tests/test-racy-mutations.t

commit: use `dirstate.change_files` to scope the associated `addremove`

This was significantly more complicated than I expected, because multiple
extensions get in the way.

I introduced a context that lazily open the transaction and associated context
to work around these complication. See the inline documentation for details.

Introducing the wrapping transaction remove the need for dirstate-guard (one of
the ultimate goal of all this), and slightly affect the result of a `hg
rollback` after a `hg commit --addremove`. That last part is deemed fine. It
aligns the behavior with what happens after a failed `hg commit --addremove` and
nobody should be using `hg rollback` anyway.

The small output change in the test come from the different transaction timing
and fact the transaction now backup the dirstate before the addremove, which
might mean "no file to backup" when the repository starts from an empty state.

#testcases skip-detection fail-if-detected

Test situations that "should" only be reproducible:
- on networked filesystems, or
- user using `hg debuglocks` to eliminate the lock file, or
- something (that doesn't respect the lock file) writing to the .hg directory
while we're running


Initial setup
-------------

  $ hg init base-repo
  $ cd base-repo

  $ cat > "$TESTTMP_FORWARD_SLASH/waitlock_editor.sh" <<EOF
  >     [ -n "\${WAITLOCK_ANNOUNCE:-}" ] && touch "\${WAITLOCK_ANNOUNCE}"
  >     f="\${WAITLOCK_FILE}"
  >     start=\`date +%s\`
  >     timeout=5
  >     "$RUNTESTDIR_FORWARD_SLASH/testlib/wait-on-file" "\$timeout" "\$f"
  >     if [ \$# -gt 1 ]; then
  >         cat "\$@"
  >     fi
  > EOF

Things behave differently if we don't already have a 00changelog.i file when
this all starts, so let's make one.

  $ echo r0 > r0
  $ hg commit -qAm 'r0'

  $ cd ..
  $ cp -R base-repo main-client
  $ cp -R base-repo racing-client

  $ mkdir sync
  $ EDITOR_STARTED="$TESTTMP_FORWARD_SLASH/sync/.editor_started"
  $ MISCHIEF_MANAGED="$TESTTMP_FORWARD_SLASH/sync/.mischief_managed"
  $ JOBS_FINISHED="$TESTTMP_FORWARD_SLASH/sync/.jobs_finished"

Actual test
-----------

Start an hg commit that will take a while

  $ cd main-client

#if fail-if-detected
  $ cat >> $HGRCPATH << EOF
  > [debug]
  > revlog.verifyposition.changelog = fail
  > EOF
#endif

  $ echo foo > foo
  $ (
  >    unset HGEDITOR;
  >    WAITLOCK_ANNOUNCE="${EDITOR_STARTED}" \
  >    WAITLOCK_FILE="${MISCHIEF_MANAGED}" \
  >    hg commit -qAm 'r1 (foo)' --edit foo \
  >    --config ui.editor="sh $TESTTMP_FORWARD_SLASH/waitlock_editor.sh" \
  >    > .foo_commit_out 2>&1 ;\
  >    touch "${JOBS_FINISHED}"
  > ) &

Wait for the "editor" to actually start
  $ sh "$RUNTESTDIR_FORWARD_SLASH/testlib/wait-on-file" 5 "${EDITOR_STARTED}"


Do a concurrent edition
  $ cd ../racing-client
  $ touch ../pre-race
  $ sleep 1
  $ echo bar > bar
  $ hg --repository ../racing-client commit -qAm 'r2 (bar)' bar
  $ hg --repository ../racing-client debugrevlogindex -c
     rev linkrev nodeid       p1           p2
       0       0 222799e2f90b 000000000000 000000000000
       1       1 6f124f6007a0 222799e2f90b 000000000000

We simulate an network FS race by overwriting raced repo content with the new
content of the files changed in the racing repository

  $ for x in `find . -type f -newer ../pre-race`; do
  >    cp $x ../main-client/$x
  > done
  $ cd ../main-client

Awaken the editor from that first commit
  $ touch "${MISCHIEF_MANAGED}"
And wait for it to finish
  $ WAITLOCK_FILE="${JOBS_FINISHED}" sh "$TESTTMP_FORWARD_SLASH/waitlock_editor.sh"

#if skip-detection
(Ensure there was no output)
  $ cat .foo_commit_out
And observe a corrupted repository -- rev 2's linkrev is 1, which should never
happen for the changelog (the linkrev should always refer to itself).
  $ hg debugrevlogindex -c
     rev linkrev nodeid       p1           p2
       0       0 222799e2f90b 000000000000 000000000000
       1       1 6f124f6007a0 222799e2f90b 000000000000
       2       1 ac80e6205bb2 222799e2f90b 000000000000
#endif

#if fail-if-detected
  $ cat .foo_commit_out
  note: commit message saved in .hg/last-message.txt
  note: use 'hg commit --logfile .hg/last-message.txt --edit' to reuse it
  transaction abort!
  rollback completed
  abort: 00changelog.i: file cursor at position 249, expected 121
And no corruption in the changelog.
  $ hg debugrevlogindex -c
     rev linkrev nodeid       p1           p2
       0       0 222799e2f90b 000000000000 000000000000
       1       1 6f124f6007a0 222799e2f90b 000000000000 (missing-correct-output !)
And, because of transactions, there's none in the manifestlog either.
  $ hg debugrevlogindex -m
     rev linkrev nodeid       p1           p2
       0       0 7b7020262a56 000000000000 000000000000
       1       1 ad3fe36d86d9 7b7020262a56 000000000000
#endif