tests/test-archive.t

changelog: disable delta chains

This patch disables delta chains on changelogs. After this patch, new
entries on changelogs - including existing changelogs - will be stored
as the fulltext of that data (likely compressed). No delta computation
will be performed.

An overview of delta chains and data justifying this change follows.

Revlogs try to store entries as a delta against a previous entry (either
a parent revision in the case of generaldelta or the previous physical
revision when not using generaldelta). Most of the time this is the
correct thing to do: it frequently results in less CPU usage and smaller
storage.

Delta chains are most effective when the base revision being deltad
against is similar to the current data. This tends to occur naturally
for manifests and file data, since only small parts of each tend to
change with each revision. Changelogs, however, are a different story.

Changelog entries represent changesets/commits. And unless commits in a
repository are homogonous (same author, changing same files, similar
commit messages, etc), a delta from one entry to the next tends to be
relatively large compared to the size of the entry. This means that
delta chains tend to be short. How short? Here is the full vs delta
revision breakdown on some real world repos:

Repo             % Full    % Delta   Max Length
hg                45.8       54.2        6
mozilla-central   42.4       57.6        8
mozilla-unified   42.5       57.5       17
pypy              46.1       53.9        6
python-zstandard  46.1       53.9        3

(I threw in python-zstandard as an example of a repo that is homogonous.
It contains a small Python project with changes all from the same
author.)

Contrast this with the manifest revlog for these repos, where 99+% of
revisions are deltas and delta chains run into the thousands.

So delta chains aren't as useful on changelogs. But even a short delta
chain may provide benefits. Let's measure that.

Delta chains may require less CPU to read revisions if the CPU time
spent reading smaller deltas is less than the CPU time used to
decompress larger individual entries. We can measure this via
`hg perfrevlog -c -d 1` to iterate a revlog to resolve each revision's
fulltext. Here are the results of that command on a repo using delta
chains in its changelog and on a repo without delta chains:

hg (forward)
! wall 0.407008 comb 0.410000 user 0.410000 sys 0.000000 (best of 25)
! wall 0.390061 comb 0.390000 user 0.390000 sys 0.000000 (best of 26)

hg (reverse)
! wall 0.515221 comb 0.520000 user 0.520000 sys 0.000000 (best of 19)
! wall 0.400018 comb 0.400000 user 0.390000 sys 0.010000 (best of 25)

mozilla-central (forward)
! wall 4.508296 comb 4.490000 user 4.490000 sys 0.000000 (best of 3)
! wall 4.370222 comb 4.370000 user 4.350000 sys 0.020000 (best of 3)

mozilla-central (reverse)
! wall 5.758995 comb 5.760000 user 5.720000 sys 0.040000 (best of 3)
! wall 4.346503 comb 4.340000 user 4.320000 sys 0.020000 (best of 3)

mozilla-unified (forward)
! wall 4.957088 comb 4.950000 user 4.940000 sys 0.010000 (best of 3)
! wall 4.660528 comb 4.650000 user 4.630000 sys 0.020000 (best of 3)

mozilla-unified (reverse)
! wall 6.119827 comb 6.110000 user 6.090000 sys 0.020000 (best of 3)
! wall 4.675136 comb 4.670000 user 4.670000 sys 0.000000 (best of 3)

pypy (forward)
! wall 1.231122 comb 1.240000 user 1.230000 sys 0.010000 (best of 8)
! wall 1.164896 comb 1.160000 user 1.160000 sys 0.000000 (best of 9)

pypy (reverse)
! wall 1.467049 comb 1.460000 user 1.460000 sys 0.000000 (best of 7)
! wall 1.160200 comb 1.170000 user 1.160000 sys 0.010000 (best of 9)

The data clearly shows that it takes less wall and CPU time to resolve
revisions when there are no delta chains in the changelogs, regardless
of the direction of traversal. Furthermore, not using a delta chain
means that fulltext resolution in reverse is as fast as iterating
forward. So not using delta chains on the changelog is a clear CPU win
for reading operations.

An example of a user-visible operation showing this speed-up is revset
evaluation. Here are results for
`hg perfrevset 'author(gps) or author(mpm)'`:

hg
! wall 1.655506 comb 1.660000 user 1.650000 sys 0.010000 (best of 6)
! wall 1.612723 comb 1.610000 user 1.600000 sys 0.010000 (best of 7)

mozilla-central
! wall 17.629826 comb 17.640000 user 17.600000 sys 0.040000 (best of 3)
! wall 17.311033 comb 17.300000 user 17.260000 sys 0.040000 (best of 3)

What about 00changelog.i size?

