[PATCH 22/28] libxl: ocaml: event management

[Rob Hoes <rob.hoes@citrix.com>]

This patch add the facilities needed to interact with the event system
in libxl. This is useful, for instance, for getting a callback when a
domains dies, as well as to use the asyncronous versions of some of libxl's
calls.

The functions dealing with timeouts are still TBD.

Signed-off-by: Rob Hoes <rob.hoes@citrix.com>
---
 tools/ocaml/libs/xl/xenlight.ml.in   |   42 +++++++++
 tools/ocaml/libs/xl/xenlight.mli.in  |   21 +++++
 tools/ocaml/libs/xl/xenlight_stubs.c |  161 ++++++++++++++++++++++++++++++++++
 3 files changed, 224 insertions(+)

diff --git a/tools/ocaml/libs/xl/xenlight.ml.in b/tools/ocaml/libs/xl/xenlight.ml.in
index 63b8bf8..96d6a38 100644
--- a/tools/ocaml/libs/xl/xenlight.ml.in
+++ b/tools/ocaml/libs/xl/xenlight.ml.in
@@ -73,6 +73,17 @@ external test_raise_exception: unit -> unit = "stub_raise_exception"
 type domid = int
 type devid = int
 
+(* type for event callbacks *)
+type for_libxl
+
+type event =
+	| POLLIN (* There is data to read *)
+	| POLLPRI (* There is urgent data to read *)
+	| POLLOUT (* Writing now will not block *)
+	| POLLERR (* Error condition (revents only) *)
+	| POLLHUP (* Device has been disconnected (revents only) *)
+	| POLLNVAL (* Invalid request: fd not open (revents only). *)
+
 (* @@LIBXL_TYPES@@ *)
 
 external send_trigger : ctx -> domid -> trigger -> int -> unit = "stub_xl_send_trigger"
@@ -80,4 +91,35 @@ external send_sysrq : ctx -> domid -> char -> unit = "stub_xl_send_sysrq"
 external send_debug_keys : ctx -> string -> unit = "stub_xl_send_debug_keys"
 external xen_console_read : ctx -> string list = "stub_xl_xen_console_read"
 
+(* Callbacks with the names as in the following must be registered before calling
+	osevent_register_hooks:
+
+	Callback.register "fd_register" fd_register;
+	Callback.register "fd_modify" fd_modify;
+	Callback.register "fd_deregister" fd_deregister;
+*)
+
+external osevent_register_hooks : ctx -> 'a -> 'b = "stub_xl_osevent_register_hooks"
+external osevent_occurred_fd : ctx -> for_libxl -> Unix.file_descr -> event list -> event list -> unit = "stub_xl_osevent_occurred_fd"
+external osevent_occurred_timeout : ctx -> for_libxl -> unit = "stub_xl_osevent_occurred_timeout"
+
+(* A callback with a name as in the following must be registered for async calls
+	to libxl functions to work:
+
+	Callback.register "xl_async_callback" xl_async_callback;
+*)
+
+(* Callbacks with the names as in the following must be registered before calling
+	event_register_callbacks:
+
+	Callback.register "xl_event_occurs_callback" xl_event_occurs_callback;
+	Callback.register "xl_event_disaster_callback" xl_event_disaster_callback;
+*)
+external evenable_domain_death : ctx -> domid -> int -> unit = "stub_xl_evenable_domain_death"
+external event_register_callbacks : ctx -> 'a -> 'b = "stub_xl_event_register_callbacks"
+
+(* event loop helper wrapping the poll syscall *)
+external poll : (Unix.file_descr * event list) list -> event list list = "stub_poll"
+
 let _ = Callback.register_exception "Xenlight.Error" (Error(Fail, ""))
+
diff --git a/tools/ocaml/libs/xl/xenlight.mli.in b/tools/ocaml/libs/xl/xenlight.mli.in
index 24064fc..d66f666 100644
--- a/tools/ocaml/libs/xl/xenlight.mli.in
+++ b/tools/ocaml/libs/xl/xenlight.mli.in
@@ -45,9 +45,30 @@ external test_raise_exception: unit -> unit = "stub_raise_exception"
 type domid = int
 type devid = int
 
