view tests/test-churn.out @ 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.

% create test repository
adding a
adding b
adding c
% churn separate directories
user1      1 ***************************************************************
% churn all
user3      3 ***************************************************************
user1      3 ***************************************************************
user2      2 ******************************************
% churn up to rev 2
user2      2 ***************************************************************
user1      1 *******************************
% churn with aliases
alias3      3 **************************************************************
alias1      3 **************************************************************
user2       2 *****************************************
% churn with .hgchurn
alias3      3 **************************************************************
alias1      3 **************************************************************
user2       2 *****************************************
% churn with column specifier
user3      3 ***********************
user1      3 ***********************
user2      2 ***************
% churn by hour
06      1 ****************
09      2 *********************************
12      4 ******************************************************************
13      1 ****************