Repo                Delta Chains     No Delta Chains
hg                    7,033,250         6,976,771
mozilla-central      82,978,748        81,574,623
mozilla-unified      88,112,349        86,702,162
pypy                 20,740,699        20,659,741

The data shows that removing delta chains from the changelog makes the
changelog smaller.

Delta chains are also used during changegroup generation. This
operation essentially converts a series of revisions to one large
delta chain. And changegroup generation is smart: if the delta in
the revlog matches what the changegroup is emitting, it will reuse
the delta instead of recalculating it. We can measure the impact
removing changelog delta chains has on changegroup generation via
`hg perfchangegroupchangelog`:

hg
! wall 1.589245 comb 1.590000 user 1.590000 sys 0.000000 (best of 7)
! wall 1.788060 comb 1.790000 user 1.790000 sys 0.000000 (best of 6)

mozilla-central
! wall 17.382585 comb 17.380000 user 17.340000 sys 0.040000 (best of 3)
! wall 20.161357 comb 20.160000 user 20.120000 sys 0.040000 (best of 3)

mozilla-unified
! wall 18.722839 comb 18.720000 user 18.680000 sys 0.040000 (best of 3)
! wall 21.168075 comb 21.170000 user 21.130000 sys 0.040000 (best of 3)

pypy
! wall 4.828317 comb 4.830000 user 4.820000 sys 0.010000 (best of 3)
! wall 5.415455 comb 5.420000 user 5.410000 sys 0.010000 (best of 3)

The data shows eliminating delta chains makes the changelog part of
changegroup generation slower. This is expected since we now have to
compute deltas for revisions where we could recycle the delta before.

It is worth putting this regression into context of overall changegroup
times. Here is the rough total CPU time spent in changegroup generation
for various repos while using delta chains on the changelog:

Repo              CPU Time (s)    CPU Time w/ compression
hg                  4.50              7.05
mozilla-central   111.1             222.0
pypy               28.68             75.5

Before compression, removing delta chains from the changegroup adds
~4.4% overhead to hg changegroup generation, 1.3% to mozilla-central,
and 2.0% to pypy. When you factor in zlib compression, these percentages
are roughly divided by 2.

While the increased CPU usage for changegroup generation is unfortunate,
I think it is acceptable because the percentage is small, server
operators (those likely impacted most by this) have other mechanisms
to mitigate CPU consumption (namely reducing zlib compression level and
pre-generated clone bundles), and because there is room to optimize this
in the future. For example, we could use the nullid as the base revision,
effectively encoding the full revision for each entry in the changegroup.
When doing this, `hg perfchangegroupchangelog` nearly halves:

mozilla-unified
! wall 21.168075 comb 21.170000 user 21.130000 sys 0.040000 (best of 3)
! wall 11.196461 comb 11.200000 user 11.190000 sys 0.010000 (best of 3)

This looks very promising as a future optimization opportunity.

It's worth that the changes in test-acl.t to the changegroup part size.
This is because revision 6 in the changegroup had a delta chain of
length 2 before and after this patch the base revision is nullrev.
When the base revision is nullrev, cg2packer.deltaparent() hardcodes
the *previous* revision from the changegroup as the delta parent.
This caused the delta in the changegroup to switch base revisions,
the delta to change, and the size to change accordingly. While the
size increased in this case, I think sizes will remain the same
on average, as the delta base for changelog revisions doesn't matter
too much (as this patch shows). So, I don't consider this a regression.

#require serve

  $ hg init test
  $ cd test
  $ echo foo>foo
  $ hg commit -Am 1 -d '1 0'
  adding foo
  $ echo bar>bar
  $ hg commit -Am 2 -d '2 0'
  adding bar
  $ mkdir baz
  $ echo bletch>baz/bletch
  $ hg commit -Am 3 -d '1000000000 0'
  adding baz/bletch
  $ hg init subrepo
  $ touch subrepo/sub
  $ hg -q -R subrepo ci -Am "init subrepo"
  $ echo "subrepo = subrepo" > .hgsub
  $ hg add .hgsub
  $ hg ci -m "add subrepo"
  $ echo "[web]" >> .hg/hgrc
  $ echo "name = test-archive" >> .hg/hgrc
  $ echo "archivesubrepos = True" >> .hg/hgrc
  $ cp .hg/hgrc .hg/hgrc-base
  > test_archtype() {
  >     echo "allow_archive = $1" >> .hg/hgrc
  >     hg serve -p $HGPORT -d --pid-file=hg.pid -E errors.log
  >     cat hg.pid >> $DAEMON_PIDS
  >     echo % $1 allowed should give 200
  >     get-with-headers.py localhost:$HGPORT "archive/tip.$2" | head -n 1
  >     echo % $3 and $4 disallowed should both give 403
  >     get-with-headers.py localhost:$HGPORT "archive/tip.$3" | head -n 1
  >     get-with-headers.py localhost:$HGPORT "archive/tip.$4" | head -n 1
  >     killdaemons.py
  >     cat errors.log
  >     cp .hg/hgrc-base .hg/hgrc
  > }

