view tests/test-diff-upgrade.t @ 23702:c48924787eaa

filectx.parents: enforce changeid of parent to be in own changectx ancestors

Because of the way filenodes are computed, you can have multiple changesets
"introducing" the same file revision. For example, in the changeset graph
below, changeset 2 and 3 both change a file -to- and -from- the same content.

  o 3: content = new
  |
  | o 2: content = new
  |/
  o 1: content = old

In such cases, the file revision is create once, when 2 is added, and just reused
for 3. So the file change in '3' (from "old" to "new)" has no linkrev pointing
to it).  We'll call this situation "linkrev-shadowing". As the linkrev is used for
optimization purposes when walking a file history, the linkrev-shadowing
results in an unexpected jump to another branch during such a walk.. This leads to
multiple bugs with log, annotate and rename detection.

One element to fix such bugs is to ensure that walking the file history sticks on
the same topology as the changeset's history. For this purpose, we extend the
logic in 'basefilectx.parents' so that it always defines the proper changeset
to associate the parent file revision with. This "proper" changeset has to be an
ancestor of the changeset associated with the child file revision.

This logic is performed in the '_adjustlinkrev' function. This function is
given the starting changeset and all the information regarding the parent file
revision. If the linkrev for the file revision is an ancestor of the starting
changeset, the linkrev is valid and will be used. If it is not, we detected a
topological jump caused by linkrev shadowing, we are going to walk the
ancestors of the starting changeset until we find one setting the file to the
revision we are trying to create.

The performance impact appears acceptable:

- We are walking the changelog once for each filelog traversal (as there should
  be no overlap between searches),

- changelog traversal itself is fairly cheap, compared to what is likely going
  to be perform on the result on the filelog traversal,

- We only touch the manifest for ancestors touching the file, And such
  changesets are likely to be the one introducing the file. (except in
  pathological cases involving merge),

- We use manifest diff instead of full manifest unpacking to check manifest
  content, so it does not involve applying multiple diffs in most case.

- linkrev shadowing is not the common case.

Tests for fixed issues in log, annotate and rename detection have been
added.

But this changeset does not solve all problems. It fixes -ancestry-
computation, but if the linkrev-shadowed changesets is the starting one, we'll
still get things wrong. We'll have to fix the bootstrapping of such operations
in a later changeset. Also, the usage of `hg log FILE`  without --follow still
has issues with linkrev pointing to hidden changesets, because it relies on the
`filelog` revset which implement its own traversal logic that is still to be
fixed.

Thanks goes to:
- Matt Mackall: for nudging me in the right direction
- Julien Cristau and Rémi Cardona: for keep telling me linkrev bug were an
  evolution show stopper for 3 years.
- Durham Goode: for finding a new linkrev issue every few weeks
- Mads Kiilerich: for that last rename bug who raise this topic over my
  anoyance limit.

#require execbit

  $ cat <<EOF >> $HGRCPATH
  > [extensions]
  > autodiff = $TESTDIR/autodiff.py
  > [diff]
  > nodates = 1
  > EOF

  $ hg init repo
  $ cd repo



make a combination of new, changed and deleted file

  $ echo regular > regular
  $ echo rmregular > rmregular
  $ $PYTHON -c "file('bintoregular', 'wb').write('\0')"
  $ touch rmempty
  $ echo exec > exec
  $ chmod +x exec
  $ echo rmexec > rmexec
  $ chmod +x rmexec
  $ echo setexec > setexec
  $ echo unsetexec > unsetexec
  $ chmod +x unsetexec
  $ echo binary > binary
  $ $PYTHON -c "file('rmbinary', 'wb').write('\0')"
  $ hg ci -Am addfiles
  adding binary
  adding bintoregular
  adding exec
  adding regular
  adding rmbinary
  adding rmempty
  adding rmexec
  adding rmregular
  adding setexec
  adding unsetexec
  $ echo regular >> regular
  $ echo newregular >> newregular
  $ rm rmempty
  $ touch newempty
  $ rm rmregular
  $ echo exec >> exec
  $ echo newexec > newexec
  $ echo bintoregular > bintoregular
  $ chmod +x newexec
  $ rm rmexec
  $ chmod +x setexec
  $ chmod -x unsetexec
  $ $PYTHON -c "file('binary', 'wb').write('\0\0')"
  $ $PYTHON -c "file('newbinary', 'wb').write('\0')"
  $ rm rmbinary
  $ hg addremove -s 0
  adding newbinary
  adding newempty
  adding newexec
  adding newregular
  removing rmbinary
  removing rmempty
  removing rmexec
  removing rmregular

git=no: regular diff for all files

  $ hg autodiff --git=no
  diff -r a66d19b9302d binary
  Binary file binary has changed
  diff -r a66d19b9302d bintoregular
  Binary file bintoregular has changed
  diff -r a66d19b9302d exec
  --- a/exec
  +++ b/exec
  @@ -1,1 +1,2 @@
   exec
  +exec
  diff -r a66d19b9302d newbinary
  Binary file newbinary has changed
  diff -r a66d19b9302d newexec
  --- /dev/null
  +++ b/newexec
  @@ -0,0 +1,1 @@
  +newexec
  diff -r a66d19b9302d newregular
  --- /dev/null
  +++ b/newregular
  @@ -0,0 +1,1 @@
  +newregular
  diff -r a66d19b9302d regular
  --- a/regular
  +++ b/regular
  @@ -1,1 +1,2 @@
   regular
  +regular
  diff -r a66d19b9302d rmbinary
  Binary file rmbinary has changed
  diff -r a66d19b9302d rmexec
  --- a/rmexec
  +++ /dev/null
  @@ -1,1 +0,0 @@
  -rmexec
  diff -r a66d19b9302d rmregular
  --- a/rmregular
  +++ /dev/null
  @@ -1,1 +0,0 @@
  -rmregular

