Merge backout of 57776eee74f2.

4 files changed, 117 insertions, 749 deletions

diff --git a/Lib/functools.py b/Lib/functools.py
index 09df068..19c25e1 100644
--- a/Lib/functools.py
+++ b/Lib/functools.py
@@ -419,129 +419,120 @@ def lru_cache(maxsize=128, typed=False):
     if maxsize is not None and not isinstance(maxsize, int):
         raise TypeError('Expected maxsize to be an integer or None')
 
-    def decorating_function(user_function):
-        wrapper = _lru_cache_wrapper(user_function, maxsize, typed, _CacheInfo)
-        return update_wrapper(wrapper, user_function)
-
-    return decorating_function
-
-def _lru_cache_wrapper(user_function, maxsize, typed, _CacheInfo):
     # Constants shared by all lru cache instances:
     sentinel = object()          # unique object used to signal cache misses
     make_key = _make_key         # build a key from the function arguments
     PREV, NEXT, KEY, RESULT = 0, 1, 2, 3   # names for the link fields
 
-    cache = {}
-    hits = misses = 0
-    full = False
-    cache_get = cache.get    # bound method to lookup a key or return None
-    lock = RLock()           # because linkedlist updates aren't threadsafe
-    root = []                # root of the circular doubly linked list
-    root[:] = [root, root, None, None]     # initialize by pointing to self
-
-    if maxsize == 0:
-
-        def wrapper(*args, **kwds):
-            # No caching -- just a statistics update after a successful call
-            nonlocal misses
-            result = user_function(*args, **kwds)
-            misses += 1
-            return result
-
-    elif maxsize is None:
-
-        def wrapper(*args, **kwds):
-            # Simple caching without ordering or size limit
-            nonlocal hits, misses
-            key = make_key(args, kwds, typed)
-            result = cache_get(key, sentinel)
-            if result is not sentinel:
-                hits += 1
+    def decorating_function(user_function):
+        cache = {}
+        hits = misses = 0
+        full = False
+        cache_get = cache.get    # bound method to lookup a key or return None
+        lock = RLock()           # because linkedlist updates aren't threadsafe
+        root = []                # root of the circular doubly linked list
+        root[:] = [root, root, None, None]     # initialize by pointing to self
+
+        if maxsize == 0:
+
+            def wrapper(*args, **kwds):
+                # No caching -- just a statistics update after a successful call
+                nonlocal misses
+                result = user_function(*args, **kwds)
+                misses += 1
                 return result
-            result = user_function(*args, **kwds)
-            cache[key] = result
-            misses += 1
-            return result
 
-    else:
+        elif maxsize is None:
 
-        def wrapper(*args, **kwds):
-            # Size limited caching that tracks accesses by recency
-            nonlocal root, hits, misses, full
-            key = make_key(args, kwds, typed)
-            with lock:
-                link = cache_get(key)
-                if link is not None:
-                    # Move the link to the front of the circular queue
-                    link_prev, link_next, _key, result = link
-                    link_prev[NEXT] = link_next
-                    link_next[PREV] = link_prev
-                    last = root[PREV]
-                    last[NEXT] = root[PREV] = link
-                    link[PREV] = last
-                    link[NEXT] = root
+            def wrapper(*args, **kwds):
+                # Simple caching without ordering or size limit
+                nonlocal hits, misses
+                key = make_key(args, kwds, typed)
+                result = cache_get(key, sentinel)
+                if result is not sentinel:
                     hits += 1
                     return result
-            result = user_function(*args, **kwds)
-            with lock:
-                if key in cache:
-                    # Getting here means that this same key was added to the
-                    # cache while the lock was released.  Since the link
-                    # update is already done, we need only return the
-                    # computed result and update the count of misses.
-                    pass
-                elif full:
-                    # Use the old root to store the new key and result.
-                    oldroot = root
-                    oldroot[KEY] = key
-                    oldroot[RESULT] = result
-                    # Empty the oldest link and make it the new root.
-                    # Keep a reference to the old key and old result to
-                    # prevent their ref counts from going to zero during the
-                    # update. That will prevent potentially arbitrary object
-                    # clean-up code (i.e. __del__) from running while we're
-                    # still adjusting the links.
-                    root = oldroot[NEXT]
-                    oldkey = root[KEY]
-                    oldresult = root[RESULT]
-                    root[KEY] = root[RESULT] = None
-                    # Now update the cache dictionary.
-                    del cache[oldkey]
-                    # Save the potentially reentrant cache[key] assignment
-                    # for last, after the root and links have been put in
-                    # a consistent state.
-                    cache[key] = oldroot
-                else:
-                    # Put result in a new link at the front of the queue.
-                    last = root[PREV]
-                    link = [last, root, key, result]
-                    last[NEXT] = root[PREV] = cache[key] = link
-                    full = (len(cache) >= maxsize)
+                result = user_function(*args, **kwds)
+                cache[key] = result
                 misses += 1
-            return result
+                return result
 
