EmbeddedPkg: Extend NvVarStoreFormattedLib LIBRARY_CLASS

[mirror_edk2.git] / AppPkg / Applications / Python / Python-2.7.2 / Lib / test / test_gc.py

import unittest\r
from test.test_support import verbose, run_unittest\r
import sys\r
import gc\r
import weakref\r
\r
### Support code\r
###############################################################################\r
\r
# Bug 1055820 has several tests of longstanding bugs involving weakrefs and\r
# cyclic gc.\r
\r
# An instance of C1055820 has a self-loop, so becomes cyclic trash when\r
# unreachable.\r
class C1055820(object):\r
    def __init__(self, i):\r
        self.i = i\r
        self.loop = self\r
\r
class GC_Detector(object):\r
    # Create an instance I.  Then gc hasn't happened again so long as\r
    # I.gc_happened is false.\r
\r
    def __init__(self):\r
        self.gc_happened = False\r
\r
        def it_happened(ignored):\r
            self.gc_happened = True\r
\r
        # Create a piece of cyclic trash that triggers it_happened when\r
        # gc collects it.\r
        self.wr = weakref.ref(C1055820(666), it_happened)\r
\r
\r
### Tests\r
###############################################################################\r
\r
class GCTests(unittest.TestCase):\r
    def test_list(self):\r
        l = []\r
        l.append(l)\r
        gc.collect()\r
        del l\r
        self.assertEqual(gc.collect(), 1)\r
\r
    def test_dict(self):\r
        d = {}\r
        d[1] = d\r
        gc.collect()\r
        del d\r
        self.assertEqual(gc.collect(), 1)\r
\r
    def test_tuple(self):\r
        # since tuples are immutable we close the loop with a list\r
        l = []\r
        t = (l,)\r
        l.append(t)\r
        gc.collect()\r
        del t\r
        del l\r
        self.assertEqual(gc.collect(), 2)\r
\r
    def test_class(self):\r
        class A:\r
            pass\r
        A.a = A\r
        gc.collect()\r
        del A\r
        self.assertNotEqual(gc.collect(), 0)\r
\r
    def test_newstyleclass(self):\r
        class A(object):\r
            pass\r
        gc.collect()\r
        del A\r
        self.assertNotEqual(gc.collect(), 0)\r
\r
    def test_instance(self):\r
        class A:\r
            pass\r
        a = A()\r
        a.a = a\r
        gc.collect()\r
        del a\r
        self.assertNotEqual(gc.collect(), 0)\r
\r
    def test_newinstance(self):\r
        class A(object):\r
            pass\r
        a = A()\r
        a.a = a\r
        gc.collect()\r
        del a\r
        self.assertNotEqual(gc.collect(), 0)\r
        class B(list):\r
            pass\r
        class C(B, A):\r
            pass\r
        a = C()\r
        a.a = a\r
        gc.collect()\r
        del a\r
        self.assertNotEqual(gc.collect(), 0)\r
        del B, C\r
        self.assertNotEqual(gc.collect(), 0)\r
        A.a = A()\r
        del A\r
        self.assertNotEqual(gc.collect(), 0)\r
        self.assertEqual(gc.collect(), 0)\r
\r
    def test_method(self):\r
        # Tricky: self.__init__ is a bound method, it references the instance.\r
        class A:\r
            def __init__(self):\r
                self.init = self.__init__\r
        a = A()\r
        gc.collect()\r
        del a\r
        self.assertNotEqual(gc.collect(), 0)\r
\r
    def test_finalizer(self):\r
        # A() is uncollectable if it is part of a cycle, make sure it shows up\r
        # in gc.garbage.\r
        class A:\r
            def __del__(self): pass\r
        class B:\r
            pass\r
        a = A()\r
        a.a = a\r
        id_a = id(a)\r
        b = B()\r
        b.b = b\r
        gc.collect()\r
        del a\r
        del b\r
        self.assertNotEqual(gc.collect(), 0)\r
        for obj in gc.garbage:\r
            if id(obj) == id_a:\r
                del obj.a\r
                break\r
        else:\r
            self.fail("didn't find obj in garbage (finalizer)")\r
        gc.garbage.remove(obj)\r
\r
    def test_finalizer_newclass(self):\r
        # A() is uncollectable if it is part of a cycle, make sure it shows up\r
        # in gc.garbage.\r
        class A(object):\r
            def __del__(self): pass\r
        class B(object):\r
            pass\r
        a = A()\r
        a.a = a\r
        id_a = id(a)\r
        b = B()\r
        b.b = b\r
        gc.collect()\r
        del a\r
        del b\r
        self.assertNotEqual(gc.collect(), 0)\r
