tests/test-update-branches.t

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)

  $ cat >> $HGRCPATH <<EOF
  > [commands]
  > status.verbose=1
  > EOF

# Construct the following history tree:
#
# @  5:e1bb631146ca  b1
# |
# o  4:a4fdb3b883c4 0:b608b9236435  b1
# |
# | o  3:4b57d2520816 1:44592833ba9f
# | |
# | | o  2:063f31070f65
# | |/
# | o  1:44592833ba9f
# |/
# o  0:b608b9236435

  $ mkdir b1
  $ cd b1
  $ hg init
  $ echo foo > foo
  $ echo zero > a
  $ hg init sub
  $ echo suba > sub/suba
  $ hg --cwd sub ci -Am addsuba
  adding suba
  $ echo 'sub = sub' > .hgsub
  $ hg ci -qAm0
  $ echo one > a ; hg ci -m1
  $ echo two > a ; hg ci -m2
  $ hg up -q 1
  $ echo three > a ; hg ci -qm3
  $ hg up -q 0
  $ hg branch -q b1
  $ echo four > a ; hg ci -qm4
  $ echo five > a ; hg ci -qm5

Initial repo state:

  $ hg log -G --template '{rev}:{node|short} {parents} {branches}\n'
  @  5:ff252e8273df  b1
  |
  o  4:d047485b3896 0:60829823a42a  b1
  |
  | o  3:6efa171f091b 1:0786582aa4b1
  | |
  | | o  2:bd10386d478c
  | |/
  | o  1:0786582aa4b1
  |/
  o  0:60829823a42a
  

Make sure update doesn't assume b1 is a repository if invoked from outside:

  $ cd ..
  $ hg update b1
  abort: no repository found in '$TESTTMP' (.hg not found)!
  [255]
  $ cd b1

Test helper functions:

  $ revtest () {
  >     msg=$1
  >     dirtyflag=$2   # 'clean', 'dirty' or 'dirtysub'
  >     startrev=$3
  >     targetrev=$4
  >     opt=$5
  >     hg up -qC $startrev
  >     test $dirtyflag = dirty && echo dirty > foo
  >     test $dirtyflag = dirtysub && echo dirty > sub/suba
  >     hg up $opt $targetrev
  >     hg parent --template 'parent={rev}\n'
  >     hg stat -S
  > }

  $ norevtest () {
  >     msg=$1
  >     dirtyflag=$2   # 'clean', 'dirty' or 'dirtysub'
  >     startrev=$3
  >     opt=$4
  >     hg up -qC $startrev
  >     test $dirtyflag = dirty && echo dirty > foo
  >     test $dirtyflag = dirtysub && echo dirty > sub/suba
  >     hg up $opt
  >     hg parent --template 'parent={rev}\n'
  >     hg stat -S
  > }

Test cases are documented in a table in the update function of merge.py.
Cases are run as shown in that table, row by row.

  $ norevtest 'none clean linear' clean 4
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=5

  $ norevtest 'none clean same'   clean 2
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  updated to "bd10386d478c: 2"
  1 other heads for branch "default"
  parent=2


  $ revtest 'none clean linear' clean 1 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=2

  $ revtest 'none clean same'   clean 2 3
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=3

  $ revtest 'none clean cross'  clean 3 4
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=4


  $ revtest 'none dirty linear' dirty 1 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=2
  M foo

  $ revtest 'none dirtysub linear' dirtysub 1 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=2
  M sub/suba

  $ revtest 'none dirty same'   dirty 2 3
  abort: uncommitted changes
  (commit or update --clean to discard changes)
  parent=2
  M foo

  $ revtest 'none dirtysub same'   dirtysub 2 3
  abort: uncommitted changes
  (commit or update --clean to discard changes)
  parent=2
  M sub/suba

  $ revtest 'none dirty cross'  dirty 3 4
  abort: uncommitted changes
  (commit or update --clean to discard changes)
  parent=3
  M foo

  $ norevtest 'none dirty cross'  dirty 2
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  updated to "bd10386d478c: 2"
  1 other heads for branch "default"
  parent=2
  M foo

  $ revtest 'none dirtysub cross'  dirtysub 3 4
  abort: uncommitted changes
  (commit or update --clean to discard changes)
  parent=3
  M sub/suba

  $ revtest '-C dirty linear'   dirty 1 2 -C
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=2

  $ revtest '-c dirty linear'   dirty 1 2 -c
  abort: uncommitted changes
  parent=1
  M foo

  $ revtest '-m dirty linear'   dirty 1 2 -m
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=2
  M foo

