Mercurial > hg
view tests/test-basic.t @ 27475:a2e2a8fa5fd1
revlog: avoid string slice when decompressing u* chunks
Revlog chunks can be stored uncompressed. If the first byte of the
raw data is \0, we store the data as is. Else we prefix it with 'u'.
Before, we performed a string slice to strip out the 'u' prefix.
With this patch, we use a buffer to avoid an extra memory copy and
associated garbage collection overhead.
I was unable to verify any performance impact of this patch. For both
mozilla-central and the hg repos, the number of manifest revisions
with 'u' prefixes is very small - under 1%. So this change likely
isn't called enough to have an impact on manifest reading. However,
the reasoning behind this change is solid, so it should be safe.
author | Gregory Szorc <gregory.szorc@gmail.com> |
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date | Sun, 20 Dec 2015 16:00:27 -0800 |
parents | 8f88f768e24c |
children | 3aa50c9d89a0 |
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Create a repository: $ hg config defaults.backout=-d "0 0" defaults.commit=-d "0 0" defaults.shelve=--date "0 0" defaults.tag=-d "0 0" devel.all-warnings=true largefiles.usercache=$TESTTMP/.cache/largefiles (glob) ui.slash=True ui.interactive=False ui.mergemarkers=detailed ui.promptecho=True $ hg init t $ cd t Make a changeset: $ echo a > a $ hg add a $ hg commit -m test This command is ancient: $ hg history changeset: 0:acb14030fe0a tag: tip user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: test Verify that updating to revision 0 via commands.update() works properly $ cat <<EOF > update_to_rev0.py > from mercurial import ui, hg, commands > myui = ui.ui() > repo = hg.repository(myui, path='.') > commands.update(myui, repo, rev=0) > EOF $ hg up null 0 files updated, 0 files merged, 1 files removed, 0 files unresolved $ python ./update_to_rev0.py 1 files updated, 0 files merged, 0 files removed, 0 files unresolved $ hg identify -n 0 Poke around at hashes: $ hg manifest --debug b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3 644 a $ hg cat a a Verify should succeed: $ hg verify checking changesets checking manifests crosschecking files in changesets and manifests checking files 1 files, 1 changesets, 1 total revisions At the end... $ cd ..