view tests/test-remotefilelog-sparse.t @ 46846:2819df466cae

tests: add test-remotefilelog-strip.t to demonstrate an issue with linknodes

### Background

Every time a commit is modified, remotefilelog updates the metadata for the file
object to point to the new commit (I believe that this is different from
non-remotefilelog hg, which leaves the linkrevs pointing to the obsolete
commits; doing otherwise would involve changing data in the middle of revlogs).

With `hg strip` (or other things that use repair.strip()), when you strip a
commit that's not the tip of the revlog, there may be commits after it in revnum
order that aren't descended from it and don't need to be (and shouldn't be)
stripped. These are "saved" by strip in a bundle, and that bundle is reapplied
after truncating the relevant revlogs.

### The problem

Remotefilelog generally avoids being involved at all in strip. Currently, that
includes even providing file contents to this backup bundle. This can cause the
linknode to point to a changeset that is no longer in the repository.

Example:

```
@  3 df91f74b871e
|
| x  2 70494d7ec5ef
|/
| x  1 1e423846dde0
|/
o  0 b292c1e3311f
```

Commits 1, 2, and 3 are related via obsolescence, and are description-only
changes. The linknode for the file in these commits changed each time we updated
the description, so it's currently df91f7. If I strip commits 1 and 3, however,
the linknode *remains* df91f7, which no longer exists in the repository. Commit
70494d was "saved", stripped, and then reapplied, so it is in the repository (as
revision 1 instead of 2 now), and was unobsoleted since the obsmarker was
stripped as well. The linknode for the file should point to 70494d, the most
recent commit that is in the repository that modified the file.

Remotefilelog has some logic to handle broken linknodes, but it can be slow. We
have actually disabled it internally because it's too slow for our purposes.

Differential Revision: https://phab.mercurial-scm.org/D10319

#require no-windows

  $ . "$TESTDIR/remotefilelog-library.sh"

  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [remotefilelog]
  > server=True
  > EOF
  $ echo x > x
  $ echo z > z
  $ hg commit -qAm x1
  $ echo x2 > x
  $ echo z2 > z
  $ hg commit -qAm x2
  $ hg bookmark foo

  $ cd ..

# prefetch a revision w/ a sparse checkout

  $ hgcloneshallow ssh://user@dummy/master shallow --noupdate
  streaming all changes
  2 files to transfer, 527 bytes of data
  transferred 527 bytes in 0.* seconds (*/sec) (glob)
  searching for changes
  no changes found
  $ cd shallow
  $ printf "[extensions]\nsparse=\n" >> .hg/hgrc

  $ hg debugsparse -I x
  $ hg prefetch -r 0
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)

  $ hg cat -r 0 x
  x

  $ hg debugsparse -I z
  $ hg prefetch -r 0
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)

  $ hg cat -r 0 z
  z

# prefetch sparse only on pull when configured

  $ printf "[remotefilelog]\npullprefetch=bookmark()\n" >> .hg/hgrc
  $ hg strip tip
  saved backup bundle to $TESTTMP/shallow/.hg/strip-backup/876b1317060d-b2e91d8d-backup.hg (glob)

  $ hg debugsparse --delete z

  $ clearcache
  $ hg pull
  pulling from ssh://user@dummy/master
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  updating bookmark foo
  added 1 changesets with 0 changes to 0 files
  new changesets 876b1317060d
  (run 'hg update' to get a working copy)
  prefetching file contents
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)

# Dont consider filtered files when doing copy tracing

## Push an unrelated commit
  $ cd ../

  $ hgcloneshallow ssh://user@dummy/master shallow2
  streaming all changes
  2 files to transfer, 527 bytes of data
  transferred 527 bytes in 0.* seconds (*) (glob)
  searching for changes
  no changes found
  updating to branch default
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
  $ cd shallow2
  $ printf "[extensions]\nsparse=\n" >> .hg/hgrc

  $ hg up -q 0
  2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
  $ touch a
  $ hg ci -Aqm a
  $ hg push -q -f

## Pull the unrelated commit and rebase onto it - verify unrelated file was not
pulled

  $ cd ../shallow
  $ hg up -q 1
  $ hg pull -q
  $ hg debugsparse -I z
  $ clearcache
  $ hg prefetch -r '. + .^' -I x -I z
  4 files fetched over 1 fetches - (4 misses, 0.00% hit ratio) over * (glob)
  $ hg rebase -d 2 --keep
  rebasing 1:876b1317060d foo "x2"