contrib/vim/hgtest.vim

revset: use localrepo revbranchcache for branch name filtering

Branch name filtering in revsets was expensive. For every rev it created a
changectx and called .branch() which retrieved the branch name from the
changelog.

Instead, use the revbranchcache.

The revbranchcache is used read-only. The revset implementation with generators
and callbacks makes it hard to figure out when we are done using/updating the
cache and could write it back. It would also be 'tricky' to lock the repo for
writing from within a revset execution. Finally, the branchmap update will
usually make sure that the cache is updated before any revset can be run.
The revbranchcache is used without any locking but is short-lived and used in a
tight loop where we can assume that the changelog doesn't change ... or where
it not is relevant to us if it does.

perfrevset 'branch(mobile)' on mozilla-central.
Before:
! wall 10.989637 comb 10.970000 user 10.940000 sys 0.030000 (best of 3)
After, no cache:
! wall 7.368656 comb 7.370000 user 7.360000 sys 0.010000 (best of 3)
After, with cache:
! wall 0.528098 comb 0.530000 user 0.530000 sys 0.000000 (best of 18)

The performance improvement even without cache come from being based on
branchinfo on the changelog instead of using ctx.branch().

Some tests are added to verify that the revbranchcache works and keep an eye on
when the cache files actually are updated.

" Vim syntax file
" Language: Mercurial unified tests
" Author: Steve Losh ([e-mail])
"
" Place this file in ~/.vim/syntax/ and add the following line to your
" ~/.vimrc to enable:
" au BufNewFile,BufRead *.t set filetype=hgtest
"
" If you want folding you'll need the following line as well:
" let hgtest_fold=1
"
" You might also want to set the starting foldlevel for hgtest files:
" autocmd Syntax hgtest setlocal foldlevel=1

if exists("b:current_syntax")
  finish
endif

syn include @Shell syntax/sh.vim

syn match hgtestComment /^[^ ].*$/
syn region hgtestOutput start=/^  [^$>]/ start=/^  $/ end=/\v.(\n\n*[^ ])\@=/me=s end=/^  [$>]/me=e-3 end=/^$/ fold containedin=hgtestBlock
syn match hgtestCommandStart /^  \$ / containedin=hgtestCommand
syn region hgtestCommand start=/^  \$ /hs=s+4,rs=s+4 end=/^  [^>]/me=e-3 end=/^  $/me=e-2 containedin=hgtestBlock contains=@Shell keepend
syn region hgtestBlock start=/^  /ms=e-2 end=/\v.(\n\n*[^ ])\@=/me=s end=/^$/me=e-1 fold keepend

hi link hgtestCommandStart Keyword
hi link hgtestComment Normal
hi link hgtestOutput Comment

if exists("hgtest_fold")
  setlocal foldmethod=syntax
endif

syn sync match hgtestSync grouphere NONE "^$"
syn sync maxlines=200

" It's okay to set tab settings here, because an indent of two spaces is specified
" by the file format.
setlocal tabstop=2 softtabstop=2 shiftwidth=2 expandtab

let b:current_syntax = "hgtest"