rust: peek_mut optim for lazy ancestors
This is one of the two optimizations that are also
present in the Python code: replacing pairs of pop/push
on the BinaryHeap by single updates, hence having it
under the hood maintain its consistency (sift) only once.
On Mozilla central, the measured gain (see details below)
is around 7%.
Creating the PeekMut object by calling peek_mut() right away
instead of peek() first is less efficient (gain is only 4%, stats
not included).
Our interpretation is that its creation has a cost which is vasted
in the cases where it ends by droping the value (Peekmut::pop()
just does self.heap.pop() anyway). On the other hand, the immutable
peek() is very fast: it's just taking a reference in the
underlying vector.
The Python version still has another optimization:
if parent(current) == current-1, then the heap doesn't need
to maintain its consistency, since we already know that
it's bigger than all the others in the heap.
Rust's BinaryHeap doesn't allow us to mutate its biggest
element with no housekeeping, but we tried it anyway, with a
copy of the BinaryHeap implementation with a dedicaded added
method: it's not worth the technical debt in our opinion
(we measured only a further 1.6% improvement).
One possible explanation would be that the sift is really fast
anyway in that case, whereas it's not in the case of Python,
because it's at least partly done in slow Python code.
Still it's possible that replacing BinaryHeap by something more
dedicated to discrete ordered types could be faster.
Measurements on mozilla-central:
Three runs of 'hg perfancestors' on the parent changeset:
Moyenne des médianes: 0.100587
! wall 0.100062 comb 0.100000 user 0.100000 sys 0.000000 (best of 98)
! wall 0.135804 comb 0.130000 user 0.130000 sys 0.000000 (max of 98)
! wall 0.102864 comb 0.102755 user 0.099286 sys 0.003469 (avg of 98)
! wall 0.101486 comb 0.110000 user 0.110000 sys 0.000000 (median of 98)
! wall 0.096804 comb 0.090000 user 0.090000 sys 0.000000 (best of 100)
! wall 0.132235 comb 0.130000 user 0.120000 sys 0.010000 (max of 100)
! wall 0.100258 comb 0.100300 user 0.096000 sys 0.004300 (avg of 100)
! wall 0.098384 comb 0.100000 user 0.100000 sys 0.000000 (median of 100)
! wall 0.099925 comb 0.100000 user 0.100000 sys 0.000000 (best of 98)
! wall 0.133518 comb 0.140000 user 0.130000 sys 0.010000 (max of 98)
! wall 0.102381 comb 0.102449 user 0.098265 sys 0.004184 (avg of 98)
! wall 0.101891 comb 0.090000 user 0.090000 sys 0.000000 (median of 98)
Mean of the medians: 0.100587
On the present changeset:
! wall 0.091344 comb 0.090000 user 0.090000 sys 0.000000 (best of 100)
! wall 0.122728 comb 0.120000 user 0.110000 sys 0.010000 (max of 100)
! wall 0.093268 comb 0.093300 user 0.089300 sys 0.004000 (avg of 100)
! wall 0.092567 comb 0.100000 user 0.090000 sys 0.010000 (median of 100)
! wall 0.093294 comb 0.080000 user 0.080000 sys 0.000000 (best of 100)
! wall 0.144887 comb 0.150000 user 0.140000 sys 0.010000 (max of 100)
! wall 0.097708 comb 0.097700 user 0.093400 sys 0.004300 (avg of 100)
! wall 0.094980 comb 0.100000 user 0.090000 sys 0.010000 (median of 100)
! wall 0.091262 comb 0.090000 user 0.080000 sys 0.010000 (best of 100)
! wall 0.123772 comb 0.130000 user 0.120000 sys 0.010000 (max of 100)
! wall 0.093188 comb 0.093200 user 0.089300 sys 0.003900 (avg of 100)
! wall 0.092364 comb 0.100000 user 0.090000 sys 0.010000 (median of 100)
Mean of the medians is 0.0933
Differential Revision: https://phab.mercurial-scm.org/D5358
$ hg init t
$ cd t
$ mkdir a
$ echo foo > a/a
$ echo bar > a/b
$ hg ci -Am "0"
adding a/a
adding a/b
$ hg co -C 0
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg mv a b
moving a/a to b/a
moving a/b to b/b
$ hg ci -m "1 mv a/ b/"
$ hg co -C 0
2 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ echo baz > a/c
$ echo quux > a/d
$ hg add a/c
$ hg ci -m "2 add a/c"
created new head
$ hg merge --debug 1
searching for copies back to rev 1
unmatched files in local:
a/c
unmatched files in other:
b/a
b/b
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'a/a' -> dst: 'b/a'
src: 'a/b' -> dst: 'b/b'
checking for directory renames
discovered dir src: 'a/' -> dst: 'b/'
pending file src: 'a/c' -> dst: 'b/c'
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: f9b20c0d4c51, local: ce36d17b18fb+, remote: 397f8b00a740
a/a: other deleted -> r
removing a/a
a/b: other deleted -> r
removing a/b
b/a: remote created -> g
getting b/a
b/b: remote created -> g
getting b/b
b/c: remote directory rename - move from a/c -> dm
moving a/c to b/c
3 files updated, 0 files merged, 2 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ echo a/* b/*
a/d b/a b/b b/c
$ hg st -C
M b/a
M b/b
A b/c
a/c
R a/a
R a/b
R a/c
? a/d
$ hg ci -m "3 merge 2+1"
$ hg debugrename b/c
b/c renamed from a/c:354ae8da6e890359ef49ade27b68bbc361f3ca88
$ hg co -C 1
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg merge --debug 2
searching for copies back to rev 1
unmatched files in local:
b/a
b/b
unmatched files in other:
a/c
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'a/a' -> dst: 'b/a'
src: 'a/b' -> dst: 'b/b'
checking for directory renames
discovered dir src: 'a/' -> dst: 'b/'
pending file src: 'a/c' -> dst: 'b/c'
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: f9b20c0d4c51, local: 397f8b00a740+, remote: ce36d17b18fb
starting 4 threads for background file closing (?)
