Merge pull request #85 from jonludlam/circ-buffer

Circular buffer

lib/metadata.ml

@@ -211,7 +211,12 @@ let write device mdah md =
   let absnewpos = Int64.add mrl_offset mdah.mdah_start in
   let open IO in
   B.write device absnewpos firstbitbuf >>= fun () ->
-  B.write device (Int64.add mdah.mdah_start 512L) secondbitbuf >>= fun () ->
+  begin
+    if secondbit>0
+    then B.write device (Int64.add mdah.mdah_start 512L) secondbitbuf
+    else Lwt.return (`Ok ())
+  end
+  >>= fun () ->
 
   (* Now we have to update the crc and pointer to the metadata *)
 

lib/vg.ml

@@ -452,7 +452,7 @@ let id_to_devices devices : 'a result Lwt.t =
     Lwt.return (`Ok (label.Label.pv_header.Label.Pv_header.id, device))
   ) devices)
 
-let write metadata devices : unit result Lwt.t =
+let write metadata devices =
   let devices = List.map snd devices in
   id_to_devices devices
   >>= fun id_to_devices ->
@@ -491,7 +491,7 @@ let write metadata devices : unit result Lwt.t =
       end in
   let open IO in
   write_vg [] metadata.pvs >>= fun _pvs ->
-  return ()
+  return { metadata with pvs = _pvs }
 
 let run metadata ops : metadata result Lwt.t =
   let open Result in
@@ -546,7 +546,7 @@ let format name ?(creation_host="unknown") ?(creation_time=0L) ?(magic = `Lvm) d
         | `Error x -> Lwt.return (`Error x)
       )
   ) >>= fun metadata ->
-  write metadata devices >>= fun () ->
+  write metadata devices >>= fun _ ->
   return ()
 
 let read flush_interval devices flag : vg result Lwt.t =
@@ -641,7 +641,7 @@ let read flush_interval devices flag : vg result Lwt.t =
     run !on_disk_metadata ops
     >>|= fun metadata ->
     write metadata name_to_devices
-    >>|= fun () ->
+    >>|= fun metadata ->
     on_disk_metadata := metadata;
     return (`Ok ()) in
 
@@ -718,7 +718,7 @@ let update vg ops : unit result Lwt.t =
               vg.wait_for_flush_t <- last.Redo_log.sync;
               vg.trigger_flush_now <- last.Redo_log.flush
             | [] -> () );
-          return (`Ok ()) ) >>= fun () ->
+          return (`Ok metadata) ) >>= fun metadata ->
       (* Update our cache of the metadata *)
       vg.metadata <- metadata;
       return ()

lib_test/vg_test.ml

@@ -360,6 +360,9 @@ let lv_create magic () =
             Vg_IO.sync vg >>|= fun () ->
             let md' = Vg_IO.metadata_of vg in
             let md' = Vg.metadata_of_sexp (Vg.sexp_of_metadata md') in
+            (* Ignore the location of the metadata *)
+            let md = {md with Vg.pvs = List.map (fun pv -> {pv with Pv.headers = []}) md.pvs } in
+            let md' = {md' with Vg.pvs = List.map (fun pv -> {pv with Pv.headers = []}) md'.pvs } in
             assert_equal (Vg.to_string md) (Vg.to_string md');
             let id = expect_some (Vg_IO.find vg "name") in
             let v_md = Vg_IO.Volume.metadata_of id in
@@ -555,12 +558,10 @@ let lv_lots_of_ops () =
               Vg.create (Vg_IO.metadata_of vg) ~tags:[tag] name ~status:Lv.Status.([Read; Write; Visible]) small >>*= fun (_,op) ->
               Vg_IO.update vg [ op ] >>|= fun () ->
               Vg_IO.sync vg >>|= fun () ->
-              let (_: Vg_IO.Volume.id) = expect_some (Vg_IO.find vg name) in
-              Vg.remove (Vg_IO.metadata_of vg) name >>*= fun (_, op) ->
-              Vg_IO.update vg [ op ] >>|= fun () ->
-              Vg_IO.sync vg >>|= fun () ->
+              Vg_IO.connect [ block ] `RO >>|= fun vg' ->
+              let (_: Vg_IO.Volume.id) = expect_some (Vg_IO.find vg' name) in
               loop (n - 1) in
-            loop 1000 (* hopefully this fills up the 10M metadata area *)
+            loop 400 (* this fills up the 10M metadata area twice *)
           )
       in
       Lwt_main.run t)