[Python-checkins] cpython: Issue #18810: Be optimistic with stat calls when seeing if a directory
brett.cannon
python-checkins at python.org
Fri Oct 18 19:24:23 CEST 2013
http://hg.python.org/cpython/rev/11f2f4af1979
changeset: 86444:11f2f4af1979
user: Brett Cannon <brett at python.org>
date: Fri Oct 18 13:24:13 2013 -0400
summary:
Issue #18810: Be optimistic with stat calls when seeing if a directory
exists when checking for a package.
Before there was an isdir check and then various isfile checks for
possible __init__ files when looking for a package.
This change drops the isdir check by leaning
on the assumption that a directory will not contain something named
after the module being imported which is not a directory. If the module
is a package then it saves a stat call. If there is nothing in the
directory with the potential package name it also saves a stat call.
Only if there is something in the directory named the same thing as
the potential package will the number of stat calls increase
(due to more wasteful __init__ checks).
Semantically there is no change as the isdir check moved
down so that namespace packages continue to have no chance of
accidentally collecting non-existent directories.
files:
Lib/importlib/_bootstrap.py | 19 +-
Python/importlib.h | 1537 +++++++++++-----------
2 files changed, 777 insertions(+), 779 deletions(-)
diff --git a/Lib/importlib/_bootstrap.py b/Lib/importlib/_bootstrap.py
--- a/Lib/importlib/_bootstrap.py
+++ b/Lib/importlib/_bootstrap.py
@@ -1406,16 +1406,15 @@
# Check if the module is the name of a directory (and thus a package).
if cache_module in cache:
base_path = _path_join(self.path, tail_module)
- if _path_isdir(base_path):
- for suffix, loader in self._loaders:
- init_filename = '__init__' + suffix
- full_path = _path_join(base_path, init_filename)
- if _path_isfile(full_path):
- return (loader(fullname, full_path), [base_path])
- else:
- # A namespace package, return the path if we don't also
- # find a module in the next section.
- is_namespace = True
+ for suffix, loader in self._loaders:
+ init_filename = '__init__' + suffix
+ full_path = _path_join(base_path, init_filename)
+ if _path_isfile(full_path):
+ return (loader(fullname, full_path), [base_path])
+ else:
+ # If a namespace package, return the path if we don't
+ # find a module in the next section.
+ is_namespace = _path_isdir(base_path)
# Check for a file w/ a proper suffix exists.
for suffix, loader in self._loaders:
full_path = _path_join(self.path, tail_module + suffix)
diff --git a/Python/importlib.h b/Python/importlib.h
--- a/Python/importlib.h
+++ b/Python/importlib.h
[stripped]
--
Repository URL: http://hg.python.org/cpython
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