update: add a Rust fast-path when updating from null (and clean)
This case is easy to detect and we have all we need to generate a valid
working copy and dirstate entirely in Rust, which speeds things up
considerably:
On my machine updating a repo of ~300k files goes from 10.00s down to 4.2s,
all while consuming 50% less system time, with all caches hot.
Something to note is that further improvements will probably happen
with the upcoming `InnerRevlog` series that does smarter
mmap hanlding, especially for filelogs.
Here are benchmark numbers on a machine with only 4 cores (and no SMT enabled)
```
### data-env-vars.name = heptapod-public-2024-03-25-ds2-pnm
# benchmark.name = hg.command.update
# bin-env-vars.hg.py-re2-module = default
# bin-env-vars.hg.changeset.node = <this change>
# benchmark.variants.atomic-update = no
# benchmark.variants.scenario = null-to-tip
# benchmark.variants.worker = default
default: 5.328762 ~~~~~
rust: 1.308654 (-75.44%, -4.02)
### data-env-vars.name = mercurial-devel-2024-03-22-ds2-pnm
# benchmark.name = hg.command.update
# bin-env-vars.hg.py-re2-module = default
# bin-env-vars.hg.changeset.node = <this change>
# benchmark.variants.atomic-update = no
# benchmark.variants.scenario = null-to-tip
# benchmark.variants.worker = default
default: 1.693271 ~~~~~
rust: 1.151053 (-32.02%, -0.54)
### data-env-vars.name = mozilla-unified-2024-03-22-ds2-pnm
# benchmark.name = hg.command.update
# bin-env-vars.hg.py-re2-module = default
# bin-env-vars.hg.changeset.node = <this change>
# benchmark.variants.atomic-update = no
# benchmark.variants.scenario = null-to-tip
# benchmark.variants.worker = default
default: 38.901613 ~~~~~
rust: 11.637880 (-70.08%, -27.26)
### data-env-vars.name = netbsd-xsrc-public-2024-09-19-ds2-pnm
# benchmark.name = hg.command.update
# bin-env-vars.hg.py-re2-module = default
# bin-env-vars.hg.changeset.node = <this change>
# benchmark.variants.atomic-update = no
# benchmark.variants.scenario = null-to-tip
# benchmark.variants.worker = default
default: 4.793727 ~~~~~
rust: 1.505905 (-68.59%, -3.29)
```
Path conflict checking is currently disabled by default because of issue5716.
Turn it on for this test.
$ cat >> $HGRCPATH << EOF
> [experimental]
> merge.checkpathconflicts=True
> EOF
$ hg init repo
$ cd repo
$ echo base > base
$ hg add base
$ hg commit -m "base"
$ hg bookmark -i base
$ mkdir a
$ echo 1 > a/b
$ hg add a/b
$ hg commit -m "file"
$ hg bookmark -i file
$ echo 2 > a/b
$ hg commit -m "file2"
$ hg bookmark -i file2
$ hg up 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ mkdir a
#if symlink
$ ln -s c a/b
#else
$ touch a/b
#endif
$ hg add a/b
$ hg commit -m "link"
created new head
$ hg bookmark -i link
$ hg up 0
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ mkdir -p a/b/c
$ echo 2 > a/b/c/d
$ hg add a/b/c/d
$ hg commit -m "dir"
created new head
$ hg bookmark -i dir
Update - local file conflicts with remote directory:
$ hg up -q 0
$ mkdir a
$ echo 9 > a/b
$ hg up dir
a/b: untracked file conflicts with directory
abort: untracked files in working directory differ from files in requested revision
[20]
$ hg up dir --config merge.checkunknown=warn
a/b: replacing untracked file
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(activating bookmark dir)
$ cat a/b.orig
9
$ rm a/b.orig
Update - local symlink conflicts with remote directory:
$ hg up -q 0
$ mkdir a
#if symlink
$ ln -s x a/b
#else
$ touch a/b
#endif
$ hg up dir
a/b: untracked file conflicts with directory
abort: untracked files in working directory differ from files in requested revision
[20]
$ hg up dir --config merge.checkunknown=warn
a/b: replacing untracked file
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(activating bookmark dir)
#if symlink
$ readlink.py a/b.orig
a/b.orig -> x
#endif
$ rm a/b.orig
Update - local directory conflicts with remote file
$ hg up -q 0
$ mkdir -p a/b/c
$ echo 9 > a/b/c/d
$ hg up file
a/b: untracked directory conflicts with file
abort: untracked files in working directory differ from files in requested revision
[20]
$ hg up file --config merge.checkunknown=warn
a/b: replacing untracked files in directory
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(activating bookmark file)
$ cat a/b
1
$ test -d a/b.orig
$ rm -rf a/b.orig
Update - local directory conflicts with remote symlink
$ hg up -q 0
$ mkdir -p a/b/c
$ echo 9 > a/b/c/d
$ hg up link
a/b: untracked directory conflicts with file
abort: untracked files in working directory differ from files in requested revision
[20]
$ hg up link --config merge.checkunknown=warn
a/b: replacing untracked files in directory
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(activating bookmark link)
#if symlink
$ readlink.py a/b
a/b -> c
#endif
$ test -d a/b.orig
$ rm -rf a/b.orig
Update - local renamed file conflicts with remote directory
$ hg up -q 0
$ hg mv base a
$ hg status -C
A a
base
R base
$ hg up --check dir
abort: uncommitted changes
[20]
$ hg up dir
a: path conflict - a file or link has the same name as a directory
the local file has been renamed to a~d20a80d4def3
resolve manually then use 'hg resolve --mark a'
1 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges
(activating bookmark dir)
[1]
$ hg status -C
A a~d20a80d4def3
base
R base
$ hg resolve --list
P a
$ hg up --clean -q 0
Update clean - local directory conflicts with changed remote file
$ hg up -q file
$ rm a/b
$ mkdir a/b
$ echo 9 > a/b/c
$ hg up file2 --check --config merge.checkunknown=warn
abort: uncommitted changes
[20]
$ hg up file2 --clean
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(activating bookmark file2)