  $ revtest '-m dirty cross'  dirty 3 4 -m
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=4
  M foo

  $ revtest '-c dirtysub linear'   dirtysub 1 2 -c
  abort: uncommitted changes in subrepository "sub"
  parent=1
  M sub/suba

  $ norevtest '-c clean same'   clean 2 -c
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  updated to "bd10386d478c: 2"
  1 other heads for branch "default"
  parent=2

  $ revtest '-cC dirty linear'  dirty 1 2 -cC
  abort: cannot specify both --clean and --check
  parent=1
  M foo

  $ revtest '-mc dirty linear'  dirty 1 2 -mc
  abort: cannot specify both --check and --merge
  parent=1
  M foo

  $ revtest '-mC dirty linear'  dirty 1 2 -mC
  abort: cannot specify both --clean and --merge
  parent=1
  M foo

  $ echo '[commands]' >> .hg/hgrc
  $ echo 'update.check = abort' >> .hg/hgrc

  $ revtest 'none dirty linear' dirty 1 2
  abort: uncommitted changes
  parent=1
  M foo

  $ revtest 'none dirty linear' dirty 1 2 -c
  abort: uncommitted changes
  parent=1
  M foo

  $ revtest 'none dirty linear' dirty 1 2 -C
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=2

  $ echo 'update.check = none' >> .hg/hgrc

  $ revtest 'none dirty cross'  dirty 3 4
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=4
  M foo

  $ revtest 'none dirty linear' dirty 1 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=2
  M foo

  $ revtest 'none dirty linear' dirty 1 2 -c
  abort: uncommitted changes
  parent=1
  M foo

  $ revtest 'none dirty linear' dirty 1 2 -C
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=2

  $ hg co -qC 3
  $ echo dirty >> a
  $ hg co --tool :merge3 4
  merging a
  warning: conflicts while merging a! (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
  [1]
  $ hg log -G --template '{rev}:{node|short} {parents} {branches}\n'
  o  5:ff252e8273df  b1
  |
  @  4:d047485b3896 0:60829823a42a  b1
  |
  | %  3:6efa171f091b 1:0786582aa4b1
  | |
  | | o  2:bd10386d478c
  | |/
  | o  1:0786582aa4b1
  |/
  o  0:60829823a42a
  
  $ hg st
  M a
  ? a.orig
  # Unresolved merge conflicts:
  # 
  #     a
  # 
  # To mark files as resolved:  hg resolve --mark FILE
  
  $ cat a
  <<<<<<< working copy: 6efa171f091b - test: 3
  three
  dirty
  ||||||| base
  three
  =======
  four
  >>>>>>> destination:  d047485b3896 b1 - test: 4
  $ rm a.orig

  $ echo 'update.check = noconflict' >> .hg/hgrc

  $ revtest 'none dirty cross'  dirty 3 4
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=4
  M foo

  $ revtest 'none dirty linear' dirty 1 2
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=2
  M foo

  $ revtest 'none dirty linear' dirty 1 2 -c
  abort: uncommitted changes
  parent=1
  M foo

  $ revtest 'none dirty linear' dirty 1 2 -C
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=2

Locally added file is allowed
  $ hg up -qC 3
  $ echo a > bar
  $ hg add bar
  $ hg up -q 4
  $ hg st
  A bar
  $ hg forget bar
  $ rm bar

Locally removed file is allowed
  $ hg up -qC 3
  $ hg rm foo
  $ hg up -q 4

File conflict is not allowed
  $ hg up -qC 3
  $ echo dirty >> a
  $ hg up -q 4
  abort: conflicting changes
  (commit or update --clean to discard changes)
  [255]
  $ hg up -m 4
  merging a
  warning: conflicts while merging a! (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
  [1]
  $ rm a.orig
  $ hg status
  M a
  # Unresolved merge conflicts:
  # 
  #     a
  # 
  # To mark files as resolved:  hg resolve --mark FILE
  
  $ hg resolve -l
  U a

Try to make empty commit while there are conflicts
  $ hg revert -r . a
  $ rm a.orig
  $ hg ci -m empty
  abort: unresolved merge conflicts (see 'hg help resolve')
  [255]
  $ hg resolve -m a
  (no more unresolved files)
  $ hg resolve -l
  R a
  $ hg ci -m empty
  nothing changed
  [1]
  $ hg resolve -l

Change/delete conflict is not allowed
  $ hg up -qC 3
  $ hg rm foo
  $ hg up -q 4

Uses default value of "linear" when value is misspelled
  $ echo 'update.check = linyar' >> .hg/hgrc

  $ revtest 'dirty cross'  dirty 3 4
  abort: uncommitted changes
  (commit or update --clean to discard changes)
  parent=3
  M foo

Setup for later tests
  $ revtest 'none dirty linear' dirty 1 2 -c
  abort: uncommitted changes
  parent=1
  M foo

  $ cd ..

