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Differential D517

journal: do not use atomictemp
ClosedPublic

Authored by quark on Aug 25 2017, 12:42 AM.

Details

Reviewers
yuja
Group Reviewers
hg-reviewers
Commits
rHGe6d421566906: journal: do not use atomictemp (issue5338)
Summary

Writing journal files using atomictemp leads to quadratic performance that
could be problematic if automation runs many commands. Other logs like
blackbox does not use atomictemp, and journal logs are not critical for repo
correctness. So let's make them non-atomictemp.

Diff Detail

Repository
rHG Mercurial
Lint
Automatic diff as part of commit; lint not applicable.
Unit
Automatic diff as part of commit; unit tests not applicable.

Event Timeline

quark created this revision.Aug 25 2017, 12:42 AM
quark edited the summary of this revision. (Show Details)Aug 25 2017, 12:44 AM
yuja accepted this revision.Aug 25 2017, 10:34 AM
yuja added a subscriber: yuja.

Flagged as (issue5338) and queued, thanks.

This revision is now accepted and ready to land.Aug 25 2017, 10:34 AM
Closed by commit rHGe6d421566906: journal: do not use atomictemp (issue5338) (authored by quark). · Explain WhyAug 25 2017, 11:25 AM
This revision was automatically updated to reflect the committed changes.

Revision Contents
Changeset List

PathPackages
Mhgext/journal.py (2 lines)

Diff 1293

hgext/journal.py

vfs = self.sharedvfs vfs = self.sharedvfs
self._write(vfs, entry) self._write(vfs, entry)
def _write(self, vfs, entry): def _write(self, vfs, entry):
with self.jlock(vfs): with self.jlock(vfs):
version = None version = None
# open file in amend mode to ensure it is created if missing # open file in amend mode to ensure it is created if missing
with vfs('namejournal', mode='a+b', atomictemp=True) as f: with vfs('namejournal', mode='a+b') as f:
f.seek(0, os.SEEK_SET) f.seek(0, os.SEEK_SET)
# Read just enough bytes to get a version number (up to 2 # Read just enough bytes to get a version number (up to 2
# digits plus separator) # digits plus separator)
version = f.read(3).partition('\0')[0] version = f.read(3).partition('\0')[0]
if version and version != str(storageversion): if version and version != str(storageversion):
# different version of the storage. Exit early (and not # different version of the storage. Exit early (and not
# write anything) if this is not a version we can handle or # write anything) if this is not a version we can handle or
# the file is corrupt. In future, perhaps rotate the file # the file is corrupt. In future, perhaps rotate the file