view tests/test-histedit-edit.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=
  > strip=
  > EOF

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

  $ initrepo

log before edit
  $ hg log --graph
  @  changeset:   6:3c6a8ed2ebe8
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     g
  |
  o  changeset:   5:652413bf663e
  |  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
  
dirty a file
  $ echo a > g
  $ hg histedit 177f92b77385 --commands - 2>&1 << EOF
  > EOF
  abort: uncommitted changes
  [255]
  $ echo g > g

edit the history
  $ hg histedit 177f92b77385 --commands - 2>&1 << EOF| fixbundle
  > pick 177f92b77385 c
  > pick 055a42cdd887 d
  > edit e860deea161a e
  > pick 652413bf663e f
  > pick 3c6a8ed2ebe8 g
  > EOF
  0 files updated, 0 files merged, 3 files removed, 0 files unresolved
  Editing (e860deea161a), you may commit or record as needed now.
  (hg histedit --continue to resume)

try to update and get an error
  $ hg update tip
  abort: histedit in progress
  (use 'hg histedit --continue' or 'hg histedit --abort')
  [255]

edit the plan via the editor
  $ cat >> $TESTTMP/editplan.sh <<EOF
  > cat > \$1 <<EOF2
  > drop e860deea161a e
  > drop 652413bf663e f
  > drop 3c6a8ed2ebe8 g
  > EOF2
  > EOF
  $ HGEDITOR="sh $TESTTMP/editplan.sh" hg histedit --edit-plan
  $ cat .hg/histedit-state
  v1
  055a42cdd88768532f9cf79daa407fc8d138de9b
  3c6a8ed2ebe862cc949d2caa30775dd6f16fb799
  False
  3
  drop
  e860deea161a2f77de56603b340ebbb4536308ae
  drop
  652413bf663ef2a641cab26574e46d5f5a64a55a
  drop
  3c6a8ed2ebe862cc949d2caa30775dd6f16fb799
  0
  strip-backup/177f92b77385-0ebe6a8f-histedit.hg

edit the plan via --commands
  $ hg histedit --edit-plan --commands - 2>&1 << EOF
  > edit e860deea161a e
  > pick 652413bf663e f
  > drop 3c6a8ed2ebe8 g
  > EOF
  $ cat .hg/histedit-state
  v1
  055a42cdd88768532f9cf79daa407fc8d138de9b
  3c6a8ed2ebe862cc949d2caa30775dd6f16fb799
  False
  3
  edit
  e860deea161a2f77de56603b340ebbb4536308ae
  pick
  652413bf663ef2a641cab26574e46d5f5a64a55a
  drop
  3c6a8ed2ebe862cc949d2caa30775dd6f16fb799
  0
  strip-backup/177f92b77385-0ebe6a8f-histedit.hg

Go at a random point and try to continue

  $ hg id -n
  3+
  $ hg up 0
  abort: histedit in progress
  (use 'hg histedit --continue' or 'hg histedit --abort')
  [255]

Try to delete necessary commit
  $ hg strip -r 652413b
  abort: histedit in progress, can't strip 652413bf663e
  [255]

commit, then edit the revision
  $ hg ci -m 'wat'
  created new head
  $ echo a > e

qnew should fail while we're in the middle of the edit step

  $ hg --config extensions.mq= qnew please-fail
  abort: histedit in progress
  (use 'hg histedit --continue' or 'hg histedit --abort')
  [255]
  $ HGEDITOR='echo foobaz > ' hg histedit --continue 2>&1 | fixbundle

  $ hg log --graph
  @  changeset:   6:b5f70786f9b0
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   5:a5e1ba2f7afb
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     foobaz
  |
  o  changeset:   4:1a60820cd1f6
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     wat
  |
  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
  

  $ hg cat e
  a

Stripping necessary commits should not break --abort

  $ hg histedit 1a60820cd1f6 --commands - 2>&1 << EOF| fixbundle
  > edit 1a60820cd1f6 wat
  > pick a5e1ba2f7afb foobaz
  > pick b5f70786f9b0 g
  > EOF
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  Editing (1a60820cd1f6), you may commit or record as needed now.
  (hg histedit --continue to resume)

  $ mv .hg/histedit-state .hg/histedit-state.bak
  $ hg strip -q -r b5f70786f9b0
  $ mv .hg/histedit-state.bak .hg/histedit-state
  $ hg histedit --abort
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 3 files
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log -r .
  changeset:   6:b5f70786f9b0
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     f
  

check histedit_source

  $ hg log --debug --rev 5
  changeset:   5:a5e1ba2f7afb899ef1581cea528fd885d2fca70d
  phase:       draft
  parent:      4:1a60820cd1f6004a362aa622ebc47d59bc48eb34
  parent:      -1:0000000000000000000000000000000000000000
  manifest:    5:5ad3be8791f39117565557781f5464363b918a45
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       e
  extra:       branch=default
  extra:       histedit_source=e860deea161a2f77de56603b340ebbb4536308ae
  description:
  foobaz
  
  

  $ hg histedit tip --commands - 2>&1 <<EOF| fixbundle
  > edit b5f70786f9b0 f
  > EOF
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  Editing (b5f70786f9b0), you may commit or record as needed now.
  (hg histedit --continue to resume)
  $ hg status
  A f

  $ hg summary
  parent: 5:a5e1ba2f7afb 
   foobaz
  branch: default
  commit: 1 added (new branch head)
  update: 1 new changesets (update)
  phases: 7 draft
  hist:   1 remaining (histedit --continue)

(test also that editor is invoked if histedit is continued for
"edit" action)

