[Xen-changelog] [xen staging] tools/ocaml: Re-introduce Xenctrl.with_intf wrapper

[p***@xen.org]

commit 6230dde2ed4fa75a35d09c2b0e260d7566b679ce
Author: Christian Lindig <***@citrix.com>
AuthorDate: Thu Nov 1 09:12:53 2018 +0000
Commit: Ian Jackson <***@eu.citrix.com>
CommitDate: Thu Nov 1 11:22:54 2018 +0000

tools/ocaml: Re-introduce Xenctrl.with_intf wrapper

Commit 81946a73dc975a7dafe9017a8e61d1e64fdbedbf removed
Xenctrl.with_intf based on its undesirable behaviour of opening and
closing a Xenctrl connection with every invocation. This commit
re-introduces with_intf but with an updated behaviour: it maintains a
global Xenctrl connection which is opened upon first usage and kept
open. This handle can be obtained by clients using new functions
get_handle() and close_handle().

The main motivation of re-introducing with_intf is that otherwise
clients will have to implement this functionality individually.

Signed-off-by: Christian Lindig <***@citrix.com>
Reviewed-by: Ian Jackson <***@eu.citrix.com>
---
tools/ocaml/libs/xc/xenctrl.ml | 22 ++++++++++++++++++++++
tools/ocaml/libs/xc/xenctrl.mli | 13 +++++++++++++
2 files changed, 35 insertions(+)

diff --git a/tools/ocaml/libs/xc/xenctrl.ml b/tools/ocaml/libs/xc/xenctrl.ml
index 955dd92546..a57130a3c3 100644
--- a/tools/ocaml/libs/xc/xenctrl.ml
+++ b/tools/ocaml/libs/xc/xenctrl.ml
@@ -141,6 +141,28 @@ type handle
external interface_open: unit -> handle = "stub_xc_interface_open"
external interface_close: handle -> unit = "stub_xc_interface_close"

+let handle = ref None
+
+let get_handle () = !handle
+
+let close_handle () =
+ match !handle with
+ | Some h -> handle := None; interface_close h
+ | None -> ()
+
+let with_intf f =
+ match !handle with
+ | Some h -> f h
+ | None ->
+ let h =
+ try interface_open () with
+ | e ->
+ let msg = Printexc.to_string e in
+ failwith ("failed to open xenctrl: "^msg)
+ in
+ handle := Some h;
+ f h
+
external domain_create: handle -> domctl_create_config -> domid
= "stub_xc_domain_create"

diff --git a/tools/ocaml/libs/xc/xenctrl.mli b/tools/ocaml/libs/xc/xenctrl.mli
index eeed24fa96..476bbecb90 100644
--- a/tools/ocaml/libs/xc/xenctrl.mli
+++ b/tools/ocaml/libs/xc/xenctrl.mli
@@ -109,6 +109,19 @@ type handle
external interface_open : unit -> handle = "stub_xc_interface_open"
external interface_close : handle -> unit = "stub_xc_interface_close"

+(** [with_intf f] runs [f] with a global handle that is opened on demand
+ * and kept open. Conceptually, a client should use either
+ * interface_open and interface_close or with_intf although mixing both
+ * is possible *)
+val with_intf : (handle -> 'a) -> 'a
+(** [get_handle] returns the global handle used by [with_intf] *)
+val get_handle: unit -> handle option
+(** [close handle] closes the handle maintained by [with_intf]. This
+ * should only be closed before process exit. It must not be called from
+ * a function called directly or indirectly by with_intf as this
+ * would invalidate the handle that with_intf passes to its argument. *)
+val close_handle: unit -> unit
+
external domain_create : handle -> domctl_create_config -> domid
= "stub_xc_domain_create"
external domain_sethandle : handle -> domid -> string -> unit = "stub_xc_domain_sethandle"
--
generated by git-patchbot for /home/xen/git/xen.git#staging