view tests/test-histedit-commute.t @ 30442:41a8106789ca

util: implement zstd compression engine

Now that zstd is vendored and being built (in some configurations), we
can implement a compression engine for zstd!

The zstd engine is a little different from existing engines. Because
it may not always be present, we have to defer load the module in case
importing it fails. We facilitate this via a cached property that holds
a reference to the module or None. The "available" method is
implemented to reflect reality.

The zstd engine declares its ability to handle bundles using the
"zstd" human name and the "ZS" internal name. The latter was chosen
because internal names are 2 characters (by only convention I think)
and "ZS" seems reasonable.

The engine, like others, supports specifying the compression level.
However, there are no consumers of this API that yet pass in that
argument. I have plans to change that, so stay tuned.

Since all we need to do to support bundle generation with a new
compression engine is implement and register the compression engine,
bundle generation with zstd "just works!" Tests demonstrating this
have been added.

How does performance of zstd for bundle generation compare? On the
mozilla-unified repo, `hg bundle --all -t <engine>-v2` yields the
following on my i7-6700K on Linux:

engine        CPU time     bundle size   vs orig size   throughput
none            97.0s     4,054,405,584     100.0%       41.8 MB/s
bzip2 (l=9)    393.6s       975,343,098      24.0%       10.3 MB/s
gzip (l=6)     184.0s     1,140,533,074      28.1%       22.0 MB/s
zstd (l=1)     108.2s     1,119,434,718      27.6%       37.5 MB/s
zstd (l=2)     111.3s     1,078,328,002      26.6%       36.4 MB/s
zstd (l=3)     113.7s     1,011,823,727      25.0%       35.7 MB/s
zstd (l=4)     116.0s     1,008,965,888      24.9%       35.0 MB/s
zstd (l=5)     121.0s       977,203,148      24.1%       33.5 MB/s
zstd (l=6)     131.7s       927,360,198      22.9%       30.8 MB/s
zstd (l=7)     139.0s       912,808,505      22.5%       29.2 MB/s
zstd (l=12)    198.1s       854,527,714      21.1%       20.5 MB/s
zstd (l=18)    681.6s       789,750,690      19.5%        5.9 MB/s

On compression, zstd for bundle generation delivers:

* better compression than gzip with significantly less CPU utilization
* better than bzip2 compression ratios while still being significantly
  faster than gzip
* ability to aggressively tune compression level to achieve
  significantly smaller bundles

That last point is important. With clone bundles, a server can
pre-generate a bundle file, upload it to a static file server, and
redirect clients to transparently download it during clone. The server
could choose to produce a zstd bundle with the highest compression
settings possible. This would take a very long time - a magnitude
longer than a typical zstd bundle generation - but the result would
be hundreds of megabytes smaller! For the clone volume we do at
Mozilla, this could translate to petabytes of bandwidth savings
per year and faster clones (due to smaller transfer size).

I don't have detailed numbers to report on decompression. However,
zstd decompression is fast: >1 GB/s output throughput on this machine,
even through the Python bindings. And it can do that regardless of the
compression level of the input. By the time you have enough data to
worry about overhead of decompression, you have plenty of other things
to worry about performance wise.

zstd is wins all around. I can't wait to implement support for it
on the wire protocol and in revlogs.

  $ . "$TESTDIR/histedit-helpers.sh"

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > histedit=
  > EOF

  $ initrepo ()
  > {
  >     hg init r
  >     cd r
  >     for x in a b c d e f ; do
  >         echo $x > $x
  >         hg add $x
  >         hg ci -m $x
  >     done
  > }

  $ initrepo

log before edit
  $ hg log --graph
  @  changeset:   5:652413bf663e
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   4:e860deea161a
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   3:055a42cdd887
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   2:177f92b77385
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  

show the edit commands offered
  $ HGEDITOR=cat hg histedit 177f92b77385
  pick 177f92b77385 2 c
  pick 055a42cdd887 3 d
  pick e860deea161a 4 e
  pick 652413bf663e 5 f
  