        for obj in gc.garbage:\r
            if id(obj) == id_a:\r
                del obj.a\r
                break\r
        else:\r
            self.fail("didn't find obj in garbage (finalizer)")\r
        gc.garbage.remove(obj)\r
\r
    def test_function(self):\r
        # Tricky: f -> d -> f, code should call d.clear() after the exec to\r
        # break the cycle.\r
        d = {}\r
        exec("def f(): pass\n") in d\r
        gc.collect()\r
        del d\r
        self.assertEqual(gc.collect(), 2)\r
\r
    def test_frame(self):\r
        def f():\r
            frame = sys._getframe()\r
        gc.collect()\r
        f()\r
        self.assertEqual(gc.collect(), 1)\r
\r
    def test_saveall(self):\r
        # Verify that cyclic garbage like lists show up in gc.garbage if the\r
        # SAVEALL option is enabled.\r
\r
        # First make sure we don't save away other stuff that just happens to\r
        # be waiting for collection.\r
        gc.collect()\r
        # if this fails, someone else created immortal trash\r
        self.assertEqual(gc.garbage, [])\r
\r
        L = []\r
        L.append(L)\r
        id_L = id(L)\r
\r
        debug = gc.get_debug()\r
        gc.set_debug(debug | gc.DEBUG_SAVEALL)\r
        del L\r
        gc.collect()\r
        gc.set_debug(debug)\r
\r
        self.assertEqual(len(gc.garbage), 1)\r
        obj = gc.garbage.pop()\r
        self.assertEqual(id(obj), id_L)\r
\r
    def test_del(self):\r
        # __del__ methods can trigger collection, make this to happen\r
        thresholds = gc.get_threshold()\r
        gc.enable()\r
        gc.set_threshold(1)\r
\r
        class A:\r
            def __del__(self):\r
                dir(self)\r
        a = A()\r
        del a\r
\r
        gc.disable()\r
        gc.set_threshold(*thresholds)\r
\r
    def test_del_newclass(self):\r
        # __del__ methods can trigger collection, make this to happen\r
        thresholds = gc.get_threshold()\r
        gc.enable()\r
        gc.set_threshold(1)\r
\r
        class A(object):\r
            def __del__(self):\r
                dir(self)\r
        a = A()\r
        del a\r
\r
        gc.disable()\r
        gc.set_threshold(*thresholds)\r
\r
    # The following two tests are fragile:\r
    # They precisely count the number of allocations,\r
    # which is highly implementation-dependent.\r
    # For example:\r
    # - disposed tuples are not freed, but reused\r
    # - the call to assertEqual somehow avoids building its args tuple\r
    def test_get_count(self):\r
        # Avoid future allocation of method object\r
        assertEqual = self._baseAssertEqual\r
        gc.collect()\r
        assertEqual(gc.get_count(), (0, 0, 0))\r
        a = dict()\r
        # since gc.collect(), we created two objects:\r
        # the dict, and the tuple returned by get_count()\r
        assertEqual(gc.get_count(), (2, 0, 0))\r
\r
    def test_collect_generations(self):\r
        # Avoid future allocation of method object\r
        assertEqual = self.assertEqual\r
        gc.collect()\r
        a = dict()\r
        gc.collect(0)\r
        assertEqual(gc.get_count(), (0, 1, 0))\r
        gc.collect(1)\r
        assertEqual(gc.get_count(), (0, 0, 1))\r
        gc.collect(2)\r
        assertEqual(gc.get_count(), (0, 0, 0))\r
\r
    def test_trashcan(self):\r
        class Ouch:\r
            n = 0\r
            def __del__(self):\r
                Ouch.n = Ouch.n + 1\r
                if Ouch.n % 17 == 0:\r
                    gc.collect()\r
\r
        # "trashcan" is a hack to prevent stack overflow when deallocating\r
        # very deeply nested tuples etc.  It works in part by abusing the\r
        # type pointer and refcount fields, and that can yield horrible\r
        # problems when gc tries to traverse the structures.\r
        # If this test fails (as it does in 2.0, 2.1 and 2.2), it will\r
        # most likely die via segfault.\r
\r
        # Note:  In 2.3 the possibility for compiling without cyclic gc was\r
        # removed, and that in turn allows the trashcan mechanism to work\r
        # via much simpler means (e.g., it never abuses the type pointer or\r
        # refcount fields anymore).  Since it's much less likely to cause a\r
        # problem now, the various constants in this expensive (we force a lot\r
