[infer][PR] Use SQLite in a way that is compatible with current state of WSL

Summary:
To resole #797  this adds runtime option to select VFS for SQLite,

When infer runs on WSL this defaults to "unix-excl" (https://sqlite.org/vfs.html) and if VFS is specified, then   WAL  is not enabled (since WAL is non compatible with custom VFS  - https://www.sqlite.org/wal.html).
Closes https://github.com/facebook/infer/pull/798

Reviewed By: jvillard

Differential Revision: D6335037

Pulled By: dulmarod

fbshipit-source-id: d9b9a58

infer/src/base/Config.ml

@@ -1869,6 +1869,19 @@ and specs_library =
   specs_library
 
 
+and sqlite_vfs =
+  let default =
+    match Utils.read_file "/proc/version" with
+    | Result.Ok [line] ->
+        let re = Str.regexp "Linux.+-Microsoft" in
+        (* on WSL (bash on Windows) standard SQLite VFS can't be used, see WSL/issues/1927 WSL/issues/2395 *)
+        if Str.string_match re line 0 then Some "unix-excl" else None
+    | _ ->
+        None
+  in
+  CLOpt.mk_string_opt ?default ~long:"sqlite-vfs" "VFS for SQLite"
+
+
 and stacktrace =
   CLOpt.mk_path_opt ~deprecated:["st"] ~long:"stacktrace"
     ~in_help:CLOpt.([(Analyze, manual_crashcontext)])
@@ -2652,6 +2665,8 @@ and sourcepath = !sourcepath
 
 and spec_abs_level = !spec_abs_level
 
+and sqlite_vfs = !sqlite_vfs
+
 and stacktrace = !stacktrace
 
 and stacktraces_dir = !stacktraces_dir

infer/src/base/Config.mli

@@ -643,6 +643,8 @@ val spec_abs_level : int
 
 val specs_library : string list
 
+val sqlite_vfs : string option
+
 val stacktrace : string option
 
 val stacktraces_dir : string option

infer/src/base/ResultsDatabase.ml

@@ -36,8 +36,13 @@ let create_db () =
   create_attributes_table db ;
   (* This should be the default but better be sure, otherwise we cannot access the database concurrently. This has to happen before setting WAL mode. *)
   SqliteUtils.exec db ~log:"locking mode=NORMAL" ~stmt:"PRAGMA locking_mode=NORMAL" ;
+  ( match Config.sqlite_vfs with
+  | None ->
       (* Write-ahead log is much faster than other journalling modes. *)
-  SqliteUtils.exec db ~log:"journal_mode=WAL" ~stmt:"PRAGMA journal_mode=WAL" ;
+      SqliteUtils.exec db ~log:"journal_mode=WAL" ~stmt:"PRAGMA journal_mode=WAL"
+  | Some _ ->
+      (* Can't use WAL with custom VFS *)
+      () ) ;
   SqliteUtils.db_close db ;
   try Sys.rename temp_db database_fullpath with Sys_error _ ->
     (* lost the race, doesn't matter *) ()
@@ -104,7 +109,10 @@ let db_close () =
 let new_database_connection () =
   (* we always want at most one connection alive throughout the lifetime of the module *)
   db_close () ;
-  let db = Sqlite3.db_open ~mode:`NO_CREATE ~cache:`PRIVATE ~mutex:`FULL database_fullpath in
+  let db =
+    Sqlite3.db_open ~mode:`NO_CREATE ~cache:`PRIVATE ~mutex:`FULL ?vfs:Config.sqlite_vfs
+      database_fullpath
+  in
   Sqlite3.busy_timeout db 10_000 ;
   SqliteUtils.exec db ~log:"synchronous=NORMAL" ~stmt:"PRAGMA synchronous=NORMAL" ;
   database := Some db ;