tests/test-bundle2-multiple-changegroups.t

sparse-revlog: implement algorithm to write sparse delta chains (issue5480)

The classic behavior of revlog._isgooddeltainfo is to consider the span size
of the whole delta chain, and limit it to 4 * textlen.
Once sparse-revlog writing is allowed (and enforced with a requirement),
revlog._isgooddeltainfo considers the span of the largest chunk as the
distance used in the verification, instead of using the span of the whole
delta chain.

In order to compute the span of the largest chunk, we need to slice into
chunks a chain with the new revision at the top of the revlog, and take the
maximal span of these chunks. The sparse read density is a parameter to the
slicing, as it will stop when the global read density reaches this threshold.
For instance, a density of 50% means that 2 of 4 read bytes are actually used
for the reconstruction of the revision (the others are part of other chains).

This allows a new revision to be potentially stored with a diff against
another revision anywhere in the history, instead of forcing it in the last 4
* textlen. The result is a much better compression on repositories that have
many concurrent branches. Here are a comparison between using deltas from
current upstream (aggressive-merge-deltas on by default) and deltas from a
sparse-revlog

Comparison of `.hg/store/` size:

    mercurial (6.74% merges):
        before:     46,831,873 bytes
        after:      46,795,992 bytes (no relevant change)
    pypy (8.30% merges):
        before:    333,524,651 bytes
        after:     308,417,511 bytes -8%
    netbeans (34.21% merges):
        before:  1,141,847,554 bytes
        after:   1,131,093,161 bytes -1%
    mozilla-central (4.84% merges):
        before:  2,344,248,850 bytes
        after:   2,328,459,258 bytes -1%
    large-private-repo-A (merge 19.73%)
        before: 41,510,550,163 bytes
        after:   8,121,763,428 bytes -80%
    large-private-repo-B (23.77%)
        before: 58,702,221,709 bytes
        after:   8,351,588,828 bytes -76%

Comparison of `00manifest.d` size:

    mercurial (6.74% merges):
        before:      6,143,044 bytes
        after:       6,107,163 bytes
    pypy (8.30% merges):
        before:     52,941,780 bytes
        after:      27,834,082 bytes -48%
    netbeans (34.21% merges):
        before:    130,088,982 bytes
        after:     119,337,636 bytes -10%
    mozilla-central (4.84% merges):
        before:    215,096,339 bytes
        after:     199,496,863 bytes -8%
    large-private-repo-A (merge 19.73%)
        before: 33,725,285,081 bytes
        after:     390,302,545 bytes -99%
    large-private-repo-B (23.77%)
        before: 49,457,701,645 bytes
        after:   1,366,752,187 bytes -97%


The better delta chains provide a performance boost in relevant repositories:

    pypy, bundling 1000 revisions:
        before: 1.670s
        after:  1.149s -31%

Unbundling got a bit slower. probably because the sparse algorithm is still
pure
python.

    pypy, unbundling 1000 revisions:
        before: 4.062s
        after:  4.507s +10%

Performance of bundle/unbundle in repository with few concurrent branches (eg:
mercurial) are unaffected.

No significant differences have been noticed then timing `hg push` and `hg
pull` locally. More state timings are being gathered.

Same as for aggressive-merge-delta, better delta comes with longer delta
chains. Longer chains have a performance impact. For example. The length of
the chain needed to get the manifest of pypy's tip moves from 82 item to 1929
items. This moves the restore time from 3.88ms to 11.3ms.

Delta chain length is an independent issue that affects repository without
this changes. It will be dealt with independently.

No significant differences have been observed on repositories where
`sparse-revlog` have not much effect (mercurial, unity, netbeans). On pypy,
small differences have been observed on some operation affected by delta chain
building and retrieval.


    pypy, perfmanifest
        before: 0.006162s
        after:  0.017899s +190%

    pypy, commit:
        before: 0.382
        after:  0.376 -1%

    pypy, status:
        before: 0.157
        after:  0.168 +7%

More comprehensive and stable timing comparisons are in progress.