git=yes: git diff for single regular file

  $ hg autodiff --git=yes regular
  diff --git a/regular b/regular
  --- a/regular
  +++ b/regular
  @@ -1,1 +1,2 @@
   regular
  +regular

git=auto: regular diff for regular files and non-binary removals

  $ hg autodiff --git=auto regular newregular rmregular rmexec
  diff -r a66d19b9302d newregular
  --- /dev/null
  +++ b/newregular
  @@ -0,0 +1,1 @@
  +newregular
  diff -r a66d19b9302d regular
  --- a/regular
  +++ b/regular
  @@ -1,1 +1,2 @@
   regular
  +regular
  diff -r a66d19b9302d rmexec
  --- a/rmexec
  +++ /dev/null
  @@ -1,1 +0,0 @@
  -rmexec
  diff -r a66d19b9302d rmregular
  --- a/rmregular
  +++ /dev/null
  @@ -1,1 +0,0 @@
  -rmregular

  $ for f in exec newexec setexec unsetexec binary newbinary newempty rmempty rmbinary bintoregular; do
  >     echo
  >     echo '% git=auto: git diff for' $f
  >     hg autodiff --git=auto $f
  > done
  
  % git=auto: git diff for exec
  diff -r a66d19b9302d exec
  --- a/exec
  +++ b/exec
  @@ -1,1 +1,2 @@
   exec
  +exec
  
  % git=auto: git diff for newexec
  diff --git a/newexec b/newexec
  new file mode 100755
  --- /dev/null
  +++ b/newexec
  @@ -0,0 +1,1 @@
  +newexec
  
  % git=auto: git diff for setexec
  diff --git a/setexec b/setexec
  old mode 100644
  new mode 100755
  
  % git=auto: git diff for unsetexec
  diff --git a/unsetexec b/unsetexec
  old mode 100755
  new mode 100644
  
  % git=auto: git diff for binary
  diff --git a/binary b/binary
  index a9128c283485202893f5af379dd9beccb6e79486..09f370e38f498a462e1ca0faa724559b6630c04f
  GIT binary patch
  literal 2
  Jc${Nk0000200961
  
  
  % git=auto: git diff for newbinary
  diff --git a/newbinary b/newbinary
  new file mode 100644
  index e69de29bb2d1d6434b8b29ae775ad8c2e48c5391..f76dd238ade08917e6712764a16a22005a50573d
  GIT binary patch
  literal 1
  Ic${MZ000310RR91
  
  
  % git=auto: git diff for newempty
  diff --git a/newempty b/newempty
  new file mode 100644
  
  % git=auto: git diff for rmempty
  diff --git a/rmempty b/rmempty
  deleted file mode 100644
  
  % git=auto: git diff for rmbinary
  diff --git a/rmbinary b/rmbinary
  deleted file mode 100644
  index f76dd238ade08917e6712764a16a22005a50573d..e69de29bb2d1d6434b8b29ae775ad8c2e48c5391
  GIT binary patch
  literal 0
  Hc$@<O00001
  
  
  % git=auto: git diff for bintoregular
  diff --git a/bintoregular b/bintoregular
  index f76dd238ade08917e6712764a16a22005a50573d..9c42f2b6427d8bf034b7bc23986152dc01bfd3ab
  GIT binary patch
  literal 13
  Uc$`bh%qz(+N=+}#Ni5<5043uE82|tP
  


git=warn: regular diff with data loss warnings

  $ hg autodiff --git=warn
  diff -r a66d19b9302d binary
  Binary file binary has changed
  diff -r a66d19b9302d bintoregular
  Binary file bintoregular has changed
  diff -r a66d19b9302d exec
  --- a/exec
  +++ b/exec
  @@ -1,1 +1,2 @@
   exec
  +exec
  diff -r a66d19b9302d newbinary
  Binary file newbinary has changed
  diff -r a66d19b9302d newexec
  --- /dev/null
  +++ b/newexec
  @@ -0,0 +1,1 @@
  +newexec
  diff -r a66d19b9302d newregular
  --- /dev/null
  +++ b/newregular
  @@ -0,0 +1,1 @@
  +newregular
  diff -r a66d19b9302d regular
  --- a/regular
  +++ b/regular
  @@ -1,1 +1,2 @@
   regular
  +regular
  diff -r a66d19b9302d rmbinary
  Binary file rmbinary has changed
  diff -r a66d19b9302d rmexec
  --- a/rmexec
  +++ /dev/null
  @@ -1,1 +0,0 @@
  -rmexec
  diff -r a66d19b9302d rmregular
  --- a/rmregular
  +++ /dev/null
  @@ -1,1 +0,0 @@
  -rmregular
  data lost for: binary
  data lost for: bintoregular
  data lost for: newbinary
  data lost for: newempty
  data lost for: newexec
  data lost for: rmbinary
  data lost for: rmempty
  data lost for: setexec
  data lost for: unsetexec

git=abort: fail on execute bit change

  $ hg autodiff --git=abort regular setexec
  abort: losing data for setexec
  [255]

git=abort: succeed on regular file

  $ hg autodiff --git=abort regular
  diff -r a66d19b9302d regular
  --- a/regular
  +++ b/regular
  @@ -1,1 +1,2 @@
   regular
  +regular

  $ cd ..