check http return codes

  $ test_archtype gz tar.gz tar.bz2 zip
  % gz allowed should give 200
  200 Script output follows
  % tar.bz2 and zip disallowed should both give 403
  403 Archive type not allowed: bz2
  403 Archive type not allowed: zip
  $ test_archtype bz2 tar.bz2 zip tar.gz
  % bz2 allowed should give 200
  200 Script output follows
  % zip and tar.gz disallowed should both give 403
  403 Archive type not allowed: zip
  403 Archive type not allowed: gz
  $ test_archtype zip zip tar.gz tar.bz2
  % zip allowed should give 200
  200 Script output follows
  % tar.gz and tar.bz2 disallowed should both give 403
  403 Archive type not allowed: gz
  403 Archive type not allowed: bz2

  $ echo "allow_archive = gz bz2 zip" >> .hg/hgrc
  $ hg serve -p $HGPORT -d --pid-file=hg.pid -E errors.log
  $ cat hg.pid >> $DAEMON_PIDS

invalid arch type should give 404

  $ get-with-headers.py localhost:$HGPORT "archive/tip.invalid" | head -n 1
  404 Unsupported archive type: None

  $ TIP=`hg id -v | cut -f1 -d' '`
  $ QTIP=`hg id -q`
  $ cat > getarchive.py <<EOF
  > from __future__ import absolute_import
  > import os
  > import sys
  > from mercurial import (
  >     util,
  > )
  > try:
  >     # Set stdout to binary mode for win32 platforms
  >     import msvcrt
  >     msvcrt.setmode(sys.stdout.fileno(), os.O_BINARY)
  > except ImportError:
  >     pass
  > if len(sys.argv) <= 3:
  >     node, archive = sys.argv[1:]
  >     requeststr = 'cmd=archive;node=%s;type=%s' % (node, archive)
  > else:
  >     node, archive, file = sys.argv[1:]
  >     requeststr = 'cmd=archive;node=%s;type=%s;file=%s' % (node, archive, file)
  > try:
  >     stdout = sys.stdout.buffer
  > except AttributeError:
  >     stdout = sys.stdout
  > try:
  >     f = util.urlreq.urlopen('http://127.0.0.1:%s/?%s'
  >                     % (os.environ['HGPORT'], requeststr))
  >     stdout.write(f.read())
  > except util.urlerr.httperror as e:
  >     sys.stderr.write(str(e) + '\n')
  > EOF
  $ python getarchive.py "$TIP" gz | gunzip | tar tf - 2>/dev/null
  test-archive-1701ef1f1510/.hg_archival.txt
  test-archive-1701ef1f1510/.hgsub
  test-archive-1701ef1f1510/.hgsubstate
  test-archive-1701ef1f1510/bar
  test-archive-1701ef1f1510/baz/bletch
  test-archive-1701ef1f1510/foo
  test-archive-1701ef1f1510/subrepo/sub
  $ python getarchive.py "$TIP" bz2 | bunzip2 | tar tf - 2>/dev/null
  test-archive-1701ef1f1510/.hg_archival.txt
  test-archive-1701ef1f1510/.hgsub
  test-archive-1701ef1f1510/.hgsubstate
  test-archive-1701ef1f1510/bar
  test-archive-1701ef1f1510/baz/bletch
  test-archive-1701ef1f1510/foo
  test-archive-1701ef1f1510/subrepo/sub
  $ python getarchive.py "$TIP" zip > archive.zip
  $ unzip -t archive.zip
  Archive:  archive.zip
      testing: test-archive-1701ef1f1510/.hg_archival.txt*OK (glob)
      testing: test-archive-1701ef1f1510/.hgsub*OK (glob)
      testing: test-archive-1701ef1f1510/.hgsubstate*OK (glob)
      testing: test-archive-1701ef1f1510/bar*OK (glob)
      testing: test-archive-1701ef1f1510/baz/bletch*OK (glob)
      testing: test-archive-1701ef1f1510/foo*OK (glob)
      testing: test-archive-1701ef1f1510/subrepo/sub*OK (glob)
  No errors detected in compressed data of archive.zip.

