status: prefer relative paths in Rust code
… when the repository root is under the current directory,
so the kernel needs to traverse fewer directory in every call
to `read_dir` or `symlink_metadata`.
Better yet would be to use libc functions like `openat` and `fstatat`
to remove such repeated traversals entirely, but the standard library
does not provide APIs based on those.
Maybe with a crate like https://crates.io/crates/openat instead?
Benchmarks of `rhg status` show that this patch is neutral in some configurations,
and makes the command up to ~20% faster in others.
Below is semi-arbitrary subset of results. The four numeric columns are:
time (in seconds) with this changeset’s parent, time with this changeset,
time difference (negative is better), time ratio (less than 1 is better).
```
mercurial-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.0061 -> 0.0059: -0.0002 (0.97)
mercurial-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0029 -> 0.0028: -0.0001 (0.97)
mozilla-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.2110 -> 0.2102: -0.0007 (1.00)
mozilla-dirstate-v2 | default-copies-clean.ignored.pbr | 0.0489 -> 0.0401: -0.0088 (0.82)
mozilla-dirstate-v2 | default-copies-clean.no-iu.pbr | 0.0479 -> 0.0393: -0.0085 (0.82)
mozilla-dirstate-v2 | default-copies-large.all.pbr | 0.1262 -> 0.1210: -0.0051 (0.96)
mozilla-dirstate-v2 | default-copies-small.ignored-unknown.pbr | 0.1262 -> 0.1200: -0.0062 (0.95)
mozilla-dirstate-v2 | default-copies-small.ignored.pbr | 0.0536 -> 0.0417: -0.0119 (0.78)
mozilla-dirstate-v2 | default-copies-small.no-iu.pbr | 0.0482 -> 0.0393: -0.0089 (0.81)
mozilla-dirstate-v2 | default-plain-clean.ignored.pbr | 0.0518 -> 0.0402: -0.0116 (0.78)
mozilla-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0481 -> 0.0392: -0.0088 (0.82)
mozilla-dirstate-v2 | default-plain-large.all.pbr | 0.1271 -> 0.1218: -0.0052 (0.96)
mozilla-dirstate-v2 | default-plain-small.ignored-unknown.pbr | 0.1225 -> 0.1202: -0.0022 (0.98)
mozilla-dirstate-v2 | default-plain-small.ignored.pbr | 0.0510 -> 0.0418: -0.0092 (0.82)
mozilla-dirstate-v2 | default-plain-small.no-iu.pbr | 0.0480 -> 0.0394: -0.0086 (0.82)
netbeans-dirstate-v1 | default-plain-clean.no-iu.pbr | 0.1442 -> 0.1422: -0.0020 (0.99)
netbeans-dirstate-v2 | default-plain-clean.no-iu.pbr | 0.0325 -> 0.0282: -0.0043 (0.87)
```
Differential Revision: https://phab.mercurial-scm.org/D12175
Tests of the file helper tool
$ f -h
?sage: f [options] [filenames] (glob)
?ptions: (glob)
-h, --help show this help message and exit
-t, --type show file type (file or directory)
-m, --mode show file mode
-l, --links show number of links
-s, --size show size of file
-n NEWER, --newer=NEWER
check if file is newer (or same)
-r, --recurse recurse into directories
-S, --sha1 show sha1 hash of the content
--sha256 show sha256 hash of the content
-M, --md5 show md5 hash of the content
-D, --dump dump file content
-H, --hexdump hexdump file content
-B BYTES, --bytes=BYTES
number of characters to dump
-L LINES, --lines=LINES
number of lines to dump
-q, --quiet no default output
$ mkdir dir
$ cd dir
$ f --size
size=0
$ echo hello | f --md5 --size
size=6, md5=b1946ac92492d2347c6235b4d2611184
$ f foo
foo: file not found
$ echo foo > foo
$ f foo
foo:
$ f --sha1 foo
foo: sha1=f1d2d2f924e986ac86fdf7b36c94bcdf32beec15
$ f --sha256 foo
foo: sha256=b5bb9d8014a0f9b1d61e21e796d78dccdf1352f23cd32812f4850b878ae4944c
#if symlink
$ f foo --mode
foo: mode=644
#endif
#if no-windows
$ "$PYTHON" $TESTDIR/seq.py 10 > bar
#else
Convert CRLF -> LF for consistency
$ "$PYTHON" $TESTDIR/seq.py 10 | sed "s/$//" > bar
#endif
#if unix-permissions symlink
$ chmod +x bar
$ f bar --newer foo --mode --type --size --dump --links --bytes 7
bar: file, size=21, mode=755, links=1, newer than foo
>>>
1
2
3
4
<<< no trailing newline
#endif
#if unix-permissions
$ ln bar baz
$ f bar -n baz -l --hexdump -t --sha1 --lines=9 -B 20
bar: file, links=2, newer than baz, sha1=612ca68d0305c821750a
0000: 31 0a 32 0a 33 0a 34 0a 35 0a 36 0a 37 0a 38 0a |1.2.3.4.5.6.7.8.|
0010: 39 0a |9.|
$ rm baz
#endif
#if unix-permissions symlink
$ ln -s yadda l
$ f . --recurse -MStmsB4
.: directory with 3 files, mode=755
./bar: file, size=21, mode=755, md5=3b03, sha1=612c
./foo: file, size=4, mode=644, md5=d3b0, sha1=f1d2
./l: link, size=5, md5=2faa, sha1=af93
#endif
$ f --quiet bar -DL 3
1
2
3
$ cd ..
Yadda is a symlink
$ f -qr dir -HB 17
dir: directory with 3 files (symlink !)
dir: directory with 2 files (no-symlink !)
dir/bar:
0000: 31 0a 32 0a 33 0a 34 0a 35 0a 36 0a 37 0a 38 0a |1.2.3.4.5.6.7.8.|
0010: 39 |9|
dir/foo:
0000: 66 6f 6f 0a |foo.|
dir/l: (symlink !)
0000: 79 61 64 64 61 |yadda| (symlink !)