mitogen/tests/fork_test.py

import ctypes
import os
import random
import ssl
import struct
import sys

import mitogen
import unittest2

import testlib
import plain_old_module


IS_64BIT = struct.calcsize('P') == 8
PLATFORM_TO_PATH = {
    ('darwin', False): '/usr/lib/libssl.dylib',
    ('darwin', True): '/usr/lib/libssl.dylib',
    ('linux2', False): '/usr/lib/libssl.so',
    ('linux2', True): '/usr/lib/x86_64-linux-gnu/libssl.so',
}

c_ssl = ctypes.CDLL(PLATFORM_TO_PATH[sys.platform, IS_64BIT])
c_ssl.RAND_pseudo_bytes.argtypes = [ctypes.c_char_p, ctypes.c_int]
c_ssl.RAND_pseudo_bytes.restype = ctypes.c_int


def ping():
    return 123


def random_random():
    return random.random()


def RAND_pseudo_bytes(n=32):
    buf = ctypes.create_string_buffer(n)
    assert 1 == c_ssl.RAND_pseudo_bytes(buf, n)
    return buf[:]


def exercise_importer(n):
    """
    Ensure the forked child has a sensible importer.
    """
    sys.path.remove(testlib.DATA_DIR)
    import simple_pkg.a
    return simple_pkg.a.subtract_one_add_two(n)


class ForkTest(testlib.RouterMixin, unittest2.TestCase):
    def test_okay(self):
        context = self.router.fork()
        self.assertNotEqual(context.call(os.getpid), os.getpid())
        self.assertEqual(context.call(os.getppid), os.getpid())

    def test_random_module_diverges(self):
        context = self.router.fork()
        self.assertNotEqual(context.call(random_random), random_random())

    def test_ssl_module_diverges(self):
        # Ensure generator state is initialized.
        RAND_pseudo_bytes()
        context = self.router.fork()
        self.assertNotEqual(context.call(RAND_pseudo_bytes),
                            RAND_pseudo_bytes())

    def test_importer(self):
        context = self.router.fork()
        self.assertEqual(2, context.call(exercise_importer, 1))


class DoubleChildTest(testlib.RouterMixin, unittest2.TestCase):
    def test_okay(self):
        # When forking from the master process, Mitogen had nothing to do with
        # setting up stdio -- that was inherited wherever the Master is running
        # (supervisor, iTerm, etc). When forking from a Mitogen child context
        # however, Mitogen owns all of fd 0, 1, and 2, and during the fork
        # procedure, it deletes all of these descriptors. That leaves the
        # process in a weird state that must be handled by some combination of
        # fork.py and ExternalContext.main().

        # Below we simply test whether ExternalContext.main() managed to boot
        # successfully. In future, we need lots more tests.
        c1 = self.router.fork()
        c2 = self.router.fork(via=c1)
        self.assertEquals(123, c2.call(ping))

    def test_importer(self):
        c1 = self.router.fork(name='c1')
        c2 = self.router.fork(name='c2', via=c1)
        self.assertEqual(2, c2.call(exercise_importer, 1))


if __name__ == '__main__':
    unittest2.main()