gh-91539: improve performance of get_proxies_environment (#91566)

* improve performance of get_proxies_environment when there are many environment variables * 📜🤖 Added by blurb_it. * fix case of short env name * fix formatting * fix whitespace * whitespace * Update Lib/urllib/request.py Co-authored-by: Carl Meyer <[email protected]> * Update Lib/urllib/request.py Co-authored-by: Carl Meyer <[email protected]> * Update Lib/urllib/request.py Co-authored-by: Carl Meyer <[email protected]> * Update Lib/urllib/request.py Co-authored-by: Carl Meyer <[email protected]> * whitespace * Update Misc/NEWS.d/next/Library/2022-04-15-11-29-38.gh-issue-91539.7WgVuA.rst Co-authored-by: Carl Meyer <[email protected]> * Update Lib/urllib/request.py Co-authored-by: Carl Meyer <[email protected]> Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com> Co-authored-by: Carl Meyer <[email protected]>
python · Oct 5, 2022 · aeb28f5 · aeb28f5
1 parent 9442105
commit aeb28f5
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Showing 2 changed files with 17 additions and 10 deletions.
diff --git a/Lib/urllib/request.py b/Lib/urllib/request.py
@@ -2508,28 +2508,34 @@ def getproxies_environment():
     this seems to be the standard convention.  If you need a
     different way, you can pass a proxies dictionary to the
     [Fancy]URLopener constructor.
-
     """
- proxies = {}
  # in order to prefer lowercase variables, process environment in
  # two passes: first matches any, second pass matches lowercase only
- for name, value in os.environ.items():
- name = name.lower()
- if value and name[-6:] == '_proxy':
- proxies[name[:-6]] = value
+
+ # select only environment variables which end in (after making lowercase) _proxy
+ proxies = {}
+ environment = []
+ for name in os.environ.keys():
+ # fast screen underscore position before more expensive case-folding
+ if len(name) > 5 and name[-6] == "_" and name[-5:].lower() == "proxy":
+ value = os.environ[name]
+ proxy_name = name[:-6].lower()
+ environment.append((name, value, proxy_name))
+ if value:
+ proxies[proxy_name] = value
  # CVE-2016-1000110 - If we are running as CGI script, forget HTTP_PROXY
  # (non-all-lowercase) as it may be set from the web server by a "Proxy:"
  # header from the client
  # If "proxy" is lowercase, it will still be used thanks to the next block
  if 'REQUEST_METHOD' in os.environ:
  proxies.pop('http', None)
- for name, value in os.environ.items():
+ for name, value, proxy_name in environment:
+ # not case-folded, checking here for lower-case env vars only
  if name[-6:] == '_proxy':
- name = name.lower()
  if value:
- proxies[name[:-6]] = value
+ proxies[proxy_name] = value
  else:
- proxies.pop(name[:-6], None)
+ proxies.pop(proxy_name, None)
  return proxies
 
 def proxy_bypass_environment(host, proxies=None):

diff --git a/Misc/NEWS.d/next/Library/2022-04-15-11-29-38.gh-issue-91539.7WgVuA.rst b/Misc/NEWS.d/next/Library/2022-04-15-11-29-38.gh-issue-91539.7WgVuA.rst
@@ -0,0 +1 @@
+Improve performance of ``urllib.request.getproxies_environment`` when there are many environment variables