view tests/test-remotefilelog-linknodes.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

# Tests for the complicated linknode logic in remotefilelog.py::ancestormap()

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

  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [remotefilelog]
  > server=True
  > serverexpiration=-1
  > EOF
  $ echo x > x
  $ hg commit -qAm x
  $ cd ..

  $ hgcloneshallow ssh://user@dummy/master shallow -q
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)

# Rebase produces correct log -f linknodes

  $ cd shallow
  $ echo y > y
  $ hg commit -qAm y
  $ hg up 0
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo x >> x
  $ hg commit -qAm xx
  $ hg log -f x --template "{node|short}\n"
  0632994590a8
  b292c1e3311f

  $ hg rebase -d 1
  rebasing 2:0632994590a8 tip "xx"
  saved backup bundle to $TESTTMP/shallow/.hg/strip-backup/0632994590a8-0bc786d8-rebase.hg (glob)
  $ hg log -f x --template "{node|short}\n"
  81deab2073bc
  b292c1e3311f

# Rebase back, log -f still works

  $ hg rebase -d 0 -r 2
  rebasing 2:81deab2073bc tip "xx"
  saved backup bundle to $TESTTMP/shallow/.hg/strip-backup/81deab2073bc-80cb4fda-rebase.hg (glob)
  $ hg log -f x --template "{node|short}\n"
  b3fca10fb42d
  b292c1e3311f

  $ hg rebase -d 1 -r 2
  rebasing 2:b3fca10fb42d tip "xx"
  saved backup bundle to $TESTTMP/shallow/.hg/strip-backup/b3fca10fb42d-da73a0c7-rebase.hg (glob)

  $ cd ..

# Reset repos
  $ clearcache

  $ rm -rf master
  $ rm -rf shallow
  $ hg init master
  $ cd master
  $ cat >> .hg/hgrc <<EOF
  > [remotefilelog]
  > server=True
  > serverexpiration=-1
  > EOF
  $ echo x > x
  $ hg commit -qAm x
  $ cd ..

  $ hgcloneshallow ssh://user@dummy/master shallow -q
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)

# Rebase stack onto landed commit

  $ cd master
  $ echo x >> x
  $ hg commit -Aqm xx

  $ cd ../shallow
  $ echo x >> x
  $ hg commit -Aqm xx2
  $ echo y >> x
  $ hg commit -Aqm xxy

  $ hg pull -q
  $ hg rebase -d tip
  rebasing 1:4549721d828f "xx2"
  note: not rebasing 1:4549721d828f "xx2", its destination already has all its changes
  rebasing 2:5ef6d97e851c "xxy"
  saved backup bundle to $TESTTMP/shallow/.hg/strip-backup/4549721d828f-b084e33c-rebase.hg (glob)
  $ hg log -f x --template '{node|short}\n'
  4ae8e31c85ef
  0632994590a8
  b292c1e3311f

  $ cd ..

# system cache has invalid linknode, but .hg/store/data has valid

  $ cd shallow
  $ hg strip -r 1 -q
  $ rm -rf .hg/store/data/*
  $ echo x >> x
  $ hg commit -Aqm xx_local
  $ hg log -f x --template '{rev}:{node|short}\n'
  1:21847713771d
  0:b292c1e3311f

  $ cd ..
  $ rm -rf shallow

/* Local linknode is invalid; remote linknode is valid (formerly slow case) */

  $ hgcloneshallow ssh://user@dummy/master shallow -q
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over * (glob)
  $ cd shallow
  $ echo x >> x
  $ hg commit -Aqm xx2
  $ cd ../master
  $ echo y >> y
  $ hg commit -Aqm yy2
  $ echo x >> x
  $ hg commit -Aqm xx2-fake-rebased
  $ echo y >> y
  $ hg commit -Aqm yy3
  $ cd ../shallow
  $ hg pull --config remotefilelog.debug=True
  pulling from ssh://user@dummy/master
  searching for changes
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 0 changes to 0 files (+1 heads)
  new changesets 01979f9404f8:7200df4e0aca
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg update tip -q
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
  $ echo x > x
  $ hg commit -qAm xx3

# At this point, the linknode points to c1254e70bad1 instead of 32e6611f6149
  $ hg log -G -T '{node|short} {desc} {phase} {files}\n'
  @  a5957b6bf0bd xx3 draft x
  |
  o  7200df4e0aca yy3 public y
  |
  o  32e6611f6149 xx2-fake-rebased public x
  |
  o  01979f9404f8 yy2 public y
  |
  | o  c1254e70bad1 xx2 draft x
  |/
  o  0632994590a8 xx public x
  |
  o  b292c1e3311f x public x
  
# Check the contents of the local blob for incorrect linknode
  $ hg debugremotefilelog .hg/store/data/11f6ad8ec52a2984abaafd7c3b516503785c2072/d4a3ed9310e5bd9887e3bf779da5077efab28216
  size: 6 bytes
  path: .hg/store/data/11f6ad8ec52a2984abaafd7c3b516503785c2072/d4a3ed9310e5bd9887e3bf779da5077efab28216 
  key: d4a3ed9310e5 
  
          node =>           p1            p2      linknode     copyfrom
  d4a3ed9310e5 => aee31534993a  000000000000  c1254e70bad1  
  aee31534993a => 1406e7411862  000000000000  0632994590a8  
  1406e7411862 => 000000000000  000000000000  b292c1e3311f  

# Verify that we do a fetch on the first log (remote blob fetch for linkrev fix)
  $ hg log -f x -T '{node|short} {desc} {phase} {files}\n'
  a5957b6bf0bd xx3 draft x
  32e6611f6149 xx2-fake-rebased public x
  0632994590a8 xx public x
  b292c1e3311f x public x
  1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)

# But not after that
  $ hg log -f x -T '{node|short} {desc} {phase} {files}\n'
  a5957b6bf0bd xx3 draft x
  32e6611f6149 xx2-fake-rebased public x
  0632994590a8 xx public x
  b292c1e3311f x public x

# Check the contents of the remote blob for correct linknode
  $ hg debugremotefilelog $CACHEDIR/master/11/f6ad8ec52a2984abaafd7c3b516503785c2072/d4a3ed9310e5bd9887e3bf779da5077efab28216
  size: 6 bytes
  path: $TESTTMP/hgcache/master/11/f6ad8ec52a2984abaafd7c3b516503785c2072/d4a3ed9310e5bd9887e3bf779da5077efab28216 
  key: d4a3ed9310e5 
  
          node =>           p1            p2      linknode     copyfrom
  d4a3ed9310e5 => aee31534993a  000000000000  32e6611f6149  
  aee31534993a => 1406e7411862  000000000000  0632994590a8  
  1406e7411862 => 000000000000  000000000000  b292c1e3311f