tests/test-diff-binary-file.t

commit: improve the files field of changelog for merges

Currently, the files list of merge commits repeats all the deletions
(either actual deletions, or files that got renamed) that happened
between base and p2 of the merge. If p2 is the main branch, the list
can easily be much bigger than the change being merged.

This results in various problems worth improving:
- changelog is bigger than necessary
- `hg log directory` lists many unrelated merge commits, and `hg log
  -v -r commit` frequently fills multiple screens worth of files
- it possibly slows down adjustlinkrev, by forcing it to read more
  manifests, and that function can certainly be a bottleneck
- the server side of pulls can waste a lot of time simply opening the
  filelogs for pointless files (the constant factors for opening even
  a tiny filelog is apparently pretty bad)

So stop listing such files as described in the code.  Impacted merge
commits and their descendants get a different hash than they would
have without this. This doesn't seem problematic, except for
convert. The previous commit helped with that in the hg->hg case (but
if you do svn->hg twice from scratch, hashes can still change).

The rest of the description is numbers. I don't have much to report,
because recreating the files list of existing repositories is not
easy:
- debugupgradeformat and bundle/unbundle don't recreate the list
- export/import tends to choke quickly applying patches or on
  description that contain diffs,
- merge commits from the convert extension don't have the right files
  list for reasons orthogonal to the current commit
- replaying the merge with hg update/hg merge/hg revert --all/hg
  commit can end up failing in hg revert
- I wasn't sure that using debugsetparents + debugrebuilddirstate
  would really build the right thing

I measured commit time before and after this change, in a case with no
files filtered out, several files filtered out (no difference) and 5k
files filtered out (+1% time).

Recreating the 100 more recent merges in a private repo, the
concatenated uncompressed files lists goes from 1.12MB to
0.52MB. Excluding 3 merges that are not representative, then the size
goes from 570k to 15k.
I converted part of mozilla-central, and observed file list shrinking
quite a bit too, starting at the very first merge, 733641d9feaf, going
from 550 files to 10 files (although they have relatively few merges,
so they probably wouldn't care).

Differential Revision: https://phab.mercurial-scm.org/D6613

  $ hg init a
  $ cd a
  $ cp "$TESTDIR/binfile.bin" .
  $ hg add binfile.bin
  $ hg ci -m 'add binfile.bin'

  $ echo >> binfile.bin
  $ hg ci -m 'change binfile.bin'

  $ hg revert -r 0 binfile.bin
  $ hg ci -m 'revert binfile.bin'
  $ hg cp binfile.bin nonbinfile
  $ echo text > nonbinfile
  $ hg ci -m 'make non-binary copy of binary file'

  $ hg diff --nodates -r 0 -r 1
  diff -r 48b371597640 -r acea2ab458c8 binfile.bin
  Binary file binfile.bin has changed

  $ hg diff --nodates -r 0 -r 2

  $ hg diff --git -r 0 -r 1
  diff --git a/binfile.bin b/binfile.bin
  index 37ba3d1c6f17137d9c5f5776fa040caf5fe73ff9..58dc31a9e2f40f74ff3b45903f7d620b8e5b7356
  GIT binary patch
  literal 594
  zc$@)J0<HatP)<h;3K|Lk000e1NJLTq000mG000mO0ssI2kdbIM00009a7bBm000XU
  z000XU0RWnu7ytkO2XskIMF-Uh9TW;VpMjwv0005-Nkl<ZD9@FWPs=e;7{<>W$NUkd
  zX$nnYLt$-$V!?uy+1V%`z&Eh=ah|duER<4|QWhju3gb^nF*8iYobxWG-qqXl=2~5M
  z*IoDB)sG^CfNuoBmqLTVU^<;@nwHP!1wrWd`{(mHo6VNXWtyh{alzqmsH*yYzpvLT
  zLdY<T=ks|woh-`&01!ej#(xbV1f|pI*=%;d-%F*E*X#ZH`4I%6SS+$EJDE&ct=8po
  ziN#{?_j|kD%Cd|oiqds`xm@;oJ-^?NG3Gdqrs?5u*zI;{nogxsx~^|Fn^Y?Gdc6<;
  zfMJ+iF1J`LMx&A2?dEwNW8ClebzPTbIh{@$hS6*`kH@1d%Lo7fA#}N1)oN7`gm$~V
  z+wDx#)OFqMcE{s!JN0-xhG8ItAjVkJwEcb`3WWlJfU2r?;Pd%dmR+q@mSri5q9_W-
  zaR2~ECX?B2w+zELozC0s*6Z~|QG^f{3I#<`?)Q7U-JZ|q5W;9Q8i_=pBuSzunx=U;
  z9C)5jBoYw9^?EHyQl(M}1OlQcCX>lXB*ODN003Z&P17_@)3Pi=i0wb04<W?v-u}7K
  zXmmQA+wDgE!qR9o8jr`%=ab_&uh(l?R=r;Tjiqon91I2-hIu?57~@*4h7h9uORK#=
  gQItJW-{SoTm)8|5##k|m00000NkvXXu0mjf3JwksH2?qr
  

  $ hg diff --git -r 0 -r 2

  $ hg diff --config diff.nobinary=True --git -r 0 -r 1
  diff --git a/binfile.bin b/binfile.bin
  Binary file binfile.bin has changed