  # Edit history between 177f92b77385 and 652413bf663e
  #
  # Commits are listed from least to most recent
  #
  # You can reorder changesets by reordering the lines
  #
  # Commands:
  #
  #  e, edit = use commit, but stop for amending
  #  m, mess = edit commit message without changing commit content
  #  p, pick = use commit
  #  d, drop = remove commit from history
  #  f, fold = use commit, but combine it with the one above
  #  r, roll = like fold, but discard this commit's description
  #

edit the history
(use a hacky editor to check histedit-last-edit.txt backup)

  $ EDITED="$TESTTMP/editedhistory"
  $ cat > $EDITED <<EOF
  > edit 177f92b77385 c
  > pick e860deea161a e
  > pick 652413bf663e f
  > pick 055a42cdd887 d
  > EOF
  $ HGEDITOR="cat \"$EDITED\" > " hg histedit 177f92b77385 2>&1 | fixbundle
  0 files updated, 0 files merged, 4 files removed, 0 files unresolved
  Editing (177f92b77385), you may commit or record as needed now.
  (hg histedit --continue to resume)

rules should end up in .hg/histedit-last-edit.txt:
  $ cat .hg/histedit-last-edit.txt
  edit 177f92b77385 c
  pick e860deea161a e
  pick 652413bf663e f
  pick 055a42cdd887 d

  $ hg histedit --abort
  4 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat > $EDITED <<EOF
  > pick 177f92b77385 c
  > pick e860deea161a e
  > pick 652413bf663e f
  > pick 055a42cdd887 d
  > EOF
  $ HGEDITOR="cat \"$EDITED\" > " hg histedit 177f92b77385 2>&1 | fixbundle

log after edit
  $ hg log --graph
  @  changeset:   5:07114f51870f
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   4:8ade9693061e
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   3:d8249471110a
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   2:177f92b77385
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  

put things back

  $ hg histedit 177f92b77385 --commands - 2>&1 << EOF | fixbundle
  > pick 177f92b77385 c
  > pick 07114f51870f d
  > pick d8249471110a e
  > pick 8ade9693061e f
  > EOF

  $ hg log --graph
  @  changeset:   5:7eca9b5b1148
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   4:915da888f2de
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   3:10517e47bbbb
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   2:177f92b77385
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  

slightly different this time

  $ hg histedit 177f92b77385 --commands - << EOF 2>&1 | fixbundle
  > pick 10517e47bbbb d
  > pick 7eca9b5b1148 f
  > pick 915da888f2de e
  > pick 177f92b77385 c
  > EOF
  $ hg log --graph
  @  changeset:   5:38b92f448761
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  o  changeset:   4:de71b079d9ce
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   3:be9ae3a309c6
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   2:799205341b6b
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  

keep prevents stripping dead revs
  $ hg histedit 799205341b6b --keep --commands - 2>&1 << EOF | fixbundle
  > pick 799205341b6b d
  > pick be9ae3a309c6 f
  > pick 38b92f448761 c
  > pick de71b079d9ce e
  > EOF
  $ hg log --graph
  @  changeset:   7:803ef1c6fcfd
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   6:ece0b8d93dda
  |  parent:      3:be9ae3a309c6
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  | o  changeset:   5:38b92f448761
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     c
  | |
  | o  changeset:   4:de71b079d9ce
  |/   user:        test
  |    date:        Thu Jan 01 00:00:00 1970 +0000
  |    summary:     e
  |
  o  changeset:   3:be9ae3a309c6
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   2:799205341b6b
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  

try with --rev
  $ hg histedit --commands - --rev -2 2>&1 <<EOF | fixbundle
  > pick de71b079d9ce e
  > pick 38b92f448761 c
  > EOF
  hg: parse error: pick "de71b079d9ce" changeset was not a candidate
  (only use listed changesets)
  $ hg log --graph
  @  changeset:   7:803ef1c6fcfd
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   6:ece0b8d93dda
  |  parent:      3:be9ae3a309c6
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  | o  changeset:   5:38b92f448761
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     c
  | |
  | o  changeset:   4:de71b079d9ce
  |/   user:        test
  |    date:        Thu Jan 01 00:00:00 1970 +0000
  |    summary:     e
  |
  o  changeset:   3:be9ae3a309c6
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   2:799205341b6b
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   1:d2ae7f538514
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  
Verify that revsetalias entries work with histedit:
  $ cat >> $HGRCPATH <<EOF
  > [revsetalias]
  > grandparent(ARG) = p1(p1(ARG))
  > EOF
  $ echo extra commit >> c
  $ hg ci -m 'extra commit to c'
  $ HGEDITOR=cat hg histedit 'grandparent(.)'
  pick ece0b8d93dda 6 c
  pick 803ef1c6fcfd 7 e
  pick 9c863c565126 8 extra commit to c
  