-    def cache_info():
-        """Report cache statistics"""
-        with lock:
-            return _CacheInfo(hits, misses, maxsize, len(cache))
+        else:
 
-    def cache_clear():
-        """Clear the cache and cache statistics"""
-        nonlocal hits, misses, full
-        with lock:
-            cache.clear()
-            root[:] = [root, root, None, None]
-            hits = misses = 0
-            full = False
+            def wrapper(*args, **kwds):
+                # Size limited caching that tracks accesses by recency
+                nonlocal root, hits, misses, full
+                key = make_key(args, kwds, typed)
+                with lock:
+                    link = cache_get(key)
+                    if link is not None:
+                        # Move the link to the front of the circular queue
+                        link_prev, link_next, _key, result = link
+                        link_prev[NEXT] = link_next
+                        link_next[PREV] = link_prev
+                        last = root[PREV]
+                        last[NEXT] = root[PREV] = link
+                        link[PREV] = last
+                        link[NEXT] = root
+                        hits += 1
+                        return result
+                result = user_function(*args, **kwds)
+                with lock:
+                    if key in cache:
+                        # Getting here means that this same key was added to the
+                        # cache while the lock was released.  Since the link
+                        # update is already done, we need only return the
+                        # computed result and update the count of misses.
+                        pass
+                    elif full:
+                        # Use the old root to store the new key and result.
+                        oldroot = root
+                        oldroot[KEY] = key
+                        oldroot[RESULT] = result
+                        # Empty the oldest link and make it the new root.
+                        # Keep a reference to the old key and old result to
+                        # prevent their ref counts from going to zero during the
+                        # update. That will prevent potentially arbitrary object
+                        # clean-up code (i.e. __del__) from running while we're
+                        # still adjusting the links.
+                        root = oldroot[NEXT]
+                        oldkey = root[KEY]
+                        oldresult = root[RESULT]
+                        root[KEY] = root[RESULT] = None
+                        # Now update the cache dictionary.
+                        del cache[oldkey]
+                        # Save the potentially reentrant cache[key] assignment
+                        # for last, after the root and links have been put in
+                        # a consistent state.
+                        cache[key] = oldroot
+                    else:
+                        # Put result in a new link at the front of the queue.
+                        last = root[PREV]
+                        link = [last, root, key, result]
+                        last[NEXT] = root[PREV] = cache[key] = link
+                        full = (len(cache) >= maxsize)
+                    misses += 1
+                return result
 
-    wrapper.cache_info = cache_info
-    wrapper.cache_clear = cache_clear
-    return update_wrapper(wrapper, user_function)
+        def cache_info():
+            """Report cache statistics"""
+            with lock:
+                return _CacheInfo(hits, misses, maxsize, len(cache))
 
-try:
-    from _functools import _lru_cache_wrapper
-except ImportError:
-    pass
+        def cache_clear():
+            """Clear the cache and cache statistics"""
+            nonlocal hits, misses, full
+            with lock:
+                cache.clear()
+                root[:] = [root, root, None, None]
+                hits = misses = 0
+                full = False
+
+        wrapper.cache_info = cache_info
+        wrapper.cache_clear = cache_clear
+        return update_wrapper(wrapper, user_function)
+
+    return decorating_function
 
 
 ################################################################################
diff --git a/Lib/test/test_functools.py b/Lib/test/test_functools.py
index 271d655..03dd545 100644
--- a/Lib/test/test_functools.py
+++ b/Lib/test/test_functools.py
@@ -7,10 +7,6 @@ import sys
 from test import support
 import unittest
 from weakref import proxy
-try:
-    import threading
-except ImportError:
-    threading = None
 
 import functools
 
@@ -916,12 +912,12 @@ class Orderable_LT:
         return self.value == other.value
 
 
-class TestLRU:
+class TestLRU(unittest.TestCase):
 
     def test_lru(self):
         def orig(x, y):
             return 3 * x + y
-        f = self.module.lru_cache(maxsize=20)(orig)
+        f = functools.lru_cache(maxsize=20)(orig)
         hits, misses, maxsize, currsize = f.cache_info()
         self.assertEqual(maxsize, 20)
         self.assertEqual(currsize, 0)
@@ -959,7 +955,7 @@ class TestLRU:
         self.assertEqual(currsize, 1)
 
