comparison tests/test-bundle.t @ 27251:d9bfe6289acf

revlog: don't consider nullrev when choosing delta base

In the most complex case, we try using the incoming delta base, then
we try both parents, and then we try the previous revlog entry. If
none of these result in a good delta, we natually use the null
revision as base. However, we sometimes consider the nullrev before we
have exhausted our other options. Specifically, when both parents are
null, we use the nullrev as delta base if it produces a good delta
(according to _isgooddelta()), and we fail to try the previous revlog
entry as delta base. After 20a9226bdc8a (addrevision: use general
delta when the incoming base delta is bad, 2015-12-01), it can also
happen for non-merge commits when the incoming delta is not good.

The Firefox repo (from many months back) shrinks a tiny bit with this
patch: from 1.855GB to 1.830GB (1.4%). The hg repo itself shrinks even
less: by less than 0.1%. There may be repos that get larger instead.

This undoes the unexplained test change in 20a9226bdc8a.

27250:bff71fe05768

  [255]

packed1 is produced properly

  $ hg -R test debugcreatestreamclonebundle packed.hg
  writing 2667 bytes for 6 files
  bundle requirements: generaldelta, revlogv1

  $ f -B 64 --size --sha1 --hexdump packed.hg
  packed.hg: size=2830, sha1=c28255110a88ffa52ddc44985cad295b1ab349bc
  0000: 48 47 53 31 55 4e 00 00 00 00 00 00 00 06 00 00 |HGS1UN..........|
  0010: 00 00 00 00 0a 6b 00 16 67 65 6e 65 72 61 6c 64 |.....k..generald|
  0020: 65 6c 74 61 2c 72 65 76 6c 6f 67 76 31 00 64 61 |elta,revlogv1.da|
  0030: 74 61 2f 61 64 69 66 66 65 72 65 6e 74 66 69 6c |ta/adifferentfil|

generaldelta requirement is listed in stream clone bundles

27251:d9bfe6289acf

  [255]

packed1 is produced properly

  $ hg -R test debugcreatestreamclonebundle packed.hg
  writing 2663 bytes for 6 files
  bundle requirements: generaldelta, revlogv1

  $ f -B 64 --size --sha1 --hexdump packed.hg
  packed.hg: size=2826, sha1=e139f97692a142b19cdcff64a69697d5307ce6d4
  0000: 48 47 53 31 55 4e 00 00 00 00 00 00 00 06 00 00 |HGS1UN..........|
  0010: 00 00 00 00 0a 67 00 16 67 65 6e 65 72 61 6c 64 |.....g..generald|
  0020: 65 6c 74 61 2c 72 65 76 6c 6f 67 76 31 00 64 61 |elta,revlogv1.da|
  0030: 74 61 2f 61 64 69 66 66 65 72 65 6e 74 66 69 6c |ta/adifferentfil|

generaldelta requirement is listed in stream clone bundles