Create an extension to test bundle2 with multiple changegroups

  $ cat > bundle2.py <<EOF
  > """
  > """
  > from mercurial import changegroup, discovery, exchange
  > 
  > def _getbundlechangegrouppart(bundler, repo, source, bundlecaps=None,
  >                               b2caps=None, heads=None, common=None,
  >                               **kwargs):
  >     # Create two changegroups given the common changesets and heads for the
  >     # changegroup part we are being requested. Use the parent of each head
  >     # in 'heads' as intermediate heads for the first changegroup.
  >     intermediates = [repo[r].p1().node() for r in heads]
  >     outgoing = discovery.outgoing(repo, common, intermediates)
  >     cg = changegroup.makechangegroup(repo, outgoing, b'01',
  >                                      source, bundlecaps=bundlecaps)
  >     bundler.newpart(b'output', data=b'changegroup1')
  >     bundler.newpart(b'changegroup', data=cg.getchunks())
  >     outgoing = discovery.outgoing(repo, common + intermediates, heads)
  >     cg = changegroup.makechangegroup(repo, outgoing, b'01',
  >                                      source, bundlecaps=bundlecaps)
  >     bundler.newpart(b'output', data=b'changegroup2')
  >     bundler.newpart(b'changegroup', data=cg.getchunks())
  > 
  > def _pull(repo, *args, **kwargs):
  >   pullop = _orig_pull(repo, *args, **kwargs)
  >   repo.ui.write(b'pullop.cgresult is %d\n' % pullop.cgresult)
  >   return pullop
  > 
  > _orig_pull = exchange.pull
  > exchange.pull = _pull
  > exchange.getbundle2partsmapping[b'changegroup'] = _getbundlechangegrouppart
  > EOF

  $ cat >> $HGRCPATH << EOF
  > [ui]
  > logtemplate={rev}:{node|short} {phase} {author} {bookmarks} {desc|firstline}
  > EOF

Start with a simple repository with a single commit

  $ hg init repo
  $ cd repo
  $ cat > .hg/hgrc << EOF
  > [extensions]
  > bundle2=$TESTTMP/bundle2.py
  > EOF

  $ echo A > A
  $ hg commit -A -m A -q
  $ cd ..

Clone

  $ hg clone -q repo clone

Add two linear commits

  $ cd repo
  $ echo B > B
  $ hg commit -A -m B -q
  $ echo C > C
  $ hg commit -A -m C -q

  $ cd ../clone
  $ cat >> .hg/hgrc <<EOF
  > [hooks]
  > pretxnchangegroup = sh -c "printenv.py pretxnchangegroup"
  > changegroup = sh -c "printenv.py changegroup"
  > incoming = sh -c "printenv.py incoming"
  > EOF

Pull the new commits in the clone

  $ hg pull
  pulling from $TESTTMP/repo
  searching for changes
  remote: changegroup1
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  pretxnchangegroup hook: HG_HOOKNAME=pretxnchangegroup HG_HOOKTYPE=pretxnchangegroup HG_NODE=27547f69f25460a52fff66ad004e58da7ad3fb56 HG_NODE_LAST=27547f69f25460a52fff66ad004e58da7ad3fb56 HG_PENDING=$TESTTMP/clone HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  remote: changegroup2
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  pretxnchangegroup hook: HG_HOOKNAME=pretxnchangegroup HG_HOOKTYPE=pretxnchangegroup HG_NODE=f838bfaca5c7226600ebcfd84f3c3c13a28d3757 HG_NODE_LAST=f838bfaca5c7226600ebcfd84f3c3c13a28d3757 HG_PENDING=$TESTTMP/clone HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  new changesets 27547f69f254:f838bfaca5c7
  changegroup hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=27547f69f25460a52fff66ad004e58da7ad3fb56 HG_NODE_LAST=27547f69f25460a52fff66ad004e58da7ad3fb56 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  incoming hook: HG_HOOKNAME=incoming HG_HOOKTYPE=incoming HG_NODE=27547f69f25460a52fff66ad004e58da7ad3fb56 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  changegroup hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=f838bfaca5c7226600ebcfd84f3c3c13a28d3757 HG_NODE_LAST=f838bfaca5c7226600ebcfd84f3c3c13a28d3757 HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  incoming hook: HG_HOOKNAME=incoming HG_HOOKTYPE=incoming HG_NODE=f838bfaca5c7226600ebcfd84f3c3c13a28d3757 HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  pullop.cgresult is 1
  (run 'hg update' to get a working copy)
  $ hg update
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg log -G
  @  2:f838bfaca5c7 public test  C
  |
  o  1:27547f69f254 public test  B
  |
  o  0:4a2df7238c3b public test  A
  
