[Python-checkins] cpython: Add a spacing saving heuristic to deque's extend methods
raymond.hettinger
python-checkins at python.org
Tue Jul 9 09:13:31 CEST 2013
http://hg.python.org/cpython/rev/904399fae081
changeset: 84524:904399fae081
user: Raymond Hettinger <python at rcn.com>
date: Tue Jul 09 00:13:21 2013 -0700
summary:
Add a spacing saving heuristic to deque's extend methods
files:
Lib/test/test_deque.py | 4 ++--
Modules/_collectionsmodule.c | 16 ++++++++++++++++
2 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/Lib/test/test_deque.py b/Lib/test/test_deque.py
--- a/Lib/test/test_deque.py
+++ b/Lib/test/test_deque.py
@@ -543,8 +543,8 @@
check = self.check_sizeof
check(deque(), basesize + blocksize)
check(deque('a'), basesize + blocksize)
- check(deque('a' * (BLOCKLEN // 2)), basesize + blocksize)
- check(deque('a' * (BLOCKLEN // 2 + 1)), basesize + 2 * blocksize)
+ check(deque('a' * (BLOCKLEN - 1)), basesize + blocksize)
+ check(deque('a' * BLOCKLEN), basesize + 2 * blocksize)
check(deque('a' * (42 * BLOCKLEN)), basesize + 43 * blocksize)
class TestVariousIteratorArgs(unittest.TestCase):
diff --git a/Modules/_collectionsmodule.c b/Modules/_collectionsmodule.c
--- a/Modules/_collectionsmodule.c
+++ b/Modules/_collectionsmodule.c
@@ -332,6 +332,14 @@
return result;
}
+ /* Space saving heuristic. Start filling from the left */
+ if (Py_SIZE(deque) == 0) {
+ assert(deque->leftblock == deque->rightblock);
+ assert(deque->leftindex == deque->rightindex+1);
+ deque->leftindex = 1;
+ deque->rightindex = 0;
+ }
+
it = PyObject_GetIter(iterable);
if (it == NULL)
return NULL;
@@ -385,6 +393,14 @@
return result;
}
+ /* Space saving heuristic. Start filling from the right */
+ if (Py_SIZE(deque) == 0) {
+ assert(deque->leftblock == deque->rightblock);
+ assert(deque->leftindex == deque->rightindex+1);
+ deque->leftindex = BLOCKLEN - 1;
+ deque->rightindex = BLOCKLEN - 2;
+ }
+
it = PyObject_GetIter(iterable);
if (it == NULL)
return NULL;
--
Repository URL: http://hg.python.org/cpython
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