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
This test test the low-level definition of stack, agnostic from all formatting
Initial setup
$ cat << EOF >> $HGRCPATH
> [ui]
> logtemplate = {rev} {branch} {phase} {desc|firstline}\n
> [extensions]
> rebase=
> [experimental]
> evolution=createmarkers,exchange,allowunstable
> EOF
$ hg init main
$ cd main
$ hg branch other
marked working directory as branch other
(branches are permanent and global, did you want a bookmark?)
$ echo aaa > aaa
$ hg add aaa
$ hg commit -m c_a
$ echo aaa > bbb
$ hg add bbb
$ hg commit -m c_b
$ hg branch foo
marked working directory as branch foo
$ echo aaa > ccc
$ hg add ccc
$ hg commit -m c_c
$ echo aaa > ddd
$ hg add ddd
$ hg commit -m c_d
$ echo aaa > eee
$ hg add eee
$ hg commit -m c_e
$ echo aaa > fff
$ hg add fff
$ hg commit -m c_f
$ hg log -G
@ 5 foo draft c_f
|
o 4 foo draft c_e
|
o 3 foo draft c_d
|
o 2 foo draft c_c
|
o 1 other draft c_b
|
o 0 other draft c_a
Check that stack doesn't include public changesets
--------------------------------------------------
$ hg up other
0 files updated, 0 files merged, 4 files removed, 0 files unresolved
$ hg log -G -r "stack()"
@ 1 other draft c_b
|
o 0 other draft c_a
$ hg phase --public 'branch("other")'
$ hg log -G -r "stack()"
$ hg up foo
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
Simple test
-----------
'stack()' list all changeset in the branch
$ hg branch
foo
$ hg log -G -r "stack()"
@ 5 foo draft c_f
|
o 4 foo draft c_e
|
o 3 foo draft c_d
|
o 2 foo draft c_c
|
~
Case with some of the branch unstable
------------------------------------
$ hg up 3
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ echo bbb > ddd
$ hg commit --amend
2 new orphan changesets
$ hg log -G
@ 6 foo draft c_d
|
| * 5 foo draft c_f
| |
| * 4 foo draft c_e
| |
| x 3 foo draft c_d
|/
o 2 foo draft c_c
|
o 1 other public c_b
|
o 0 other public c_a
$ hg log -G -r "stack()"
@ 6 foo draft c_d
|
~
$ hg up -r "desc(c_e)"
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg log -G -r "stack()"
@ 4 foo draft c_e
|
x 3 foo draft c_d
|
~
$ hg up -r "desc(c_d)"
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg log -G -r "stack()"
@ 6 foo draft c_d
|
~
Case with multiple topological heads
------------------------------------
Make things linear again
$ hg rebase -s 'desc(c_e)' -d 'desc(c_d) - obsolete()'
rebasing 4:4f2a69f6d380 "c_e"
rebasing 5:913c298d8b0a "c_f"
$ hg log -G
o 8 foo draft c_f
|
o 7 foo draft c_e
|
@ 6 foo draft c_d
|
o 2 foo draft c_c
|
o 1 other public c_b
|
o 0 other public c_a
Create the second branch
$ hg up 'desc(c_d)'
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo aaa > ggg
$ hg add ggg
$ hg commit -m c_g
created new head
$ echo aaa > hhh
$ hg add hhh
$ hg commit -m c_h
$ hg log -G
@ 10 foo draft c_h
|
o 9 foo draft c_g
|
| o 8 foo draft c_f
| |
| o 7 foo draft c_e
|/
o 6 foo draft c_d
|
o 2 foo draft c_c
|
o 1 other public c_b
|
o 0 other public c_a
Test output
$ hg log -G -r "stack(10)"
@ 10 foo draft c_h
|
o 9 foo draft c_g
|
~
$ hg log -G -r "stack(8)"
o 8 foo draft c_f
|
o 7 foo draft c_e
|
~
$ hg log -G -r "stack(head())"
@ 10 foo draft c_h
|
o 9 foo draft c_g
|
~
o 8 foo draft c_f
|
o 7 foo draft c_e
|
~
Check the stack order
$ hg log -r "first(stack())"
9 foo draft c_g
$ hg log -r "first(stack(10))"
9 foo draft c_g
$ hg log -r "first(stack(8))"
7 foo draft c_e
$ hg log -r "first(stack(head()))"
7 foo draft c_e
Case with multiple heads with unstability involved
--------------------------------------------------
We amend the message to make sure the display base pick the right changeset
$ hg up 'desc(c_d)'
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ echo ccc > ddd
$ hg commit --amend -m 'c_D'
4 new orphan changesets
$ hg rebase -d . -s 'desc(c_g)'
rebasing 9:2ebb6e48ab8a "c_g"
rebasing 10:634f38e27a1d "c_h"
$ hg log -G
o 13 foo draft c_h
|
o 12 foo draft c_g
|
@ 11 foo draft c_D
|
| * 8 foo draft c_f
| |
| * 7 foo draft c_e
| |
| x 6 foo draft c_d
|/
o 2 foo draft c_c
|
o 1 other public c_b
|
o 0 other public c_a
We should improve stack definition to also show 12 and 13 here
$ hg log -G -r "stack()"
@ 11 foo draft c_D
|
~