[PATCH] revlog: teach revlog to construct a revision from parentdeltas

[Matt Mackall]

On Sat, 2010-08-07 at 12:00 +0530, in3xes at gmail.com wrote:
> # HG changeset patch
> # User Pradeepkumar Gayam <in3xes at gmail.com>
> # Date 1281138500 -19800
> # Node ID 12a41d114b113af32329386b32d88709c0f28816
> # Parent  db0f8a9594be4ecde3c1cc0ba71087997650ca9a
> revlog: teach revlog to construct a revision from parentdeltas

Ok, this versions passes tests when I force parentdelta (with expected
breakage in debugindex), and it also passes verify on convert. But it
doesn't pass verify as a benchmark (the first one I reached for):

# stable hg on non-delta repo
$ time hgs verify
checking changesets
checking manifests
crosschecking files in changesets and
manifests                                 
checking files
1555 files, 11766 changesets, 23269 total
revisions                             

real	0m11.670s
user	0m11.033s
sys	0m0.290s

# default branch without your patches on non-delta repo
$ time hg -R hg2 verify
checking changesets
checking manifests
crosschecking files in changesets and
manifests                                 
checking files
1555 files, 11766 changesets, 23269 total
revisions                             

real	0m11.225s
user	0m10.929s
sys	0m0.247s

# hg with your patches on non-delta repo
$ time hg verify
checking changesets
checking manifests
crosschecking files in changesets and
manifests                                 
checking files
1555 files, 11766 changesets, 23269 total
revisions                             

real	0m16.802s
user	0m16.472s
sys	0m0.213s

# hg with your patch on delta repo
$ time hg -R p2 verify
checking changesets
checking manifests
crosschecking files in changesets and
manifests                                 
checking files
1555 files, 11766 changesets, 23269 total
revisions                             

real	0m49.717s
user	0m48.773s
sys	0m0.383s


We obviously can't take these patches if it makes verify of existing
repos 50% slower. And 5x slower when parentdelta is actually enabled
isn't great either. FYI, the slowness appears with this patch.

-- 
Mathematics is the supreme nostalgia of our time.