➜
This issue tracker has been migrated to GitHub,
and is currently read-only.
For more information,
see the GitHub FAQs in the Python's Developer Guide.
Created on 2022-02-24 12:43 by rumpelsepp, last changed 2022-04-11 14:59 by admin. This issue is now closed.
| Pull Requests | |||
|---|---|---|---|
| URL | Status | Linked | Edit |
| PR 31554 | closed | rumpelsepp, 2022-02-24 12:52 | |
| PR 31625 | merged | Dennis Sweeney, 2022-03-01 01:09 | |
| PR 31642 | merged | vstinner, 2022-03-02 10:34 | |
| Messages (7) | |||
|---|---|---|---|
| msg413902 - (view) | Author: Stefan Tatschner (rumpelsepp) * | Date: 2022-02-24 12:43 | |
The mmap.find() in function uses a naive loop to search string matches. This can be optimized “for free” by using libc's memmap(3) function instead. The relevant file is Modules/mmapmodule.c, the relevant function is mmap_gfind(). |
|||
| msg413903 - (view) | Author: Stefan Tatschner (rumpelsepp) * | Date: 2022-02-24 12:45 | |
Sorry, I mean memmem(3). :) |
|||
| msg413968 - (view) | Author: (benrg) | Date: 2022-02-25 07:14 | |
memmem isn't a standard C function, and some libraries don't have it, notably Microsoft's. newlib's memmem seems to be the same as glibc's, but is under a BSD 3-clause license instead of LGPL. An older version of newlib's memmem (prior to 2019-01-01) has the license "Permission to use, copy, modify, and distribute this software is freely granted, provided that this notice is preserved", and is still highly optimized and much better than a naive implementation. Of course, bundling it would no longer be quite so "free". Old newlib memmem: https://sourceware.org/git/?p=newlib-cygwin.git;a=blob_plain;f=newlib/libc/string/memmem.c;h=25704e467decff5971b34f4189ddfff04ac5fa8e New newlib memmem: https://sourceware.org/git/?p=newlib-cygwin.git;a=blob_plain;f=newlib/libc/string/memmem.c Helper file for both: https://sourceware.org/git/?p=newlib-cygwin.git;a=blob_plain;f=newlib/libc/string/str-two-way.h |
|||
| msg414237 - (view) | Author: Dennis Sweeney (Dennis Sweeney) *  |
Date: 2022-03-01 03:30 | |
PR 31625 is an alternative proposal. It uses the Crochemore and Perrin's Two-Way algorithm that @benrg references (see Objects/stringlib/fastsearch.h and Objects/stringlib/stringlib_find_two_way_notes.txt), and is platform-independent. |
|||
| msg414326 - (view) | Author: Dennis Sweeney (Dennis Sweeney) * |
Date: 2022-03-02 04:46 | |
New changeset 6ddb09f35b922a3bbb59e408a3ca7636a6938468 by Dennis Sweeney in branch 'main': bpo-46848: Use stringlib/fastsearch in mmap (GH-31625) https://github.com/python/cpython/commit/6ddb09f35b922a3bbb59e408a3ca7636a6938468 |
|||
| msg414327 - (view) | Author: Dennis Sweeney (Dennis Sweeney) * |
Date: 2022-03-02 04:49 | |
Thanks for the report! |
|||
| msg414342 - (view) | Author: STINNER Victor (vstinner) * |
Date: 2022-03-02 13:15 | |
New changeset b6b711a1aa233001c1874af1d920e459b6bf962c by Victor Stinner in branch 'main': bpo-46848: Move _PyBytes_Find() to internal C API (GH-31642) https://github.com/python/cpython/commit/b6b711a1aa233001c1874af1d920e459b6bf962c |
|||
| History | |||
|---|---|---|---|
| Date | User | Action | Args |
| 2022-04-11 14:59:56 | admin | set | github: 91004 |
| 2022-03-02 13:15:30 | vstinner | set | messages: + msg414342 |
| 2022-03-02 10:34:06 | vstinner | set | nosy:
+ vstinner pull_requests: + pull_request29762 |
| 2022-03-02 04:49:27 | Dennis Sweeney | set | status: open -> closed type: performance messages: + msg414327 resolution: fixed stage: patch review -> resolved |
| 2022-03-02 04:46:33 | Dennis Sweeney | set | messages: + msg414326 |
| 2022-03-01 03:30:19 | Dennis Sweeney | set | messages: + msg414237 |
| 2022-03-01 01:09:24 | Dennis Sweeney | set | nosy:
+ Dennis Sweeney pull_requests: + pull_request29749 |
| 2022-02-25 07:14:36 | benrg | set | nosy:
+ benrg messages: + msg413968 |
| 2022-02-24 12:52:28 | rumpelsepp | set | keywords:
+ patch stage: patch review pull_requests: + pull_request29675 |
| 2022-02-24 12:45:31 | rumpelsepp | set | messages: + msg413903 |
| 2022-02-24 12:43:50 | rumpelsepp | create | |