dirstate-tree: Avoid BTreeMap double-lookup when inserting a dirstate entry
The child nodes of a given node in the tree-shaped dirstate are kept in a
`BTreeMap` where keys are file names as strings. Finding or inserting a value
in the map takes `O(log(n))` string comparisons, which adds up when constructing
the tree.
The `entry` API allows finding a "spot" in the map that may or may not be
occupied and then access that value or insert a new one without doing map
lookup again. However the current API is limited in that calling `entry`
requires an owned key (and so a memory allocation), even if it ends up not
being used in the case where the map already has a value with an equal key.
This is still a win, with 4% better end-to-end time for `hg status` measured
here with hyperfine:
```
Benchmark #1: ../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1
Time (mean ± σ): 1.337 s ± 0.018 s [User: 892.9 ms, System: 437.5 ms]
Range (min … max): 1.316 s … 1.373 s 10 runs
Benchmark #2: ./hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1
Time (mean ± σ): 1.291 s ± 0.008 s [User: 853.4 ms, System: 431.1 ms]
Range (min … max): 1.283 s … 1.309 s 10 runs
Summary
'./hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1' ran
1.04 ± 0.02 times faster than '../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1'
```
* ./hg is this revision
* ../hg2/hg is its parent
* $REPO is an old snapshot of mozilla-central
Differential Revision: https://phab.mercurial-scm.org/D10550
Test temp file used with an editor has the expected suffix.
$ hg init
Create an editor that writes its arguments to stdout and set it to $HGEDITOR.
$ cat > editor.sh << EOF
> echo "\$@"
> exit 1
> EOF
$ hg add editor.sh
$ HGEDITOR="sh $TESTTMP/editor.sh"
$ export HGEDITOR
Verify that the path for a commit editor has the expected suffix.
$ hg commit
*.commit.hg.txt (glob)
abort: edit failed: sh exited with status 1
[250]
Verify that the path for a histedit editor has the expected suffix.
$ cat >> $HGRCPATH <<EOF
> [extensions]
> rebase=
> histedit=
> EOF
$ hg commit --message 'At least one commit for histedit.'
$ hg histedit
*.histedit.hg.txt (glob)
abort: edit failed: sh exited with status 1
[250]
Verify that when performing an action that has the side-effect of creating an
editor for a diff, the file ends in .diff.
$ echo 1 > one
$ echo 2 > two
$ hg add
adding one
adding two
$ hg commit --interactive --config ui.interactive=true --config ui.interface=text << EOF
> y
> e
> q
> EOF
diff --git a/one b/one
new file mode 100644
examine changes to 'one'?
(enter ? for help) [Ynesfdaq?] y
@@ -0,0 +1,1 @@
+1
record change 1/2 to 'one'?
(enter ? for help) [Ynesfdaq?] e
*.diff (glob)
editor exited with exit code 1
record change 1/2 to 'one'?
(enter ? for help) [Ynesfdaq?] q
abort: user quit
[250]