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

#require reporevlogstore

  $ CONTRIBDIR="$TESTDIR/../contrib"

  $ hg init repo-a
  $ cd repo-a

  $ echo this is file a > a
  $ hg add a
  $ hg commit -m first

  $ echo adding to file a >> a
  $ hg commit -m second

  $ echo adding more to file a >> a
  $ hg commit -m third
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 3 changesets with 3 changes to 1 files

Dumping revlog of file a to stdout:
  $ "$PYTHON" "$CONTRIBDIR/dumprevlog" .hg/store/data/a.i
  file: .hg/store/data/a.i
  node: 183d2312b35066fb6b3b449b84efc370d50993d0
  linkrev: 0
  parents: 0000000000000000000000000000000000000000 0000000000000000000000000000000000000000
  length: 15
  -start-
  this is file a
  
  -end-
  node: b1047953b6e6b633c0d8197eaa5116fbdfd3095b
  linkrev: 1
  parents: 183d2312b35066fb6b3b449b84efc370d50993d0 0000000000000000000000000000000000000000
  length: 32
  -start-
  this is file a
  adding to file a
  
  -end-
  node: 8c4fd1f7129b8cdec6c7f58bf48fb5237a4030c1
  linkrev: 2
  parents: b1047953b6e6b633c0d8197eaa5116fbdfd3095b 0000000000000000000000000000000000000000
  length: 54
  -start-
  this is file a
  adding to file a
  adding more to file a
  
  -end-

Dump all revlogs to file repo.dump:

  $ find .hg/store -name "*.i" | sort | xargs "$PYTHON" "$CONTRIBDIR/dumprevlog" > ../repo.dump
  $ cd ..

Undumping into repo-b:

  $ hg init repo-b
  $ cd repo-b
  $ "$PYTHON" "$CONTRIBDIR/undumprevlog" < ../repo.dump
  .hg/store/00changelog.i
  .hg/store/00manifest.i
  .hg/store/data/a.i
  $ cd ..

Rebuild fncache with clone --pull:

  $ hg clone --pull -U repo-b repo-c
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files
  new changesets de1da620e7d8:46946d278c50

Verify:

  $ hg -R repo-c verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 3 changesets with 3 changes to 1 files

Compare repos:

  $ hg -R repo-c incoming repo-a
  comparing with repo-a
  searching for changes
  no changes found
  [1]

  $ hg -R repo-a incoming repo-c
  comparing with repo-c
  searching for changes
  no changes found
  [1]