rplugin: Call s:LoadRemotePlugins() on startup.

Dispense with the FuncUndefined/CmdUndefined quasi-optimization.
If there are no rplugins, plugin/rplugin.vim takes less than 1ms.

Closes #5821
Closes #6250

Helped-by: Qiming zhao <chemzqm@gmail.com>

3 files changed, 55 insertions, 95 deletions

diff --git a/runtime/autoload/remote/host.vim b/runtime/autoload/remote/host.vim
index 51f7e5886f..e695fb7df7 100644
--- a/runtime/autoload/remote/host.vim
+++ b/runtime/autoload/remote/host.vim
@@ -2,7 +2,6 @@ let s:hosts = {}
 let s:plugin_patterns = {}
 let s:plugins_for_host = {}
 
-
 " Register a host by associating it with a factory(funcref)
 function! remote#host#Register(name, pattern, factory) abort
   let s:hosts[a:name] = {'factory': a:factory, 'channel': 0, 'initialized': 0}
@@ -13,7 +12,6 @@ function! remote#host#Register(name, pattern, factory) abort
   endif
 endfunction
 
-
 " Register a clone to an existing host. The new host will use the same factory
 " as `source`, but it will run as a different process. This can be used by
 " plugins that should run isolated from other plugins created for the same host
@@ -31,12 +29,8 @@ function! remote#host#RegisterClone(name, orig_name) abort
         \ }
 endfunction
 
-
 " Get a host channel, bootstrapping it if necessary
 function! remote#host#Require(name) abort
-  if empty(s:plugins_for_host)
-    call remote#host#LoadRemotePlugins()
-  endif
   if !has_key(s:hosts, a:name)
     throw 'No host named "'.a:name.'" is registered'
   endif
@@ -52,7 +46,6 @@ function! remote#host#Require(name) abort
   return host.channel
 endfunction
 
-
 function! remote#host#IsRunning(name) abort
   if !has_key(s:hosts, a:name)
     throw 'No host named "'.a:name.'" is registered'
@@ -60,7 +53,6 @@ function! remote#host#IsRunning(name) abort
   return s:hosts[a:name].channel != 0
 endfunction
 
-
 " Example of registering a Python plugin with two commands (one async), one
 " autocmd (async) and one function (sync):
 "
@@ -117,73 +109,6 @@ function! remote#host#RegisterPlugin(host, path, specs) abort
   call add(plugins, {'path': a:path, 'specs': a:specs})
 endfunction
 
-
-" Get the path to the rplugin manifest file.
-function! s:GetManifestPath() abort
-  let manifest_base = ''
-
-  if exists('$NVIM_RPLUGIN_MANIFEST')
-    return fnamemodify($NVIM_RPLUGIN_MANIFEST, ':p')
-  endif
-
-  let dest = has('win32') ? '$LOCALAPPDATA' : '$XDG_DATA_HOME'
-  if !exists(dest)
-    let dest = has('win32') ? '~/AppData/Local' : '~/.local/share'
-  endif
-
-  let dest = fnamemodify(expand(dest), ':p')
-  if !empty(dest) && !filereadable(dest)
-    let dest .= ('/' ==# dest[-1:] ? '' : '/') . 'nvim'
-    call mkdir(dest, 'p', 0700)
-    let manifest_base = dest
-  endif
-
-  return manifest_base.'/rplugin.vim'
-endfunction
-
-
-" Old manifest file based on known script locations.
-function! s:GetOldManifestPath() abort
-  let prefix = exists('$MYVIMRC')
-        \ ? $MYVIMRC
-        \ : matchstr(get(split(execute('scriptnames'), '\n'), 0, ''), '\f\+$')
-  return fnamemodify(expand(prefix, 1), ':h')
-        \.'/.'.fnamemodify(prefix, ':t').'-rplugin~'
-endfunction
-
-
-function! s:GetManifest() abort
-  let manifest = s:GetManifestPath()
-
-  if !filereadable(manifest)
-    " Check if an old manifest file exists and move it to the new location.
-    let old_manifest = s:GetOldManifestPath()
-    if filereadable(old_manifest)
-      call rename(old_manifest, manifest)
-    endif
-  endif
-
-  return manifest
-endfunction
-
-
-function! remote#host#LoadRemotePlugins() abort
-  let manifest = s:GetManifest()
-  if filereadable(manifest)
-    execute 'source' fnameescape(manifest)
-  endif
-endfunction
-
-
-function! remote#host#LoadRemotePluginsEvent(event, pattern) abort
-  autocmd! nvim-rplugin
-  call remote#host#LoadRemotePlugins()
-  if exists('#'.a:event.'#'.a:pattern)  " Avoid 'No matching autocommands'.
-    execute 'silent doautocmd <nomodeline>' a:event a:pattern
-  endif
-endfunction
-
-
 function! s:RegistrationCommands(host) abort
   " Register a temporary host clone for discovering specs
   let host_id = a:host.'-registration-clone'
@@ -228,7 +153,6 @@ function! s:RegistrationCommands(host) abort
   return lines
 endfunction
 
