Mercurial > hg
view tests/test-custom-filters.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 | 56b2bcea2529 |
children | 6e713711331b |
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$ hg init $ cat > .hg/hgrc <<EOF > [extensions] > prefixfilter = prefix.py > [encode] > *.txt = stripprefix: Copyright 2046, The Masters > [decode] > *.txt = insertprefix: Copyright 2046, The Masters > EOF $ cat > prefix.py <<EOF > from mercurial import error > def stripprefix(s, cmd, filename, **kwargs): > header = '%s\n' % cmd > if s[:len(header)] != header: > raise error.Abort('missing header "%s" in %s' % (cmd, filename)) > return s[len(header):] > def insertprefix(s, cmd): > return '%s\n%s' % (cmd, s) > def reposetup(ui, repo): > repo.adddatafilter('stripprefix:', stripprefix) > repo.adddatafilter('insertprefix:', insertprefix) > EOF $ cat > .hgignore <<EOF > .hgignore > prefix.py > prefix.pyc > EOF $ cat > stuff.txt <<EOF > Copyright 2046, The Masters > Some stuff to ponder very carefully. > EOF $ hg add stuff.txt $ hg ci -m stuff Repository data: $ hg cat stuff.txt Some stuff to ponder very carefully. Fresh checkout: $ rm stuff.txt $ hg up -C 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ cat stuff.txt Copyright 2046, The Masters Some stuff to ponder very carefully. $ echo "Very very carefully." >> stuff.txt $ hg stat M stuff.txt $ echo "Unauthorized material subject to destruction." > morestuff.txt Problem encoding: $ hg add morestuff.txt $ hg ci -m morestuff abort: missing header "Copyright 2046, The Masters" in morestuff.txt [255] $ hg stat M stuff.txt A morestuff.txt