         # test size zero (which means "never-cache")
-        @self.module.lru_cache(0)
+        @functools.lru_cache(0)
         def f():
             nonlocal f_cnt
             f_cnt += 1
@@ -975,7 +971,7 @@ class TestLRU:
         self.assertEqual(currsize, 0)
 
         # test size one
-        @self.module.lru_cache(1)
+        @functools.lru_cache(1)
         def f():
             nonlocal f_cnt
             f_cnt += 1
@@ -991,7 +987,7 @@ class TestLRU:
         self.assertEqual(currsize, 1)
 
         # test size two
-        @self.module.lru_cache(2)
+        @functools.lru_cache(2)
         def f(x):
             nonlocal f_cnt
             f_cnt += 1
@@ -1008,7 +1004,7 @@ class TestLRU:
         self.assertEqual(currsize, 2)
 
     def test_lru_with_maxsize_none(self):
-        @self.module.lru_cache(maxsize=None)
+        @functools.lru_cache(maxsize=None)
         def fib(n):
             if n < 2:
                 return n
@@ -1016,26 +1012,17 @@ class TestLRU:
         self.assertEqual([fib(n) for n in range(16)],
             [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610])
         self.assertEqual(fib.cache_info(),
-            self.module._CacheInfo(hits=28, misses=16, maxsize=None, currsize=16))
+            functools._CacheInfo(hits=28, misses=16, maxsize=None, currsize=16))
         fib.cache_clear()
         self.assertEqual(fib.cache_info(),
-            self.module._CacheInfo(hits=0, misses=0, maxsize=None, currsize=0))
-
-    def test_lru_with_maxsize_negative(self):
-        @self.module.lru_cache(maxsize=-10)
-        def eq(n):
-            return n
-        for i in (0, 1):
-            self.assertEqual([eq(n) for n in range(150)], list(range(150)))
-        self.assertEqual(eq.cache_info(),
-            self.module._CacheInfo(hits=0, misses=300, maxsize=-10, currsize=1))
+            functools._CacheInfo(hits=0, misses=0, maxsize=None, currsize=0))
 
     def test_lru_with_exceptions(self):
         # Verify that user_function exceptions get passed through without
         # creating a hard-to-read chained exception.
         # http://bugs.python.org/issue13177
         for maxsize in (None, 128):
-            @self.module.lru_cache(maxsize)
+            @functools.lru_cache(maxsize)
             def func(i):
                 return 'abc'[i]
             self.assertEqual(func(0), 'a')
@@ -1048,7 +1035,7 @@ class TestLRU:
 
     def test_lru_with_types(self):
         for maxsize in (None, 128):
-            @self.module.lru_cache(maxsize=maxsize, typed=True)
+            @functools.lru_cache(maxsize=maxsize, typed=True)
             def square(x):
                 return x * x
             self.assertEqual(square(3), 9)
@@ -1063,7 +1050,7 @@ class TestLRU:
             self.assertEqual(square.cache_info().misses, 4)
 
     def test_lru_with_keyword_args(self):
-        @self.module.lru_cache()
+        @functools.lru_cache()
         def fib(n):
             if n < 2:
                 return n
@@ -1073,13 +1060,13 @@ class TestLRU:
             [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610]
         )
         self.assertEqual(fib.cache_info(),
-            self.module._CacheInfo(hits=28, misses=16, maxsize=128, currsize=16))
+            functools._CacheInfo(hits=28, misses=16, maxsize=128, currsize=16))
         fib.cache_clear()
         self.assertEqual(fib.cache_info(),
-            self.module._CacheInfo(hits=0, misses=0, maxsize=128, currsize=0))
+            functools._CacheInfo(hits=0, misses=0, maxsize=128, currsize=0))
 
