view tests/test-pull-r @ 8849:80cc4b1a62d0

compare grep result between target and its parent

I found that typical case is that grep target is added at (*) revision
in the tree shown below.

     +--- 1(*) --- 3
     0
     +--- 2 ------ 4

Now, I expect 'hg grep --all' to show only rev:1 which is first
appearance of target line.

But 'hg grep --all' will tell:

  target line dis-appeared at 3 => 4
  target line     appeared at 2 => 3
  target line dis-appeared at 1 => 2
  target line     appeared at 0 => 1

because current 'hg grep' implementation compares not between target
revision and its parent, but between neighbor revisions in walkthrough
order.

I checked performance of this patch by "hg grep --follow --all
walkchangerevs" on whole Mercurial repo, and patched version could
complete as fast as un-patched one.

#!/bin/sh

hg init repo
cd repo
echo foo > foo
hg ci -qAm 'add foo'
echo >> foo
hg ci -m 'change foo'
hg up -qC 0
echo bar > bar
hg ci -qAm 'add bar'
hg log
cd ..
hg init copy
cd copy

echo '% pull a missing revision'
hg pull -qr missing ../repo

echo '% pull -r 0'
hg pull -qr 0 ../repo
hg log

echo '% pull -r 1'
hg pull -qr 1 ../repo
hg log

# this used to abort: received changelog group is empty
echo '% pull -r 1 again'
hg pull -qr 1 ../repo