Mercurial > hg
view tests/test-copy-move-merge.t @ 44950:f9734b2d59cc
py3: make stdout line-buffered if connected to a TTY
Status messages that are to be shown on the terminal should be written to the
file descriptor before anything further is done, to keep the user updated.
One common way to achieve this is to make stdout line-buffered if it is
connected to a TTY. This is done on Python 2 (except on Windows, where libc,
which the CPython 2 streams depend on, does not properly support this).
Python 3 rolls it own I/O streams. On Python 3, buffered binary streams can't be
set line-buffered. The previous code (added in 227ba1afcb65) incorrectly
assumed that on Python 3, pycompat.stdout (sys.stdout.buffer) is already
line-buffered. However the interpreter initializes it with a block-buffered
stream or an unbuffered stream (when the -u option or the PYTHONUNBUFFERED
environment variable is set), never with a line-buffered stream.
One example where the current behavior is unacceptable is when running
`hg pull https://www.mercurial-scm.org/repo/hg` on Python 3, where the line
"pulling from https://www.mercurial-scm.org/repo/hg" does not appear on the
terminal before the hg process blocks while waiting for the server.
Various approaches to fix this problem are possible, including:
1. Weaken the contract of procutil.stdout to not give any guarantees about
buffering behavior. In this case, users of procutil.stdout need to be
changed to do enough flushes. In particular,
1. either ui must insert enough flushes for ui.write() and friends, or
2. ui.write() and friends get split into flushing and fully buffered
methods, or
3. users of ui.write() and friends must flush explicitly.
2. Make stdout unbuffered.
3. Make stdout line-buffered. Since Python 3 does not natively support that for
binary streams, we must implement it ourselves.
(2.) is problematic because using unbuffered I/O changes the performance
characteristics significantly compared to line-buffered (which is used on
Python 2) and this would be a regression.
(1.2.) and (1.3) are a substantial amount of work. It’s unclear whether the
added complexity would be justified, given that raw performance doesn’t matter
that much when writing to a terminal much faster than the user could read it.
(1.1.) pushes complexity into the ui class instead of separating the concern of
how stdout is buffered. Other users of procutil.stdout would still need to take
care of the flushes.
This patch implements (3.). The general performance considerations are very
similar to (1.1.). The extra method invocation and method forwarding add a
little more overhead if the class is used. In exchange, it doesn’t add overhead
if not used.
For the benchmarks, I compared the previous implementation (incorrect on Python
3), (1.1.), (3.) and (2.). The command was chosen so that the streams were
configured as if they were writing to a TTY, but actually write to a pager,
which is also the default:
HGRCPATH=/dev/null python3 ./hg --cwd ~/vcs/mozilla-central --time --pager yes --config pager.pager='cat > /dev/null' status --all
previous:
time: real 7.880 secs (user 7.290+0.050 sys 0.580+0.170)
time: real 7.830 secs (user 7.220+0.070 sys 0.590+0.140)
time: real 7.800 secs (user 7.210+0.050 sys 0.570+0.170)
(1.1.) using Yuya Nishihara’s patch:
time: real 9.860 secs (user 8.670+0.350 sys 1.160+0.830)
time: real 9.540 secs (user 8.430+0.370 sys 1.100+0.770)
time: real 9.830 secs (user 8.630+0.370 sys 1.180+0.840)
(3.) using this patch:
time: real 9.580 secs (user 8.480+0.350 sys 1.090+0.770)
time: real 9.670 secs (user 8.480+0.330 sys 1.170+0.860)
time: real 9.640 secs (user 8.500+0.350 sys 1.130+0.810)
(2.) using a previous patch by me:
time: real 10.480 secs (user 8.850+0.720 sys 1.590+1.500)
time: real 10.490 secs (user 8.750+0.750 sys 1.710+1.470)
time: real 10.240 secs (user 8.600+0.700 sys 1.590+1.510)
As expected, there’s no difference on Python 2, as exactly the same code paths
are used:
previous:
time: real 6.950 secs (user 5.870+0.330 sys 1.070+0.770)
time: real 7.040 secs (user 6.040+0.360 sys 0.980+0.750)
time: real 7.070 secs (user 5.950+0.360 sys 1.100+0.760)
this patch:
time: real 7.010 secs (user 5.900+0.390 sys 1.070+0.730)
time: real 7.000 secs (user 5.850+0.350 sys 1.120+0.760)
time: real 7.000 secs (user 5.790+0.380 sys 1.170+0.710)
author | Manuel Jacob <me@manueljacob.de> |
---|---|
date | Wed, 10 Jun 2020 13:02:39 +0200 |
parents | 9659ec161644 |
children | f90a5c211251 |
line wrap: on
line source