        # of full collections) test are cut back from the 2.2 version.\r
        gc.enable()\r
        N = 150\r
        for count in range(2):\r
            t = []\r
            for i in range(N):\r
                t = [t, Ouch()]\r
            u = []\r
            for i in range(N):\r
                u = [u, Ouch()]\r
            v = {}\r
            for i in range(N):\r
                v = {1: v, 2: Ouch()}\r
        gc.disable()\r
\r
    def test_boom(self):\r
        class Boom:\r
            def __getattr__(self, someattribute):\r
                del self.attr\r
                raise AttributeError\r
\r
        a = Boom()\r
        b = Boom()\r
        a.attr = b\r
        b.attr = a\r
\r
        gc.collect()\r
        garbagelen = len(gc.garbage)\r
        del a, b\r
        # a<->b are in a trash cycle now.  Collection will invoke\r
        # Boom.__getattr__ (to see whether a and b have __del__ methods), and\r
        # __getattr__ deletes the internal "attr" attributes as a side effect.\r
        # That causes the trash cycle to get reclaimed via refcounts falling to\r
        # 0, thus mutating the trash graph as a side effect of merely asking\r
        # whether __del__ exists.  This used to (before 2.3b1) crash Python.\r
        # Now __getattr__ isn't called.\r
        self.assertEqual(gc.collect(), 4)\r
        self.assertEqual(len(gc.garbage), garbagelen)\r
\r
    def test_boom2(self):\r
        class Boom2:\r
            def __init__(self):\r
                self.x = 0\r
\r
            def __getattr__(self, someattribute):\r
                self.x += 1\r
                if self.x > 1:\r
                    del self.attr\r
                raise AttributeError\r
\r
        a = Boom2()\r
        b = Boom2()\r
        a.attr = b\r
        b.attr = a\r
\r
        gc.collect()\r
        garbagelen = len(gc.garbage)\r
        del a, b\r
        # Much like test_boom(), except that __getattr__ doesn't break the\r
        # cycle until the second time gc checks for __del__.  As of 2.3b1,\r
        # there isn't a second time, so this simply cleans up the trash cycle.\r
        # We expect a, b, a.__dict__ and b.__dict__ (4 objects) to get\r
        # reclaimed this way.\r
        self.assertEqual(gc.collect(), 4)\r
        self.assertEqual(len(gc.garbage), garbagelen)\r
\r
    def test_boom_new(self):\r
        # boom__new and boom2_new are exactly like boom and boom2, except use\r
        # new-style classes.\r
\r
        class Boom_New(object):\r
            def __getattr__(self, someattribute):\r
                del self.attr\r
                raise AttributeError\r
\r
        a = Boom_New()\r
        b = Boom_New()\r
        a.attr = b\r
        b.attr = a\r
\r
        gc.collect()\r
        garbagelen = len(gc.garbage)\r
        del a, b\r
        self.assertEqual(gc.collect(), 4)\r
        self.assertEqual(len(gc.garbage), garbagelen)\r
\r
    def test_boom2_new(self):\r
        class Boom2_New(object):\r
            def __init__(self):\r
                self.x = 0\r
\r
            def __getattr__(self, someattribute):\r
                self.x += 1\r
                if self.x > 1:\r
                    del self.attr\r
                raise AttributeError\r
\r
        a = Boom2_New()\r
        b = Boom2_New()\r
        a.attr = b\r
        b.attr = a\r
\r
        gc.collect()\r
        garbagelen = len(gc.garbage)\r
        del a, b\r
        self.assertEqual(gc.collect(), 4)\r
        self.assertEqual(len(gc.garbage), garbagelen)\r
\r
    def test_get_referents(self):\r
        alist = [1, 3, 5]\r
        got = gc.get_referents(alist)\r
        got.sort()\r
        self.assertEqual(got, alist)\r
\r
        atuple = tuple(alist)\r
        got = gc.get_referents(atuple)\r
        got.sort()\r
        self.assertEqual(got, alist)\r
\r
        adict = {1: 3, 5: 7}\r
        expected = [1, 3, 5, 7]\r
        got = gc.get_referents(adict)\r
        got.sort()\r
        self.assertEqual(got, expected)\r
\r
        got = gc.get_referents([1, 2], {3: 4}, (0, 0, 0))\r
        got.sort()\r
        self.assertEqual(got, [0, 0] + range(5))\r
\r
        self.assertEqual(gc.get_referents(1, 'a', 4j), [])\r
\r
    def test_is_tracked(self):\r
        # Atomic built-in types are not tracked, user-defined objects and\r
        # mutable containers are.\r
        # NOTE: types with special optimizations (e.g. tuple) have tests\r