     def test_lru_with_keyword_args_maxsize_none(self):
-        @self.module.lru_cache(maxsize=None)
+        @functools.lru_cache(maxsize=None)
         def fib(n):
             if n < 2:
                 return n
@@ -1087,71 +1074,15 @@ class TestLRU:
         self.assertEqual([fib(n=number) for number in range(16)],
             [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610])
         self.assertEqual(fib.cache_info(),
-            self.module._CacheInfo(hits=28, misses=16, maxsize=None, currsize=16))
+            functools._CacheInfo(hits=28, misses=16, maxsize=None, currsize=16))
         fib.cache_clear()
         self.assertEqual(fib.cache_info(),
-            self.module._CacheInfo(hits=0, misses=0, maxsize=None, currsize=0))
-
-    def test_lru_cache_decoration(self):
-        def f(zomg: 'zomg_annotation'):
-            """f doc string"""
-            return 42
-        g = self.module.lru_cache()(f)
-        for attr in self.module.WRAPPER_ASSIGNMENTS:
-            self.assertEqual(getattr(g, attr), getattr(f, attr))
-
-    @unittest.skipUnless(threading, 'This test requires threading.')
-    def test_lru_cache_threaded(self):
-        def orig(x, y):
-            return 3 * x + y
-        f = self.module.lru_cache(maxsize=20)(orig)
-        hits, misses, maxsize, currsize = f.cache_info()
-        self.assertEqual(currsize, 0)
-
-        def full(f, *args):
-            for _ in range(10):
-                f(*args)
-
-        def clear(f):
-            for _ in range(10):
-                f.cache_clear()
-
-        orig_si = sys.getswitchinterval()
-        sys.setswitchinterval(1e-6)
-        try:
-            # create 5 threads in order to fill cache
-            threads = []
-            for k in range(5):
-                t = threading.Thread(target=full, args=[f, k, k])
-                t.start()
-                threads.append(t)
-
-            for t in threads:
-                t.join()
-
-            hits, misses, maxsize, currsize = f.cache_info()
-            self.assertEqual(hits, 45)
-            self.assertEqual(misses, 5)
-            self.assertEqual(currsize, 5)
-
-            # create 5 threads in order to fill cache and 1 to clear it
-            cleaner = threading.Thread(target=clear, args=[f])
-            cleaner.start()
-            threads = [cleaner]
-            for k in range(5):
-                t = threading.Thread(target=full, args=[f, k, k])
-                t.start()
-                threads.append(t)
-
-            for t in threads:
-                t.join()
-        finally:
-            sys.setswitchinterval(orig_si)
+            functools._CacheInfo(hits=0, misses=0, maxsize=None, currsize=0))
 
     def test_need_for_rlock(self):
         # This will deadlock on an LRU cache that uses a regular lock
 
-        @self.module.lru_cache(maxsize=10)
+        @functools.lru_cache(maxsize=10)
         def test_func(x):
             'Used to demonstrate a reentrant lru_cache call within a single thread'
             return x
@@ -1179,12 +1110,6 @@ class TestLRU:
             def f():
                 pass
 
-class TestLRUC(TestLRU, unittest.TestCase):
-    module = c_functools
-
-class TestLRUPy(TestLRU, unittest.TestCase):
-    module = py_functools
-
 
 class TestSingleDispatch(unittest.TestCase):
     def test_simple_overloads(self):
diff --git a/Misc/NEWS b/Misc/NEWS
index fa387ab..ef2a0f0 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -63,9 +63,6 @@ Core and Builtins
 Library
 -------
 
-- Issue #14373: Added C implementation of functools.lru_cache().  Based on
-  patches by Matt Joiner and Alexey Kachayev.
-
 - Issue 24230: The tempfile module now accepts bytes for prefix, suffix and dir
   parameters and returns bytes in such situations (matching the os module APIs).
 
diff --git a/Modules/_functoolsmodule.c b/Modules/_functoolsmodule.c
index 99b50b0..3c82e51 100644
--- a/Modules/_functoolsmodule.c
+++ b/Modules/_functoolsmodule.c
@@ -590,539 +590,6 @@ For example, reduce(lambda x, y: x+y, [1, 2, 3, 4, 5]) calculates\n\
 of the sequence in the calculation, and serves as a default when the\n\
 sequence is empty.");
 
