Add method to clean the results directory

Summary:
I observed a bug in incremental analysis for thread safety analysis, where a thread safety violation was not being reported because the folder `racerd` was not being cleaned. This meant that the violation was determined to be a preexisting issue when it was actually an introduced issue.

This method can be used to fix this problem by cleaning the `racerd` folder. It also cleans the `captured` folder, I've done this following the original version of the method (see D16602417).

I'm not sure if the `captured` folder is used; it wasn't used in the tests I did. Thoughts about this?

Reviewed By: ngorogiannis

Differential Revision: D17261504

fbshipit-source-id: 8fea23e98

infer/src/base/DBWriter.mli

@@ -35,7 +35,7 @@ val merge_dbs : infer_out_src:string -> unit
 val canonicalize : unit -> unit
 (** put the database on disk in deterministic form *)
 
-val reset_capture_tables : unit -> unit [@@warning "-32"]
+val reset_capture_tables : unit -> unit
 
 val start : unit -> unit
 

infer/src/base/ResultsDir.ml

@@ -34,6 +34,24 @@ let non_empty_directory_exists results_dir =
   Sys.is_directory results_dir = `Yes && not (Utils.directory_is_empty results_dir)
 
 
+let dirs_to_clean ~cache_capture =
+  let open Config in
+  let common_list =
+    [backend_stats_dir_name; classnames_dir_name; frontend_stats_dir_name; reporting_stats_dir_name]
+  in
+  if cache_capture then common_list
+  else captured_dir_name :: racerd_issues_dir_name :: starvation_issues_dir_name :: common_list
+
+
+let delete_capture_and_results_data () =
+  DBWriter.reset_capture_tables () ;
+  let dirs_to_delete =
+    List.map ~f:(Filename.concat Config.results_dir) (dirs_to_clean ~cache_capture:true)
+  in
+  List.iter ~f:Utils.rmtree dirs_to_delete ;
+  ()
+
+
 let remove_results_dir () =
   if non_empty_directory_exists Config.results_dir then (
     if not Config.force_delete_results_dir then

infer/src/base/ResultsDir.mli

@@ -15,3 +15,10 @@ val remove_results_dir : unit -> unit
 
 val create_results_dir : unit -> unit
 (** Create the results dir and sets up logging, the database, etc. *)
+
+val delete_capture_and_results_data : unit -> unit
+  [@@warning "-32"]
+(** delete capture and results data in the results directory *)
+
+val dirs_to_clean : cache_capture:bool -> string list
+(** directories in the results directory containing capture or results data *)

infer/src/integration/Driver.ml

@@ -81,17 +81,7 @@ let clean_results_dir () =
   ResultsDatabase.db_close () ;
   (* In Buck flavors mode we keep all capture data, but in Java mode we keep only the tenv *)
   let should_delete_dir =
-    let dirs_to_delete =
+    let dirs_to_delete = ResultsDir.dirs_to_clean ~cache_capture in
-      let open Config in
-      let common_list =
-        [ backend_stats_dir_name
-        ; classnames_dir_name
-        ; frontend_stats_dir_name
-        ; reporting_stats_dir_name ]
-      in
-      if cache_capture then common_list
-      else captured_dir_name :: racerd_issues_dir_name :: starvation_issues_dir_name :: common_list
-    in
     List.mem ~equal:String.equal dirs_to_delete
   in
   let should_delete_file =