Add more changesets with multiple heads to the original repository

  $ cd ../repo
  $ echo D > D
  $ hg commit -A -m D -q
  $ hg up -r 1
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ echo E > E
  $ hg commit -A -m E -q
  $ echo F > F
  $ hg commit -A -m F -q
  $ hg up -r 1
  0 files updated, 0 files merged, 2 files removed, 0 files unresolved
  $ echo G > G
  $ hg commit -A -m G -q
  $ hg up -r 3
  2 files updated, 0 files merged, 1 files removed, 0 files unresolved
  $ echo H > H
  $ hg commit -A -m H -q
  $ hg log -G
  @  7:5cd59d311f65 draft test  H
  |
  | o  6:1d14c3ce6ac0 draft test  G
  | |
  | | o  5:7f219660301f draft test  F
  | | |
  | | o  4:8a5212ebc852 draft test  E
  | |/
  o |  3:b3325c91a4d9 draft test  D
  | |
  o |  2:f838bfaca5c7 draft test  C
  |/
  o  1:27547f69f254 draft test  B
  |
  o  0:4a2df7238c3b draft test  A
  
New heads are reported during transfer and properly accounted for in
pullop.cgresult

  $ cd ../clone
  $ hg pull
  pulling from $TESTTMP/repo
  searching for changes
  remote: changegroup1
  adding changesets
  adding manifests
  adding file changes
  added 2 changesets with 2 changes to 2 files (+1 heads)
  pretxnchangegroup hook: HG_HOOKNAME=pretxnchangegroup HG_HOOKTYPE=pretxnchangegroup HG_NODE=b3325c91a4d916bcc4cdc83ea3fe4ece46a42f6e HG_NODE_LAST=8a5212ebc8527f9fb821601504794e3eb11a1ed3 HG_PENDING=$TESTTMP/clone HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  remote: changegroup2
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 3 changes to 3 files (+1 heads)
  pretxnchangegroup hook: HG_HOOKNAME=pretxnchangegroup HG_HOOKTYPE=pretxnchangegroup HG_NODE=7f219660301fe4c8a116f714df5e769695cc2b46 HG_NODE_LAST=5cd59d311f6508b8e0ed28a266756c859419c9f1 HG_PENDING=$TESTTMP/clone HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  new changesets b3325c91a4d9:5cd59d311f65
  changegroup hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=b3325c91a4d916bcc4cdc83ea3fe4ece46a42f6e HG_NODE_LAST=8a5212ebc8527f9fb821601504794e3eb11a1ed3 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  incoming hook: HG_HOOKNAME=incoming HG_HOOKTYPE=incoming HG_NODE=b3325c91a4d916bcc4cdc83ea3fe4ece46a42f6e HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  incoming hook: HG_HOOKNAME=incoming HG_HOOKTYPE=incoming HG_NODE=8a5212ebc8527f9fb821601504794e3eb11a1ed3 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  changegroup hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=7f219660301fe4c8a116f714df5e769695cc2b46 HG_NODE_LAST=5cd59d311f6508b8e0ed28a266756c859419c9f1 HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  incoming hook: HG_HOOKNAME=incoming HG_HOOKTYPE=incoming HG_NODE=7f219660301fe4c8a116f714df5e769695cc2b46 HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  incoming hook: HG_HOOKNAME=incoming HG_HOOKTYPE=incoming HG_NODE=1d14c3ce6ac0582d2809220d33e8cd7a696e0156 HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  incoming hook: HG_HOOKNAME=incoming HG_HOOKTYPE=incoming HG_NODE=5cd59d311f6508b8e0ed28a266756c859419c9f1 HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  pullop.cgresult is 3
  (run 'hg heads' to see heads, 'hg merge' to merge)
  $ hg log -G
  o  7:5cd59d311f65 public test  H
  |
  | o  6:1d14c3ce6ac0 public test  G
  | |
  | | o  5:7f219660301f public test  F
  | | |
  | | o  4:8a5212ebc852 public test  E
  | |/
  o |  3:b3325c91a4d9 public test  D
  | |
  @ |  2:f838bfaca5c7 public test  C
  |/
  o  1:27547f69f254 public test  B
  |
  o  0:4a2df7238c3b public test  A
  
