view tests/test-convert-authormap.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

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > convert=
  > EOF

Prepare orig repo

  $ hg init orig
  $ cd orig
  $ echo foo > foo
  $ HGUSER='user name' hg ci -qAm 'foo'
  $ cd ..

Explicit --authors

  $ cat > authormap.txt <<EOF
  > user name = Long User Name
  > 
  > # comment
  > this line is ignored
  > EOF
  $ hg convert --authors authormap.txt orig new
  initializing destination new repository
  ignoring bad line in author map file authormap.txt: this line is ignored
  scanning source...
  sorting...
  converting...
  0 foo
  writing author map file $TESTTMP/new/.hg/authormap
  $ cat new/.hg/authormap
  user name=Long User Name
  $ hg -Rnew log
  changeset:   0:d89716e88087
  tag:         tip
  user:        Long User Name
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     foo
  
  $ rm -rf new

Implicit .hg/authormap

  $ hg init new
  $ mv authormap.txt new/.hg/authormap
  $ hg convert orig new
  ignoring bad line in author map file $TESTTMP/new/.hg/authormap: this line is ignored
  scanning source...
  sorting...
  converting...
  0 foo
  $ hg -Rnew log
  changeset:   0:d89716e88087
  tag:         tip
  user:        Long User Name
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     foo