-/* lru_cache object **********************************************************/
-
-/* this object is used delimit args and keywords in the cache keys */
-static PyObject *kwd_mark = NULL;
-
-struct lru_list_elem;
-struct lru_cache_object;
-
-typedef struct lru_list_elem {
-    PyObject_HEAD
-    struct lru_list_elem *prev, *next;  /* borrowed links */
-    PyObject *key, *result;
-} lru_list_elem;
-
-static void
-lru_list_elem_dealloc(lru_list_elem *link)
-{
-    _PyObject_GC_UNTRACK(link);
-    Py_XDECREF(link->key);
-    Py_XDECREF(link->result);
-    PyObject_GC_Del(link);
-}
-
-static int
-lru_list_elem_traverse(lru_list_elem *link, visitproc visit, void *arg)
-{
-    Py_VISIT(link->key);
-    Py_VISIT(link->result);
-    return 0;
-}
-
-static int
-lru_list_elem_clear(lru_list_elem *link)
-{
-    Py_CLEAR(link->key);
-    Py_CLEAR(link->result);
-    return 0;
-}
-
-static PyTypeObject lru_list_elem_type = {
-    PyVarObject_HEAD_INIT(&PyType_Type, 0)
-    "functools._lru_list_elem",         /* tp_name */
-    sizeof(lru_list_elem),              /* tp_basicsize */
-    0,                                  /* tp_itemsize */
-    /* methods */
-    (destructor)lru_list_elem_dealloc,  /* tp_dealloc */
-    0,                                  /* tp_print */
-    0,                                  /* tp_getattr */
-    0,                                  /* tp_setattr */
-    0,                                  /* tp_reserved */
-    0,                                  /* tp_repr */
-    0,                                  /* tp_as_number */
-    0,                                  /* tp_as_sequence */
-    0,                                  /* tp_as_mapping */
-    0,                                  /* tp_hash */
-    0,                                  /* tp_call */
-    0,                                  /* tp_str */
-    0,                                  /* tp_getattro */
-    0,                                  /* tp_setattro */
-    0,                                  /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,  /* tp_flags */
-    0,                                  /* tp_doc */
-    (traverseproc)lru_list_elem_traverse,  /* tp_traverse */
-    (inquiry)lru_list_elem_clear,       /* tp_clear */
-};
-
-
-typedef PyObject *(*lru_cache_ternaryfunc)(struct lru_cache_object *, PyObject *, PyObject *);
-
-typedef struct lru_cache_object {
-    lru_list_elem root;  /* includes PyObject_HEAD */
-    Py_ssize_t maxsize;
-    PyObject *maxsize_O;
-    PyObject *func;
-    lru_cache_ternaryfunc wrapper;
-    PyObject *cache;
-    PyObject *cache_info_type;
-    Py_ssize_t misses, hits;
-    int typed;
-    PyObject *dict;
-    int full;
-} lru_cache_object;
-
-static PyTypeObject lru_cache_type;
-
-static PyObject *
-lru_cache_make_key(PyObject *args, PyObject *kwds, int typed)
-{
-    PyObject *key, *sorted_items;
-    Py_ssize_t key_size, pos, key_pos;
-
-    /* short path, key will match args anyway, which is a tuple */
-    if (!typed && !kwds) {
-        Py_INCREF(args);
-        return args;
-    }
-
-    if (kwds && PyDict_Size(kwds) > 0) {
-        sorted_items = PyDict_Items(kwds);
-        if (!sorted_items)
-            return NULL;
-        if (PyList_Sort(sorted_items) < 0) {
-            Py_DECREF(sorted_items);
-            return NULL;
-        }
-    } else
-        sorted_items = NULL;
-
-    key_size = PyTuple_GET_SIZE(args);
-    if (sorted_items)
-        key_size += PyList_GET_SIZE(sorted_items);
-    if (typed)
-        key_size *= 2;
-    if (sorted_items)
-        key_size++;
-
-    key = PyTuple_New(key_size);
-    if (key == NULL)
-        goto done;
-
-    key_pos = 0;
-    for (pos = 0; pos < PyTuple_GET_SIZE(args); ++pos) {
-        PyObject *item = PyTuple_GET_ITEM(args, pos);
-        Py_INCREF(item);
-        PyTuple_SET_ITEM(key, key_pos++, item);
-    }
-    if (sorted_items) {
-        Py_INCREF(kwd_mark);
-        PyTuple_SET_ITEM(key, key_pos++, kwd_mark);
-        for (pos = 0; pos < PyList_GET_SIZE(sorted_items); ++pos) {
-            PyObject *item = PyList_GET_ITEM(sorted_items, pos);
-            Py_INCREF(item);
-            PyTuple_SET_ITEM(key, key_pos++, item);
-        }
-    }
-    if (typed) {
-        for (pos = 0; pos < PyTuple_GET_SIZE(args); ++pos) {
-            PyObject *item = (PyObject *)Py_TYPE(PyTuple_GET_ITEM(args, pos));
-            Py_INCREF(item);
-            PyTuple_SET_ITEM(key, key_pos++, item);
-        }
-        if (sorted_items) {
-            for (pos = 0; pos < PyList_GET_SIZE(sorted_items); ++pos) {
-                PyObject *tp_items = PyList_GET_ITEM(sorted_items, pos);
-                PyObject *item = (PyObject *)Py_TYPE(PyTuple_GET_ITEM(tp_items, 1));
-                Py_INCREF(item);
-                PyTuple_SET_ITEM(key, key_pos++, item);
-            }
-        }
-    }
-    assert(key_pos == key_size);
-
-done:
-    if (sorted_items)
-        Py_DECREF(sorted_items);
-    return key;
-}
-
-static PyObject *
-uncached_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds)
-{
-    PyObject *result = PyObject_Call(self->func, args, kwds);
-    if (!result)
-        return NULL;
-    self->misses++;
-    return result;
-}
-
-static PyObject *
-infinite_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds)
-{
-    PyObject *result;
-    PyObject *key = lru_cache_make_key(args, kwds, self->typed);
-    if (!key)
-        return NULL;
-    result = PyDict_GetItemWithError(self->cache, key);
-    if (result) {
-        Py_INCREF(result);
-        self->hits++;
-        Py_DECREF(key);
-        return result;
-    }
-    if (PyErr_Occurred()) {
-        Py_DECREF(key);
-        return NULL;
-    }
