view tests/test-bundle-phases.t @ 49777:e1953a34c110

bundle: emit full snapshot as is, without doing a redelta

With the new `forced` delta-reused policy, it become important to be able to
send full snapshot where full snapshot are needed. Otherwise, the fallback delta
will simply be used on the client side… creating monstrous delta chain, since
revision that are meant as a reset of delta-chain chain becoming too complex are
simply adding a new full delta-tree on the leaf of another one.

In the `non-forced` cases, client process full snapshot from the bundle
differently from deltas, so client will still try to convert the full snapshot
into a delta if possible. So this will no lead to pathological storage
explosion.

I have considered making this configurable, but the impact seems limited enough
that it does not seems to be worth it. Especially with the current
sparse-revlog format that use "delta-tree" with multiple level snapshots, full
snapshot are much less frequent and not that different from other intermediate
snapshot that we are already sending over the wire anyway.

CPU wise, this will help the bundling side a little as it will not need to
reconstruct revisions and compute deltas. The unbundling side might save a tiny
amount of CPU as it won't need to reconstruct the delta-base to reconstruct the
revision full text. This only slightly visible in some of the benchmarks. And
have no real impact on most of them.

### data-env-vars.name      = pypy-2018-08-01-zstd-sparse-revlog
  # benchmark.name          = perf-bundle
  # benchmark.variants.revs = last-40000
before:          11.467186 seconds
just-emit-full:  11.190576 seconds   (-2.41%)
with-pull-force: 11.041091 seconds   (-3.72%)
  # benchmark.name          = perf-unbundle
  # benchmark.variants.revs = last-40000
before:     16.744862
just-emit-full:: 16.561036 seconds   (-1.10%)
with-pull-force: 16.389344 seconds   (-2.12%)
  # benchmark.name          = pull
  # benchmark.variants.revs = last-40000
before:     26.870569
just-emit-full:  26.391188 seconds   (-1.78%)
with-pull-force: 25.633184 seconds   (-4.60%)


Space wise (so network-wise) the impact is fairly small. When taking compression into
account.

Below are tests the size of `hg bundle --all` for a handful of benchmark repositories
(with bzip, zstd compression and without it)

This show a small increase in the bundle size, but nothing really significant
except maybe for mozilla-try (+12%) that nobody really pulls large chunk of anyway.
Mozilla-try is also the repository that benefit the most for not having to
recompute deltas client size.

### mercurial:
bzip-before:     26 406 342 bytes
bzip-after:      26 691 543 bytes  +1.08%

zstd-before:     27 918 645 bytes
zstd-after:      28 075 896 bytes  +0.56%

none-before:     98 675 601 bytes
none-after:     100 411 237 bytes  +1.76%


### pypy
bzip-before:    201 295 752 bytes
bzip-after:     209 780 282 bytes  +4.21%

zstd-before:    202 974 795 bytes
zstd-after:     205 165 780 bytes  +1.08%

none-before:    871 070 261 bytes
none-after:     993 595 057 bytes +14.07%


### netbeans
bzip-before:    601 314 330 bytes
bzip-after:     614 246 241 bytes  +2.15%

zstd-before:    604 745 136 bytes
zstd-after:     615 497 705 bytes  +1.78%

none-before:  3 338 238 571 bytes
none-after:   3 439 422 535 bytes  +3.03%


### mozilla-central
bzip-before:  1 493 006 921 bytes
bzip-after:   1 549 650 570 bytes  +3.79%

zstd-before:  1 481 910 102 bytes
zstd-after:   1 513 052 415 bytes  +2.10%

none-before:  6 535 929 910 bytes
none-after:   7 010 191 342 bytes  +7.26%


### mozilla-try
bzip-before:  6 583 425 999 bytes
bzip-after:   7 423 536 928 bytes +12.76%

zstd-before:  6 021 009 212 bytes
zstd-after:   6 674 922 420 bytes +10.86%

none-before: 22 954 739 558 bytes
none-after:  26 013 854 771 bytes +13.32%

  $ cat >> $HGRCPATH <<EOF
  > [experimental]
  > bundle-phases=yes
  > [extensions]
  > strip=
  > drawdag=$TESTDIR/drawdag.py
  > EOF

Set up repo with linear history
  $ hg init linear
  $ cd linear
  $ hg debugdrawdag <<'EOF'
  > E
  > |
  > D
  > |
  > C
  > |
  > B
  > |
  > A
  > EOF
  $ hg phase --public A
  $ hg phase --force --secret D
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
Phases are restored when unbundling
  $ hg bundle --base B -r E bundle
  3 changesets found
  $ hg debugbundle bundle
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 3, targetphase: 2, version: 02} (mandatory: True)
      26805aba1e600a82e93661149f2313866a221a7b
      f585351a92f85104bff7c284233c338b10eb1df7
      9bc730a19041f9ec7cb33c626e811aa233efb18c
  cache:rev-branch-cache -- {} (mandatory: False)
  phase-heads -- {} (mandatory: True)
      26805aba1e600a82e93661149f2313866a221a7b draft
  $ hg strip --no-backup C
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
Root revision's phase is preserved
  $ hg bundle -a bundle
  5 changesets found
  $ hg strip --no-backup A
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
Completely public history can be restored
  $ hg phase --public E
  $ hg bundle -a bundle
  5 changesets found
  $ hg strip --no-backup A
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E public
  |
  o  D public
  |
  o  C public
  |
  o  B public
  |
  o  A public
  
