feat(#1974): experimental.git.async see https://github.com/nvim-tree/nvim-tree.lua/issues/2104 (#2094)

* async git watcher reload; callback hell for now

* async git watcher reload; revert unnecessary extractions

* async git watcher reload; callback and non-callback functions are required for sync codepaths that loop

* async git watcher reload

* async git watcher reload

* feat(#1974): experimental.git.async

* feat(#1974): experimental.git.async

lua/nvim-tree/git/runner.lua

@@ -69,7 +69,7 @@ function Runner:_log_raw_output(output)
   end
 end
 
-function Runner:_run_git_job()
+function Runner:_run_git_job(callback)
   local handle, pid
   local stdout = vim.loop.new_pipe(false)
   local stderr = vim.loop.new_pipe(false)
@@ -78,6 +78,9 @@ function Runner:_run_git_job()
   local function on_finish(rc)
     self.rc = rc or 0
     if timer:is_closing() or stdout:is_closing() or stderr:is_closing() or (handle and handle:is_closing()) then
+      if callback then
+        callback()
+      end
       return
     end
     timer:stop()
@@ -91,6 +94,10 @@ function Runner:_run_git_job()
     end
 
     pcall(vim.loop.kill, pid)
+
+    if callback then
+      callback()
+    end
   end
 
   local opts = self:_getopts(stdout, stderr)
@@ -142,25 +149,7 @@ function Runner:_wait()
   end
 end
 
--- This module runs a git process, which will be killed if it takes more than timeout which defaults to 400ms
-function Runner.run(opts)
-  local profile = log.profile_start("git job %s %s", opts.project_root, opts.path)
-
-  local self = setmetatable({
-    project_root = opts.project_root,
-    path = opts.path,
-    list_untracked = opts.list_untracked,
-    list_ignored = opts.list_ignored,
-    timeout = opts.timeout or 400,
-    output = {},
-    rc = nil, -- -1 indicates timeout
-  }, Runner)
-
-  self:_run_git_job()
-  self:_wait()
-
-  log.profile_end(profile)
-
+function Runner:_finalise(opts)
   if self.rc == -1 then
     log.line("git", "job timed out  %s %s", opts.project_root, opts.path)
     timeouts = timeouts + 1
@@ -179,8 +168,55 @@ function Runner.run(opts)
   else
     log.line("git", "job success    %s %s", opts.project_root, opts.path)
   end
+end
 
-  return self.output
+--- Runs a git process, which will be killed if it takes more than timeout which defaults to 400ms
+--- @param opts table
+--- @param callback function|nil executed passing return when complete
+--- @return table|nil status by absolute path, nil if callback present
+function Runner.run(opts, callback)
+  local self = setmetatable({
+    project_root = opts.project_root,
+    path = opts.path,
+    list_untracked = opts.list_untracked,
+    list_ignored = opts.list_ignored,
+    timeout = opts.timeout or 400,
+    output = {},
+    rc = nil, -- -1 indicates timeout
+  }, Runner)
+
+  local async = callback ~= nil and self.config.git_async
+  local profile = log.profile_start("git %s job %s %s", async and "async" or "sync", opts.project_root, opts.path)
+
+  if async and callback then
+    -- async, always call back
+    self:_run_git_job(function()
+      log.profile_end(profile)
+
+      self:_finalise(opts)
+
+      callback(self.output)
+    end)
+  else
+    -- sync, maybe call back
+    self:_run_git_job()
+    self:_wait()
+
+    log.profile_end(profile)
+
+    self:_finalise(opts)
+
+    if callback then
+      callback(self.output)
+    else
+      return self.output
+    end
+  end
+end
+
+function Runner.setup(opts)
+  Runner.config = {}
+  Runner.config.git_async = opts.experimental.git.async
 end
 
 return Runner