tests/test-rollback.t

commit: improve the files field of changelog for merges

Currently, the files list of merge commits repeats all the deletions
(either actual deletions, or files that got renamed) that happened
between base and p2 of the merge. If p2 is the main branch, the list
can easily be much bigger than the change being merged.

This results in various problems worth improving:
- changelog is bigger than necessary
- `hg log directory` lists many unrelated merge commits, and `hg log
  -v -r commit` frequently fills multiple screens worth of files
- it possibly slows down adjustlinkrev, by forcing it to read more
  manifests, and that function can certainly be a bottleneck
- the server side of pulls can waste a lot of time simply opening the
  filelogs for pointless files (the constant factors for opening even
  a tiny filelog is apparently pretty bad)

So stop listing such files as described in the code.  Impacted merge
commits and their descendants get a different hash than they would
have without this. This doesn't seem problematic, except for
convert. The previous commit helped with that in the hg->hg case (but
if you do svn->hg twice from scratch, hashes can still change).

The rest of the description is numbers. I don't have much to report,
because recreating the files list of existing repositories is not
easy:
- debugupgradeformat and bundle/unbundle don't recreate the list
- export/import tends to choke quickly applying patches or on
  description that contain diffs,
- merge commits from the convert extension don't have the right files
  list for reasons orthogonal to the current commit
- replaying the merge with hg update/hg merge/hg revert --all/hg
  commit can end up failing in hg revert
- I wasn't sure that using debugsetparents + debugrebuilddirstate
  would really build the right thing

I measured commit time before and after this change, in a case with no
files filtered out, several files filtered out (no difference) and 5k
files filtered out (+1% time).

Recreating the 100 more recent merges in a private repo, the
concatenated uncompressed files lists goes from 1.12MB to
0.52MB. Excluding 3 merges that are not representative, then the size
goes from 570k to 15k.
I converted part of mozilla-central, and observed file list shrinking
quite a bit too, starting at the very first merge, 733641d9feaf, going
from 550 files to 10 files (although they have relatively few merges,
so they probably wouldn't care).

Differential Revision: https://phab.mercurial-scm.org/D6613

setup repo
  $ hg init t
  $ cd t
  $ echo a > a
  $ hg commit -Am'add a'
  adding a
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 1 changesets with 1 changes to 1 files
  $ hg parents
  changeset:   0:1f0dee641bb7
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     add a
  

rollback to null revision
  $ hg status
  $ hg rollback
  repository tip rolled back to revision -1 (undo commit)
  working directory now based on revision -1
  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 0 changesets with 0 changes to 0 files
  $ hg parents
  $ hg status
  A a

Two changesets this time so we rollback to a real changeset
  $ hg commit -m'add a again'
  $ echo a >> a
  $ hg commit -m'modify a'

Test issue 902 (current branch is preserved)
  $ hg branch test
  marked working directory as branch test
  (branches are permanent and global, did you want a bookmark?)
  $ hg rollback
  repository tip rolled back to revision 0 (undo commit)
  working directory now based on revision 0
  $ hg branch
  default

Test issue 1635 (commit message saved)
  $ cat .hg/last-message.txt ; echo
  modify a

Test rollback of hg before issue 902 was fixed

  $ hg commit -m "test3"
  $ hg branch test
  marked working directory as branch test
  (branches are permanent and global, did you want a bookmark?)
  $ rm .hg/undo.branch
  $ hg rollback
  repository tip rolled back to revision 0 (undo commit)
  named branch could not be reset: current branch is still 'test'
  working directory now based on revision 0
  $ hg branch
  test

working dir unaffected by rollback: do not restore dirstate et. al.
  $ hg log --template '{rev}  {branch}  {desc|firstline}\n'
  0  default  add a again
  $ hg status
  M a
  $ hg bookmark foo
  $ hg commit -m'modify a again'
  $ echo b > b
  $ hg bookmark bar -r default #making bar active, before the transaction
  $ hg commit -Am'add b'
  adding b
  $ hg log --template '{rev}  {branch}  {desc|firstline}\n'
  2  test  add b
  1  test  modify a again
  0  default  add a again
  $ hg update bar
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  (activating bookmark bar)
  $ cat .hg/undo.branch ; echo
  test
  $ hg rollback -f
  repository tip rolled back to revision 1 (undo commit)
  $ hg id -n
  0
  $ hg branch
  default
  $ cat .hg/bookmarks.current ; echo
  bar
  $ hg bookmark --delete foo bar

rollback by pretxncommit saves commit message (issue1635)

