From 329a6d82cbd28104fa80c6139a04b8b1151d869a Mon Sep 17 00:00:00 2001
From: Lewis Russell <lewis6991@gmail.com>
Date: Sat, 30 Nov 2024 17:58:05 +0000
Subject: [PATCH] feat(vim.loader): defer writing cache files

---
 runtime/lua/vim/loader.lua | 36 ++++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/runtime/lua/vim/loader.lua b/runtime/lua/vim/loader.lua
index 71d0188128..415d27f2ae 100644
--- a/runtime/lua/vim/loader.lua
+++ b/runtime/lua/vim/loader.lua
@@ -120,21 +120,33 @@ local function cache_filename(name)
   return ret:sub(-4) == '.lua' and (ret .. 'c') or (ret .. '.luac')
 end
 
+local writing = {} --- @type table<string,function>
+
 --- Saves the cache entry for a given module or file
 --- @param cname string cache filename
 --- @param hash vim.loader.CacheHash
 --- @param chunk function
 local function write_cachefile(cname, hash, chunk)
-  local f = assert(uv.fs_open(cname, 'w', 438))
-  local header = {
-    VERSION,
-    hash.size,
-    hash.mtime.sec,
-    hash.mtime.nsec,
-  }
-  uv.fs_write(f, table.concat(header, ',') .. '\0')
-  uv.fs_write(f, string.dump(chunk))
-  uv.fs_close(f)
+  if writing[cname] then
+    return
+  end
+
+  writing[cname] = chunk
+  uv.fs_open(cname, 'w', 438, function(err, f)
+    if err then
+      error(err)
+    end
+    local header = {
+      VERSION,
+      hash.size,
+      hash.mtime.sec,
+      hash.mtime.nsec,
+    }
+    uv.fs_write(f, table.concat(header, ',') .. '\0')
+    uv.fs_write(f, string.dump(chunk))
+    uv.fs_close(f)
+    writing[cname] = nil
+  end)
 end
 
 --- @param path string
@@ -255,6 +267,10 @@ local function loadfile_cached(filename, mode, env)
     end
   end
 
+  if writing[cname] then
+    return writing[cname]
+  end
+
   local chunk, err = _loadfile(modpath, mode, env)
   if chunk and stat then
     write_cachefile(cname, stat, chunk)