[sqlite] Normalize blobs used for comparison

Summary:
Using `Marshal.to_string` to create SQLite values used in comparisons is brittle as there is no guarantee that it will return the same value for structurally equal values.
When adding sharing, this will definitely break.

From the SQLite queries I found, only `SourceFile` and `Procname` are used in comparisons.
I haven't tested performance.
It shouldn't change anything for `SourceFile` as there is no possible sharing.
It shouldn't change much for `Procname` as they are pretty small anyway.

Reviewed By: ngorogiannis

Differential Revision: D15923122

fbshipit-source-id: ce4af1fe3

infer/src/IR/ProcAttributes.ml

@@ -173,6 +173,6 @@ let pp f
   F.fprintf f "; proc_id= %s }@]" (Typ.Procname.to_unique_id proc_name)
 
 
-module SQLite = SqliteUtils.MarshalledData (struct
+module SQLite = SqliteUtils.MarshalledDataNOTForComparison (struct
   type nonrec t = t
 end)

infer/src/IR/Procdesc.ml

@@ -867,7 +867,7 @@ let is_connected proc_desc =
       error
 
 
-module SQLite = SqliteUtils.MarshalledNullableData (struct
+module SQLite = SqliteUtils.MarshalledNullableDataNOTForComparison (struct
   type nonrec t = t
 end)
 

infer/src/IR/Tenv.ml

@@ -76,6 +76,10 @@ let pp_per_file fmt = function
 
 
 module SQLite : SqliteUtils.Data with type t = per_file = struct
+  module Serializer = SqliteUtils.MarshalledDataNOTForComparison (struct
+    type nonrec t = t
+  end)
+
   type t = per_file
 
   let global_string = "global"
@@ -84,14 +88,14 @@ module SQLite : SqliteUtils.Data with type t = per_file = struct
     | Global ->
         Sqlite3.Data.TEXT global_string
     | FileLocal tenv ->
-        Sqlite3.Data.BLOB (Marshal.to_string tenv [])
+        Serializer.serialize tenv
 
 
-  let deserialize = function[@warning "-8"]
+  let deserialize = function
     | Sqlite3.Data.TEXT g when String.equal g global_string ->
         Global
-    | Sqlite3.Data.BLOB b ->
-        FileLocal (Marshal.from_string b 0)
+    | blob ->
+        FileLocal (Serializer.deserialize blob)
 end
 
 let merge ~src ~dst = TypenameHash.iter (fun pname cfg -> TypenameHash.replace dst pname cfg) src

infer/src/IR/Typ.ml

@@ -19,7 +19,7 @@ module IntegerWidths = struct
 
   let java = {char_width= 16; short_width= 16; int_width= 32; long_width= 64; longlong_width= 64}
 
-  module SQLite = SqliteUtils.MarshalledNullableData (struct
+  module SQLite = SqliteUtils.MarshalledNullableDataNOTForComparison (struct
     type nonrec t = t
   end)
 
@@ -1359,33 +1359,31 @@ module Procname = struct
   let to_filename ?crc_only pname = to_concrete_filename ?crc_only pname
 
   module SQLite = struct
-    let pname_to_key =
-      Base.Hashtbl.create
-        ( module struct
-          type nonrec t = t
+    module T = struct
+      type nonrec t = t
 
-          let compare = compare
+      let compare = compare
 
-          let hash = hash
+      let hash = hash
 
-          let sexp_of_t p = Sexp.Atom (to_string p)
-        end )
+      let sexp_of_t p = Sexp.Atom (to_string p)
+    end
+
+    module Serializer = SqliteUtils.MarshalledDataForComparison (T)
 
+    let pname_to_key = Base.Hashtbl.create (module T)
 
     let serialize pname =
-      let default () = Sqlite3.Data.BLOB (Marshal.to_string pname []) in
+      let default () = Serializer.serialize pname in
       Base.Hashtbl.find_or_add pname_to_key pname ~default
 
 
-    let deserialize : Sqlite3.Data.t -> t = function[@warning "-8"]
-      | Sqlite3.Data.BLOB b ->
-          Marshal.from_string b 0
-
+    let deserialize = Serializer.deserialize
 
     let clear_cache () = Base.Hashtbl.clear pname_to_key
   end
 
-  module SQLiteList = SqliteUtils.MarshalledData (struct
+  module SQLiteList = SqliteUtils.MarshalledDataNOTForComparison (struct
     type nonrec t = t list
   end)
 end

infer/src/base/SourceFile.ml

@@ -180,19 +180,24 @@ let changed_sources_from_changed_files changed_files =
 
 
 module SQLite = struct
-  type nonrec t = t
+  module T = struct
+    type nonrec t = t
+  end
+
+  module Serializer = SqliteUtils.MarshalledDataForComparison (T)
+  include T
 
   let serialize = function
     | RelativeProjectRoot path ->
         (* show the most common paths as text (for debugging, possibly perf) *)
         Sqlite3.Data.TEXT path
     | _ as x ->
-        Sqlite3.Data.BLOB (Marshal.to_string x [])
+        Serializer.serialize x
 
 
-  let deserialize = function[@warning "-8"]
+  let deserialize = function
     | Sqlite3.Data.TEXT rel_path ->
         RelativeProjectRoot rel_path
-    | Sqlite3.Data.BLOB b ->
-        Marshal.from_string b 0
+    | blob ->
+        Serializer.deserialize blob
 end

infer/src/base/SqliteUtils.ml

@@ -107,10 +107,25 @@ module type Data = sig
   val deserialize : Sqlite3.Data.t -> t
 end
 
-module MarshalledData (D : sig
+module type T = sig
   type t
-end) =
-struct
+end
+
+module MarshalledDataForComparison (D : T) = struct
+  type t = D.t
+
+  let deserialize = function[@warning "-8"] Sqlite3.Data.BLOB b -> Marshal.from_string b 0
+
+  (*
+    If the serialized data is used for comparison (e.g. used in WHERE clause), we need to normalize it.
+    Marshalling is brittle as it depends on sharing.
+
+    For now let's suppose that marshalling with no sharing is normalizing.
+  *)
+  let serialize x = Sqlite3.Data.BLOB (Marshal.to_string x [Marshal.No_sharing])
+end
+
+module MarshalledDataNOTForComparison (D : T) = struct
   type t = D.t
 
   let deserialize = function[@warning "-8"] Sqlite3.Data.BLOB b -> Marshal.from_string b 0
@@ -118,10 +133,7 @@ struct
   let serialize x = Sqlite3.Data.BLOB (Marshal.to_string x [])
 end
 
-module MarshalledNullableData (D : sig
-  type t
-end) =
-struct
+module MarshalledNullableDataNOTForComparison (D : T) = struct
   type t = D.t option
 
   let deserialize = function[@warning "-8"]

infer/src/base/SqliteUtils.mli

@@ -72,12 +72,17 @@ module type Data = sig
   val deserialize : Sqlite3.Data.t -> t
 end
 
+(** A default implementation of the Data API that encodes every objects as marshalled blobs with no sharing *)
+module MarshalledDataForComparison (D : sig
+  type t
+end) : Data with type t = D.t
+
 (** A default implementation of the Data API that encodes every objects as marshalled blobs *)
-module MarshalledData (D : sig
+module MarshalledDataNOTForComparison (D : sig
   type t
 end) : Data with type t = D.t
 
 (** A default implementation of the Data API that encodes None as a NULL SQLite value *)
-module MarshalledNullableData (D : sig
+module MarshalledNullableDataNOTForComparison (D : sig
   type t
 end) : Data with type t = D.t option