  # Edit history between ece0b8d93dda and 9c863c565126
  #
  # Commits are listed from least to most recent
  #
  # You can reorder changesets by reordering the lines
  #
  # Commands:
  #
  #  e, edit = use commit, but stop for amending
  #  m, mess = edit commit message without changing commit content
  #  p, pick = use commit
  #  d, drop = remove commit from history
  #  f, fold = use commit, but combine it with the one above
  #  r, roll = like fold, but discard this commit's description
  #

should also work if a commit message is missing
  $ BUNDLE="$TESTDIR/missing-comment.hg"
  $ hg init missing
  $ cd missing
  $ hg unbundle $BUNDLE
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 1 files
  (run 'hg update' to get a working copy)
  $ hg co tip
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log --graph
  @  changeset:   2:bd22688093b3
  |  tag:         tip
  |  user:        Robert Altman <[e-mail]>
  |  date:        Mon Nov 28 16:40:04 2011 +0000
  |  summary:     Update file.
  |
  o  changeset:   1:3b3e956f9171
  |  user:        Robert Altman <[e-mail]>
  |  date:        Mon Nov 28 16:37:57 2011 +0000
  |
  o  changeset:   0:141947992243
     user:        Robert Altman <[e-mail]>
     date:        Mon Nov 28 16:35:28 2011 +0000
     summary:     Checked in text file
  
  $ hg histedit 0
  $ cd ..

  $ cd ..


Test to make sure folding renames doesn't cause bogus conflicts (issue4251):
  $ hg init issue4251
  $ cd issue4251

  $ mkdir initial-dir
  $ echo foo > initial-dir/initial-file
  $ hg add initial-dir/initial-file
  $ hg commit -m "initial commit"

Move the file to a new directory, and in the same commit, change its content:
  $ mkdir another-dir
  $ hg mv initial-dir/initial-file another-dir/
  $ echo changed > another-dir/initial-file
  $ hg commit -m "moved and changed"

Rename the file:
  $ hg mv another-dir/initial-file another-dir/renamed-file
  $ hg commit -m "renamed"

Now, let's try to fold the second commit into the first:
  $ cat > editor.sh <<EOF
  > #!/bin/sh
  > cat > \$1 <<ENDOF
  > pick b0f4233702ca 0 initial commit
  > fold 5e8704a8f2d2 1 moved and changed
  > pick 40e7299e8fa7 2 renamed
  > ENDOF
  > EOF

  $ HGEDITOR="sh ./editor.sh" hg histedit 0
  saved backup bundle to $TESTTMP/issue4251/.hg/strip-backup/*-backup.hg (glob)
  saved backup bundle to $TESTTMP/issue4251/.hg/strip-backup/*-backup.hg (glob)

  $ hg --config diff.git=yes export 0
  # HG changeset patch
  # User test
  # Date 0 0
  #      Thu Jan 01 00:00:00 1970 +0000
  # Node ID fffadc26f8f85623ce60b028a3f1ccc3730f8530
  # Parent  0000000000000000000000000000000000000000
  pick b0f4233702ca 0 initial commit
  fold 5e8704a8f2d2 1 moved and changed
  pick 40e7299e8fa7 2 renamed
  
  diff --git a/another-dir/initial-file b/another-dir/initial-file
  new file mode 100644
  --- /dev/null
  +++ b/another-dir/initial-file
  @@ -0,0 +1,1 @@
  +changed

  $ hg --config diff.git=yes export 1
  # HG changeset patch
  # User test
  # Date 0 0
  #      Thu Jan 01 00:00:00 1970 +0000
  # Node ID 9b730d82b00af8a2766facebfa47cc124405a118
  # Parent  fffadc26f8f85623ce60b028a3f1ccc3730f8530
  renamed
  
  diff --git a/another-dir/initial-file b/another-dir/renamed-file
  rename from another-dir/initial-file
  rename to another-dir/renamed-file

  $ cd ..