tags-cache: directly perform a monimal walk for hgtagsfnodescache warming
We do something narrower than the path retrieving data. So lets use dedicated
code instead.
This provides further useful speedup:
### data-env-vars.name = mozilla-try-2023-03-22-zstd-sparse-revlog
# benchmark.name = hg.debug.debug-update-cache
# bin-env-vars.hg.flavor = default
# bin-env-vars.hg.py-re2-module = default
# benchmark.variants.pre-state = warm
before-this-series: 19.947581
skip-fnode-filter: 18.916804 (-5.17%, -1.03)
use-rev-num: 17.493725 (-12.30%, -2.45)
this-changesets: 15.919466 (-20.19%, -4.03)
$ cat <<EOF >> $HGRCPATH
> [extensions]
> purge =
> EOF
$ hg init test
$ cd test
$ echo a > changed
$ echo a > removed
$ echo a > source
$ hg ci -Am addfiles
adding changed
adding removed
adding source
$ echo a >> changed
$ echo a > added
$ hg add added
$ hg rm removed
$ hg cp source copied
$ hg diff --git > ../unknown.diff
Test adding on top of an unknown file
$ hg up -qC 0
$ hg purge
$ echo a > added
$ hg import --no-commit ../unknown.diff
applying ../unknown.diff
file added already exists
1 out of 1 hunks FAILED -- saving rejects to file added.rej
abort: patch failed to apply
[20]
Test modifying an unknown file
$ hg revert -aq
$ hg purge
$ hg rm changed
$ hg ci -m removechanged
$ echo a > changed
$ hg import --no-commit ../unknown.diff
applying ../unknown.diff
abort: cannot patch changed: file is not tracked
[20]
Test removing an unknown file
$ hg up -qC 0
$ hg purge
$ hg rm removed
$ hg ci -m removeremoved
created new head
$ echo a > removed
$ hg import --no-commit ../unknown.diff
applying ../unknown.diff
abort: cannot patch removed: file is not tracked
[20]
Test copying onto an unknown file
$ hg up -qC 0
$ hg purge
$ echo a > copied
$ hg import --no-commit ../unknown.diff
applying ../unknown.diff
abort: cannot create copied: destination already exists
[20]
$ cd ..