Merge pull request #17386 from bfredl/neothread

support threads in lua

2 files changed, 69 insertions, 0 deletions

diff --git a/runtime/doc/lua.txt b/runtime/doc/lua.txt
index 355c31090e..4ea78c2426 100644
--- a/runtime/doc/lua.txt
+++ b/runtime/doc/lua.txt
@@ -568,6 +568,26 @@ Example: TCP echo-server                                *tcp-server*
     end)
     print('TCP echo-server listening on port: '..server:getsockname().port)
 
+
+Multithreading						*lua-loop-threading*
+
+Plugins can perform work in separate (os-level) threads using the threading
+APIs in luv, for instance `vim.loop.new_thread`. Note that every thread
+gets its own separate lua interpreter state, with no access to lua globals
+in the main thread. Neither can the state of the editor (buffers, windows,
+etc) be directly accessed from threads.
+
+A subset of the `vim.*` API is available in threads. This includes:
+
+- `vim.loop` with a separate event loop per thread.
+- `vim.mpack` and `vim.json` (useful for serializing messages between threads)
+- `require` in threads can use lua packages from the global |lua-package-path|
+- `print()` and `vim.inspect`
+- `vim.diff`
+- most utility functions in `vim.*` for working with pure lua values
+  like `vim.split`, `vim.tbl_*`, `vim.list_*`, and so on.
+- `vim.is_thread()` returns true from a non-main thread.
+
 ------------------------------------------------------------------------------
 VIM.HIGHLIGHT                                           *lua-highlight*
 
diff --git a/runtime/lua/vim/_load_package.lua b/runtime/lua/vim/_load_package.lua
new file mode 100644
index 0000000000..525f603438
--- /dev/null
+++ b/runtime/lua/vim/_load_package.lua
@@ -0,0 +1,49 @@
+-- prevents luacheck from making lints for setting things on vim
+local vim = assert(vim)
+
+local pathtrails = {}
+vim._so_trails = {}
+for s in  (package.cpath..';'):gmatch('[^;]*;') do
+    s = s:sub(1, -2)  -- Strip trailing semicolon
+  -- Find out path patterns. pathtrail should contain something like
+  -- /?.so, \?.dll. This allows not to bother determining what correct
+  -- suffixes are.
+  local pathtrail = s:match('[/\\][^/\\]*%?.*$')
+  if pathtrail and not pathtrails[pathtrail] then
+    pathtrails[pathtrail] = true
+    table.insert(vim._so_trails, pathtrail)
+  end
+end
+
+function vim._load_package(name)
+  local basename = name:gsub('%.', '/')
+  local paths = {"lua/"..basename..".lua", "lua/"..basename.."/init.lua"}
+  local found = vim.api.nvim__get_runtime(paths, false, {is_lua=true})
+  if #found > 0 then
+    local f, err = loadfile(found[1])
+    return f or error(err)
+  end
+
+  local so_paths = {}
+  for _,trail in ipairs(vim._so_trails) do
+    local path = "lua"..trail:gsub('?', basename) -- so_trails contains a leading slash
+    table.insert(so_paths, path)
+  end
+
+  found = vim.api.nvim__get_runtime(so_paths, false, {is_lua=true})
+  if #found > 0 then
+    -- Making function name in Lua 5.1 (see src/loadlib.c:mkfuncname) is
+    -- a) strip prefix up to and including the first dash, if any
+    -- b) replace all dots by underscores
+    -- c) prepend "luaopen_"
+    -- So "foo-bar.baz" should result in "luaopen_bar_baz"
+    local dash = name:find("-", 1, true)
+    local modname = dash and name:sub(dash + 1) or name
+    local f, err = package.loadlib(found[1], "luaopen_"..modname:gsub("%.", "_"))
+    return f or error(err)
+  end
+  return nil
+end
+
+-- Insert vim._load_package after the preloader at position 2
+table.insert(package.loaders, 2, vim._load_package)