  $ HGPLAIN=1 hg diff --config diff.nobinary=True --git -r 0 -r 1
  diff --git a/binfile.bin b/binfile.bin
  index 37ba3d1c6f17137d9c5f5776fa040caf5fe73ff9..58dc31a9e2f40f74ff3b45903f7d620b8e5b7356
  GIT binary patch
  literal 594
  zc$@)J0<HatP)<h;3K|Lk000e1NJLTq000mG000mO0ssI2kdbIM00009a7bBm000XU
  z000XU0RWnu7ytkO2XskIMF-Uh9TW;VpMjwv0005-Nkl<ZD9@FWPs=e;7{<>W$NUkd
  zX$nnYLt$-$V!?uy+1V%`z&Eh=ah|duER<4|QWhju3gb^nF*8iYobxWG-qqXl=2~5M
  z*IoDB)sG^CfNuoBmqLTVU^<;@nwHP!1wrWd`{(mHo6VNXWtyh{alzqmsH*yYzpvLT
  zLdY<T=ks|woh-`&01!ej#(xbV1f|pI*=%;d-%F*E*X#ZH`4I%6SS+$EJDE&ct=8po
  ziN#{?_j|kD%Cd|oiqds`xm@;oJ-^?NG3Gdqrs?5u*zI;{nogxsx~^|Fn^Y?Gdc6<;
  zfMJ+iF1J`LMx&A2?dEwNW8ClebzPTbIh{@$hS6*`kH@1d%Lo7fA#}N1)oN7`gm$~V
  z+wDx#)OFqMcE{s!JN0-xhG8ItAjVkJwEcb`3WWlJfU2r?;Pd%dmR+q@mSri5q9_W-
  zaR2~ECX?B2w+zELozC0s*6Z~|QG^f{3I#<`?)Q7U-JZ|q5W;9Q8i_=pBuSzunx=U;
  z9C)5jBoYw9^?EHyQl(M}1OlQcCX>lXB*ODN003Z&P17_@)3Pi=i0wb04<W?v-u}7K
  zXmmQA+wDgE!qR9o8jr`%=ab_&uh(l?R=r;Tjiqon91I2-hIu?57~@*4h7h9uORK#=
  gQItJW-{SoTm)8|5##k|m00000NkvXXu0mjf3JwksH2?qr
  


  $ hg diff --git -r 2 -r 3
  diff --git a/binfile.bin b/nonbinfile
  copy from binfile.bin
  copy to nonbinfile
  index 37ba3d1c6f17137d9c5f5776fa040caf5fe73ff9..8e27be7d6154a1f68ea9160ef0e18691d20560dc
  GIT binary patch
  literal 5
  Mc$_OqttjCF00uV!&;S4c
  
  $ cd ..

Test text mode with extended git-style diff format
  $ hg init b
  $ cd b
  $ cat > writebin.py <<EOF
  > import sys
  > path = sys.argv[1]
  > open(path, 'wb').write(b'\x00\x01\x02\x03')
  > EOF
  $ "$PYTHON" writebin.py binfile.bin
  $ hg add binfile.bin
  $ hg ci -m 'add binfile.bin'

  $ echo >> binfile.bin
  $ hg ci -m 'change binfile.bin'

  $ hg diff --git -a -r 0 -r 1
  diff --git a/binfile.bin b/binfile.bin
  --- a/binfile.bin
  +++ b/binfile.bin
  @@ -1,1 +1,1 @@
  -\x00\x01\x02\x03 (esc)
  \ No newline at end of file
  +\x00\x01\x02\x03 (esc)

  $ HGPLAIN=1 hg diff --git -a -r 0 -r 1
  diff --git a/binfile.bin b/binfile.bin
  --- a/binfile.bin
  +++ b/binfile.bin
  @@ -1,1 +1,1 @@
  -\x00\x01\x02\x03 (esc)
  \ No newline at end of file
  +\x00\x01\x02\x03 (esc)

Test binary mode with extended git-style diff format
  $ hg diff --no-binary -r 0 -r 1
  diff -r fb45f71337ad -r 9ca112d1a3c1 binfile.bin
  Binary file binfile.bin has changed

  $ hg diff --git --no-binary -r 0 -r 1
  diff --git a/binfile.bin b/binfile.bin
  Binary file binfile.bin has changed

  $ hg diff --git --binary -r 0 -r 1
  diff --git a/binfile.bin b/binfile.bin
  index eaf36c1daccfdf325514461cd1a2ffbc139b5464..ba71a782e93f3fb63a428383706065e3ec2828e9
  GIT binary patch
  literal 5
  Mc${NkWMbw50018V5dZ)H
  
  $ hg diff --git --binary --config diff.nobinary=True -r 0 -r 1
  diff --git a/binfile.bin b/binfile.bin
  index eaf36c1daccfdf325514461cd1a2ffbc139b5464..ba71a782e93f3fb63a428383706065e3ec2828e9
  GIT binary patch
  literal 5
  Mc${NkWMbw50018V5dZ)H
  

  $ hg diff --git --binary --text -r 0 -r 1
  diff --git a/binfile.bin b/binfile.bin
  --- a/binfile.bin
  +++ b/binfile.bin
  @@ -1,1 +1,1 @@
  -\x00\x01\x02\x03 (esc)
  \ No newline at end of file
  +\x00\x01\x02\x03 (esc)

  $ cd ..