-    result = PyObject_Call(self->func, args, kwds);
-    if (!result) {
-        Py_DECREF(key);
-        return NULL;
-    }
-    if (PyDict_SetItem(self->cache, key, result) < 0) {
-        Py_DECREF(result);
-        Py_DECREF(key);
-        return NULL;
-    }
-    Py_DECREF(key);
-    self->misses++;
-    return result;
-}
-
-static void
-lru_cache_extricate_link(lru_list_elem *link)
-{
-    link->prev->next = link->next;
-    link->next->prev = link->prev;
-}
-
-static void
-lru_cache_append_link(lru_cache_object *self, lru_list_elem *link)
-{
-    lru_list_elem *root = &self->root;
-    lru_list_elem *last = root->prev;
-    last->next = root->prev = link;
-    link->prev = last;
-    link->next = root;
-}
-
-static PyObject *
-bounded_lru_cache_wrapper(lru_cache_object *self, PyObject *args, PyObject *kwds)
-{
-    lru_list_elem *link;
-    PyObject *key, *result;
-
-    key = lru_cache_make_key(args, kwds, self->typed);
-    if (!key)
-        return NULL;
-    link  = (lru_list_elem *)PyDict_GetItemWithError(self->cache, key);
-    if (link) {
-        lru_cache_extricate_link(link);
-        lru_cache_append_link(self, link);
-        self->hits++;
-        result = link->result;
-        Py_INCREF(result);
-        Py_DECREF(key);
-        return result;
-    }
-    if (PyErr_Occurred()) {
-        Py_DECREF(key);
-        return NULL;
-    }
-    result = PyObject_Call(self->func, args, kwds);
-    if (!result) {
-        Py_DECREF(key);
-        return NULL;
-    }
-    if (self->full && self->root.next != &self->root) {
-        /* Use the oldest item to store the new key and result. */
-        PyObject *oldkey, *oldresult;
-        /* Extricate the oldest item. */
-        link = self->root.next;
-        lru_cache_extricate_link(link);
-        /* Remove it from the cache.
-           The cache dict holds one reference to the link,
-           and the linked list holds yet one reference to it. */
-        if (PyDict_DelItem(self->cache, link->key) < 0) {
-            lru_cache_append_link(self, link);
-            Py_DECREF(key);
-            Py_DECREF(result);
-            return NULL;
-        }
-        /* Keep a reference to the old key and old result to
-           prevent their ref counts from going to zero during the
-           update. That will prevent potentially arbitrary object
-           clean-up code (i.e. __del__) from running while we're
-           still adjusting the links. */
-        oldkey = link->key;
-        oldresult = link->result;
-
-        link->key = key;
-        link->result = result;
-        if (PyDict_SetItem(self->cache, key, (PyObject *)link) < 0) {
-            Py_DECREF(link);
-            Py_DECREF(oldkey);
-            Py_DECREF(oldresult);
-            return NULL;
-        }
-        lru_cache_append_link(self, link);
-        Py_INCREF(result); /* for return */
-        Py_DECREF(oldkey);
-        Py_DECREF(oldresult);
-    } else {
-        /* Put result in a new link at the front of the queue. */
-        link = (lru_list_elem *)PyObject_GC_New(lru_list_elem,
-                                                &lru_list_elem_type);
-        if (link == NULL) {
-            Py_DECREF(key);
-            Py_DECREF(result);
-            return NULL;
-        }
-
-        link->key = key;
-        link->result = result;
-        _PyObject_GC_TRACK(link);
-        if (PyDict_SetItem(self->cache, key, (PyObject *)link) < 0) {
-            Py_DECREF(link);
-            return NULL;
-        }
-        lru_cache_append_link(self, link);
-        Py_INCREF(result); /* for return */
-        self->full = (PyDict_Size(self->cache) >= self->maxsize);
-    }
-    self->misses++;
-    return result;
-}
-
-static PyObject *
-lru_cache_new(PyTypeObject *type, PyObject *args, PyObject *kw)
-{
-    PyObject *func, *maxsize_O, *cache_info_type;
-    int typed;
-    lru_cache_object *obj;
-    Py_ssize_t maxsize;
-    PyObject *(*wrapper)(lru_cache_object *, PyObject *, PyObject *);
-    static char *keywords[] = {"user_function", "maxsize", "typed",
-                               "cache_info_type", NULL};
-
-    if (!PyArg_ParseTupleAndKeywords(args, kw, "OOpO:lru_cache", keywords,
-                                     &func, &maxsize_O, &typed,
-                                     &cache_info_type)) {
-        return NULL;
-    }
-
-    if (!PyCallable_Check(func)) {
-        PyErr_SetString(PyExc_TypeError,
-                        "the first argument must be callable");
-        return NULL;
-    }
-
-    /* select the caching function, and make/inc maxsize_O */
-    if (maxsize_O == Py_None) {
-        wrapper = infinite_lru_cache_wrapper;
-        /* use this only to initialize lru_cache_object attribute maxsize */
-        maxsize = -1;
-    } else if (PyIndex_Check(maxsize_O)) {
-        maxsize = PyNumber_AsSsize_t(maxsize_O, PyExc_OverflowError);
-        if (maxsize == -1 && PyErr_Occurred())
-            return NULL;
-        if (maxsize == 0)
-            wrapper = uncached_lru_cache_wrapper;
-        else
-            wrapper = bounded_lru_cache_wrapper;
-    } else {
-        PyErr_SetString(PyExc_TypeError, "maxsize should be integer or None");
-        return NULL;
-    }
-
-    obj = (lru_cache_object *)type->tp_alloc(type, 0);
-    if (obj == NULL)
-        return NULL;
-
-    if (!(obj->cache = PyDict_New())) {
-        Py_DECREF(obj);
-        return NULL;
-    }
-
-    obj->root.prev = &obj->root;
-    obj->root.next = &obj->root;
-    obj->maxsize = maxsize;
-    Py_INCREF(maxsize_O);
-    obj->maxsize_O = maxsize_O;
-    Py_INCREF(func);
-    obj->func = func;
-    obj->wrapper = wrapper;
-    obj->misses = obj->hits = 0;
