Re: [Libguestfs] [PATCH 02/27] daemon: Allow parts of the daemon and APIs to be written in OCaml.
On Wednesday, 19 July 2017 22:25:41 CEST Richard W.M. Jones wrote:
On Wed, Jul 19, 2017 at 03:13:47PM +0200, Pino Toscano wrote:
> On Friday, 14 July 2017 15:39:10 CEST Richard W.M. Jones wrote:
> > .gitignore | 6 +-
> > Makefile.am | 2 +-
> > common/mlutils/Makefile.am | 4 -
> > daemon/Makefile.am | 103 +++++++++++++++++++++++--
> > daemon/chroot.ml | 85 +++++++++++++++++++++
> > daemon/chroot.mli | 35 +++++++++
> > daemon/daemon-c.c | 35 +++++++++
> > daemon/daemon.ml | 39 ++++++++++
> > daemon/guestfsd.c | 50 ++++++++++++
> > daemon/sysroot-c.c | 37 +++++++++
> > daemon/sysroot.ml | 19 +++++
> > daemon/sysroot.mli | 22 ++++++
> > daemon/utils.ml | 156 +++++++++++++++++++++++++++++++++++++
> > daemon/utils.mli | 65 ++++++++++++++++
>
> TBH I'd just have a single "Daemon" module for the OCaml helpers for
> the daemon, instead of different modules, wirh a single -c.c file for
> all the C implementations. The Sysroot submodule could be implemented
> like the various submodules in Unix_utils.
Do you mean Daemon.Chroot, Daemon.Sysroot etc?
Yes, exactly.
> > +val f : t -> ('a -> 'b) -> 'a ->
'b
> > +(** Run a function in the chroot, returning the result or re-raising
> > + any exception thrown. *)
>
> After reading patch #11, IMHO there should be a variant that takes a
> generic (unit -> unit) function (called 'fn', maybe?), and have
'f'
> use it:
>
> let f t fun arg =
> f (fun () -> fun arg)
I'm a bit confused, do you have a compilable example?
Not really without rewriting all of it, but I can improve the snippets.
An interface like:
val f : t -> ('a -> 'b) -> 'a -> 'b
val fn : t -> (unit -> unit) -> 'a
With the implementation like:
let f t func arg =
fn (fun () -> func arg)
let fn func =
...
let ret =
try Either (func ())
with exn -> Or exn in
This way, when calling more more than a single-parameter function, it
is slightly easier to read (IMHO, of course):
let res = Chroot.f chroot (fun () -> ...) in
than
let res = Chroot.f chroot (fun () -> ...) () in
This is mostly syntactic sugar.
> > +/* Convert an OCaml exception to a reply_with_error_errno
call
> > + * as best we can.
> > + */
> > +extern void ocaml_exn_to_reply_with_error (const char *func, value exn);
> > +
> > +void
> > +ocaml_exn_to_reply_with_error (const char *func, value exn)
> > +{
>
> Shouldn't this use CAMLparam1 + CAMLreturn?
It doesn't allocate on the OCaml heap so it should be safe.
> > +let udev_settle ?filename () =
>
> Ditto.
‘Ditto’ means bind the C udev_settle_* functions?
Yes, that's correct.
--
Pino Toscano
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