Performance improvement in Row

Various performance improvements to Row instanciation
- avoid passing processors if they are all None
- improve processor logic in cython
- improve tuplegetter using slices when contiguous indexes are used

Some timing follow.

In particular [base_]row_new_proc that tests using processors has
a 25% improvement compared to before in cython.
Looking at the [b]row_new_proc_none that test a list of processors
all None, this has 50% improvement in cython when passing the none list,
but in this patch it would usually be disabled by passing None, so the
performance gain is actually 90%, since it would run the case
[base_]row_new.

Tuplegetter is a bit faster in the single item get and when getting
sequential indexes (like indexes 1,2,3,4) at the cost of a bit
longer creation time in python, cython is mostly the same.

Current times
                    | python      | cython      | cy / py     |
base_row_new        | 0.639817400 | 0.118265500 | 0.184842582 |
row_new             | 0.680355100 | 0.129714600 | 0.190657202 |
base_row_new_proc   | 3.076538900 | 1.488428600 | 0.483799701 |
row_new_proc        | 3.119700100 | 1.532197500 | 0.491136151 |
brow_new_proc_none  | 1.917702300 | 0.475511500 | 0.247958977 |
row_new_proc_none   | 1.956253300 | 0.497803100 | 0.254467609 |

tuplegetter_one     | 0.152512600 | 0.148523900 | 0.973846751 |
tuplegetter_many    | 0.184394100 | 0.184511500 | 1.000636680 |
tuplegetter_seq     | 0.154832800 | 0.156270100 | 1.009282917 |
tuplegetter_new_one | 0.523730000 | 0.343402200 | 0.655685563 |
tuplegetter_new_many| 0.738924400 | 0.420961400 | 0.569694816 |
tuplegetter_new_seq | 1.062036900 | 0.495462000 | 0.466520514 |

Parent commit times
                    | python      | cython      | cy / py     |
base_row_new        | 0.643890800 | 0.113548300 | 0.176347138 |
row_new             | 0.674885900 | 0.124391800 | 0.184315304 |
base_row_new_proc   | 3.072020400 | 2.017367000 | 0.656690626 |
row_new_proc        | 3.109943400 | 2.048359400 | 0.658648450 |
brow_new_proc_none  | 1.967133700 | 1.006326000 | 0.511569702 |
row_new_proc_none   | 1.960814900 | 1.025217800 | 0.522852922 |

tuplegetter_one     | 0.197359900 | 0.205999000 | 1.043773330 |
tuplegetter_many    | 0.196575900 | 0.194888500 | 0.991416038 |
tuplegetter_seq     | 0.192723900 | 0.205635000 | 1.066992729 |
tuplegetter_new_one | 0.534644500 | 0.414311700 | 0.774929322 |
tuplegetter_new_many| 0.479376500 | 0.417448100 | 0.870814694 |
tuplegetter_new_seq | 0.481580200 | 0.412697900 | 0.856966088 |

Change-Id: I2ca1f49dca2beff625c283f1363c29c8ccc0c3f7

1 files changed, 27 insertions, 11 deletions

diff --git a/lib/sqlalchemy/cyextension/resultproxy.pyx b/lib/sqlalchemy/cyextension/resultproxy.pyx
index c358f043f..0d7eeece9 100644
--- a/lib/sqlalchemy/cyextension/resultproxy.pyx
+++ b/lib/sqlalchemy/cyextension/resultproxy.pyx
@@ -13,12 +13,7 @@ cdef class BaseRow:
         self._key_to_index = key_to_index
 
         if processors:
-            self._data = tuple(
-                [
-                    proc(value) if proc else value
-                    for proc, value in zip(processors, data)
-                ]
-            )
+            self._data = _apply_processors(processors, data)
         else:
             self._data = tuple(data)
 
@@ -64,6 +59,20 @@ cdef class BaseRow:
     def __getattr__(self, name):
         return self._get_by_key_impl(name, 1)
 
+    def _to_tuple_instance(self):
+        return self._data
+
+
+cdef tuple _apply_processors(proc, data):
+    res = []
+    for i in range(len(proc)):
+        p = proc[i]
+        if p is None:
+            res.append(data[i])
+        else:
+            res.append(p(data[i]))
+    return tuple(res)
+
 
 def rowproxy_reconstructor(cls, state):
     obj = cls.__new__(cls)
@@ -71,10 +80,17 @@ def rowproxy_reconstructor(cls, state):
     return obj
 
 
-def tuplegetter(*indexes):
-    it = operator.itemgetter(*indexes)
+cdef int is_contiguous(tuple indexes):
+    cdef int i
+    for i in range(1, len(indexes)):
+        if indexes[i-1] != indexes[i] -1:
+            return 0
+    return 1
+
 
-    if len(indexes) > 1:
-        return it
+def tuplegetter(*indexes):
+    if len(indexes) == 1 or is_contiguous(indexes) != 0:
+        # slice form is faster but returns a list if input is list
+        return operator.itemgetter(slice(indexes[0], indexes[-1] + 1))
     else:
-        return lambda row: (it(row),)
+        return operator.itemgetter(*indexes)