-    obj->typed = typed;
-    Py_INCREF(cache_info_type);
-    obj->cache_info_type = cache_info_type;
-
-    return (PyObject *)obj;
-}
-
-static lru_list_elem *
-lru_cache_unlink_list(lru_cache_object *self)
-{
-    lru_list_elem *root = &self->root;
-    lru_list_elem *link = root->next;
-    if (link == root)
-        return NULL;
-    root->prev->next = NULL;
-    root->next = root->prev = root;
-    return link;
-}
-
-static void
-lru_cache_clear_list(lru_list_elem *link)
-{
-    while (link != NULL) {
-        lru_list_elem *next = link->next;
-        Py_DECREF(link);
-        link = next;
-    }
-}
-
-static void
-lru_cache_dealloc(lru_cache_object *obj)
-{
-    lru_list_elem *list = lru_cache_unlink_list(obj);
-    Py_XDECREF(obj->maxsize_O);
-    Py_XDECREF(obj->func);
-    Py_XDECREF(obj->cache);
-    Py_XDECREF(obj->dict);
-    Py_XDECREF(obj->cache_info_type);
-    lru_cache_clear_list(list);
-    Py_TYPE(obj)->tp_free(obj);
-}
-
-static PyObject *
-lru_cache_call(lru_cache_object *self, PyObject *args, PyObject *kwds)
-{
-    return self->wrapper(self, args, kwds);
-}
-
-static PyObject *
-lru_cache_cache_info(lru_cache_object *self, PyObject *unused)
-{
-    return PyObject_CallFunction(self->cache_info_type, "nnOn",
-                                 self->hits, self->misses, self->maxsize_O,
-                                 PyDict_Size(self->cache));
-}
-
-static PyObject *
-lru_cache_cache_clear(lru_cache_object *self, PyObject *unused)
-{
-    lru_list_elem *list = lru_cache_unlink_list(self);
-    self->hits = self->misses = 0;
-    self->full = 0;
-    PyDict_Clear(self->cache);
-    lru_cache_clear_list(list);
-    Py_RETURN_NONE;
-}
-
-static int
-lru_cache_tp_traverse(lru_cache_object *self, visitproc visit, void *arg)
-{
-    lru_list_elem *link = self->root.next;
-    while (link != &self->root) {
-        lru_list_elem *next = link->next;
-        Py_VISIT(link);
-        link = next;
-    }
-    Py_VISIT(self->maxsize_O);
-    Py_VISIT(self->func);
-    Py_VISIT(self->cache);
-    Py_VISIT(self->cache_info_type);
-    Py_VISIT(self->dict);
-    return 0;
-}
-
-static int
-lru_cache_tp_clear(lru_cache_object *self)
-{
-    lru_list_elem *list = lru_cache_unlink_list(self);
-    Py_CLEAR(self->maxsize_O);
-    Py_CLEAR(self->func);
-    Py_CLEAR(self->cache);
-    Py_CLEAR(self->cache_info_type);
-    Py_CLEAR(self->dict);
-    lru_cache_clear_list(list);
-    return 0;
-}
-
-
-PyDoc_STRVAR(lru_cache_doc,
-"Create a cached callable that wraps another function.\n\
-\n\
-user_function:      the function being cached\n\
-\n\
-maxsize:  0         for no caching\n\
-          None      for unlimited cache size\n\
-          n         for a bounded cache\n\
-\n\
-typed:    False     cache f(3) and f(3.0) as identical calls\n\
-          True      cache f(3) and f(3.0) as distinct calls\n\
-\n\
-cache_info_type:    namedtuple class with the fields:\n\
-                        hits misses currsize maxsize\n"
-);
-
-static PyMethodDef lru_cache_methods[] = {
-    {"cache_info", (PyCFunction)lru_cache_cache_info, METH_NOARGS},
-    {"cache_clear", (PyCFunction)lru_cache_cache_clear, METH_NOARGS},
-    {NULL}
-};
-
-static PyGetSetDef lru_cache_getsetlist[] = {
-    {"__dict__", PyObject_GenericGetDict, PyObject_GenericSetDict},
-    {NULL}
-};
-
-static PyTypeObject lru_cache_type = {
-    PyVarObject_HEAD_INIT(NULL, 0)
-    "functools._lru_cache_wrapper",     /* tp_name */
-    sizeof(lru_cache_object),           /* tp_basicsize */
-    0,                                  /* tp_itemsize */
-    /* methods */
-    (destructor)lru_cache_dealloc,      /* tp_dealloc */
-    0,                                  /* tp_print */
-    0,                                  /* tp_getattr */
-    0,                                  /* tp_setattr */
-    0,                                  /* tp_reserved */
-    0,                                  /* tp_repr */
-    0,                                  /* tp_as_number */
-    0,                                  /* tp_as_sequence */
-    0,                                  /* tp_as_mapping */
-    0,                                  /* tp_hash */
-    (ternaryfunc)lru_cache_call,        /* tp_call */
-    0,                                  /* tp_str */
-    0,                                  /* tp_getattro */
-    0,                                  /* tp_setattro */
-    0,                                  /* tp_as_buffer */
-    Py_TPFLAGS_DEFAULT|Py_TPFLAGS_BASETYPE|Py_TPFLAGS_HAVE_GC,
-                                        /* tp_flags */
-    lru_cache_doc,                      /* tp_doc */
-    (traverseproc)lru_cache_tp_traverse,/* tp_traverse */
-    (inquiry)lru_cache_tp_clear,        /* tp_clear */
-    0,                                  /* tp_richcompare */
-    0,                                  /* tp_weaklistoffset */
-    0,                                  /* tp_iter */
-    0,                                  /* tp_iternext */
-    lru_cache_methods,                  /* tp_methods */
-    0,                                  /* tp_members */
-    lru_cache_getsetlist,               /* tp_getset */
-    0,                                  /* tp_base */
-    0,                                  /* tp_dict */
-    0,                                  /* tp_descr_get */
-    0,                                  /* tp_descr_set */
-    offsetof(lru_cache_object, dict),   /* tp_dictoffset */
-    0,                                  /* tp_init */
-    0,                                  /* tp_alloc */
-    lru_cache_new,                      /* tp_new */
-};
-
 /* module level code ********************************************************/
 
