view tests/test-issue2137.t @ 23971:6becb9dbca25 stable

merge: mark .hgsubstate as possibly dirty before submerge for consistency

Before this patch, failure of updating subrepos may cause inconsistent
".hgsubstate". For example:

  1. dirstate entry for ".hgsubstate" of the parent repo is filled
     with valid size/date (via "hg state" or so)

  2. "hg update" is invoked at the parent repo

  3. ".hgsubstate" of the parent repo is updated on the filesystem as
     a part of "g"(et) action in "merge.applyupdates"

  4. it is assumed that size/date of ".hgsubstate" on the filesystem
     aren't changed from ones at (1)

     this is not so difficult condition, because just changing hash
     ids (every ids are same in length) in ".hgsubstate" doesn't
     change the file size of it

  5. "subrepo.submerge()" is invoked to update subrepos

  6. failure of updating in one of subrepos raises exception
     (e.g. "untracked file differs")

  7. "hg update" is aborted without updating dirstate of the parent repo

     dirstate entry for ".hgsubstate" still holds size/date at (1)

Then, ".hgsubstate" of the parent repo is treated as "CLEAN"
unexpectedly, because updating ".hgsubstate" at (3) doesn't change
size/date of it on the filesystem: see assumption at (4).

This inconsistent ".hgsubstate" status causes unexpected behavior, for
example:

  - "hg revert" forgets to revert ".hgsubstate"

  - "hg update" misunderstands that (not yet updated) subrepos diverge
    (then, it shows the prompt to confirm user's decision)

To avoid inconsistent ".hgsubstate" status above, this patch marks
".hgsubstate" as possibly dirty before "submerge" invocation.
"normallookup"-ed (= dirty) dirstate should be written out, even if
processing is aborted by failure.

This patch marks ".hgsubstate" as possibly dirty before "submerge",
also when it is removed or merged while merging, for safety. This
should prevent Mercurial from misunderstanding inconsistent
".hgsubstate" as clean.

To satisfy conditions at (1) and (4) above, this patch uses "hg status
--config debug.dirstate.delaywrite=2" (to fill valid size/date into
dirstate) and "touch" (to fix date of the file).

http://mercurial.selenic.com/bts/issue2137

Setup:

create a little extension that has 3 side-effects:
1) ensure changelog data is not inlined
2) make revlog to use lazyparser
3) test that repo.lookup() works
1 and 2 are preconditions for the bug; 3 is the bug.

  $ cat > commitwrapper.py <<EOF
  > from mercurial import extensions, node, revlog
  > 
  > def reposetup(ui, repo):
  >     class wraprepo(repo.__class__):
  >         def commit(self, *args, **kwargs):
  >             result = super(wraprepo, self).commit(*args, **kwargs)
  >             tip1 = node.short(repo.changelog.tip())
  >             tip2 = node.short(repo.lookup(tip1))
  >             assert tip1 == tip2
  >             ui.write('new tip: %s\n' % tip1)
  >             return result
  >     repo.__class__ = wraprepo
  > 
  > def extsetup(ui):
  >     revlog._maxinline = 8             # split out 00changelog.d early
  >     revlog._prereadsize = 8           # use revlog.lazyparser
  > EOF

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > commitwrapper = `pwd`/commitwrapper.py
  > EOF

  $ hg init repo1
  $ cd repo1
  $ echo a > a
  $ hg commit -A -m'add a with a long commit message to make the changelog a bit bigger'
  adding a
  new tip: 553596fad57b

Test that new changesets are visible to repo.lookup():

  $ echo a >> a
  $ hg commit -m'one more commit to demonstrate the bug'
  new tip: 799ae3599e0e

  $ hg tip
  changeset:   1:799ae3599e0e
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     one more commit to demonstrate the bug
  

  $ cd ..