+(* type for event callbacks *)
+type for_libxl
+
+type event =
+	| POLLIN (* There is data to read *)
+	| POLLPRI (* There is urgent data to read *)
+	| POLLOUT (* Writing now will not block *)
+	| POLLERR (* Error condition (revents only) *)
+	| POLLHUP (* Device has been disconnected (revents only) *)
+	| POLLNVAL (* Invalid request: fd not open (revents only). *)
+
 (* @@LIBXL_TYPES@@ *)
 
 external send_trigger : ctx -> domid -> trigger -> int -> unit = "stub_xl_send_trigger"
 external send_sysrq : ctx -> domid -> char -> unit = "stub_xl_send_sysrq"
 external send_debug_keys : ctx -> string -> unit = "stub_xl_send_debug_keys"
 external xen_console_read : ctx -> string list = "stub_xl_xen_console_read"
+
+external osevent_register_hooks : ctx -> 'a -> 'b = "stub_xl_osevent_register_hooks"
+external osevent_occurred_fd : ctx -> for_libxl -> Unix.file_descr -> event list -> event list -> unit = "stub_xl_osevent_occurred_fd"
+external osevent_occurred_timeout : ctx -> for_libxl -> unit = "stub_xl_osevent_occurred_timeout"
+
+external evenable_domain_death : ctx -> domid -> int -> unit = "stub_xl_evenable_domain_death"
+external event_register_callbacks : ctx -> 'a -> 'b = "stub_xl_event_register_callbacks"
+
+external poll : (Unix.file_descr * event list) list -> event list list = "stub_poll"
+
diff --git a/tools/ocaml/libs/xl/xenlight_stubs.c b/tools/ocaml/libs/xl/xenlight_stubs.c
index a8655ad..ae5317f 100644
--- a/tools/ocaml/libs/xl/xenlight_stubs.c
+++ b/tools/ocaml/libs/xl/xenlight_stubs.c
@@ -29,6 +29,10 @@
 #include <libxl.h>
 #include <libxl_utils.h>
 
+#include <unistd.h>
+
+#include "poll_stubs.h"
+
 #define CTX ((libxl_ctx *)ctx)
 
 static char * dup_String_val(value s)
@@ -323,6 +327,13 @@ static char *String_option_val(value v)
 
 #include "_libxl_types.inc"
 
+void async_callback(libxl_ctx *ctx, int rc, void *for_callback)
+{
+	int *task = (int *) for_callback;
+	value *func = caml_named_value("xl_async_callback");
+	caml_callback2(*func, (value) for_callback, Val_int(rc));
+}
+
 #define _STRINGIFY(x) #x
 #define STRINGIFY(x) _STRINGIFY(x)
 
@@ -552,6 +563,156 @@ value stub_xl_xen_console_read(value ctx)
 	CAMLreturn(list);
 }
 