        # in their own test files instead.\r
        self.assertFalse(gc.is_tracked(None))\r
        self.assertFalse(gc.is_tracked(1))\r
        self.assertFalse(gc.is_tracked(1.0))\r
        self.assertFalse(gc.is_tracked(1.0 + 5.0j))\r
        self.assertFalse(gc.is_tracked(True))\r
        self.assertFalse(gc.is_tracked(False))\r
        self.assertFalse(gc.is_tracked("a"))\r
        self.assertFalse(gc.is_tracked(u"a"))\r
        self.assertFalse(gc.is_tracked(bytearray("a")))\r
        self.assertFalse(gc.is_tracked(type))\r
        self.assertFalse(gc.is_tracked(int))\r
        self.assertFalse(gc.is_tracked(object))\r
        self.assertFalse(gc.is_tracked(object()))\r
\r
        class OldStyle:\r
            pass\r
        class NewStyle(object):\r
            pass\r
        self.assertTrue(gc.is_tracked(gc))\r
        self.assertTrue(gc.is_tracked(OldStyle))\r
        self.assertTrue(gc.is_tracked(OldStyle()))\r
        self.assertTrue(gc.is_tracked(NewStyle))\r
        self.assertTrue(gc.is_tracked(NewStyle()))\r
        self.assertTrue(gc.is_tracked([]))\r
        self.assertTrue(gc.is_tracked(set()))\r
\r
    def test_bug1055820b(self):\r
        # Corresponds to temp2b.py in the bug report.\r
\r
        ouch = []\r
        def callback(ignored):\r
            ouch[:] = [wr() for wr in WRs]\r
\r
        Cs = [C1055820(i) for i in range(2)]\r
        WRs = [weakref.ref(c, callback) for c in Cs]\r
        c = None\r
\r
        gc.collect()\r
        self.assertEqual(len(ouch), 0)\r
        # Make the two instances trash, and collect again.  The bug was that\r
        # the callback materialized a strong reference to an instance, but gc\r
        # cleared the instance's dict anyway.\r
        Cs = None\r
        gc.collect()\r
        self.assertEqual(len(ouch), 2)  # else the callbacks didn't run\r
        for x in ouch:\r
            # If the callback resurrected one of these guys, the instance\r
            # would be damaged, with an empty __dict__.\r
            self.assertEqual(x, None)\r
\r
class GCTogglingTests(unittest.TestCase):\r
    def setUp(self):\r
        gc.enable()\r
\r
    def tearDown(self):\r
        gc.disable()\r
\r
    def test_bug1055820c(self):\r
        # Corresponds to temp2c.py in the bug report.  This is pretty\r
        # elaborate.\r
\r
        c0 = C1055820(0)\r
        # Move c0 into generation 2.\r
        gc.collect()\r
\r
        c1 = C1055820(1)\r
        c1.keep_c0_alive = c0\r
        del c0.loop # now only c1 keeps c0 alive\r
\r
        c2 = C1055820(2)\r
        c2wr = weakref.ref(c2) # no callback!\r
\r
        ouch = []\r
        def callback(ignored):\r
            ouch[:] = [c2wr()]\r
\r
        # The callback gets associated with a wr on an object in generation 2.\r
        c0wr = weakref.ref(c0, callback)\r
\r
        c0 = c1 = c2 = None\r
\r
        # What we've set up:  c0, c1, and c2 are all trash now.  c0 is in\r
        # generation 2.  The only thing keeping it alive is that c1 points to\r
        # it. c1 and c2 are in generation 0, and are in self-loops.  There's a\r
        # global weakref to c2 (c2wr), but that weakref has no callback.\r
        # There's also a global weakref to c0 (c0wr), and that does have a\r
        # callback, and that callback references c2 via c2wr().\r
        #\r
        #               c0 has a wr with callback, which references c2wr\r
        #               ^\r
        #               |\r
        #               |     Generation 2 above dots\r
        #. . . . . . . .|. . . . . . . . . . . . . . . . . . . . . . . .\r
        #               |     Generation 0 below dots\r
        #               |\r
        #               |\r
        #            ^->c1   ^->c2 has a wr but no callback\r
        #            |  |    |  |\r
        #            <--v    <--v\r
        #\r
        # So this is the nightmare:  when generation 0 gets collected, we see\r
        # that c2 has a callback-free weakref, and c1 doesn't even have a\r
        # weakref.  Collecting generation 0 doesn't see c0 at all, and c0 is\r
        # the only object that has a weakref with a callback.  gc clears c1\r
        # and c2.  Clearing c1 has the side effect of dropping the refcount on\r
        # c0 to 0, so c0 goes away (despite that it's in an older generation)\r
        # and c0's wr callback triggers.  That in turn materializes a reference\r