-
 function! remote#host#UpdateRemotePlugins() abort
   let commands = []
   let hosts = keys(s:hosts)
@@ -245,12 +169,11 @@ function! remote#host#UpdateRemotePlugins() abort
       endtry
     endif
   endfor
-  call writefile(commands, s:GetManifest())
+  call writefile(commands, g:loaded_remote_plugins)
   echomsg printf('remote/host: generated rplugin manifest: %s',
-        \ s:GetManifest())
+        \ g:loaded_remote_plugins)
 endfunction
 
-
 function! remote#host#PluginsForHost(host) abort
   if !has_key(s:plugins_for_host, a:host)
     let s:plugins_for_host[a:host] = []
@@ -258,7 +181,6 @@ function! remote#host#PluginsForHost(host) abort
   return s:plugins_for_host[a:host]
 endfunction
 
-
 function! remote#host#LoadErrorForHost(host, log) abort
   return 'Failed to load '. a:host . ' host. '.
         \ 'You can try to see what happened by starting nvim with '.
@@ -266,7 +188,6 @@ function! remote#host#LoadErrorForHost(host, log) abort
         \ ' Also, the host stderr is available in messages.'
 endfunction
 
-
 " Registration of standard hosts
 
 " Python/Python3
diff --git a/runtime/plugin/rplugin.vim b/runtime/plugin/rplugin.vim
index b4b03032b3..7d83668a30 100644
--- a/runtime/plugin/rplugin.vim
+++ b/runtime/plugin/rplugin.vim
@@ -1,16 +1,59 @@
 if exists('g:loaded_remote_plugins')
   finish
 endif
-let g:loaded_remote_plugins = 1
+let g:loaded_remote_plugins = '/path/to/manifest'
+
+" Get the path to the rplugin manifest file.
+function! s:GetManifestPath() abort
+  let manifest_base = ''
+
+  if exists('$NVIM_RPLUGIN_MANIFEST')
+    return fnamemodify($NVIM_RPLUGIN_MANIFEST, ':p')
+  endif
+
+  let dest = has('win32') ? '$LOCALAPPDATA' : '$XDG_DATA_HOME'
+  if !exists(dest)
+    let dest = has('win32') ? '~/AppData/Local' : '~/.local/share'
+  endif
+
+  let dest = fnamemodify(expand(dest), ':p')
+  if !empty(dest) && !filereadable(dest)
+    let dest .= ('/' ==# dest[-1:] ? '' : '/') . 'nvim'
+    call mkdir(dest, 'p', 0700)
+    let manifest_base = dest
+  endif
+
+  return manifest_base.'/rplugin.vim'
+endfunction
+
+" Old manifest file based on known script locations.
+function! s:GetOldManifestPath() abort
+  let prefix = exists('$MYVIMRC')
+        \ ? $MYVIMRC
+        \ : matchstr(get(split(execute('scriptnames'), '\n'), 0, ''), '\f\+$')
+  return fnamemodify(expand(prefix, 1), ':h')
+        \.'/.'.fnamemodify(prefix, ':t').'-rplugin~'
+endfunction
+
+function! s:GetManifest() abort
+  let manifest = s:GetManifestPath()
+  if !filereadable(manifest)
+    " Check if an old manifest file exists and move it to the new location.
+    let old_manifest = s:GetOldManifestPath()
+    if filereadable(old_manifest)
+      call rename(old_manifest, manifest)
+    endif
+  endif
+  return manifest
+endfunction
+
+function! s:LoadRemotePlugins() abort
+  let g:loaded_remote_plugins = s:GetManifest()
+  if filereadable(g:loaded_remote_plugins)
+    execute 'source' fnameescape(g:loaded_remote_plugins)
+  endif
+endfunction
 
 command! UpdateRemotePlugins call remote#host#UpdateRemotePlugins()
 
-augroup nvim-rplugin
-  autocmd!
-  autocmd FuncUndefined *
-        \ call remote#host#LoadRemotePluginsEvent(
-        \   'FuncUndefined', expand('<amatch>'))
-  autocmd CmdUndefined *
-        \ call remote#host#LoadRemotePluginsEvent(
-        \   'CmdUndefined', expand('<amatch>'))
-augroup END
+call s:LoadRemotePlugins()
diff --git a/test/functional/provider/define_spec.lua b/test/functional/provider/define_spec.lua
index b0363eb435..51a8831274 100644
--- a/test/functional/provider/define_spec.lua
+++ b/test/functional/provider/define_spec.lua
@@ -3,7 +3,6 @@ local eval, command, nvim = helpers.eval, helpers.command, helpers.nvim
 local eq, run, stop = helpers.eq, helpers.run, helpers.stop
 local clear = helpers.clear
 
-
 local function get_prefix(sync)
   if sync then
     return 'sync'
@@ -11,12 +10,10 @@ local function get_prefix(sync)
   return 'async'
 end
 
-
 local function call(fn, arguments)
   command('call '..fn..'('..arguments..')')
 end
 
-
 local function clear_and_init(init)
   return function()
     clear()
@@ -26,7 +23,6 @@ local function clear_and_init(init)
   end
 end
 
-
 local function runx(sync, handler, on_setup)
   local function setup_cb(...)
     on_setup(...)