view tests/test-subrepo-paths.t @ 47120:7109a38830c9

dirstate-tree: Fold "tracked descendants" counter update in main walk

For the purpose of implementing `has_tracked_dir` (which means "has tracked
descendants) without an expensive sub-tree traversal, we maintaing a counter
of tracked descendants on each "directory" node of the tree-shaped dirstate.

Before this changeset, mutating or inserting a node at a given path would
involve:

* Walking the tree from root through ancestors to find the node or the spot
  where to insert it
* Looking at the previous node if any to decide what counter update is needed
* Performing any node mutation
* Walking the tree *again* to update counters in ancestor nodes

When profiling `hg status` on a large repo, this second walk takes times
while loading a the dirstate from disk.

It turns out we have enough information to decide before he first tree walk
what counter update is needed. This changeset merges the two walks, gaining
~10% of the total time for `hg update` (in the same hyperfine benchmark as
the previous changeset).

---

Profiling was done by compiling with this `.cargo/config`:

    [profile.release]
    debug = true

then running with:

    py-spy record -r 500 -n -o /tmp/hg.json --format speedscope -- \
    ./hg status -R $REPO --config experimental.dirstate-tree.in-memory=1

then visualizing the recorded JSON file in https://www.speedscope.app/

Differential Revision: https://phab.mercurial-scm.org/D10554

  $ hg init outer
  $ cd outer

  $ echo '[paths]' >> .hg/hgrc
  $ echo 'default = http://example.net/' >> .hg/hgrc

hg debugsub with no remapping

  $ echo 'sub = libfoo' > .hgsub
  $ hg add .hgsub

  $ hg debugsub
  path sub
   source   libfoo
   revision 

hg debugsub with remapping

  $ echo '[subpaths]' >> .hg/hgrc
  $ printf 'http://example.net/lib(.*) = C:\\libs\\\\1-lib\\\n' >> .hg/hgrc

  $ hg debugsub
  path sub
   source   C:\libs\foo-lib\
   revision 

test cumulative remapping, the $HGRCPATH file is loaded first

  $ echo '[subpaths]' >> $HGRCPATH
  $ echo 'libfoo = libbar' >> $HGRCPATH
  $ hg debugsub
  path sub
   source   C:\libs\bar-lib\
   revision 

test absolute source path -- testing with a URL is important since
standard os.path.join wont treat that as an absolute path

  $ echo 'abs = http://example.net/abs' > .hgsub
  $ hg debugsub
  path abs
   source   http://example.net/abs
   revision 

  $ echo 'abs = /abs' > .hgsub
  $ hg debugsub
  path abs
   source   /abs
   revision 

test bad subpaths pattern

  $ cat > .hg/hgrc <<EOF
  > [subpaths]
  > .* = \1
  > EOF
  $ hg debugsub
  abort: bad subrepository pattern in $TESTTMP/outer/.hg/hgrc:2: invalid group reference* (glob)
  [255]

  $ cd ..