encoding: fix trim() to be O(n) instead of O(n^2)
`encoding.trim()` iterated over the possible lengths smaller than the
input and created a slice for each. It then calculated the column
width of the result, which is of course O(n), so the overall algorithm
was O(n). This patch rewrites it to iterate over the unicode
characters, keeping track of the length so far. Also, the old
algorithm started from the end of the string, which made it much worse
when the input is large and the limit is small (such as the typical 72
we pass to it).
You can time it by running something like this:
```
time python3 -c 'from mercurial.utils import stringutil; print(stringutil.ellipsis(b"0123456789" * 1000, 5))'
```
That drops from 4.05 s to 83 ms with this patch (and most of that is
of course startup time).
Differential Revision: https://phab.mercurial-scm.org/D12089
#require no-windows
$ . "$TESTDIR/remotefilelog-library.sh"
$ hg init master
$ cd master
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> server=True
> EOF
$ echo x > x
$ echo y > y
$ echo z > z
$ hg commit -qAm xy
$ cd ..
$ hgcloneshallow ssh://user@dummy/master shallow -q
3 files fetched over 1 fetches - (3 misses, 0.00% hit ratio) over *s (glob)
$ cd shallow
# status
$ clearcache
$ echo xx > x
$ echo yy > y
$ touch a
$ hg status
M x
M y
? a
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
$ hg add a
$ hg status
M x
M y
A a
# diff
$ hg debugrebuilddirstate # fixes dirstate non-determinism
$ hg add a
$ clearcache
$ hg diff
diff -r f3d0bb0d1e48 x
--- a/x* (glob)
+++ b/x* (glob)
@@ -1,1 +1,1 @@
-x
+xx
diff -r f3d0bb0d1e48 y
--- a/y* (glob)
+++ b/y* (glob)
@@ -1,1 +1,1 @@
-y
+yy
3 files fetched over 1 fetches - (3 misses, 0.00% hit ratio) over *s (glob)
# local commit
$ clearcache
$ echo a > a
$ echo xxx > x
$ echo yyy > y
$ hg commit -m a
? files fetched over 1 fetches - (? misses, 0.00% hit ratio) over *s (glob)
# local commit where the dirstate is clean -- ensure that we do just one fetch
# (update to a commit on the server first)
$ hg --config debug.dirstate.delaywrite=1 up 0
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ clearcache
$ hg debugdirstate
n 644 2 * x (glob)
n 644 2 * y (glob)
n 644 2 * z (glob)
$ echo xxxx > x
$ echo yyyy > y
$ hg commit -m x
created new head
2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
# restore state for future tests
$ hg -q strip .
$ hg -q up tip
# rebase
$ clearcache
$ cd ../master
$ echo w > w
$ hg commit -qAm w
$ cd ../shallow
$ hg pull
pulling from ssh://user@dummy/master
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 0 changes to 0 files (+1 heads)
new changesets fed61014d323
(run 'hg heads' to see heads, 'hg merge' to merge)
$ hg rebase -d tip
rebasing 1:9abfe7bca547 "a"
saved backup bundle to $TESTTMP/shallow/.hg/strip-backup/9abfe7bca547-8b11e5ff-rebase.hg (glob)
3 files fetched over 2 fetches - (3 misses, 0.00% hit ratio) over *s (glob)
# strip
$ clearcache
$ hg debugrebuilddirstate # fixes dirstate non-determinism
$ hg strip -r .
2 files updated, 0 files merged, 1 files removed, 0 files unresolved
saved backup bundle to $TESTTMP/shallow/.hg/strip-backup/19edf50f4de7-df3d0f74-backup.hg (glob)
3 files fetched over 2 fetches - (3 misses, 0.00% hit ratio) over *s (glob)
# unbundle
$ clearcache
$ ls -A
.hg
w
x
y
z
$ hg debugrebuilddirstate # fixes dirstate non-determinism
$ hg unbundle .hg/strip-backup/19edf50f4de7-df3d0f74-backup.hg
adding changesets
adding manifests
adding file changes
added 1 changesets with 3 changes to 3 files
new changesets 19edf50f4de7 (1 drafts)
(run 'hg update' to get a working copy)
2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
$ hg up
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
$ cat a
a
# revert
$ clearcache
$ hg revert -r .~2 y z
no changes needed to z
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
$ hg checkout -C -r . -q
# explicit bundle should produce full bundle file
$ hg bundle -r 2 --base 1 ../local.bundle
1 changesets found
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
$ cd ..
$ hgcloneshallow ssh://user@dummy/master shallow2 -q
2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
$ cd shallow2
$ hg unbundle ../local.bundle
adding changesets
adding manifests
adding file changes
added 1 changesets with 3 changes to 3 files
new changesets 19edf50f4de7 (1 drafts)
(run 'hg update' to get a working copy)
$ hg log -r 2 --stat
changeset: 2:19edf50f4de7
tag: tip
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: a
a | 1 +
x | 2 +-
y | 2 +-
3 files changed, 3 insertions(+), 2 deletions(-)
# Merge
$ echo merge >> w
$ hg commit -m w
created new head
$ hg merge 2
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg commit -m merge
$ hg strip -q -r ".^"
# commit without producing new node
$ cd $TESTTMP
$ hgcloneshallow ssh://user@dummy/master shallow3 -q
$ cd shallow3
$ echo 1 > A
$ hg commit -m foo -A A
$ hg log -r . -T '{node}\n'
383ce605500277f879b7460a16ba620eb6930b7f
$ hg update -r '.^' -q
$ echo 1 > A
$ hg commit -m foo -A A
warning: commit already existed in the repository!
$ hg log -r . -T '{node}\n'
383ce605500277f879b7460a16ba620eb6930b7f