bundle2: avoid unbound read when seeking
Currently, seekableunbundlepart.seek() will perform a read() during
seek operations. This will allocate a buffer to hold the raw data
over the seek distance. This can lead to very large allocations
and cause performance to suffer.
We change the code to perform read(32768) in a loop to avoid
potentially large allocations.
`hg perfbundleread` on an uncompressed Firefox bundle reveals
a performance impact:
! bundle2 iterparts()
! wall 2.992605 comb 2.990000 user 2.260000 sys 0.730000 (best of 4)
! bundle2 iterparts() seekable
! wall 3.863810 comb 3.860000 user 3.000000 sys 0.860000 (best of 3)
! bundle2 part seek()
! wall 6.213387 comb 6.200000 user 3.350000 sys 2.850000 (best of 3)
! wall 3.820347 comb 3.810000 user 2.980000 sys 0.830000 (best of 3)
Since seekable bundle parts are (only) used by bundlerepo, this /may/
speed up initial loading of bundle-based repos. But any improvement
will likely only be noticed on very large bundles.
Differential Revision: https://phab.mercurial-scm.org/D1394
#require test-repo
$ . "$TESTDIR/helpers-testrepo.sh"
$ check_code="$TESTDIR"/../contrib/check-code.py
$ cd "$TESTDIR"/..
New errors are not allowed. Warnings are strongly discouraged.
(The writing "no-che?k-code" is for not skipping this file when checking.)
$ testrepohg locate \
> -X contrib/python-zstandard \
> -X hgext/fsmonitor/pywatchman \
> -X mercurial/thirdparty \
> | sed 's-\\-/-g' | "$check_code" --warnings --per-file=0 - || false
Skipping i18n/polib.py it has no-che?k-code (glob)
Skipping mercurial/httpclient/__init__.py it has no-che?k-code (glob)
Skipping mercurial/httpclient/_readers.py it has no-che?k-code (glob)
Skipping mercurial/selectors2.py it has no-che?k-code (glob)
Skipping mercurial/statprof.py it has no-che?k-code (glob)
Skipping tests/badserverext.py it has no-che?k-code (glob)
@commands in debugcommands.py should be in alphabetical order.
>>> import re
>>> commands = []
>>> with open('mercurial/debugcommands.py', 'rb') as fh:
... for line in fh:
... m = re.match("^@command\('([a-z]+)", line)
... if m:
... commands.append(m.group(1))
>>> scommands = list(sorted(commands))
>>> for i, command in enumerate(scommands):
... if command != commands[i]:
... print('commands in debugcommands.py not sorted; first differing '
... 'command is %s; expected %s' % (commands[i], command))
... break
Prevent adding new files in the root directory accidentally.
$ testrepohg files 'glob:*'
.arcconfig
.clang-format
.editorconfig
.hgignore
.hgsigs
.hgtags
CONTRIBUTING
CONTRIBUTORS
COPYING
Makefile
README.rst
hg
hgeditor
hgweb.cgi
setup.py