dirstate-tree: Add tree traversal/iteration
Like Python’s, Rust’s iterators are "external" in that they are driven
by a caller who calls a `next` method. This is as opposed to "internal"
iterators who drive themselves and call a callback for each item.
Writing an internal iterator traversing a tree is easy with recursion,
but internal iterators cannot rely on the call stack in that way,
they must save in an explicit object all state that they need to be
preserved across two `next` calls.
This algorithm uses a `Vec` as a stack that contains what would be
local variables on the call stack if we could use recursion.
Differential Revision: https://phab.mercurial-scm.org/D10370
$ cat >> $HGRCPATH << EOF
> [extensions]
> fastannotate=
> [fastannotate]
> perfhack=1
> EOF
$ hg init repo
$ cd repo
a simple merge case
$ echo 1 > a
$ hg commit -qAm 'append 1'
$ echo 2 >> a
$ hg commit -m 'append 2'
$ echo 3 >> a
$ hg commit -m 'append 3'
$ hg up 1 -q
$ cat > a << EOF
> 0
> 1
> 2
> EOF
$ hg commit -qm 'insert 0'
$ hg merge 2 -q
$ echo 4 >> a
$ hg commit -m merge
$ hg log -G -T '{rev}: {desc}'
@ 4: merge
|\
| o 3: insert 0
| |
o | 2: append 3
|/
o 1: append 2
|
o 0: append 1
$ hg fastannotate a
3: 0
0: 1
1: 2
2: 3
4: 4
$ hg fastannotate -r 0 a
0: 1
$ hg fastannotate -r 1 a
0: 1
1: 2
$ hg fastannotate -udnclf a
test 3 d641cb51f61e Thu Jan 01 00:00:00 1970 +0000 a:1: 0
test 0 4994017376d3 Thu Jan 01 00:00:00 1970 +0000 a:1: 1
test 1 e940cb6d9a06 Thu Jan 01 00:00:00 1970 +0000 a:2: 2
test 2 26162a884ba6 Thu Jan 01 00:00:00 1970 +0000 a:3: 3
test 4 3ad7bcd2815f Thu Jan 01 00:00:00 1970 +0000 a:5: 4
$ hg fastannotate --linear a
3: 0
0: 1
1: 2
4: 3
4: 4
incrementally updating
$ hg fastannotate -r 0 a --debug
fastannotate: a: using fast path (resolved fctx: True)
0: 1
$ hg fastannotate -r 0 a --debug --rebuild
fastannotate: a: 1 new changesets in the main branch
0: 1
$ hg fastannotate -r 1 a --debug
fastannotate: a: 1 new changesets in the main branch
0: 1
1: 2
$ hg fastannotate -r 3 a --debug
fastannotate: a: 1 new changesets in the main branch
3: 0
0: 1
1: 2
$ hg fastannotate -r 4 a --debug
fastannotate: a: 1 new changesets in the main branch
3: 0
0: 1
1: 2
2: 3
4: 4
$ hg fastannotate -r 1 a --debug
fastannotate: a: using fast path (resolved fctx: True)
0: 1
1: 2
rebuild happens automatically if unable to update
$ hg fastannotate -r 2 a --debug
fastannotate: a: cache broken and deleted
fastannotate: a: 3 new changesets in the main branch
0: 1
1: 2
2: 3
config option "fastannotate.mainbranch"
$ hg fastannotate -r 1 --rebuild --config fastannotate.mainbranch=tip a --debug
fastannotate: a: 4 new changesets in the main branch
0: 1
1: 2
$ hg fastannotate -r 4 a --debug
fastannotate: a: using fast path (resolved fctx: True)
3: 0
0: 1
1: 2
2: 3
4: 4
rename
$ hg mv a b
$ cat > b << EOF
> 0
> 11
> 3
> 44
> EOF
$ hg commit -m b -q
$ hg fastannotate -ncf --long-hash b
3 d641cb51f61e331c44654104301f8154d7865c89 a: 0
5 d44dade239915bc82b91e4556b1257323f8e5824 b: 11
2 26162a884ba60e8c87bf4e0d6bb8efcc6f711a4e a: 3
5 d44dade239915bc82b91e4556b1257323f8e5824 b: 44
$ hg fastannotate -r 26162a884ba60e8c87bf4e0d6bb8efcc6f711a4e a
0: 1
1: 2
2: 3
fastannotate --deleted
$ hg fastannotate --deleted -nf b
3 a: 0
5 b: 11
0 a: -1
1 a: -2
2 a: 3
5 b: 44
4 a: -4
$ hg fastannotate --deleted -r 3 -nf a
3 a: 0
0 a: 1
1 a: 2
file and directories with ".l", ".m" suffixes
$ cd ..
$ hg init repo2
$ cd repo2
$ mkdir a.l b.m c.lock a.l.hg b.hg
$ for i in a b c d d.l d.m a.l/a b.m/a c.lock/a a.l.hg/a b.hg/a; do
> echo $i > $i
> done
$ hg add . -q
$ hg commit -m init
$ hg fastannotate a.l/a b.m/a c.lock/a a.l.hg/a b.hg/a d.l d.m a b c d
0: a
0: a.l.hg/a
0: a.l/a
0: b
0: b.hg/a
0: b.m/a
0: c
0: c.lock/a
0: d
0: d.l
0: d.m
empty file
$ touch empty
$ hg commit -A empty -m empty
$ hg fastannotate empty