[PATCH 2 of 5] localrepo: invoke dirstate.unsureifambig in wwrite for safety

Martin von Zweigbergk martinvonz at google.com
Mon Jun 1 13:57:16 CDT 2015


On Mon, Jun 1, 2015 at 11:07 AM FUJIWARA Katsunori <foozy at lares.dti.ne.jp>
wrote:

> At Mon, 01 Jun 2015 17:02:10 +0000,
> Martin von Zweigbergk wrote:
> >
> > [1  <text/plain; UTF-8 (7bit)>]
> > Thanks. I think I knew most of that, but the subrepo case for interrupted
> > update was a good example I had not thought about. My question remains,
> > however. In the sequence in this test case, you do this:
> >
> > $ hg update -q -C 3
> > $ touch -t 200001010000 b
> > $ hg status -A b
> > $ hg --config extensions.abort=$TESTTMP/abort.py merge 5
> > $ touch -t 200001010000 b
> >
> > What I'm wondering is what real-world scenarios could lead to file b's
> > timestamp being the same in those two cases (where you artificially touch
> > them here). Since we said that 'hg status' is run strictly after (at
> > whatever granularity is recorded by the FS, perhaps second-level), how
> can
> > the 'hg merge' produce a timestamp for file b that's the same as what 'hg
> > update' does?
>
> `hg merge` can be aborted by same reason at `hg update` before
> updating dirstate:
>
>   (0) cleanup working directory for examination of `hg merge`
>       (let's ignore this while focusing on examination of `hg merge`)
> > $ hg update -q -C 3
>
>   (1) ensure forcibly that `repo.dirstate['b']` has valid timestamp
> > $ touch -t 200001010000 b
> > $ hg status -A b
>

We said that this 'hg status' is run at 200001010000(00)+1sec (otherwise
the timestamp in the dirstate would be unset). Correct?


>
>   (2) execute `hg merge`, but it is aborted before "update dirstate"
>       for example:
>       - invalid updating in subrepositories
>       - keyboard interruption by user, file I/O error and so on
> > $ hg --config extensions.abort=$TESTTMP/abort.py merge 5
>
>   (3) (re-)set timestamp of 'b' on the filesystem for mis-leading
>       this emulates that `hg merge` update 'b' before 200001010000(00)+1sec
> > $ touch -t 200001010000 b
>

Since 'hg status' above was run at 200001010000(00)+1sec (or later), how
can this (interrupted) merge be run at 200001010000(00)?