test that we can download single directories and files

  $ python getarchive.py "$TIP" gz baz | gunzip | tar tf - 2>/dev/null
  test-archive-1701ef1f1510/baz/bletch
  $ python getarchive.py "$TIP" gz foo | gunzip | tar tf - 2>/dev/null
  test-archive-1701ef1f1510/foo

test that we detect file patterns that match no files

  $ python getarchive.py "$TIP" gz foobar
  HTTP Error 404: file(s) not found: foobar

test that we reject unsafe patterns

  $ python getarchive.py "$TIP" gz relre:baz
  HTTP Error 404: file(s) not found: relre:baz

  $ killdaemons.py

  $ hg archive -t tar test.tar
  $ tar tf test.tar
  test/.hg_archival.txt
  test/.hgsub
  test/.hgsubstate
  test/bar
  test/baz/bletch
  test/foo

  $ hg archive --debug -t tbz2 -X baz test.tar.bz2 --config progress.debug=true
  archiving: 0/4 files (0.00%)
  archiving: .hgsub 1/4 files (25.00%)
  archiving: .hgsubstate 2/4 files (50.00%)
  archiving: bar 3/4 files (75.00%)
  archiving: foo 4/4 files (100.00%)
  $ bunzip2 -dc test.tar.bz2 | tar tf - 2>/dev/null
  test/.hg_archival.txt
  test/.hgsub
  test/.hgsubstate
  test/bar
  test/foo

  $ hg archive -t tgz -p %b-%h test-%h.tar.gz
  $ gzip -dc test-$QTIP.tar.gz | tar tf - 2>/dev/null
  test-1701ef1f1510/.hg_archival.txt
  test-1701ef1f1510/.hgsub
  test-1701ef1f1510/.hgsubstate
  test-1701ef1f1510/bar
  test-1701ef1f1510/baz/bletch
  test-1701ef1f1510/foo

  $ hg archive autodetected_test.tar
  $ tar tf autodetected_test.tar
  autodetected_test/.hg_archival.txt
  autodetected_test/.hgsub
  autodetected_test/.hgsubstate
  autodetected_test/bar
  autodetected_test/baz/bletch
  autodetected_test/foo

The '-t' should override autodetection

  $ hg archive -t tar autodetect_override_test.zip
  $ tar tf autodetect_override_test.zip
  autodetect_override_test.zip/.hg_archival.txt
  autodetect_override_test.zip/.hgsub
  autodetect_override_test.zip/.hgsubstate
  autodetect_override_test.zip/bar
  autodetect_override_test.zip/baz/bletch
  autodetect_override_test.zip/foo

  $ for ext in tar tar.gz tgz tar.bz2 tbz2 zip; do
  >     hg archive auto_test.$ext
  >     if [ -d auto_test.$ext ]; then
  >         echo "extension $ext was not autodetected."
  >     fi
  > done

  $ cat > md5comp.py <<EOF
  > from __future__ import print_function
  > try:
  >     from hashlib import md5
  > except ImportError:
  >     from md5 import md5
  > import sys
  > f1, f2 = sys.argv[1:3]
  > h1 = md5(open(f1, 'rb').read()).hexdigest()
  > h2 = md5(open(f2, 'rb').read()).hexdigest()
  > print(h1 == h2 or "md5 differ: " + repr((h1, h2)))
  > EOF

archive name is stored in the archive, so create similar archives and
rename them afterwards.

  $ hg archive -t tgz tip.tar.gz
  $ mv tip.tar.gz tip1.tar.gz
  $ sleep 1
  $ hg archive -t tgz tip.tar.gz
  $ mv tip.tar.gz tip2.tar.gz
  $ python md5comp.py tip1.tar.gz tip2.tar.gz
  True

  $ hg archive -t zip -p /illegal test.zip
  abort: archive prefix contains illegal components
  [255]
  $ hg archive -t zip -p very/../bad test.zip

  $ hg archive --config ui.archivemeta=false -t zip -r 2 test.zip
  $ unzip -t test.zip
  Archive:  test.zip
      testing: test/bar*OK (glob)
      testing: test/baz/bletch*OK (glob)
      testing: test/foo*OK (glob)
  No errors detected in compressed data of test.zip.

