feat(performance): Major performance improvements using async v2 from @oberblastmeister (#987)

* start: Working w/ async jobs

* short circuit to using bad finder if you pass writer.

lua/telescope/finders/async_job_finder.lua

@@ -1,14 +1,11 @@
-local log = require "telescope.log"
-local Job = require "plenary.job"
-
-local async_lib = require "plenary.async_lib"
-local async = async_lib.async
--- local await = async_lib.await
-local void = async_lib.void
+local async_job = require "telescope._"
+local LinesPipe = require("telescope._").LinesPipe
 
 local make_entry = require "telescope.make_entry"
+local log = require "telescope.log"
 
 return function(opts)
+  log.trace("Creating async_job:", opts)
   local entry_maker = opts.entry_maker or make_entry.gen_from_string()
   local fn_command = function(prompt)
     local command_list = opts.command_generator(prompt)
@@ -18,58 +15,61 @@ return function(opts)
 
     local command = table.remove(command_list, 1)
 
-    return {
+    local res = {
       command = command,
       args = command_list,
     }
+
+    return res
   end
 
   local job
-  return setmetatable({
-    close = function() end,
-  }, {
-    __call = void(async(function(prompt, process_result, process_complete)
-      print("are we callin anything?", job)
-      if job and not job.is_shutdown then
-        log.debug "Shutting down old job"
-        job:shutdown()
-      end
 
-      local job_opts = fn_command(prompt)
-      if not job_opts then
+  local callable = function(_, prompt, process_result, process_complete)
+    if job then
+      job:close(true)
+    end
+
+    local job_opts = fn_command(prompt)
+    if not job_opts then
+      return
+    end
+
+    local writer = nil
+    -- if job_opts.writer and Job.is_job(job_opts.writer) then
+    --   writer = job_opts.writer
+    if opts.writer then
+      error "async_job_finder.writer is not yet implemented"
+      writer = async_job.writer(opts.writer)
+    end
+
+    local stdout = LinesPipe()
+
+    job = async_job.spawn {
+      command = job_opts.command,
+      args = job_opts.args,
+      cwd = job_opts.cwd or opts.cwd,
+      writer = writer,
+
+      stdout = stdout,
+    }
+
+    for line in stdout:iter(true) do
+      if process_result(entry_maker(line)) then
         return
       end
+    end
 
-      local writer = nil
-      if job_opts.writer and Job.is_job(job_opts.writer) then
-        writer = job_opts.writer
-      elseif opts.writer then
-        writer = Job:new(job_opts.writer)
+    process_complete()
+  end
+
+  return setmetatable({
+    close = function()
+      if job then
+        job:close(true)
       end
-
-      job = Job:new {
-        command = job_opts.command,
-        args = job_opts.args,
-        cwd = job_opts.cwd or opts.cwd,
-        maximum_results = opts.maximum_results,
-        writer = writer,
-        enable_recording = false,
-
-        on_stdout = vim.schedule_wrap(function(_, line)
-          if not line or line == "" then
-            return
-          end
-
-          -- TODO: shutdown job here.
-          process_result(entry_maker(line))
-        end),
-
-        on_exit = function()
-          process_complete()
-        end,
-      }
-
-      job:start()
-    end)),
+    end,
+  }, {
+    __call = callable,
   })
 end