[taskbar] leave progress bar displayed at the end of the analysis

Summary:
The code was already trying to do that but failing. Now it works.

This revealed a slight bug where the progress bar would always stop at
N-1/N 99% jobs. Fixed by moving the progress bar updates *after* the
operation that might decrease the number of jobs left.

Reviewed By: mityal

Differential Revision: D17423978

fbshipit-source-id: fc32db5f3

infer/src/backend/InferAnalyze.ml

@@ -189,7 +189,7 @@ let main ~changed_files =
   (* empty all caches to minimize the process heap to have less work to do when forking *)
   clear_caches () ;
   let stats = analyze source_files in
-  L.progress "@\nAnalysis phase finished in %a@." Mtime.Span.pp (Mtime_clock.count time0) ;
-  L.debug Analysis Quiet "collected stats:@\n%a@." BackendStats.pp stats ;
+  L.debug Analysis Quiet "Analysis phase finished in %a@\n" Mtime.Span.pp (Mtime_clock.count time0) ;
+  L.debug Analysis Quiet "Collected stats:@\n%a@." BackendStats.pp stats ;
   BackendStats.log_to_scuba stats ;
   output_json_makefile_stats source_files

infer/src/base/ProcessPool.ml

@@ -221,8 +221,6 @@ let process_updates pool buffer =
            Unix.wait (`Pid pid) |> ignore ;
            killall pool ~slot "see backtrace above"
        | Ready slot ->
-           TaskBar.set_remaining_tasks pool.task_bar (pool.tasks.remaining_tasks ()) ;
-           TaskBar.update_status pool.task_bar ~slot (Mtime_clock.now ()) "idle" ;
            ( match pool.children_states.(slot) with
            | Processing work ->
                pool.tasks.finished work
@@ -230,6 +228,8 @@ let process_updates pool buffer =
                ()
            | Idle ->
                L.die InternalError "Received a Ready message from an idle worker@." ) ;
+           TaskBar.set_remaining_tasks pool.task_bar (pool.tasks.remaining_tasks ()) ;
+           TaskBar.update_status pool.task_bar ~slot (Mtime_clock.now ()) "idle" ;
            pool.children_states.(slot) <- Idle ) ;
   (* try to schedule more work if there are idle workers *)
   if not (pool.tasks.is_empty ()) then

infer/src/base/TaskBar.ml

@@ -45,6 +45,8 @@ let rec pp_n c fmt n =
 
 let move_bol = "\r"
 
+let move_cursor_down n = Printf.sprintf "\027[%iB" n
+
 let move_cursor_up n = Printf.sprintf "\027[%iA" n
 
 let erase_eol = "\027[0K"
@@ -185,9 +187,10 @@ let tasks_done_reset task_bar =
 
 
 let finish = function
-  | MultiLine _ ->
+  | MultiLine _ as task_bar ->
+      refresh task_bar ;
       (* leave the progress bar displayed *)
-      Out_channel.output_string stderr "\n" ;
+      F.eprintf "%s%!" (move_cursor_down 1) ;
       ANSITerminal.erase Below ;
       Out_channel.flush stderr
   | NonInteractive | Quiet ->