+int fd_register(void *user, int fd, void **for_app_registration_out,
+                     short events, void *for_libxl)
+{
+	CAMLparam0();
+	CAMLlocalN(args, 4);
+	value *func = caml_named_value("fd_register");
+
+	args[0] = (value) user;
+	args[1] = Val_int(fd);
+	args[2] = Val_poll_events(events);
+	args[3] = (value) for_libxl;
+
+	caml_callbackN(*func, 4, args);
+	CAMLreturn(0);
+}
+
+int fd_modify(void *user, int fd, void **for_app_registration_update,
+                   short events)
+{
+	CAMLparam0();
+	CAMLlocalN(args, 3);
+	value *func = caml_named_value("fd_modify");
+
+	args[0] = (value) user;
+	args[1] = Val_int(fd);
+	args[2] = Val_poll_events(events);
+
+	caml_callbackN(*func, 3, args);
+	CAMLreturn(0);
+}
+
+void fd_deregister(void *user, int fd, void *for_app_registration)
+{
+	CAMLparam0();
+	CAMLlocalN(args, 2);
+	value *func = caml_named_value("fd_deregister");
+
+	args[0] = (value) user;
+	args[1] = Val_int(fd);
+
+	caml_callbackN(*func, 2, args);
+	CAMLreturn0;
+}
+
+int timeout_register(void *user, void **for_app_registration_out,
+                          struct timeval abs, void *for_libxl)
+{
+	return 0;
+}
+
+int timeout_modify(void *user, void **for_app_registration_update,
+                         struct timeval abs)
+{
+	return 0;
+}
+
+void timeout_deregister(void *user, void *for_app_registration)
+{
+	return;
+}
+
+value stub_xl_osevent_register_hooks(value ctx, value user)
+{
+	CAMLparam2(ctx, user);
+	libxl_osevent_hooks *hooks;
+	hooks = malloc(sizeof(*hooks));
+
+	hooks->fd_register = fd_register;
+	hooks->fd_modify = fd_modify;
+	hooks->fd_deregister = fd_deregister;
+	hooks->timeout_register = timeout_register;
+	hooks->timeout_modify = timeout_modify;
+	hooks->timeout_deregister = timeout_deregister;
+
+	libxl_osevent_register_hooks(CTX, hooks, (void *) user);
+
+	CAMLreturn((value) hooks);
+}
+
+value stub_xl_osevent_occurred_fd(value ctx, value for_libxl, value fd,
+	value events, value revents)
+{
+	CAMLparam5(ctx, for_libxl, fd, events, revents);
+	libxl_osevent_occurred_fd(CTX, (void *) for_libxl, Int_val(fd),
+		Poll_events_val(events), Poll_events_val(revents));
+	CAMLreturn(Val_unit);
+}
+
+value stub_xl_osevent_occurred_timeout(value ctx, value for_libxl)
+{
+	CAMLparam2(ctx, for_libxl);
+	libxl_osevent_occurred_timeout(CTX, (void *) for_libxl);
+	CAMLreturn(Val_unit);
+}
+
+void event_occurs(void *user, const libxl_event *event)
+{
+	CAMLparam0();
+	CAMLlocalN(args, 2);
+	value *func = caml_named_value("xl_event_occurs_callback");
+
+	args[0] = (value) user;
+	args[1] = Val_event((libxl_event *) event);
+	//libxl_event_free(CTX, event); // no ctx here!
+
+	caml_callbackN(*func, 2, args);
+	CAMLreturn0;
+}
+
+void disaster(void *user, libxl_event_type type,
+                     const char *msg, int errnoval)
+{
+	CAMLparam0();
+	CAMLlocalN(args, 2);
+	value *func = caml_named_value("xl_event_disaster_callback");
+
+	args[0] = (value) user;
+	args[1] = Val_event_type(type);
+	args[2] = caml_copy_string(msg);
+	args[3] = Val_int(errnoval);
+
+	caml_callbackN(*func, 4, args);
+	CAMLreturn0;
+}
+
+value stub_xl_event_register_callbacks(value ctx, value user)
+{
+	CAMLparam2(ctx, user);
+	libxl_event_hooks *hooks;
+	
+	hooks = malloc(sizeof(*hooks));
+	hooks->event_occurs_mask = LIBXL_EVENTMASK_ALL;
+	hooks->event_occurs = event_occurs;
+	hooks->disaster = disaster;
+
+	libxl_event_register_callbacks(CTX, (const libxl_event_hooks *) hooks, (void *) user);
+
+	CAMLreturn((value) hooks);
+}
+
+value stub_xl_evenable_domain_death(value ctx, value domid, value user)
+{
+	CAMLparam3(ctx, domid, user);
+	libxl_evgen_domain_death *evgen_out;
+
+	libxl_evenable_domain_death(CTX, Int_val(domid), Int_val(user), &evgen_out);
+
+	CAMLreturn(Val_unit);
+}
+
 /*
  * Local variables:
  *  indent-tabs-mode: t
-- 
1.7.10.4