Removing a head from the original repository by merging it

  $ cd ../repo
  $ hg merge -r 6 -q
  $ hg commit -m Merge
  $ echo I > I
  $ hg commit -A -m H -q
  $ hg log -G
  @  9:9d18e5bd9ab0 draft test  H
  |
  o    8:71bd7b46de72 draft test  Merge
  |\
  | o  7:5cd59d311f65 draft test  H
  | |
  o |  6:1d14c3ce6ac0 draft test  G
  | |
  | | o  5:7f219660301f draft test  F
  | | |
  +---o  4:8a5212ebc852 draft test  E
  | |
  | o  3:b3325c91a4d9 draft test  D
  | |
  | o  2:f838bfaca5c7 draft test  C
  |/
  o  1:27547f69f254 draft test  B
  |
  o  0:4a2df7238c3b draft test  A
  
Removed heads are reported during transfer and properly accounted for in
pullop.cgresult

  $ cd ../clone
  $ hg pull
  pulling from $TESTTMP/repo
  searching for changes
  remote: changegroup1
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 0 changes to 0 files (-1 heads)
  pretxnchangegroup hook: HG_HOOKNAME=pretxnchangegroup HG_HOOKTYPE=pretxnchangegroup HG_NODE=71bd7b46de72e69a32455bf88d04757d542e6cf4 HG_NODE_LAST=71bd7b46de72e69a32455bf88d04757d542e6cf4 HG_PENDING=$TESTTMP/clone HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  remote: changegroup2
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  pretxnchangegroup hook: HG_HOOKNAME=pretxnchangegroup HG_HOOKTYPE=pretxnchangegroup HG_NODE=9d18e5bd9ab09337802595d49f1dad0c98df4d84 HG_NODE_LAST=9d18e5bd9ab09337802595d49f1dad0c98df4d84 HG_PENDING=$TESTTMP/clone HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  new changesets 71bd7b46de72:9d18e5bd9ab0
  changegroup hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=71bd7b46de72e69a32455bf88d04757d542e6cf4 HG_NODE_LAST=71bd7b46de72e69a32455bf88d04757d542e6cf4 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  incoming hook: HG_HOOKNAME=incoming HG_HOOKTYPE=incoming HG_NODE=71bd7b46de72e69a32455bf88d04757d542e6cf4 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  changegroup hook: HG_HOOKNAME=changegroup HG_HOOKTYPE=changegroup HG_NODE=9d18e5bd9ab09337802595d49f1dad0c98df4d84 HG_NODE_LAST=9d18e5bd9ab09337802595d49f1dad0c98df4d84 HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  incoming hook: HG_HOOKNAME=incoming HG_HOOKTYPE=incoming HG_NODE=9d18e5bd9ab09337802595d49f1dad0c98df4d84 HG_PHASES_MOVED=1 HG_SOURCE=pull HG_TXNID=TXN:$ID$ HG_URL=file:$TESTTMP/repo
  pullop.cgresult is -2
  (run 'hg update' to get a working copy)
  $ hg log -G
  o  9:9d18e5bd9ab0 public test  H
  |
  o    8:71bd7b46de72 public test  Merge
  |\
  | o  7:5cd59d311f65 public test  H
  | |
  o |  6:1d14c3ce6ac0 public test  G
  | |
  | | o  5:7f219660301f public test  F
  | | |
  +---o  4:8a5212ebc852 public test  E
  | |
  | o  3:b3325c91a4d9 public test  D
  | |
  | @  2:f838bfaca5c7 public test  C
  |/
  o  1:27547f69f254 public test  B
  |
  o  0:4a2df7238c3b public test  A