>
>
> In addition to it, '.hgsubstate' may have to be focused on.
>
> Regardless of `hg update`/`hg merge` result, size of it on the
> filesystem is often kept, because '.hgsubstate' consists of "hashid
> subrepopath": "hashid" of hg subrepo is always 40 letters :-)
>
>
> (Do I understand your question correctly ?)
>
>
> > On Sun, May 31, 2015 at 10:24 PM FUJIWARA Katsunori <
> foozy at lares.dti.ne.jp>
> > wrote:
> >
> > > At Fri, 29 May 2015 18:05:18 +0000,
> > > Martin von Zweigbergk wrote:
> > > >
> > > > [1  <text/plain; UTF-8 (7bit)>]
> > > > On Wed, May 27, 2015 at 10:06 AM FUJIWARA Katsunori <
> > > foozy at lares.dti.ne.jp>
> > > > wrote:
> > > >
> > > > > # HG changeset patch
> > > > > # User FUJIWARA Katsunori <foozy at lares.dti.ne.jp>
> > > > > # Date 1432745859 -32400
> > > > > #      Thu May 28 01:57:39 2015 +0900
> > > > > # Node ID b82f32b8734b109b84f533dc62dd3f23195d1e0a
> > > > > # Parent  ab9f120295b59933d1acd72771f01b5fac8d221d
> > > > > localrepo: invoke dirstate.unsureifambig in wwrite for safety
> > > > >
> > > > > Modified file may be mis-recognized as clean by dirstate, if mode,
> > > > > size and timestamp of it on the filesystem aren't changed.
> > > > >
> > > > > To avoid such ambiguous situation, this patch invokes
> > > > > `dirstate.unsureifambig()` at the end of
> `localrepository.wwrite()`.
> > > > >
> > > > > When file is cleanly reverted or updated, subsequent
> > > > > `dirstate.lookup()` makes `dirstate.unsureifambig()` a little
> > > > > redundant. But it is enough cheap for keeping consistency.
> > > > >
> > > > > diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
> > > > > --- a/mercurial/localrepo.py
> > > > > +++ b/mercurial/localrepo.py
> > > > > @@ -927,7 +927,9 @@
> > > > >              self.wvfs.write(filename, data)
> > > > >              if 'x' in flags:
> > > > >                  self.wvfs.setflags(filename, False, True)
> > > > > -        return len(data)
> > > > > +        wsize = len(data)
> > > > > +        self.dirstate.unsureifambig(filename, wsize)
> > > > > +        return wsize
> > > > >
> > > > >      def wwritedata(self, filename, data):
> > > > >          return self._filter(self._decodefilterpats, filename,
> data)
> > > > > diff --git a/tests/test-merge1.t b/tests/test-merge1.t
> > > > > --- a/tests/test-merge1.t
> > > > > +++ b/tests/test-merge1.t
> > > > > @@ -206,4 +206,60 @@
> > > > >    $ hg revert -r -2 b
> > > > >    $ hg up -q -- -2
> > > > >
> > > > > +Test for ambiguity from same size, timestamp and mode
> > > > > +
> > > > > +  $ cat > $TESTTMP/abort.py <<EOF
> > > > > +  > from mercurial import extensions, merge, util
> > > > > +  > def applyupdates(orig, *args, **kwargs):
> > > > > +  >     orig(*args, **kwargs)
> > > > > +  >     # emulate aborting before "recordupdates()"
> > > > > +  >     # => files are changed without updating dirstate
> > > > > +  >     raise util.Abort('intentional aborting')
> > > > > +  > def extsetup(ui):
> > > > > +  >     extensions.wrapfunction(merge, "applyupdates",
> applyupdates)
> > > > > +  > EOF
> > > > > +
> > > > > +(file gotten from other revision)
> > > > > +
> > > > > +  $ hg update -q -C 2
> > > > > +  $ echo 'THIS IS FILE B5' > b
> > > > > +  $ hg commit -m 'commit #5'
> > > > > +
> > > > > +  $ hg update -q -C 3
> > > > > +  $ touch -t 200001010000 b
> > > > > +  $ hg status -A b
> > > > > +  C b
> > > > > +  $ cat b
> > > > > +  This is file b1
> > > > > +
> > > > > +  $ hg --config extensions.abort=$TESTTMP/abort.py merge 5
> > > > > +  abort: intentional aborting
> > > > > +  [255]
> > > > > +  $ touch -t 200001010000 b
> > > > >
> > > >
> > > > I'm sorry I'm slow, but I'm still trying to understand this series.
> This
> > > is
> > > > of course an artificial way of reproducing the problem you were
> seeing,
> > > but
> > > > how does it sometimes happen in real life? Since the dirstate is
> written
> > > on
> > > > the 'hg status' call above, and that command is run after (not
> within the
> > > > same second, as we discussed on path 1/5) the file was modified on
> disk,
> > > > how can the 'hg merge' command be run at the earlier time again
> (which
> > > you
> > > > seem to be simulating here by setting the same timestamp)?
> > >
> > > Sorry for not enough explanation. I'll add more detailed explanation
> > > in revised version.
> > >
> > > Core of `hg update` and `hg merge` consists of steps below:
> > >
> > >   1. calculate result of updating and examine some additional points
> below
> > >
> > >      - `_checkunknownfiles()` (implied by `calculateupdates()`)
> > >      - `_checkcollision()`
> > >
> > >   2. update files in the working directory in `merge.applyupdates()`
> > >
> > >      this also implies updating files in subrepositories recursively
> > >      (= `preupdate`/`update` hooks in them are also executed)
> > >
> > >   3. update dirstate in `merge.recordupdates()`
> > >
> > >   4. write in-memory dirstate changes out at releasing wlock
> > >
> > >
> > > Tests in this patch emulate that `hg update` and `hg merge` (at top of
> > > subrepo tree) are aborted between (2) and (3) by:
> > >
> > >   - invalid updating in subrepositories
> > >
> > >     for example:
> > >     - uncommitted changes
> > >     - collision against unknown files in the working directory
> > >     - case-insensitive collision between files in new revision (and
> > >       current one at merging)
> > >     - failure of `preupdate` or `update` hooks
> > >
> > >   - keyboard interruption by user, file I/O error and so on
> > >
> > > `test-subrepo.t` actually treats the former situation, and
> > > 6becb9dbca25 tried to fix (part of) this issue. Tests in this patch
> > > can be said as "generalized version of test in 6becb9dbca25".
> > >
> > >
> > > Even though some existing tests are enough as a white box test
> > > examining whether `repo.wwrite()` invokes `dirstate.unsureifambig()`
> > > correctly, testing in multiple situations should be useful to avoid
> > > unexpected regression in the future, IMHO.
> > >
> > >
> > >
> > > > > +  $ cat b
> > > > > +  THIS IS FILE B5
> > > > > +  $ hg status -A b
> > > > > +  M b
> > > > > +
> > > > > +(file merged from other revision)
> > > > > +
> > > > > +  $ hg update -q -C 3
> > > > > +  $ echo 'this is file b6' > b
> > > > > +  $ hg commit -m 'commit #6'
> > > > > +  created new head
> > > > > +  $ touch -t 200001010000 b
> > > > > +  $ hg status -A b
> > > > > +  C b
> > > > > +  $ cat b
> > > > > +  this is file b6
> > > > > +
> > > > > +  $ hg --config extensions.abort=$TESTTMP/abort.py merge --tool
> > > > > internal:other 5
> > > > > +  abort: intentional aborting
> > > > > +  [255]
> > > > > +  $ touch -t 200001010000 b
> > > > > +  $ cat b
> > > > > +  THIS IS FILE B5
> > > > > +  $ hg status -A b
> > > > > +  M b
> > > > > +
> > > > >    $ cd ..
> > > > > _______________________________________________
> > > > > Mercurial-devel mailing list
> > > > > Mercurial-devel at selenic.com
> > > > > https://selenic.com/mailman/listinfo/mercurial-devel
> > > > >
> > > > [2  <text/html; UTF-8 (quoted-printable)>]
> > > >
> > >
> > > ----------------------------------------------------------------------
> > > [FUJIWARA Katsunori]                             foozy at lares.dti.ne.jp
> > >
> > [2  <text/html; UTF-8 (quoted-printable)>]
> >
>
> ----------------------------------------------------------------------
> [FUJIWARA Katsunori]                             foozy at lares.dti.ne.jp
>
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