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

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  $ hg init

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  $ mkdir alpha

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  $ touch alpha/one

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  $ mkdir beta

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  $ touch beta/two

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  $ hg add alpha/one beta/two

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  $ hg ci -m "start"

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  $ echo 1 > alpha/one

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  $ echo 2 > beta/two

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everything

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  $ hg diff --nodates

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  diff -r 7d5ef1aea329 alpha/one

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  --- a/alpha/one

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  +++ b/alpha/one

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  @@ -0,0 +1,1 @@

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  +1

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  diff -r 7d5ef1aea329 beta/two

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  --- a/beta/two

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  +++ b/beta/two

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  @@ -0,0 +1,1 @@

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  +2

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beta only

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  $ hg diff --nodates beta

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  diff -r 7d5ef1aea329 beta/two

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  --- a/beta/two

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  +++ b/beta/two

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  @@ -0,0 +1,1 @@

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  +2

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inside beta

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  $ cd beta

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  $ hg diff --nodates .

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  diff -r 7d5ef1aea329 beta/two

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  --- a/beta/two

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  +++ b/beta/two

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  @@ -0,0 +1,1 @@

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  +2

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relative to beta

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  $ cd ..

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  $ hg diff --nodates --root beta

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  diff -r 7d5ef1aea329 two

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  --- a/two

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  +++ b/two

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  @@ -0,0 +1,1 @@

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  +2

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inside beta

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  $ cd beta

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  $ hg diff --nodates --root .

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  diff -r 7d5ef1aea329 two

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  --- a/two

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  +++ b/two

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  @@ -0,0 +1,1 @@

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  +2

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  $ cd ..