  $ hg archive -t tar - | tar tf - 2>/dev/null
  test-1701ef1f1510/.hg_archival.txt
  test-1701ef1f1510/.hgsub
  test-1701ef1f1510/.hgsubstate
  test-1701ef1f1510/bar
  test-1701ef1f1510/baz/bletch
  test-1701ef1f1510/foo

  $ hg archive -r 0 -t tar rev-%r.tar
  $ [ -f rev-0.tar ]

test .hg_archival.txt

  $ hg archive ../test-tags
  $ cat ../test-tags/.hg_archival.txt
  repo: daa7f7c60e0a224faa4ff77ca41b2760562af264
  node: 1701ef1f151069b8747038e93b5186bb43a47504
  branch: default
  latesttag: null
  latesttagdistance: 4
  changessincelatesttag: 4
  $ hg tag -r 2 mytag
  $ hg tag -r 2 anothertag
  $ hg archive -r 2 ../test-lasttag
  $ cat ../test-lasttag/.hg_archival.txt
  repo: daa7f7c60e0a224faa4ff77ca41b2760562af264
  node: 2c0277f05ed49d1c8328fb9ba92fba7a5ebcb33e
  branch: default
  tag: anothertag
  tag: mytag

  $ hg archive -t bogus test.bogus
  abort: unknown archive type 'bogus'
  [255]

enable progress extension:

  $ cp $HGRCPATH $HGRCPATH.no-progress
  $ cat >> $HGRCPATH <<EOF
  > [progress]
  > assume-tty = 1
  > format = topic bar number
  > delay = 0
  > refresh = 0
  > width = 60
  > EOF

  $ hg archive ../with-progress
  \r (no-eol) (esc)
  archiving [                                           ] 0/6\r (no-eol) (esc)
  archiving [======>                                    ] 1/6\r (no-eol) (esc)
  archiving [=============>                             ] 2/6\r (no-eol) (esc)
  archiving [====================>                      ] 3/6\r (no-eol) (esc)
  archiving [===========================>               ] 4/6\r (no-eol) (esc)
  archiving [==================================>        ] 5/6\r (no-eol) (esc)
  archiving [==========================================>] 6/6\r (no-eol) (esc)
                                                              \r (no-eol) (esc)

cleanup after progress extension test:

  $ cp $HGRCPATH.no-progress $HGRCPATH

server errors

  $ cat errors.log

empty repo

  $ hg init ../empty
  $ cd ../empty
  $ hg archive ../test-empty
  abort: no working directory: please specify a revision
  [255]

old file -- date clamped to 1980

  $ touch -t 197501010000 old
  $ hg add old
  $ hg commit -m old
  $ hg archive ../old.zip
  $ unzip -l ../old.zip
  Archive:  ../old.zip
  \s*Length.* (re)
  *-----* (glob)
  *172*80*00:00*old/.hg_archival.txt (glob)
  *0*80*00:00*old/old (glob)
  *-----* (glob)
  \s*172\s+2 files (re)

show an error when a provided pattern matches no files

  $ hg archive -I file_that_does_not_exist.foo ../empty.zip
  abort: no files match the archive pattern
  [255]

  $ hg archive -X * ../empty.zip
  abort: no files match the archive pattern
  [255]

  $ cd ..

issue3600: check whether "hg archive" can create archive files which
are extracted with expected timestamp, even though TZ is not
configured as GMT.

  $ mkdir issue3600
  $ cd issue3600

  $ hg init repo
  $ echo a > repo/a
  $ hg -R repo add repo/a
  $ hg -R repo commit -m '#0' -d '456789012 21600'
  $ cat > show_mtime.py <<EOF
  > from __future__ import print_function
  > import sys, os
  > print(int(os.stat(sys.argv[1]).st_mtime))
  > EOF

  $ hg -R repo archive --prefix tar-extracted archive.tar
  $ (TZ=UTC-3; export TZ; tar xf archive.tar)
  $ python show_mtime.py tar-extracted/a
  456789012

  $ hg -R repo archive --prefix zip-extracted archive.zip
  $ (TZ=UTC-3; export TZ; unzip -q archive.zip)
  $ python show_mtime.py zip-extracted/a
  456789012

  $ cd ..