[PATCH 1/3] Add caching to catpkgsplit function

According to cProfile, catpkgsplit is called up to 1-5.5 million times
during "emerge -uDvpU --with-bdeps=y @world". Adding a dict to cache its
results reduces the time for this command from 43.53 -> 41.53 seconds --
a 4.8% speedup.
---
 lib/portage/versions.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/lib/portage/versions.py b/lib/portage/versions.py
index 0c21373cc..ffec316ce 100644
--- a/lib/portage/versions.py
+++ b/lib/portage/versions.py
@@ -312,6 +312,7 @@ def _pkgsplit(mypkg, eapi=None):
 
 _cat_re = re.compile('^%s$' % _cat, re.UNICODE)
 _missing_cat = 'null'
+_catpkgsplit_cache = {}
 
 def catpkgsplit(mydata, silent=1, eapi=None):
 	"""
@@ -331,6 +332,11 @@ def catpkgsplit(mydata, silent=1, eapi=None):
 		return mydata.cpv_split
 	except AttributeError:
 		pass
+
+	cache_entry = _catpkgsplit_cache.get(mydata)
+	if cache_entry is not None:
+		return cache_entry
+
 	mysplit = mydata.split('/', 1)
 	p_split = None
 	if len(mysplit) == 1:
@@ -343,6 +349,7 @@ def catpkgsplit(mydata, silent=1, eapi=None):
 	if not p_split:
 		return None
 	retval = (cat, p_split[0], p_split[1], p_split[2])
+	_catpkgsplit_cache[mydata] = retval
 	return retval
 
 class _pkg_str(_unicode):
-- 
2.27.0.212.ge8ba1cc988-goog