Direct transition from public to secret can be restored
  $ hg phase --secret --force D
  $ hg bundle -a bundle
  5 changesets found
  $ hg strip --no-backup A
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C public
  |
  o  B public
  |
  o  A public
  
Revisions within bundle preserve their phase even if parent changes its phase
  $ hg phase --draft --force B
  $ hg bundle --base B -r E bundle
  3 changesets found
  $ hg strip --no-backup C
  $ hg phase --public B
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C draft
  |
  o  B public
  |
  o  A public
  
Phase of ancestors of stripped node get advanced to accommodate child
  $ hg bundle --base B -r E bundle
  3 changesets found
  $ hg strip --no-backup C
  $ hg phase --force --secret B
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E secret
  |
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
Unbundling advances phases of changesets even if they were already in the repo.
To test that, create a bundle of everything in draft phase and then unbundle
to see that secret becomes draft, but public remains public.
  $ hg phase --draft --force A
  $ hg phase --draft E
  $ hg bundle -a bundle
  5 changesets found
  $ hg phase --public A
  $ hg phase --secret --force E
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  E draft
  |
  o  D draft
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
Unbundling change in the middle of a stack does not affect later changes
  $ hg strip --no-backup E
  $ hg phase --secret --force D
  $ hg log -G -T '{desc} {phase}\n'
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  
  $ hg bundle --base A -r B bundle
  1 changesets found
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{desc} {phase}\n'
  o  D secret
  |
  o  C draft
  |
  o  B draft
  |
  o  A public
  

  $ cd ..

Set up repo with non-linear history
  $ hg init non-linear
  $ cd non-linear
  $ hg debugdrawdag <<'EOF'
  > D E
  > |\|
  > B C
  > |/
  > A
  > EOF
  $ hg phase --public C
  $ hg phase --force --secret B
  $ hg log -G -T '{node|short} {desc} {phase}\n'
  o  03ca77807e91 E draft
  |
  | o  4e4f9194f9f1 D secret
  |/|
  o |  dc0947a82db8 C public
  | |
  | o  112478962961 B secret
  |/
  o  426bada5c675 A public
  

Restore bundle of entire repo
  $ hg bundle -a bundle
  5 changesets found
  $ hg debugbundle bundle
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 5, targetphase: 2, version: 02} (mandatory: True)
      426bada5c67598ca65036d57d9e4b64b0c1ce7a0
      112478962961147124edd43549aedd1a335e44bf
      dc0947a82db884575bb76ea10ac97b08536bfa03
      4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
      03ca77807e919db8807c3749086dc36fb478cac0
  cache:rev-branch-cache -- {} (mandatory: False)
  phase-heads -- {} (mandatory: True)
      dc0947a82db884575bb76ea10ac97b08536bfa03 public
      03ca77807e919db8807c3749086dc36fb478cac0 draft
  $ hg strip --no-backup A
  $ hg unbundle -q bundle
  $ rm bundle
  $ hg log -G -T '{node|short} {desc} {phase}\n'
  o  03ca77807e91 E draft
  |
  | o  4e4f9194f9f1 D secret
  |/|
  o |  dc0947a82db8 C public
  | |
  | o  112478962961 B secret
  |/
  o  426bada5c675 A public
  

  $ hg bundle --base 'A + C' -r D bundle
  2 changesets found
  $ hg debugbundle bundle
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 2, targetphase: 2, version: 02} (mandatory: True)
      112478962961147124edd43549aedd1a335e44bf
      4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
  cache:rev-branch-cache -- {} (mandatory: False)
  phase-heads -- {} (mandatory: True)
  $ rm bundle

  $ hg bundle --base A -r D bundle
  3 changesets found
  $ hg debugbundle bundle
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 3, targetphase: 2, version: 02} (mandatory: True)
      112478962961147124edd43549aedd1a335e44bf
      dc0947a82db884575bb76ea10ac97b08536bfa03
      4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
  cache:rev-branch-cache -- {} (mandatory: False)
  phase-heads -- {} (mandatory: True)
      dc0947a82db884575bb76ea10ac97b08536bfa03 public
  $ rm bundle

  $ hg bundle --base 'B + C' -r 'D + E' bundle
  2 changesets found
  $ hg debugbundle bundle
  Stream params: {Compression: BZ}
  changegroup -- {nbchanges: 2, targetphase: 2, version: 02} (mandatory: True)
      4e4f9194f9f181c57f62e823e8bdfa46ab9e4ff4
      03ca77807e919db8807c3749086dc36fb478cac0
  cache:rev-branch-cache -- {} (mandatory: False)
  phase-heads -- {} (mandatory: True)
      03ca77807e919db8807c3749086dc36fb478cac0 draft
  $ rm bundle