Spawn multiple threads unless g:plug_threads is set to 1

README.md

@@ -73,16 +73,14 @@ installation.
 
 A `Plugfile` should contain a set of `Plug` commands for the dependent plugins.
 
-I've created two dummy repositories with Plugfiles as an example to this scheme.
+I've created three dummy repositories with Plugfiles as an example to this
+scheme.
 
-- [junegunn/dummy1](https://github.com/junegunn/dummy1)
+- [junegunn/dummy1](https://github.com/junegunn/dummy1/blob/master/Plugfile)
-  - `Plug 'junegunn/vim-scroll-position'`
+  - Plugfile includes `Plug 'junegunn/dummy2'`
-  - `Plug 'junegunn/dummy2'`
+- [junegunn/dummy2](https://github.com/junegunn/dummy2/blob/master/Plugfile)
-- [junegunn/dummy2](https://github.com/junegunn/dummy2)
+  - Plugfile includes `Plug 'junegunn/dummy3'`
-  - `Plug 'junegunn/Zenburn'`
+- [junegunn/dummy3](https://github.com/junegunn/dummy3/blob/master/Plugfile)
-  - `Plug 'junegunn/jellybeans.vim'`
-  - `Plug 'junegunn/dummy1'`
-    - (Circular dependencies are ignored)
 
 If you put `Plug 'junegunn/dummy1'` in your configuration file, and run
 `:PlugInstall`,

plug.vim

@@ -217,12 +217,7 @@ function! s:finish()
 endfunction
 
 function! s:update_impl(pull, args)
-  if has('ruby') && get(g:, 'plug_parallel', 1)
+  let threads = len(a:args) > 0 ? a:args[0] : get(g:, 'plug_threads', 16)
-    let threads = min(
-      \ [len(g:plugs), len(a:args) > 0 ? a:args[0] : get(g:, 'plug_threads', 16)])
-  else
-    let threads = 1
-  endif
 
   call s:prepare()
   call append(0, a:pull ? 'Updating plugins' : 'Installing plugins')
@@ -230,7 +225,7 @@ function! s:update_impl(pull, args)
   normal! 2G
   redraw
 
-  if threads > 1
+  if has('ruby') && threads > 1
     call s:update_parallel(a:pull, threads)
   else
     call s:update_serial(a:pull)
@@ -255,8 +250,9 @@ function! s:extend(names)
   return filter(copy(g:plugs), '!has_key(prev, v:key)')
 endfunction
 
-function! s:update_progress(cnt, total)
+function! s:update_progress(pull, cnt, total)
-  call setline(1, "Updating plugins (".a:cnt."/".a:total.")")
+  call setline(1, (a:pull ? 'Updating' : 'Installing').
+        \ " plugins (".a:cnt."/".a:total.")")
   call s:progress_bar(2, a:cnt, a:total)
   normal! 2G
   redraw
@@ -300,13 +296,13 @@ function! s:update_serial(pull)
         let result = '(x) ' . result
       endif
       call append(3, '- ' . name . ': ' . result)
-      call s:update_progress(len(done), total)
+      call s:update_progress(a:pull, len(done), total)
     endfor
 
     if !empty(s:extend(keys(todo)))
       let todo = filter(copy(g:plugs), '!has_key(done, v:key)')
       let total += len(todo)
-      call s:update_progress(len(done), total)
+      call s:update_progress(a:pull, len(done), total)
     else
       break
     endif
@@ -330,7 +326,7 @@ function! s:update_parallel(pull, threads)
   take1 = proc { mtx.synchronize { all.shift } }
   logh  = proc {
     cnt, tot = done.length, VIM::evaluate('len(g:plugs)')
-    $curbuf[1] = "Updating plugins (#{cnt}/#{tot})"
+    $curbuf[1] = "#{pull ? 'Updating' : 'Installing'} plugins (#{cnt}/#{tot})"
     $curbuf[2] = '[' + ('=' * cnt).ljust(tot) + ']'
     VIM::command('normal! 2G')
     VIM::command('redraw')