  $ HGEDITOR='cat' hg histedit --continue
  f
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to abort commit.
  HG: --
  HG: user: test
  HG: branch 'default'
  HG: added f
  saved backup bundle to $TESTTMP/r/.hg/strip-backup/b5f70786f9b0-c28d9c86-backup.hg (glob)

  $ hg status

log after edit
  $ hg log --limit 1
  changeset:   6:a107ee126658
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     f
  

say we'll change the message, but don't.
  $ cat > ../edit.sh <<EOF
  > cat "\$1" | sed s/pick/mess/ > tmp
  > mv tmp "\$1"
  > EOF
  $ HGEDITOR="sh ../edit.sh" hg histedit tip 2>&1 | fixbundle
  $ hg status
  $ hg log --limit 1
  changeset:   6:1fd3b2fe7754
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     f
  

modify the message

check saving last-message.txt, at first

  $ cat > $TESTTMP/commitfailure.py <<EOF
  > from mercurial import error
  > def reposetup(ui, repo):
  >     class commitfailure(repo.__class__):
  >         def commit(self, *args, **kwargs):
  >             raise error.Abort('emulating unexpected abort')
  >     repo.__class__ = commitfailure
  > EOF
  $ cat >> .hg/hgrc <<EOF
  > [extensions]
  > # this failure occurs before editor invocation
  > commitfailure = $TESTTMP/commitfailure.py
  > EOF

  $ cat > $TESTTMP/editor.sh <<EOF
  > echo "==== before editing"
  > cat \$1
  > echo "===="
  > echo "check saving last-message.txt" >> \$1
  > EOF

(test that editor is not invoked before transaction starting)

  $ rm -f .hg/last-message.txt
  $ HGEDITOR="sh $TESTTMP/editor.sh" hg histedit tip --commands - 2>&1 << EOF | fixbundle
  > mess 1fd3b2fe7754 f
  > EOF
  abort: emulating unexpected abort
  $ test -f .hg/last-message.txt
  [1]

  $ cat >> .hg/hgrc <<EOF
  > [extensions]
  > commitfailure = !
  > EOF
  $ hg histedit --abort -q

(test that editor is invoked and commit message is saved into
"last-message.txt")

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > # this failure occurs after editor invocation
  > pretxncommit.unexpectedabort = false
  > EOF

  $ hg status --rev '1fd3b2fe7754^1' --rev 1fd3b2fe7754
  A f

  $ rm -f .hg/last-message.txt
  $ HGEDITOR="sh $TESTTMP/editor.sh" hg histedit tip --commands - 2>&1 << EOF
  > mess 1fd3b2fe7754 f
  > EOF
  ==== before editing
  f
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to abort commit.
  HG: --
  HG: user: test
  HG: branch 'default'
  HG: added f
  ====
  note: commit message saved in .hg/last-message.txt
  transaction abort!
  rollback completed
  abort: pretxncommit.unexpectedabort hook exited with status 1
  [255]
  $ cat .hg/last-message.txt
  f
  
  
  check saving last-message.txt

(test also that editor is invoked if histedit is continued for "message"
action)

  $ HGEDITOR=cat hg histedit --continue
  f
  
  
  HG: Enter commit message.  Lines beginning with 'HG:' are removed.
  HG: Leave message empty to abort commit.
  HG: --
  HG: user: test
  HG: branch 'default'
  HG: added f
  note: commit message saved in .hg/last-message.txt
  transaction abort!
  rollback completed
  abort: pretxncommit.unexpectedabort hook exited with status 1
  [255]

  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > pretxncommit.unexpectedabort =
  > EOF
  $ hg histedit --abort -q

then, check "modify the message" itself

  $ hg histedit tip --commands - 2>&1 << EOF | fixbundle
  > mess 1fd3b2fe7754 f
  > EOF
  $ hg status
  $ hg log --limit 1
  changeset:   6:62feedb1200e
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     f
  

rollback should not work after a histedit
  $ hg rollback
  no rollback information available
  [1]

  $ cd ..
  $ hg clone -qr0 r r0
  $ cd r0
  $ hg phase -fdr0
  $ hg histedit --commands - 0 2>&1 << EOF
  > edit cb9a9f314b8b a > $EDITED
  > EOF
  0 files updated, 0 files merged, 1 files removed, 0 files unresolved
  adding a
  Editing (cb9a9f314b8b), you may commit or record as needed now.
  (hg histedit --continue to resume)
  [1]
  $ HGEDITOR=true hg histedit --continue
  saved backup bundle to $TESTTMP/r0/.hg/strip-backup/cb9a9f314b8b-cc5ccb0b-backup.hg (glob)

  $ hg log -G
  @  changeset:   0:0efcea34f18a
     tag:         tip
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  
  $ echo foo >> b
  $ hg addr
  adding b
  $ hg ci -m 'add b'
  $ echo foo >> a
  $ hg ci -m 'extend a'
  $ hg phase --public 1
Attempting to fold a change into a public change should not work:
  $ cat > ../edit.sh <<EOF
  > cat "\$1" | sed s/pick/fold/ > tmp
  > mv tmp "\$1"
  > EOF
  $ HGEDITOR="sh ../edit.sh" hg histedit 2
  warning: histedit rules saved to: .hg/histedit-last-edit.txt
  hg: parse error: cannot fold into public change 18aa70c8ad22
  [255]
  $ cat .hg/histedit-last-edit.txt
  fold 0012be4a27ea 2 extend a
  
  # Edit history between 0012be4a27ea and 0012be4a27ea
  #
  # 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, fold = 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
  #