implement cython for cache_anon_map, prefix_anon_map

These are small bits where cache_anon_map in particular
is part of the cache key generation scheme which is a key
target for cython.

changing such a tiny element of the cache key gen is
doing basically nothing yet, as the cython impl is
mostly the exact same speed as the python one.  I guess for
cython to be effective we'd need to redo the whole cache key
generation and possibly not use the same kinds of structures,
which might not be very easy to do.

Additionally, some cython runtime import errors are being
observed on jenkins, add an upfront check to the test suite
to indicate if the expected build succeeded when REQUIRE_SQLALCHEMY_CEXT
is set.

Running case CacheAnonMap
Running python .... Done
Running cython .... Done
                    | python      | cython      | cy / py     |
test_get_anon_non_present| 0.301266758 | 0.231203834 | 0.767438915 |
test_get_anon_present| 0.300919362 | 0.227336695 | 0.755473803 |
test_has_key_non_present| 0.152725077 | 0.133191719 | 0.872101171 |
test_has_key_present| 0.152689778 | 0.133673095 | 0.875455428 |
Running case PrefixAnonMap
Running python .. Done
Running cython .. Done
                    | python      | cython      | cy / py     |
test_apply_non_present| 0.358715744 | 0.335245703 | 0.934572034 |
test_apply_present  | 0.354434996 | 0.338579782 | 0.955266229 |

Change-Id: I0d3f1dd285c044afc234479141d831b2ee0455be

1 files changed, 6 insertions, 21 deletions

diff --git a/lib/sqlalchemy/sql/base.py b/lib/sqlalchemy/sql/base.py
index 4165751ca..b5a20830d 100644
--- a/lib/sqlalchemy/sql/base.py
+++ b/lib/sqlalchemy/sql/base.py
@@ -30,6 +30,12 @@ from .. import util
 from ..util import HasMemoized
 from ..util import hybridmethod
 
+try:
+    from sqlalchemy.cyextension.util import prefix_anon_map  # noqa
+except ImportError:
+    from ._py_util import prefix_anon_map  # noqa
+
+
 coercions = None
 elements = None
 type_api = None
@@ -1012,27 +1018,6 @@ class Executable(roles.StatementRole, Generative):
         return self._execution_options
 
 
-class prefix_anon_map(dict):
-    """A map that creates new keys for missing key access.
-
-    Considers keys of the form "<ident> <name>" to produce
-    new symbols "<name>_<index>", where "index" is an incrementing integer
-    corresponding to <name>.
-
-    Inlines the approach taken by :class:`sqlalchemy.util.PopulateDict` which
-    is otherwise usually used for this type of operation.
-
-    """
-
-    def __missing__(self, key):
-        (ident, derived) = key.split(" ", 1)
-        anonymous_counter = self.get(derived, 1)
-        self[derived] = anonymous_counter + 1
-        value = derived + "_" + str(anonymous_counter)
-        self[key] = value
-        return value
-
-
 class SchemaEventTarget:
     """Base class for elements that are the targets of :class:`.DDLEvents`
     events.