b/c: local directory rename - get from a/c -> dg
getting a/c to b/c
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ echo a/* b/*
a/d b/a b/b b/c
$ hg st -C
A b/c
a/c
? a/d
$ hg ci -m "4 merge 1+2"
created new head
$ hg debugrename b/c
b/c renamed from a/c:354ae8da6e890359ef49ade27b68bbc361f3ca88
Local directory rename with conflicting file added in remote source directory
and untracked in local target directory.
$ hg co -qC 1
$ echo target > b/c
$ hg merge 2
b/c: untracked file differs
abort: untracked files in working directory differ from files in requested revision
[255]
$ cat b/c
target
but it should succeed if the content matches
$ hg cat -r 2 a/c > b/c
$ hg merge 2
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg st -C
A b/c
a/c
? a/d
Local directory rename with conflicting file added in remote source directory
and committed in local target directory.
$ hg co -qC 1
$ echo target > b/c
$ hg add b/c
$ hg commit -qm 'new file in target directory'
$ hg merge 2
merging b/c and a/c to b/c
warning: conflicts while merging b/c! (edit, then use 'hg resolve --mark')
0 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
[1]
$ hg st -A
M b/c
a/c
? a/d
? b/c.orig
C b/a
C b/b
$ cat b/c
<<<<<<< working copy: f1c50ca4f127 - test: new file in target directory
target
=======
baz
>>>>>>> merge rev: ce36d17b18fb - test: 2 add a/c
$ rm b/c.orig
Remote directory rename with conflicting file added in remote target directory
and committed in local source directory.
$ hg co -qC 2
$ hg st -A
? a/d
C a/a
C a/b
C a/c
$ hg merge 5
merging a/c and b/c to b/c
warning: conflicts while merging b/c! (edit, then use 'hg resolve --mark')
2 files updated, 0 files merged, 2 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
[1]
$ hg st -A
M b/a
M b/b
M b/c
a/c
R a/a
R a/b
R a/c
? a/d
? b/c.orig
$ cat b/c
<<<<<<< working copy: ce36d17b18fb - test: 2 add a/c
baz
=======
target
>>>>>>> merge rev: f1c50ca4f127 - test: new file in target directory
Second scenario with two repos:
$ cd ..
$ hg init r1
$ cd r1
$ mkdir a
$ echo foo > a/f
$ hg add a
adding a/f
$ hg ci -m "a/f == foo"
$ cd ..
$ hg clone r1 r2
updating to branch default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd r2
$ hg mv a b
moving a/f to b/f
$ echo foo1 > b/f
$ hg ci -m" a -> b, b/f == foo1"
$ cd ..
$ cd r1
$ mkdir a/aa
$ echo bar > a/aa/g
$ hg add a/aa
adding a/aa/g
$ hg ci -m "a/aa/g"
$ hg pull ../r2
pulling from ../r2
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files (+1 heads)
new changesets 7d51ed18da25
1 local changesets published
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg merge
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg st -C
M b/f
A b/aa/g
a/aa/g
R a/aa/g
R a/f
$ cd ..
Test renames to separate directories
$ hg init a
$ cd a
$ mkdir a
$ touch a/s
$ touch a/t
$ hg ci -Am0
adding a/s
adding a/t
Add more files
$ touch a/s2
$ touch a/t2
$ hg ci -Am1
adding a/s2
adding a/t2
Do moves on a branch
$ hg up 0
0 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ mkdir s
$ mkdir t
$ hg mv a/s s
$ hg mv a/t t
$ hg ci -Am2
created new head
$ hg st --copies --change .
A s/s
a/s
A t/t
a/t
R a/s
R a/t
Merge shouldn't move s2, t2
$ hg merge
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg st --copies
M a/s2
M a/t2
Try the merge in the other direction. It may or may not be appropriate for
status to list copies here.
$ hg up -C 1
4 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ hg merge
2 files updated, 0 files merged, 2 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg st --copies
M s/s
M t/t
R a/s
R a/t