Mercurial > hg
view tests/test-issue1993.t @ 30418:1156ec81f709
util: improve iterfile so it chooses code path wisely
We have performance concerns on "iterfile" as it is 4X slower on normal
files. While modern systems have the nice property that reading a "fast"
(on-disk) file cannot be interrupted and should be made use of.
This patch dumps the related knowledge in comments. And "iterfile" chooses
code paths wisely:
1. If it's CPython 3, or PyPY, use the fast path.
2. If fp is a normal file, use the fast path.
3. If fp is not a normal file and CPython version >= 2.7.4, use the same
workaround (4x slower) as before.
4. If fp is not a normal file and CPython version < 2.7.4, use another
workaround (2x slower but may block longer then necessary) which
basically re-invents the buffer + readline logic in Python.
This will give us good confidence on both correctness and performance
dealing with EINTR in iterfile(fp) for all known supported Python versions.
author | Jun Wu <quark@fb.com> |
---|---|
date | Tue, 15 Nov 2016 20:25:51 +0000 |
parents | 4591cd6b6794 |
children |
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$ hg init a $ cd a $ echo a > a $ hg ci -Am0 adding a $ echo b > b $ hg ci -Am1 adding b $ hg tag -r0 default warning: tag default conflicts with existing branch name $ hg log changeset: 2:30a83d1e4a1e tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: Added tag default for changeset f7b1eb17ad24 changeset: 1:925d80f479bb user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: 1 changeset: 0:f7b1eb17ad24 tag: default user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: 0 $ hg update 'tag(default)' 0 files updated, 0 files merged, 2 files removed, 0 files unresolved $ hg parents changeset: 0:f7b1eb17ad24 tag: default user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: 0 $ hg update 'branch(default)' 2 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg parents changeset: 2:30a83d1e4a1e tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: Added tag default for changeset f7b1eb17ad24 $ cd ..