Test for the full copytracing algorithm ======================================= Initial Setup ============= use git diff to see rename $ cat << EOF >> $HGRCPATH > [diff] > git=yes > EOF Setup an history where one side copy and rename a file (and update it) while the other side update it. $ hg init t $ cd t $ echo 1 > a $ hg ci -qAm "first" $ hg cp a b $ hg mv a c $ echo 2 >> b $ echo 2 >> c $ hg ci -qAm "second" $ hg co -C 0 1 files updated, 0 files merged, 2 files removed, 0 files unresolved $ echo 0 > a $ echo 1 >> a $ hg ci -qAm "other" $ hg log -G --patch @ changeset: 2:add3f11052fa | tag: tip | parent: 0:b8bf91eeebbc | user: test | date: Thu Jan 01 00:00:00 1970 +0000 | summary: other | | diff --git a/a b/a | --- a/a | +++ b/a | @@ -1,1 +1,2 @@ | +0 | 1 | | o changeset: 1:17c05bb7fcb6 |/ user: test | date: Thu Jan 01 00:00:00 1970 +0000 | summary: second | | diff --git a/a b/b | rename from a | rename to b | --- a/a | +++ b/b | @@ -1,1 +1,2 @@ | 1 | +2 | diff --git a/a b/c | copy from a | copy to c | --- a/a | +++ b/c | @@ -1,1 +1,2 @@ | 1 | +2 | o changeset: 0:b8bf91eeebbc user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: first diff --git a/a b/a new file mode 100644 --- /dev/null +++ b/a @@ -0,0 +1,1 @@ +1 Test Simple Merge ================= $ hg merge --debug unmatched files in other: b c all copies found (* = to merge, ! = divergent, % = renamed and deleted): on remote side: src: 'a' -> dst: 'b' * src: 'a' -> dst: 'c' * checking for directory renames resolving manifests branchmerge: True, force: False, partial: False ancestor: b8bf91eeebbc, local: add3f11052fa+, remote: 17c05bb7fcb6 preserving a for resolve of b preserving a for resolve of c removing a starting 4 threads for background file closing (?) b: remote moved from a -> m (premerge) picked tool ':merge' for b (binary False symlink False changedelete False) merging a and b to b my b@add3f11052fa+ other b@17c05bb7fcb6 ancestor a@b8bf91eeebbc premerge successful c: remote moved from a -> m (premerge) picked tool ':merge' for c (binary False symlink False changedelete False) merging a and c to c my c@add3f11052fa+ other c@17c05bb7fcb6 ancestor a@b8bf91eeebbc premerge successful 0 files updated, 2 files merged, 0 files removed, 0 files unresolved (branch merge, don't forget to commit) file b $ cat b 0 1 2 file c $ cat c 0 1 2 Test disabling copy tracing =========================== first verify copy metadata was kept ----------------------------------- $ hg up -qC 2 $ hg rebase --keep -d 1 -b 2 --config extensions.rebase= rebasing 2:add3f11052fa "other" (tip) merging b and a to b merging c and a to c $ cat b 0 1 2 next verify copy metadata is lost when disabled ------------------------------------------------ $ hg strip -r . --config extensions.strip= 2 files updated, 0 files merged, 0 files removed, 0 files unresolved saved backup bundle to $TESTTMP/t/.hg/strip-backup/550bd84c0cd3-fc575957-backup.hg $ hg up -qC 2 $ hg rebase --keep -d 1 -b 2 --config extensions.rebase= --config experimental.copytrace=off --config ui.interactive=True << EOF > c > EOF rebasing 2:add3f11052fa "other" (tip) file 'a' was deleted in local [dest] but was modified in other [source]. You can use (c)hanged version, leave (d)eleted, or leave (u)nresolved. What do you want to do? c $ cat b 1 2 $ cd .. Verify disabling copy tracing still keeps copies from rebase source ------------------------------------------------------------------- $ hg init copydisable $ cd copydisable $ touch a $ hg ci -Aqm 'add a' $ touch b $ hg ci -Aqm 'add b, c' $ hg cp b x $ echo x >> x $ hg ci -qm 'copy b->x' $ hg up -q 1 $ touch z $ hg ci -Aqm 'add z' $ hg log -G -T '{rev} {desc}\n' @ 3 add z | | o 2 copy b->x |/ o 1 add b, c | o 0 add a $ hg rebase -d . -b 2 --config extensions.rebase= --config experimental.copytrace=off rebasing 2:6adcf8c12e7d "copy b->x" saved backup bundle to $TESTTMP/copydisable/.hg/strip-backup/6adcf8c12e7d-ce4b3e75-rebase.hg $ hg up -q 3 $ hg log -f x -T '{rev} {desc}\n' 3 copy b->x 1 add b, c $ cd ../ test storage preservation ------------------------- Verify rebase do not discard recorded copies data when copy tracing usage is disabled. Setup $ hg init copydisable3 $ cd copydisable3 $ touch a $ hg ci -Aqm 'add a' $ hg cp a b $ hg ci -Aqm 'copy a->b' $ hg mv b c $ hg ci -Aqm 'move b->c' $ hg up -q 0 $ hg cp a b $ echo b >> b $ hg ci -Aqm 'copy a->b (2)' $ hg log -G -T '{rev} {desc}\n' @ 3 copy a->b (2) | | o 2 move b->c | | | o 1 copy a->b |/ o 0 add a Actual Test A file is copied on one side and has been moved twice on the other side. the file is copied from `0:a`, so the file history of the `3:b` should trace directly to `0:a`. $ hg rebase -d 2 -s 3 --config extensions.rebase= --config experimental.copytrace=off rebasing 3:47e1a9e6273b "copy a->b (2)" (tip) saved backup bundle to $TESTTMP/copydisable3/.hg/strip-backup/47e1a9e6273b-2d099c59-rebase.hg $ hg log -G -f b @ changeset: 3:76024fb4b05b : tag: tip : user: test : date: Thu Jan 01 00:00:00 1970 +0000 : summary: copy a->b (2) : o changeset: 0:ac82d8b1f7c4 user: test date: Thu Jan 01 00:00:00 1970 +0000 summary: add a