  $ echo a >> a
  $ hg --config hooks.pretxncommit=false commit -m"precious commit message"
  transaction abort!
  rollback completed
  abort: pretxncommit hook exited with status * (glob)
  [255]
  $ cat .hg/last-message.txt ; echo
  precious commit message

same thing, but run $EDITOR

  $ cat > editor.sh << '__EOF__'
  > echo "another precious commit message" > "$1"
  > __EOF__
  $ HGEDITOR="\"sh\" \"`pwd`/editor.sh\"" hg --config hooks.pretxncommit=false commit 2>&1
  transaction abort!
  rollback completed
  note: commit message saved in .hg/last-message.txt
  abort: pretxncommit hook exited with status * (glob)
  [255]
  $ cat .hg/last-message.txt
  another precious commit message

test rollback on served repository

#if serve
  $ hg commit -m "precious commit message"
  $ hg serve -p $HGPORT -d --pid-file=hg.pid -A access.log -E errors.log
  $ cat hg.pid >> $DAEMON_PIDS
  $ cd ..
  $ hg clone http://localhost:$HGPORT u
  requesting all changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 1 files (+1 heads)
  new changesets 23b0221f3370:068774709090
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd u
  $ hg id default
  068774709090

now rollback and observe that 'hg serve' reloads the repository and
presents the correct tip changeset:

  $ hg -R ../t rollback
  repository tip rolled back to revision 1 (undo commit)
  working directory now based on revision 0
  $ hg id default
  791dd2169706

  $ killdaemons.py
#endif

update to older changeset and then refuse rollback, because
that would lose data (issue2998)
  $ cd ../t
  $ hg -q update
  $ rm `hg status -un`
  $ template='{rev}:{node|short}  [{branch}]  {desc|firstline}\n'
  $ echo 'valuable new file' > b
  $ echo 'valuable modification' >> a
  $ hg commit -A -m'a valuable change'
  adding b
  $ hg update 0
  1 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ hg rollback
  abort: rollback of last commit while not checked out may lose data
  (use -f to force)
  [255]
  $ hg tip -q
  2:4d9cd3795eea
  $ hg rollback -f
  repository tip rolled back to revision 1 (undo commit)
  $ hg status
  $ hg log --removed b   # yep, it's gone

same again, but emulate an old client that doesn't write undo.desc
  $ hg -q update
  $ echo 'valuable modification redux' >> a
  $ hg commit -m'a valuable change redux'
  $ rm .hg/undo.desc
  $ hg update 0
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg rollback
  rolling back unknown transaction
  $ cat a
  a

corrupt journal test
  $ echo "foo" > .hg/store/journal
  $ hg recover
  rolling back interrupted transaction
  couldn't read journal entry 'foo\n'!
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 2 changesets with 2 changes to 1 files

rollback disabled by config
  $ cat >> $HGRCPATH <<EOF
  > [ui]
  > rollback = false
  > EOF
  $ echo narf >> pinky-sayings.txt
  $ hg add pinky-sayings.txt
  $ hg ci -m 'First one.'
  $ hg rollback
  abort: rollback is disabled because it is unsafe
  (see `hg help -v rollback` for information)
  [255]

  $ cd ..

I/O errors on stdio are handled properly (issue5658)

  $ cat > badui.py << EOF
  > import errno
  > from mercurial.i18n import _
  > from mercurial import (
  >     error,
  >     registrar,
  >     ui as uimod,
  > )
  > 
  > configtable = {}
  > configitem = registrar.configitem(configtable)
  > 
  > configitem(b'ui', b'ioerrors',
  >     default=list,
  > )
  > 
  > def pretxncommit(ui, repo, **kwargs):
  >     ui.warn(b'warn during pretxncommit\n')
  > 
  > def pretxnclose(ui, repo, **kwargs):
  >     ui.warn(b'warn during pretxnclose\n')
  > 
  > def txnclose(ui, repo, **kwargs):
  >     ui.warn(b'warn during txnclose\n')
  > 
  > def txnabort(ui, repo, **kwargs):
  >     ui.warn(b'warn during abort\n')
  > 
  > class fdproxy(object):
  >     def __init__(self, ui, o):
  >         self._ui = ui
  >         self._o = o
  > 
  >     def __getattr__(self, attr):
  >         return getattr(self._o, attr)
  > 
  >     def write(self, msg):
  >         errors = set(self._ui.configlist(b'ui', b'ioerrors'))
  >         pretxncommit = msg == b'warn during pretxncommit\n'
  >         pretxnclose = msg == b'warn during pretxnclose\n'
  >         txnclose = msg == b'warn during txnclose\n'
  >         txnabort = msg == b'warn during abort\n'
  >         msgabort = msg == _(b'transaction abort!\n')
  >         msgrollback = msg == _(b'rollback completed\n')
  > 
  >         if pretxncommit and b'pretxncommit' in errors:
  >             raise IOError(errno.EPIPE, 'simulated epipe')
  >         if pretxnclose and b'pretxnclose' in errors:
  >             raise IOError(errno.EIO, 'simulated eio')
  >         if txnclose and b'txnclose' in errors:
  >             raise IOError(errno.EBADF, 'simulated badf')
  >         if txnabort and b'txnabort' in errors:
  >             raise IOError(errno.EPIPE, 'simulated epipe')
  >         if msgabort and b'msgabort' in errors:
  >             raise IOError(errno.EBADF, 'simulated ebadf')
  >         if msgrollback and b'msgrollback' in errors:
  >             raise IOError(errno.EIO, 'simulated eio')
  > 
  >         return self._o.write(msg)
  > 
  > def uisetup(ui):
  >     class badui(ui.__class__):
  >         def _write(self, dest, *args, **kwargs):
  >             olderr = self.ferr
  >             try:
  >                 if dest is self.ferr:
  >                     self.ferr = dest = fdproxy(self, olderr)
  >                 return super(badui, self)._write(dest, *args, **kwargs)
  >             finally:
  >                 self.ferr = olderr
  > 
  >     ui.__class__ = badui
  > 
  > def reposetup(ui, repo):
  >     ui.setconfig(b'hooks', b'pretxnclose.badui', pretxnclose, b'badui')
  >     ui.setconfig(b'hooks', b'txnclose.badui', txnclose, b'badui')
  >     ui.setconfig(b'hooks', b'pretxncommit.badui', pretxncommit, b'badui')
  >     ui.setconfig(b'hooks', b'txnabort.badui', txnabort, b'badui')
  > EOF

