tests/test-convert-svn-branches.t

obsolete: order of magnitude speedup in _computebumpedset

Reminder: a changeset is said "bumped" if it tries to obsolete a immutable
          changeset.


The previous algorithm for computing bumped changeset was:

    1) Get all public changesets
    2) Find all they successors
    3) Search for stuff that are eligible for being "bumped"
       (mutable and non obsolete)

The entry size of this algorithm is `O(len(public))` which is mostly the same as
`O(len(repo))`. Even this this approach mean fewer obsolescence marker are
traveled, this is not very scalable.

The new algorithm is:

    1) For each potential bumped changesets (non obsolete mutable)
    2) iterate over precursors
    3) if a precursors is public. changeset is bumped

We travel more obsolescence marker, but the entry size is much smaller since
the amount of potential bumped should remains mostly stable with time `O(1)`.

On some confidential gigantic repo this move bumped computation from 15.19s to
0.46s (×33 speedup…). On "smaller" repo (mercurial, cubicweb's review) no
significant gain were seen. The additional traversal of obsolescence marker is
probably probably counter balance the advantage of it.

Other optimisation could be done in the future (eg: sharing precursors cache
for divergence detection)

  $ "$TESTDIR/hghave" svn svn-bindings || exit 80

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

  $ svnadmin create svn-repo
  $ svnadmin load -q svn-repo < "$TESTDIR/svn/branches.svndump"

Convert trunk and branches

  $ cat > branchmap <<EOF
  > old3 newbranch
  > 
  > 
  > EOF
  $ hg convert --branchmap=branchmap --datesort -r 10 svn-repo A-hg
  initializing destination A-hg repository
  scanning source...
  sorting...
  converting...
  10 init projA
  9 hello
  8 branch trunk, remove c and dir
  7 change a
  6 change b
  5 move and update c
  4 move and update c
  3 change b again
  2 move to old2
  1 move back to old
  0 last change to a

Test template keywords

  $ hg -R A-hg log --template '{rev} {svnuuid}{svnpath}@{svnrev}\n'
  10 644ede6c-2b81-4367-9dc8-d786514f2cde/trunk@10
  9 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old@9
  8 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old2@8
  7 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old@7
  6 644ede6c-2b81-4367-9dc8-d786514f2cde/trunk@6
  5 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old@6
  4 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old@5
  3 644ede6c-2b81-4367-9dc8-d786514f2cde/trunk@4
  2 644ede6c-2b81-4367-9dc8-d786514f2cde/branches/old@3
  1 644ede6c-2b81-4367-9dc8-d786514f2cde/trunk@2
  0 644ede6c-2b81-4367-9dc8-d786514f2cde/trunk@1

Convert again

  $ hg convert --branchmap=branchmap --datesort svn-repo A-hg
  scanning source...
  sorting...
  converting...
  0 branch trunk@1 into old3

  $ cd A-hg
  $ hg log -G --template 'branch={branches} {rev} {desc|firstline} files: {files}\n'
  o  branch=newbranch 11 branch trunk@1 into old3 files:
  |
  | o  branch= 10 last change to a files: a
  | |
  | | o  branch=old 9 move back to old files:
  | | |
  | | o  branch=old2 8 move to old2 files:
  | | |
  | | o  branch=old 7 change b again files: b
  | | |
  | o |  branch= 6 move and update c files: b
  | | |
  | | o  branch=old 5 move and update c files: c
  | | |
  | | o  branch=old 4 change b files: b
  | | |
  | o |  branch= 3 change a files: a
  | | |
  | | o  branch=old 2 branch trunk, remove c and dir files: c
  | |/
  | o  branch= 1 hello files: a b c dir/e
  |/
  o  branch= 0 init projA files:
  

  $ hg branches
  newbranch                     11:a6d7cc050ad1
  default                       10:6e2b33404495
  old                            9:93c4b0f99529
  old2                           8:b52884d7bead (inactive)
  $ hg tags -q
  tip
  $ cd ..

Test hg failing to call itself

  $ HG=foobar hg convert svn-repo B-hg 2>&1 | grep abort
  abort: Mercurial failed to run itself, check hg executable is in PATH