stream-clone: avoid opening a revlog in case we do not need it
Opening an revlog has a cost, especially if it is inline as we have to scan the
file and construct an index.
To prevent the associated slowdown, we just do a minimal scan to check that an
inline file is still inline, and simply stream the file without creating a
revlog when we can.
This provides a big boost compared to the previous changeset, even if the full
generation is still penalized by the initial gathering of information.
All benchmarks are run on linux with Python 3.10.7.
# benchmark.name = hg.exchange.stream.generate
# benchmark.variants.version = v2
### Compared to the previous changesets
We get a large win all across the board!
# mercurial-2018-08-01-zstd-sparse-revlog
before: 0.250694 seconds
after: 0.105986 seconds (-57.72%)
# pypy-2018-08-01-zstd-sparse-revlog
before: 3.885657 seconds
after: 1.709748 seconds (-56.00%)
# netbeans-2018-08-01-zstd-sparse-revlog
before: 16.679371 seconds
after: 7.687469 seconds (-53.91%)
# mozilla-central-2018-08-01-zstd-sparse-revlog
before: 38.575482 seconds
after: 17.520316 seconds (-54.58%)
# mozilla-try-2019-02-18-zstd-sparse-revlog
before: 81.160994 seconds
after: 37.073753 seconds (-54.32%)
### Compared to 6.4.3
We are still significantly slower than 6.4.3, the extra time is usually twice
slower than the extra time we observe on the locked section, which is a quite
interesting information.
Except for mercurial-central that is much faster. That discrepancy is not really
explained yet.
# mercurial-2018-08-01-zstd-sparse-revlog
6.4.3: 0.072560 seconds
after: 0.105986 seconds (+46.07%) (- 0.03 seconds)
# pypy-2018-08-01-zstd-sparse-revlog
6.4.3: 1.211193 seconds
after: 1.709748 seconds (+41.16%) (-0.45 seconds)
# netbeans-2018-08-01-zstd-sparse-revlog
6.4.3: 4.932843 seconds
after: 7.687469 seconds (+55.84%) (-2.75 seconds)
# mozilla-central-2018-08-01-zstd-sparse-revlog
6.4.3: 34.012226 seconds
after: 17.520316 seconds (-48.49%) (-16.49 seconds)
# mozilla-try-2019-02-18-zstd-sparse-revlog
6.4.3: 23.850555 seconds
after: 37.073753 seconds (+55.44%) (+13.22 seconds)
# Support code for event tracing in Mercurial. Lives in demandimport
# so it can also be used in demandimport.
#
# Copyright 2018 Google LLC.
#
# This software may be used and distributed according to the terms of the
# GNU General Public License version 2 or any later version.
import contextlib
import os
_pipe = None
_checked = False
_session = 'none'
def _isactive():
global _pipe, _session, _checked
if _pipe is None:
if _checked:
return False
_checked = True
if 'HGCATAPULTSERVERPIPE' not in os.environ:
return False
_pipe = open(os.environ['HGCATAPULTSERVERPIPE'], 'w', 1)
_session = os.environ.get('HGCATAPULTSESSION', 'none')
return True
@contextlib.contextmanager
def log(whencefmt, *whenceargs):
if not _isactive():
yield
return
whence = whencefmt % whenceargs
try:
# Both writes to the pipe are wrapped in try/except to ignore
# errors, as we can see mysterious errors in here if the pager
# is active. Presumably other conditions could trigger
# problems too.
try:
_pipe.write('START %s %s\n' % (_session, whence))
except IOError:
pass
yield
finally:
try:
_pipe.write('END %s %s\n' % (_session, whence))
except IOError:
pass
def counter(label, amount, *labelargs):
if not _isactive():
return
l = label % labelargs
# See above in log() for why this is in a try/except.
try:
_pipe.write('COUNTER %s %d %s\n' % (_session, amount, l))
except IOError:
pass