  $ cat >> $HGRCPATH << EOF
  > [extensions]
  > badui = $TESTTMP/badui.py
  > EOF

An I/O error during pretxncommit is handled

  $ hg init ioerror-pretxncommit
  $ cd ioerror-pretxncommit
  $ echo 0 > foo
  $ hg -q commit -A -m initial
  warn during pretxncommit
  warn during pretxnclose
  warn during txnclose
  $ echo 1 > foo
  $ hg --config ui.ioerrors=pretxncommit commit -m 'error during pretxncommit'
  warn during pretxnclose
  warn during txnclose

  $ hg commit -m 'commit 1'
  nothing changed
  [1]

  $ cd ..

An I/O error during pretxnclose is handled

  $ hg init ioerror-pretxnclose
  $ cd ioerror-pretxnclose
  $ echo 0 > foo
  $ hg -q commit -A -m initial
  warn during pretxncommit
  warn during pretxnclose
  warn during txnclose

  $ echo 1 > foo
  $ hg --config ui.ioerrors=pretxnclose commit -m 'error during pretxnclose'
  warn during pretxncommit
  warn during txnclose

  $ hg commit -m 'commit 1'
  nothing changed
  [1]

  $ cd ..

An I/O error during txnclose is handled

  $ hg init ioerror-txnclose
  $ cd ioerror-txnclose
  $ echo 0 > foo
  $ hg -q commit -A -m initial
  warn during pretxncommit
  warn during pretxnclose
  warn during txnclose

  $ echo 1 > foo
  $ hg --config ui.ioerrors=txnclose commit -m 'error during txnclose'
  warn during pretxncommit
  warn during pretxnclose

  $ hg commit -m 'commit 1'
  nothing changed
  [1]

  $ cd ..

An I/O error writing "transaction abort" is handled

  $ hg init ioerror-msgabort
  $ cd ioerror-msgabort

  $ echo 0 > foo
  $ hg -q commit -A -m initial
  warn during pretxncommit
  warn during pretxnclose
  warn during txnclose

  $ echo 1 > foo
  $ hg --config ui.ioerrors=msgabort --config hooks.pretxncommit=false commit -m 'error during abort message'
  warn during abort
  rollback completed
  abort: pretxncommit hook exited with status 1
  [255]

  $ hg commit -m 'commit 1'
  warn during pretxncommit
  warn during pretxnclose
  warn during txnclose

  $ cd ..

An I/O error during txnabort should still result in rollback

  $ hg init ioerror-txnabort
  $ cd ioerror-txnabort

  $ echo 0 > foo
  $ hg -q commit -A -m initial
  warn during pretxncommit
  warn during pretxnclose
  warn during txnclose

  $ echo 1 > foo
  $ hg --config ui.ioerrors=txnabort --config hooks.pretxncommit=false commit -m 'error during abort'
  transaction abort!
  rollback completed
  abort: pretxncommit hook exited with status 1
  [255]

  $ hg commit -m 'commit 1'
  warn during pretxncommit
  warn during pretxnclose
  warn during txnclose

  $ cd ..

An I/O error writing "rollback completed" is handled

  $ hg init ioerror-msgrollback
  $ cd ioerror-msgrollback

  $ echo 0 > foo
  $ hg -q commit -A -m initial
  warn during pretxncommit
  warn during pretxnclose
  warn during txnclose

  $ echo 1 > foo

  $ hg --config ui.ioerrors=msgrollback --config hooks.pretxncommit=false commit -m 'error during rollback message'
  transaction abort!
  warn during abort
  abort: pretxncommit hook exited with status 1
  [255]

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 1 changesets with 1 changes to 1 files

  $ cd ..

Multiple I/O errors after transaction open are handled.
This is effectively what happens if a peer disconnects in the middle
of a transaction.

  $ hg init ioerror-multiple
  $ cd ioerror-multiple
  $ echo 0 > foo
  $ hg -q commit -A -m initial
  warn during pretxncommit
  warn during pretxnclose
  warn during txnclose

  $ echo 1 > foo

  $ hg --config ui.ioerrors=pretxncommit,pretxnclose,txnclose,txnabort,msgabort,msgrollback commit -m 'multiple errors'

  $ hg verify
  checking changesets
  checking manifests
  crosschecking files in changesets and manifests
  checking files
  checked 2 changesets with 2 changes to 1 files

  $ cd ..