fix(blame): do not run concurrent processes

Fixes #877

lua/gitsigns/current_line_blame.lua

@@ -2,20 +2,16 @@ local async = require('gitsigns.async')
 local cache = require('gitsigns.cache').cache
 local config = require('gitsigns.config').config
 local util = require('gitsigns.util')
-local uv = vim.loop
 
 local api = vim.api
 
 local current_buf = api.nvim_get_current_buf
+local debounce = require('gitsigns.debounce')
 
 local namespace = api.nvim_create_namespace('gitsigns_blame')
 
-local timer = assert(uv.new_timer())
-
 local M = {}
 
-local wait_timer = async.wrap(uv.timer_start, 4)
-
 --- @param bufnr integer
 --- @param row integer
 --- @param opts? table
@@ -183,9 +179,9 @@ local function get_lnum()
   return api.nvim_win_get_cursor(0)[1]
 end
 
--- Update function, must be called in async context
-local function update0()
-  local bufnr = current_buf()
+--- Update function, must be called in async context
+--- @param bufnr integer
+local function update0(bufnr)
   local lnum = get_lnum()
 
   local old_lnum = get_extmark(bufnr)
@@ -213,25 +209,21 @@ local function update0()
     return
   end
 
-  local opts = config.current_line_blame_opts
-
-  -- Note because the same timer is re-used, this call has a debouncing effect.
-  wait_timer(timer, opts.delay, 0)
-  async.scheduler()
-
   local bcache = cache[bufnr]
   if not bcache or not bcache.git_obj.object_name then
     return
   end
 
+  local opts = config.current_line_blame_opts
+
   local blame_info = run_blame(bufnr, lnum, opts)
   async.scheduler_if_buf_valid(bufnr)
 
   local lnum1 = get_lnum()
   if bufnr == current_buf() and lnum ~= lnum1 then
     -- Cursor has moved during events; abort and tr-trigger another update
     -- since it's likely blame jobs where skipped
-    update0()
+    update0(bufnr)
     return
   end
 
@@ -242,19 +234,27 @@ local function update0()
   end
 end
 
-local update = async.void(update0)
+local update = async.void(debounce.throttle_by_id(update0))
+
+--- @type fun(bufnr: integer)
+local update_debounced
 
 function M.setup()
   local group = api.nvim_create_augroup('gitsigns_blame', {})
 
+  local opts = config.current_line_blame_opts
+  update_debounced = debounce.debounce_trailing(opts.delay, update)
+
   for k, _ in pairs(cache) do
     reset(k)
   end
 
   if config.current_line_blame then
     api.nvim_create_autocmd({ 'FocusGained', 'BufEnter', 'CursorMoved', 'CursorMovedI' }, {
       group = group,
-      callback = update,
+      callback = function(args)
+        update_debounced(args.buf)
+      end
     })
 
     api.nvim_create_autocmd({ 'InsertEnter', 'FocusLost', 'BufLeave' }, {
@@ -266,7 +266,9 @@ function M.setup()
 
     -- Call via vim.schedule to avoid the debounce timer killing the async
     -- coroutine
-    vim.schedule(update)
+    vim.schedule(function()
+      update_debounced(api.nvim_get_current_buf())
+    end)
   end
 end