tests/test-issue1306.t

bundle2: inline changegroup.readexactly()

Profiling reveals this loop is pretty tight. Literally any
function call elimination can make a big difference.

This commit inlines the relatively trivial changegroup.readexactly()
method inside the loop.

The results with `hg perfbundleread` on a bundle of the Firefox repo
speak for themselves:

! read(8k)
! wall 0.679730 comb 0.680000 user 0.140000 sys 0.540000 (best of 15)
! read(16k)
! wall 0.577228 comb 0.570000 user 0.080000 sys 0.490000 (best of 17)
! read(32k)
! wall 0.516060 comb 0.520000 user 0.040000 sys 0.480000 (best of 20)
! read(128k)
! wall 0.496378 comb 0.490000 user 0.010000 sys 0.480000 (best of 20)
! bundle2 iterparts()
! wall 3.460903 comb 3.460000 user 2.760000 sys 0.700000 (best of 3)
! wall 3.056811 comb 3.050000 user 2.340000 sys 0.710000 (best of 4)
! bundle2 iterparts() seekable
! wall 4.312722 comb 4.310000 user 3.480000 sys 0.830000 (best of 3)
! wall 4.007676 comb 4.000000 user 3.170000 sys 0.830000 (best of 3)
! bundle2 part seek()
! wall 6.754764 comb 6.740000 user 3.970000 sys 2.770000 (best of 3)
! wall 6.267110 comb 6.250000 user 3.480000 sys 2.770000 (best of 3)
! bundle2 part read(8k)
! wall 3.668004 comb 3.660000 user 2.960000 sys 0.700000 (best of 3)
! wall 3.404164 comb 3.400000 user 2.650000 sys 0.750000 (best of 3)
! bundle2 part read(16k)
! wall 3.489196 comb 3.480000 user 2.750000 sys 0.730000 (best of 3)
! wall 3.197972 comb 3.200000 user 2.490000 sys 0.710000 (best of 4)
! bundle2 part read(32k)
! wall 3.388569 comb 3.380000 user 2.640000 sys 0.740000 (best of 3)
! wall 3.060557 comb 3.060000 user 2.340000 sys 0.720000 (best of 4)
! bundle2 part read(128k)
! wall 3.276415 comb 3.270000 user 2.560000 sys 0.710000 (best of 4)
! wall 2.952209 comb 2.950000 user 2.230000 sys 0.720000 (best of 4)

Differential Revision: https://phab.mercurial-scm.org/D1392

https://bz.mercurial-scm.org/1306

Initialize remote repo with branches:

  $ hg init remote
  $ cd remote

  $ echo a > a
  $ hg ci -Ama
  adding a

  $ hg branch br
  marked working directory as branch br
  (branches are permanent and global, did you want a bookmark?)
  $ hg ci -Amb

  $ echo c > c
  $ hg ci -Amc
  adding c

  $ hg log
  changeset:   2:ae3d9c30ec50
  branch:      br
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     c
  
  changeset:   1:3f7f930ca414
  branch:      br
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b
  
  changeset:   0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  

  $ cd ..

Try cloning -r branch:

  $ hg clone -rbr remote local1
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 2 files
  new changesets cb9a9f314b8b:ae3d9c30ec50
  updating to branch br
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg -R local1 parents
  changeset:   2:ae3d9c30ec50
  branch:      br
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     c
  

Try cloning -rother clone#branch:

  $ hg clone -r0 remote#br local2
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 2 files
  new changesets cb9a9f314b8b:ae3d9c30ec50
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg -R local2 parents
  changeset:   0:cb9a9f314b8b
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     a
  

Try cloning -r1 clone#branch:

  $ hg clone -r1 remote#br local3
  adding changesets
  adding manifests
  adding file changes
  added 3 changesets with 2 changes to 2 files
  new changesets cb9a9f314b8b:ae3d9c30ec50
  updating to branch br
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg -R local3 parents
  changeset:   1:3f7f930ca414
  branch:      br
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     b