        # to c2 via c2wr(), but c2 gets cleared anyway by gc.\r
\r
        # We want to let gc happen "naturally", to preserve the distinction\r
        # between generations.\r
        junk = []\r
        i = 0\r
        detector = GC_Detector()\r
        while not detector.gc_happened:\r
            i += 1\r
            if i > 10000:\r
                self.fail("gc didn't happen after 10000 iterations")\r
            self.assertEqual(len(ouch), 0)\r
            junk.append([])  # this will eventually trigger gc\r
\r
        self.assertEqual(len(ouch), 1)  # else the callback wasn't invoked\r
        for x in ouch:\r
            # If the callback resurrected c2, the instance would be damaged,\r
            # with an empty __dict__.\r
            self.assertEqual(x, None)\r
\r
    def test_bug1055820d(self):\r
        # Corresponds to temp2d.py in the bug report.  This is very much like\r
        # test_bug1055820c, but uses a __del__ method instead of a weakref\r
        # callback to sneak in a resurrection of cyclic trash.\r
\r
        ouch = []\r
        class D(C1055820):\r
            def __del__(self):\r
                ouch[:] = [c2wr()]\r
\r
        d0 = D(0)\r
        # Move all the above into generation 2.\r
        gc.collect()\r
\r
        c1 = C1055820(1)\r
        c1.keep_d0_alive = d0\r
        del d0.loop # now only c1 keeps d0 alive\r
\r
        c2 = C1055820(2)\r
        c2wr = weakref.ref(c2) # no callback!\r
\r
        d0 = c1 = c2 = None\r
\r
        # What we've set up:  d0, c1, and c2 are all trash now.  d0 is in\r
        # generation 2.  The only thing keeping it alive is that c1 points to\r
        # it.  c1 and c2 are in generation 0, and are in self-loops.  There's\r
        # a global weakref to c2 (c2wr), but that weakref has no callback.\r
        # There are no other weakrefs.\r
        #\r
        #               d0 has a __del__ method that references c2wr\r
        #               ^\r
        #               |\r
        #               |     Generation 2 above dots\r
        #. . . . . . . .|. . . . . . . . . . . . . . . . . . . . . . . .\r
        #               |     Generation 0 below dots\r
        #               |\r
        #               |\r
        #            ^->c1   ^->c2 has a wr but no callback\r
        #            |  |    |  |\r
        #            <--v    <--v\r
        #\r
        # So this is the nightmare:  when generation 0 gets collected, we see\r
        # that c2 has a callback-free weakref, and c1 doesn't even have a\r
        # weakref.  Collecting generation 0 doesn't see d0 at all.  gc clears\r
        # c1 and c2.  Clearing c1 has the side effect of dropping the refcount\r
        # on d0 to 0, so d0 goes away (despite that it's in an older\r
        # generation) and d0's __del__ triggers.  That in turn materializes\r
        # a reference to c2 via c2wr(), but c2 gets cleared anyway by gc.\r
\r
        # We want to let gc happen "naturally", to preserve the distinction\r
        # between generations.\r
        detector = GC_Detector()\r
        junk = []\r
        i = 0\r
        while not detector.gc_happened:\r
            i += 1\r
            if i > 10000:\r
                self.fail("gc didn't happen after 10000 iterations")\r
            self.assertEqual(len(ouch), 0)\r
            junk.append([])  # this will eventually trigger gc\r
\r
        self.assertEqual(len(ouch), 1)  # else __del__ wasn't invoked\r
        for x in ouch:\r
            # If __del__ resurrected c2, the instance would be damaged, with an\r
            # empty __dict__.\r
            self.assertEqual(x, None)\r
\r
def test_main():\r
    enabled = gc.isenabled()\r
    gc.disable()\r
    assert not gc.isenabled()\r
    debug = gc.get_debug()\r
    gc.set_debug(debug & ~gc.DEBUG_LEAK) # this test is supposed to leak\r
\r
    try:\r
        gc.collect() # Delete 2nd generation garbage\r
        run_unittest(GCTests, GCTogglingTests)\r
    finally:\r
        gc.set_debug(debug)\r
        # test gc.enable() even if GC is disabled by default\r
        if verbose:\r
            print "restoring automatic collection"\r
        # make sure to always test gc.enable()\r
        gc.enable()\r
        assert gc.isenabled()\r
        if not enabled:\r
            gc.disable()\r
\r
if __name__ == "__main__":\r
    test_main()\r