view contrib/vim/hg-menu.vim @ 49491:c6a1beba27e9

bisect: avoid copying ancestor list for non-merge commits

During a bisection, hg needs to compute a list of all ancestors for every
candidate commit. This is accomplished via a bottom-up traversal of the set of
candidates, during which each revision's ancestor list is populated using the
ancestor list of its parent(s). Previously, this involved copying the entire
list, which could be very long in if the bisection range was large.

To help improve this, we can observe that each candidate commit is visited
exactly once, at which point its ancestor list is copied into its children's
lists and then dropped. In the case of non-merge commits, a commit's ancestor
list consists exactly of its parent's list plus itself. This means that we can
trivially reuse the parent's existing list for one of its non-merge children,
which avoids copying entirely if that commit is the parent's only child. This
makes bisections over linear ranges of commits much faster.

During some informal testing in the large publicly-available `mozilla-central`
repository, this noticeably sped up bisections over large ranges of history:

Setup:
  $ cd mozilla-central
  $ hg bisect --reset
  $ hg bisect --good 0
  $ hg log -r tip -T '{rev}\n'
  628417

Test:
  $ time hg bisect --bad tip --noupdate

Before:
  real    3m35.927s
  user    3m35.553s
  sys     0m0.319s

After:
  real    1m41.142s
  user    1m40.810s
  sys     0m0.285s

" vim600: set foldmethod=marker:
" =============================================================================
"  Name Of File: hg-menu.vim
"   Description: Interface to Mercurial Version Control.
"        Author: Steve Borho (modified Jeff Lanzarotta's RCS script)
"          Date: Wednesday, October 5, 2005
"       Version: 0.1.0
"     Copyright: None.
"         Usage: These command and gui menu displays useful hg functions
" Configuration: Your hg executable must be in your path.
" =============================================================================

" Section: Init {{{1
if exists("loaded_hg_menu")
  finish
endif
let loaded_hg_menu = 1

" Section: Menu Options {{{1
if has("gui")
"  amenu H&G.Commit\ File<Tab>,ci :!hg commit %<CR>:e!<CR>
"  amenu H&G.Commit\ All<Tab>,call :!hg commit<CR>:e!<CR>
"  amenu H&G.-SEP1-        <nul>
  amenu H&G.Add<Tab>\\add :!hg add %<CR><CR>
  amenu H&G.Forget\ Add<Tab>\\fgt :!hg forget %<CR><CR>
  amenu H&G.Show\ Differences<Tab>\\diff :call ShowResults("FileDiff", "hg\ diff")<CR><CR>
  amenu H&G.Revert\ to\ Last\ Version<Tab>\\revert :!hg revert %<CR>:e!<CR>
  amenu H&G.Show\ History<Tab>\\log :call ShowResults("FileLog", "hg\ log")<CR><CR>
  amenu H&G.Annotate<Tab>\\an :call ShowResults("annotate", "hg\ annotate")<CR><CR>
  amenu H&G.-SEP1-        <nul>
  amenu H&G.Repo\ Status<Tab>\\stat :call ShowResults("RepoStatus", "hg\ status")<CR><CR>
  amenu H&G.Pull<Tab>\\pull :!hg pull<CR>:e!<CR>
  amenu H&G.Update<Tab>\\upd :!hg update<CR>:e!<CR>
endif

" Section: Mappings {{{1
if(v:version >= 600)
  " The default Leader is \ 'backslash'
  map <Leader>add       :!hg add %<CR><CR>
  map <Leader>fgt       :!hg forget %<CR><CR>
  map <Leader>diff      :call ShowResults("FileDiff", "hg\ diff")<CR><CR>
  map <Leader>revert    :!hg revert %<CR>:e!<CR>
  map <Leader>log       :call ShowResults("FileLog", "hg\ log")<CR><CR>
  map <Leader>an        :call ShowResults("annotate", "hg\ annotate")<CR><CR>
  map <Leader>stat      :call ShowResults("RepoStatus", "hg\ status")<CR><CR>
  map <Leader>upd       :!hg update<CR>:e!<CR>
  map <Leader>pull      :!hg pull<CR>:e!<CR>
else
  " pre 6.0, the default Leader was a comma
  map ,add          :!hg add %<CR><CR>
  map ,fgt          :!hg forget %<CR><CR>
  map ,diff         :call ShowResults("FileDiff", "hg\ diff")<CR><CR>
  map ,revert       :!hg revert<CR>:e!<CR>
  map ,log          :call ShowResults("FileLog", "hg\ log")<CR><CR>
  map ,an           :call ShowResults("annotate", "hg\ annotate")<CR><CR>
  map ,stat         :call ShowResults("RepoStatus", "hg\ status")<CR><CR>
  map ,upd          :!hg update<CR>:e!<CR>
  map ,pull         :!hg pull<CR>:e!<CR>
endif

" Section: Functions {{{1
" Show the log results of the current file with a revision control system.
function! ShowResults(bufferName, cmdName)
  " Modify the shortmess option:
  " A  don't give the "ATTENTION" message when an existing swap file is
  "    found.
  set shortmess+=A

  " Get the name of the current buffer.
  let currentBuffer = bufname("%")

  " If a buffer with the name rlog exists, delete it.
  if bufexists(a:bufferName)
    execute 'bd! ' a:bufferName
  endif

  " Create a new buffer.
  execute 'new ' a:bufferName

  " Execute the command.
  execute 'r!' a:cmdName ' ' currentBuffer

  " Make is so that the file can't be edited.
  setlocal nomodified
  setlocal nomodifiable
  setlocal readonly

  " Go to the beginning of the buffer.
  execute "normal 1G"

  " Restore the shortmess option.
  set shortmess-=A
endfunction