[infer][ondemand] also cache the result of analyzing a procedure description

Summary:
Before this diff, the `Ondemand` module would not cache the results of the function `analyze_proc_desc`, which is used by the toplvel iteration.

This should not have any effect on the performances at this point as the summaries were already cached in the `Specs` module. Now, we can start remove the use of the cache in the `Specs` module to avoid the duplication. Caching at the level of `Ondemand` is better as we can safely cache the information that the outcome of the analysis is `None`, which avoids scanning the filesystem or the DB multiple times.

Reviewed By: mbouaziz, jvillard

Differential Revision: D6713546

fbshipit-source-id: 309701b

infer/src/backend/ondemand.ml

@@ -23,6 +23,8 @@ type callbacks = {analyze_ondemand: analyze_ondemand; get_proc_desc: get_proc_de
 
 let callbacks_ref = ref None
 
+let cached_results = lazy (Typ.Procname.Hash.create 128)
+
 let set_callbacks (callbacks: callbacks) = callbacks_ref := Some callbacks
 
 let unset_callbacks () = callbacks_ref := None
@@ -166,46 +168,38 @@ let run_proc_analysis analyze_proc ~caller_pdesc callee_pdesc =
         log_error_and_continue exn initial_summary (FKcrash (Exn.to_string exn))
 
 
-let analyze_proc_desc ?caller_pdesc callee_pdesc : Specs.summary option =
+let analyze_proc_desc ?caller_pdesc callee_pdesc =
+  let cache = Lazy.force cached_results in
   let callee_pname = Procdesc.get_proc_name callee_pdesc in
-  let proc_attributes = Procdesc.get_attributes callee_pdesc in
-  match !callbacks_ref with
-  | None ->
-      L.(die InternalError)
-        "No callbacks registered to analyze proc desc %a (when analyzing %a)" Typ.Procname.pp
-        callee_pname (Pp.option Typ.Procname.pp)
-        (Option.map ~f:Procdesc.get_proc_name caller_pdesc)
-  | Some callbacks ->
+  try Typ.Procname.Hash.find cache callee_pname with Not_found ->
+    let summary_option =
+      let callbacks = Option.value_exn !callbacks_ref in
+      let proc_attributes = Procdesc.get_attributes callee_pdesc in
       if should_be_analyzed callee_pname proc_attributes then
         Some (run_proc_analysis callbacks.analyze_ondemand ~caller_pdesc callee_pdesc)
       else Specs.get_summary callee_pname
+    in
+    if not (is_active callee_pname) then Typ.Procname.Hash.add cache callee_pname summary_option ;
+    summary_option
 
 
 (** analyze_proc_name curr_pdesc proc_name performs an on-demand analysis of proc_name triggered
     during the analysis of curr_pname *)
-let analyze_proc_name : ?caller_pdesc:Procdesc.t -> Typ.Procname.t -> Specs.summary option =
-  let cached_results = Typ.Procname.Hash.create 100 in
-  fun ?caller_pdesc callee_pname ->
-    try Typ.Procname.Hash.find cached_results callee_pname with Not_found ->
-      let summary_option =
-        match !callbacks_ref with
+let analyze_proc_name ?caller_pdesc callee_pname =
+  let cache = Lazy.force cached_results in
+  try Typ.Procname.Hash.find cache callee_pname with Not_found ->
+    let summary_option =
+      let callbacks = Option.value_exn !callbacks_ref in
+      if procedure_should_be_analyzed callee_pname then
+        match callbacks.get_proc_desc callee_pname with
+        | Some callee_pdesc ->
+            analyze_proc_desc ?caller_pdesc callee_pdesc
         | None ->
-            L.(die InternalError)
-              "No callbacks registered to analyze proc name %a (when analyzing %a)@."
-              Typ.Procname.pp callee_pname (Pp.option Typ.Procname.pp)
-              (Option.map ~f:Procdesc.get_proc_name caller_pdesc)
-        | Some callbacks ->
-            if procedure_should_be_analyzed callee_pname then
-              match callbacks.get_proc_desc callee_pname with
-              | Some callee_pdesc ->
-                  analyze_proc_desc ?caller_pdesc callee_pdesc
-              | None ->
-                  Specs.get_summary callee_pname
-            else Specs.get_summary callee_pname
-      in
-      if not (is_active callee_pname) then
-        Typ.Procname.Hash.add cached_results callee_pname summary_option ;
-      summary_option
+            Specs.get_summary callee_pname
+      else Specs.get_summary callee_pname
+    in
+    if not (is_active callee_pname) then Typ.Procname.Hash.add cache callee_pname summary_option ;
+    summary_option
 
 
 (** Find a proc desc for the procedure, perhaps loading it from disk. *)