Test updating to null revision

  $ hg init null-repo
  $ cd null-repo
  $ echo a > a
  $ hg add a
  $ hg ci -m a
  $ hg up -qC 0
  $ echo b > b
  $ hg add b
  $ hg up null
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg st
  A b
  $ hg up -q 0
  $ hg st
  A b
  $ hg up -qC null
  $ hg st
  ? b
  $ cd ..

Test updating with closed head
---------------------------------------------------------------------

  $ hg clone -U -q b1 closed-heads
  $ cd closed-heads

Test updating if at least one non-closed branch head exists

if on the closed branch head:
- update to "."
- "updated to a closed branch head ...." message is displayed
- "N other heads for ...." message is displayed

  $ hg update -q -C 3
  $ hg commit --close-branch -m 6
  $ norevtest "on closed branch head" clean 6
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  no open descendant heads on branch "default", updating to a closed head
  (committing will reopen the head, use 'hg heads .' to see 1 other heads)
  parent=6

if descendant non-closed branch head exists, and it is only one branch head:
- update to it, even if its revision is less than closed one
- "N other heads for ...." message isn't displayed

  $ norevtest "non-closed 2 should be chosen" clean 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=2

if all descendant branch heads are closed, but there is another branch head:
- update to the tipmost descendant head
- "updated to a closed branch head ...." message is displayed
- "N other heads for ...." message is displayed

  $ norevtest "all descendant branch heads are closed" clean 3
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  no open descendant heads on branch "default", updating to a closed head
  (committing will reopen the head, use 'hg heads .' to see 1 other heads)
  parent=6

Test updating if all branch heads are closed

if on the closed branch head:
- update to "."
- "updated to a closed branch head ...." message is displayed
- "all heads of branch ...." message is displayed

  $ hg update -q -C 2
  $ hg commit --close-branch -m 7
  $ norevtest "all heads of branch default are closed" clean 6
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  no open descendant heads on branch "default", updating to a closed head
  (committing will reopen branch "default")
  parent=6

if not on the closed branch head:
- update to the tipmost descendant (closed) head
- "updated to a closed branch head ...." message is displayed
- "all heads of branch ...." message is displayed

  $ norevtest "all heads of branch default are closed" clean 1
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  no open descendant heads on branch "default", updating to a closed head
  (committing will reopen branch "default")
  parent=7

  $ cd ..

Test updating if "default" branch doesn't exist and no revision is
checked out (= "default" is used as current branch)

  $ hg init no-default-branch
  $ cd no-default-branch

  $ hg branch foobar
  marked working directory as branch foobar
  (branches are permanent and global, did you want a bookmark?)
  $ echo a > a
  $ hg commit -m "#0" -A
  adding a
  $ echo 1 >> a
  $ hg commit -m "#1"
  $ hg update -q 0
  $ echo 3 >> a
  $ hg commit -m "#2"
  created new head
  $ hg commit --close-branch -m "#3"

if there is at least one non-closed branch head:
- update to the tipmost branch head

  $ norevtest "non-closed 1 should be chosen" clean null
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  parent=1

if all branch heads are closed
- update to "tip"
- "updated to a closed branch head ...." message is displayed
- "all heads for branch "XXXX" are closed" message is displayed

  $ hg update -q -C 1
  $ hg commit --close-branch -m "#4"

  $ norevtest "all branches are closed" clean null
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  no open descendant heads on branch "foobar", updating to a closed head
  (committing will reopen branch "foobar")
  parent=4

  $ cd ../b1

Test obsolescence behavior
---------------------------------------------------------------------

successors should be taken in account when checking head destination

  $ cat << EOF >> $HGRCPATH
  > [ui]
  > logtemplate={rev}:{node|short} {desc|firstline}
  > [experimental]
  > evolution.createmarkers=True
  > EOF

Test no-argument update to a successor of an obsoleted changeset

  $ hg log -G
  o  5:ff252e8273df 5
  |
  o  4:d047485b3896 4
  |
  | o  3:6efa171f091b 3
  | |
  | | o  2:bd10386d478c 2
  | |/
  | @  1:0786582aa4b1 1
  |/
  o  0:60829823a42a 0
  
