator"]
        rc, out, err = self.run_tahoe(argv)
        self.failIfEqual(rc, 0, str((out, err, rc)))
        self.failUnlessEqual(out, "")
        self.failUnless("a basedir was not provided" in err)

    def test_stats_gatherer(self):
        basedir = self.workdir("test_stats_gatherer")
        sg1 = os.path.join(basedir, "sg1")
        argv = ["--quiet", "create-stats-gatherer", "--basedir", sg1]
        rc, out, err = self.run_tahoe(argv)
        self.failUnlessEqual(err, "")
        self.failUnlessEqual(out, "")
        self.failUnlessEqual(rc, 0)
        self.failUnless(os.path.exists(sg1))
        self.failUnless(os.path.exists(os.path.join(sg1, "tahoe-stats-gatherer.tac")))

        # creating it a second time should be rejected
        rc, out, err = self.run_tahoe(argv)
        self.failIfEqual(rc, 0, str((out, err, rc)))
        self.failUnlessEqual(out, "")
        self.failUnless("is not empty." in err)

        # test the non --basedir form
        kg2 = os.path.join(basedir, "kg2")
        argv = ["--quiet", "create-stats-gatherer", kg2]
        rc, out, err = self.run_tahoe(argv)
        self.failUnlessEqual(err, "", err)
        self.failUnlessEqual(out, "")
        self.failUnlessEqual(rc, 0)
        self.failUnless(os.path.exists(kg2))
        self.failUnless(os.path.exists(os.path.join(kg2,"tahoe-stats-gatherer.tac")))

        # make sure it rejects too many arguments
        argv = ["create-stats-gatherer", "basedir", "extraarg"]
        self.failUnlessRaises(usage.UsageError,
                              runner.runner, argv,
                              run_by_human=False)

        # make sure it rejects a missing basedir specification
        argv = ["create-stats-gatherer"]
        rc, out, err = self.run_tahoe(argv)
        self.failIfEqual(rc, 0, str((out, err, rc)))
        self.failUnlessEqual(out, "")
        self.failUnless("a basedir was not provided" in err)

    def test_subcommands(self):
        # no arguments should trigger a command listing, via UsageError
        self.failUnlessRaises(usage.UsageError,
                              runner.runner,
                              [],
                              run_by_human=False)


class RunNode(common_util.SignalMixin, unittest.TestCase, pollmixin.PollMixin,
              SkipMixin):
    # exercise "tahoe start", for both introducer, client node, and
    # key-generator, by spawning "tahoe start" as a subprocess. This doesn't
    # get us figleaf-based line-level coverage, but it does a better job of
    # confirming that the user can actually run "./bin/tahoe start" and
    # expect it to work. This verifies that bin/tahoe sets up PYTHONPATH and
    # the like correctly.

    # This doesn't work on cygwin (it hangs forever), so we skip this test
    # when we're on cygwin. It is likely that "tahoe start" itself doesn't
    # work on cygwin: twisted seems unable to provide a version of
    # spawnProcess which really works there.

    def workdir(self, name):
        basedir = os.path.join("test_runner", "RunNode", name)
        fileutil.make_dirs(basedir)
        return basedir

    def test_introducer(self):
        self.skip_if_cannot_daemonize()
        basedir = self.workdir("test_introducer")
        c1 = os.path.join(basedir, "c1")
        HOTLINE_FILE = os.path.join(c1, "suicide_prevention_hotline")
        TWISTD_PID_FILE = os.path.join(c1, "twistd.pid")
        INTRODUCER_FURL_FILE = os.path.join(c1, "introducer.furl")

        d = utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "create-introducer", "--basedir", c1], env=os.environ)
        def _cb(res):
            out, err, rc_or_sig = res
            self.failUnlessEqual(rc_or_sig, 0)
            # by writing this file, we get ten seconds before the node will
            # exit. This insures that even if the test fails (and the 'stop'
            # command doesn't work), the client should still terminate.
            open(HOTLINE_FILE, "w").write("")
            # now it's safe to start the node
        d.addCallback(_cb)

        def _then_start_the_node(res):
            return utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "start", c1], env=os.environ)
        d.addCallback(_then_start_the_node)

        def _cb2(res):
            out, err, rc_or_sig = res

            open(HOTLINE_FILE, "w").write("")
            errstr = "rc=%d, OUT: '%s', ERR: '%s'" % (rc_or_sig, out, err)
            self.failUnlessEqual(rc_or_sig, 0, errstr)
            self.failUnlessEqual(out, "", errstr)
            # self.failUnlessEqual(err, "", errstr) # See test_client_no_noise -- for now we ignore noise.

            # the parent (twistd) has exited. However, twistd writes the pid
            # from the child, not the parent, so we can't expect twistd.pid
            # to exist quite yet.

            # the node is running, but it might not have made it past the
            # first reactor turn yet, and if we kill it too early, it won't
            # remove the twistd.pid file. So wait until it does something
            # that we know it won't do until after the first turn.
        d.addCallback(_cb2)

        def _node_has_started():
            return os.path.exists(INTRODUCER_FURL_FILE)
        d.addCallback(lambda res: self.poll(_node_has_started))

        def _started(res):
            open(HOTLINE_FILE, "w").write("")
            self.failUnless(os.path.exists(TWISTD_PID_FILE))
            # rm this so we can detect when the second incarnation is ready
            os.unlink(INTRODUCER_FURL_FILE)
            return utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "restart", c1], env=os.environ)
        d.addCallback(_started)

        def _then(res):
            out, err, rc_or_sig = res
            open(HOTLINE_FILE, "w").write("")
            errstr = "rc=%d, OUT: '%s', ERR: '%s'" % (rc_or_sig, out, err)
            self.failUnlessEqual(rc_or_sig, 0, errstr)
            self.failUnlessEqual(out, "", errstr)
            # self.failUnlessEqual(err, "", errstr) # See test_client_no_noise -- for now we ignore noise.
        d.addCallback(_then)

        # again, the second incarnation of the node might not be ready yet,
        # so poll until it is
        d.addCallback(lambda res: self.poll(_node_has_started))

        # now we can kill it. TODO: On a slow machine, the node might kill
        # itself before we get a chance too, especially if spawning the
        # 'tahoe stop' command takes a while.
        def _stop(res):
            open(HOTLINE_FILE, "w").write("")
            self.failUnless(os.path.exists(TWISTD_PID_FILE))

            return utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "stop", c1], env=os.environ)
        d.addCallback(_stop)

        def _after_stopping(res):
            out, err, rc_or_sig = res
            open(HOTLINE_FILE, "w").write("")
            # the parent has exited by now
            errstr = "rc=%d, OUT: '%s', ERR: '%s'" % (rc_or_sig, out, err)
            self.failUnlessEqual(rc_or_sig, 0, errstr)
            self.failUnlessEqual(out, "", errstr)
            # self.failUnlessEqual(err, "", errstr) # See test_client_no_noise -- for now we ignore noise.
            # the parent was supposed to poll and wait until it sees
            # twistd.pid go away before it exits, so twistd.pid should be
            # gone by now.
            self.failIf(os.path.exists(TWISTD_PID_FILE))
        d.addCallback(_after_stopping)

        def _remove_hotline(res):
            os.unlink(HOTLINE_FILE)
            return res
        d.addBoth(_remove_hotline)
        return d
    test_introducer.timeout = 480 # This hit the 120-second timeout on "François Lenny-armv5tel", then it hit a 240-second timeout on our feisty2.5 buildslave: http://allmydata.org/buildbot/builders/feisty2.5/builds/2381/steps/test/logs/test.log

    def test_client(self):
        self.skip_if_cannot_daemonize()
        basedir = self.workdir("test_client")
        c1 = os.path.join(basedir, "c1")
        HOTLINE_FILE = os.path.join(c1, "suicide_prevention_hotline")
        TWISTD_PID_FILE = os.path.join(c1, "twistd.pid")
        PORTNUMFILE = os.path.join(c1, "client.port")

        d = utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "create-node", "--basedir", c1, "--webport", "0"], env=os.environ)
        def _cb(res):
            out, err, rc_or_sig = res
            self.failUnlessEqual(rc_or_sig, 0)
            # By writing this file, we get sixty seconds before the client will exit. This insures
            # that even if the 'stop' command doesn't work (and the test fails), the client should
            # still terminate.
            open(HOTLINE_FILE, "w").write("")
            open(os.path.join(c1, "introducer.furl"), "w").write("pb://xrndsskn2zuuian5ltnxrte7lnuqdrkz@127.0.0.1:55617/introducer\n")
            # now it's safe to start the node
        d.addCallback(_cb)

        def _start(res):
            return utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "start", c1], env=os.environ)
        d.addCallback(_start)

        def _cb2(res):
            out, err, rc_or_sig = res
            open(HOTLINE_FILE, "w").write("")
            errstr = "rc=%d, OUT: '%s', ERR: '%s'" % (rc_or_sig, out, err)
            self.failUnlessEqual(rc_or_sig, 0, errstr)
            self.failUnlessEqual(out, "", errstr)
            # self.failUnlessEqual(err, "", errstr) # See test_client_no_noise -- for now we ignore noise.

            # the parent (twistd) has exited. However, twistd writes the pid
            # from the child, not the parent, so we can't expect twistd.pid
            # to exist quite yet.

            # the node is running, but it might not have made it past the
            # first reactor turn yet, and if we kill it too early, it won't
            # remove the twistd.pid file. So wait until it does something
            # that we know it won't do until after the first turn.
        d.addCallback(_cb2)

        def _node_has_started():
            return os.path.exists(PORTNUMFILE)
        d.addCallback(lambda res: self.poll(_node_has_started))

        def _started(res):
            open(HOTLINE_FILE, "w").write("")
            self.failUnless(os.path.exists(TWISTD_PID_FILE))
            # rm this so we can detect when the second incarnation is ready
            os.unlink(PORTNUMFILE)

            return utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "restart", c1], env=os.environ)
        d.addCallback(_started)

        def _cb3(res):
            out, err, rc_or_sig = res

            open(HOTLINE_FILE, "w").write("")
            errstr = "rc=%d, OUT: '%s', ERR: '%s'" % (rc_or_sig, out, err)
            self.failUnlessEqual(rc_or_sig, 0, errstr)
            self.failUnlessEqual(out, "", errstr)
            # self.failUnlessEqual(err, "", errstr) # See test_client_no_noise -- for now we ignore noise.
        d.addCallback(_cb3)

        # again, the second incarnation of the node might not be ready yet,
        # so poll until it is
        d.addCallback(lambda res: self.poll(_node_has_started))

        # now we can kill it. TODO: On a slow machine, the node might kill
        # itself before we get a chance too, especially if spawning the
        # 'tahoe stop' command takes a while.
        def _stop(res):
            open(HOTLINE_FILE, "w").write("")
            self.failUnless(os.path.exists(TWISTD_PID_FILE), (TWISTD_PID_FILE, os.listdir(os.path.dirname(TWISTD_PID_FILE))))
            return utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "stop", c1], env=os.environ)
        d.addCallback(_stop)

        def _cb4(res):
            out, err, rc_or_sig = res

            open(HOTLINE_FILE, "w").write("")
            # the parent has exited by now
            errstr = "rc=%d, OUT: '%s', ERR: '%s'" % (rc_or_sig, out, err)
            self.failUnlessEqual(rc_or_sig, 0, errstr)
            self.failUnlessEqual(out, "", errstr)
            # self.failUnlessEqual(err, "", errstr) # See test_client_no_noise -- for now we ignore noise.
            # the parent was supposed to poll and wait until it sees
            # twistd.pid go away before it exits, so twistd.pid should be
            # gone by now.
            self.failIf(os.path.exists(TWISTD_PID_FILE))
        d.addCallback(_cb4)
        def _remove_hotline(res):
            os.unlink(HOTLINE_FILE)
            return res
        d.addBoth(_remove_hotline)
        return d

    def test_baddir(self):
        self.skip_if_cannot_daemonize()
        basedir = self.workdir("test_baddir")
        fileutil.make_dirs(basedir)

        d = utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "start", "--basedir", basedir], env=os.environ)
        def _cb(res):
            out, err, rc_or_sig = res
            self.failUnlessEqual(rc_or_sig, 1)
            self.failUnless("does not look like a node directory" in err)
        d.addCallback(_cb)

        def _then_stop_it(res):
            return utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "stop", "--basedir", basedir], env=os.environ)
        d.addCallback(_then_stop_it)

        def _cb2(res):
            out, err, rc_or_sig = res
            self.failUnlessEqual(rc_or_sig, 2)
            self.failUnless("does not look like a running node directory" in err)
        d.addCallback(_cb2)

        def _then_start_in_bogus_basedir(res):
            not_a_dir = os.path.join(basedir, "bogus")
            return utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "start", "--basedir", not_a_dir], env=os.environ)
        d.addCallback(_then_start_in_bogus_basedir)

        def _cb3(res):
            out, err, rc_or_sig = res
            self.failUnlessEqual(rc_or_sig, 1)
            self.failUnless("does not look like a directory at all" in err, err)
        d.addCallback(_cb3)
        return d

    def test_keygen(self):
        self.skip_if_cannot_daemonize()
        basedir = self.workdir("test_keygen")
        c1 = os.path.join(basedir, "c1")
        TWISTD_PID_FILE = os.path.join(c1, "twistd.pid")
        KEYGEN_FURL_FILE = os.path.join(c1, "key_generator.furl")

        d = utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "create-key-generator", "--basedir", c1], env=os.environ)
        def _cb(res):
            out, err, rc_or_sig = res
            self.failUnlessEqual(rc_or_sig, 0)
        d.addCallback(_cb)

        def _start(res):
            return utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "start", c1], env=os.environ)
        d.addCallback(_start)

        def _cb2(res):
            out, err, rc_or_sig = res
            errstr = "rc=%d, OUT: '%s', ERR: '%s'" % (rc_or_sig, out, err)
            self.failUnlessEqual(rc_or_sig, 0, errstr)
            self.failUnlessEqual(out, "", errstr)
            # self.failUnlessEqual(err, "", errstr) # See test_client_no_noise -- for now we ignore noise.

            # the parent (twistd) has exited. However, twistd writes the pid
            # from the child, not the parent, so we can't expect twistd.pid
            # to exist quite yet.

            # the node is running, but it might not have made it past the
            # first reactor turn yet, and if we kill it too early, it won't
            # remove the twistd.pid file. So wait until it does something
            # that we know it won't do until after the first turn.
        d.addCallback(_cb2)

        def _node_has_started():
            return os.path.exists(KEYGEN_FURL_FILE)
        d.addCallback(lambda res: self.poll(_node_has_started))

        def _started(res):
            self.failUnless(os.path.exists(TWISTD_PID_FILE))
            # rm this so we can detect when the second incarnation is ready
            os.unlink(KEYGEN_FURL_FILE)
            return utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "restart", c1], env=os.environ)
        d.addCallback(_started)

        def _cb3(res):
            out, err, rc_or_sig = res
            errstr = "rc=%d, OUT: '%s', ERR: '%s'" % (rc_or_sig, out, err)
            self.failUnlessEqual(rc_or_sig, 0, errstr)
            self.failUnlessEqual(out, "", errstr)
            # self.failUnlessEqual(err, "", errstr) # See test_client_no_noise -- for now we ignore noise.
        d.addCallback(_cb3)

        # again, the second incarnation of the node might not be ready yet,
        # so poll until it is
        d.addCallback(lambda res: self.poll(_node_has_started))

        # now we can kill it. TODO: On a slow machine, the node might kill
        # itself before we get a chance too, especially if spawning the
        # 'tahoe stop' command takes a while.
        def _stop(res):
            self.failUnless(os.path.exists(TWISTD_PID_FILE))
            return utils.getProcessOutputAndValue(bintahoe, args=["--quiet", "stop", c1], env=os.environ)
        d.addCallback(_stop)

        def _cb4(res):
            out, err, rc_or_sig = res
            # the parent has exited by now
            errstr = "rc=%d, OUT: '%s', ERR: '%s'" % (rc_or_sig, out, err)
            self.failUnlessEqual(rc_or_sig, 0, errstr)
            self.failUnlessEqual(out, "", errstr)
            # self.failUnlessEqual(err, "", errstr) # See test_client_no_noise -- for now we ignore noise.
            # the parent was supposed to poll and wait until it sees
            # twistd.pid go away before it exits, so twistd.pid should be
            # gone by now.
            self.failIf(os.path.exists(TWISTD_PID_FILE))
        d.addCallback(_cb4)
        return d