 PyDoc_STRVAR(module_doc,
@@ -1135,11 +602,6 @@ static PyMethodDef module_methods[] = {
     {NULL,              NULL}           /* sentinel */
 };
 
-static void
-module_free(void *m)
-{
-    Py_CLEAR(kwd_mark);
-}
 
 static struct PyModuleDef _functoolsmodule = {
     PyModuleDef_HEAD_INIT,
@@ -1150,7 +612,7 @@ static struct PyModuleDef _functoolsmodule = {
     NULL,
     NULL,
     NULL,
-    module_free,
+    NULL
 };
 
 PyMODINIT_FUNC
@@ -1161,7 +623,6 @@ PyInit__functools(void)
     char *name;
     PyTypeObject *typelist[] = {
         &partial_type,
-        &lru_cache_type,
         NULL
     };
 
@@ -1169,12 +630,6 @@ PyInit__functools(void)
     if (m == NULL)
         return NULL;
 
-    kwd_mark = PyObject_CallObject((PyObject *)&PyBaseObject_Type, NULL);
-    if (!kwd_mark) {
-        Py_DECREF(m);
-        return NULL;
-    }
-
     for (i=0 ; typelist[i] != NULL ; i++) {
         if (PyType_Ready(typelist[i]) < 0) {
             Py_DECREF(m);