  $ hg book bm -r 3
  $ hg status
  M foo

We add simple obsolescence marker between 3 and 4 (indirect successors)

  $ hg id --debug -i -r 3
  6efa171f091b00a3c35edc15d48c52a498929953
  $ hg id --debug -i -r 4
  d047485b3896813b2a624e86201983520f003206
  $ hg debugobsolete 6efa171f091b00a3c35edc15d48c52a498929953 aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa
  1 new obsolescence markers
  obsoleted 1 changesets
  $ hg debugobsolete aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa d047485b3896813b2a624e86201983520f003206
  1 new obsolescence markers

Test that 5 is detected as a valid destination from 3 and also accepts moving
the bookmark (issue4015)

  $ hg up --quiet --hidden 3
  $ hg up 5
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg book bm
  moving bookmark 'bm' forward from 6efa171f091b
  $ hg bookmarks
   * bm                        5:ff252e8273df

Test that we abort before we warn about the hidden commit if the working
directory is dirty
  $ echo conflict > a
  $ hg up --hidden 3
  abort: uncommitted changes
  (commit or update --clean to discard changes)
  [255]

Test that we still warn also when there are conflicts
  $ hg up -m --hidden 3
  merging a
  warning: conflicts while merging a! (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
  (leaving bookmark bm)
  updated to hidden changeset 6efa171f091b
  (hidden revision '6efa171f091b' was rewritten as: d047485b3896)
  [1]

Test that statuses are reported properly before and after merge resolution.
  $ rm a.orig
  $ hg resolve -l
  U a
  $ hg status
  M a
  M foo
  # Unresolved merge conflicts:
  # 
  #     a
  # 
  # To mark files as resolved:  hg resolve --mark FILE
  

  $ hg revert -r . a

  $ rm a.orig
  $ hg resolve -l
  U a
  $ hg status
  M foo
  # Unresolved merge conflicts:
  # 
  #     a
  # 
  # To mark files as resolved:  hg resolve --mark FILE
  
  $ hg status -Tjson
  [
   {
    "itemtype": "file",
    "path": "foo",
    "status": "M"
   },
   {
    "itemtype": "file",
    "path": "a",
    "unresolved": true
   }
  ]

  $ hg resolve -m
  (no more unresolved files)

  $ hg resolve -l
  R a
  $ hg status
  M foo
  # No unresolved merge conflicts.
  
  $ hg status -Tjson
  [
   {
    "itemtype": "file",
    "path": "foo",
    "status": "M"
   }
  ]

Test that 4 is detected as the no-argument destination from 3 and also moves
the bookmark with it
  $ hg up --quiet 0          # we should be able to update to 3 directly
  $ hg status
  M foo
  $ hg up --quiet --hidden 3 # but not implemented yet.
  updated to hidden changeset 6efa171f091b
  (hidden revision '6efa171f091b' was rewritten as: d047485b3896)
  $ hg book -f bm
  $ hg up
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  updating bookmark bm
  $ hg book
   * bm                        4:d047485b3896

Test that 5 is detected as a valid destination from 1
  $ hg up --quiet 0          # we should be able to update to 3 directly
  $ hg up --quiet --hidden 3 # but not implemented yet.
  updated to hidden changeset 6efa171f091b
  (hidden revision '6efa171f091b' was rewritten as: d047485b3896)
  $ hg up 5
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

Test that 5 is not detected as a valid destination from 2
  $ hg up --quiet 0
  $ hg up --quiet 2
  $ hg up 5
  abort: uncommitted changes
  (commit or update --clean to discard changes)
  [255]

Test that we don't crash when updating from a pruned changeset (i.e. has no
successors). Behavior should probably be that we update to the first
non-obsolete parent but that will be decided later.
  $ hg id --debug -r 2
  bd10386d478cd5a9faf2e604114c8e6da62d3889
  $ hg up --quiet 0
  $ hg up --quiet 2
  $ hg debugobsolete bd10386d478cd5a9faf2e604114c8e6da62d3889
  1 new obsolescence markers
  obsoleted 1 changesets
  $ hg up
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

Test experimental revset support

  $ hg log -r '_destupdate()'
  2:bd10386d478c 2 (no-eol)

Test that boolean flags allow --no-flag specification to override [defaults]
  $ cat >> $HGRCPATH <<EOF
  > [defaults]
  > update = --check
  > EOF
  $ hg co 2
  abort: uncommitted changes
  [255]
  $ hg co --no-check 2
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved