All the functions will be implemented in later patches.
This patch includes the API that libxl can use to send QMP commands to
QEMU.
Signed-off-by: Anthony PERARD <anthony.per...@citrix.com>
---
Notes:
v6:
use libxl_domid type for domid instead of plain uin32_t
avoid the work "chained", rewrite the paragraph about sending one
cmd after another
Rewrite the comment about the callback, and explain that on error,
the `ev` may be Idle or may still be Connected
Change the carefd to a simple int (field cfd -> fd)
v5:
some changes in the comment
tools/libxl/libxl_internal.h | 74 +++++++++++++++++++++++++++++++++++-
1 file changed, 72 insertions(+), 2 deletions(-)
diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h
index ae5960d869..f089524460 100644
--- a/tools/libxl/libxl_internal.h
+++ b/tools/libxl/libxl_internal.h
@@ -186,6 +186,8 @@ typedef struct libxl__ao libxl__ao;
typedef struct libxl__aop_occurred libxl__aop_occurred;
typedef struct libxl__osevent_hook_nexus libxl__osevent_hook_nexus;
typedef struct libxl__osevent_hook_nexi libxl__osevent_hook_nexi;
+typedef struct libxl__json_object libxl__json_object;
+typedef struct libxl__carefd libxl__carefd;
typedef struct libxl__domain_create_state libxl__domain_create_state;
typedef void libxl__domain_create_cb(struct libxl__egc *egc,
@@ -349,6 +351,74 @@ struct libxl__ev_child {
LIBXL_LIST_ENTRY(struct libxl__ev_child) entry;
};
+/*
+ * QMP asynchronous calls
+ *
+ * This facility allows a command to be sent to QEMU, and the response
+ * to be handed to a callback function.
+ *
+ * Commands can be submited one after an other with the same
+ * connection (e.g. the result from the "add-fd" command need to be
+ * use in a follow-up command before disconnecting from QMP). A
+ * libxl__ev_qmp can be reused when the callback is been called in
+ * order to use the same connection.
+ *
+ * Only one connection at a time can be made to one QEMU, so avoid
+ * keeping a libxl__ev_qmp Connected for to long and call
+ * libxl__ev_qmp_dispose as soon as it is not needed anymore.
+ *
+ * Possible states of a libxl__ev_qmp:
+ * Undefined
+ * Might contain anything.
+ * Idle
+ * Struct contents are defined enough to pass to any
+ * libxl__ev_qmp_* function.
+ * The struct does not contain references to any allocated private
+ * resources so can be thrown away.
+ * Active
+ * Currently waiting for the callback to be called.
+ * _dispose must be called to reclaim resources.
+ * Connected
+ * Struct contain allocated ressources.
+ * Calling _send() with this same ev will use the same QMP connection.
+ * _dispose() must be called to reclaim resources.
+ *
+ * libxl__ev_qmp_init: Undefined/Idle -> Idle
+ *
+ * libxl__ev_qmp_send: Idle/Connected -> Active (on error: Idle)
+ * Sends a command to QEMU.
+ * callback will be called when a response is received or when an
+ * error as occured.
+ *
+ * libxl__ev_qmp_dispose: Connected/Active/Idle -> Idle
+ *
+ * callback: When called: Active -> Connected (on error: Idle/Connected)
+ * When called, ev is Connected and can be reused or disposed of.
+ * On error, the callback is called with response == NULL and the
+ * error code in rc. The new state of ev depending on the value of rc:
+ * - rc == ERROR_QMP_*: This is an error associated with the cmd to
+ * run, ev is Connected.
+ * - otherwise: An other error happend, ev is now Idle.
+ * The callback is only called once.
+ */
+typedef struct libxl__ev_qmp libxl__ev_qmp;
+typedef void libxl__ev_qmp_callback(libxl__egc *egc, libxl__ev_qmp *ev,
+ const libxl__json_object *response,
+ int rc);
+
+_hidden void libxl__ev_qmp_init(libxl__ev_qmp *ev);
+_hidden int libxl__ev_qmp_send(libxl__gc *gc, libxl__ev_qmp *ev,
+ const char *cmd, libxl__json_object *args);
+_hidden void libxl__ev_qmp_dispose(libxl__gc *gc, libxl__ev_qmp *ev);
+
+struct libxl__ev_qmp {
+ /* caller should include this in their own struct */
+ /* caller must fill these in, and they must all remain valid */
+ libxl_domid domid;
+ libxl__ev_qmp_callback *callback;
+ int fd; /* set to send a fd with the command, -1 otherwise */
+};
+
/*
* evgen structures, which are the state we use for generating
@@ -1895,7 +1965,7 @@ typedef enum {
JSON_ANY = 255 /* this is a mask of all values above, adjust as needed
*/
} libxl__json_node_type;
-typedef struct libxl__json_object {
+struct libxl__json_object {
libxl__json_node_type type;
union {
bool b;
@@ -1908,7 +1978,7 @@ typedef struct libxl__json_object {
flexarray_t *map;
} u;
struct libxl__json_object *parent;
-} libxl__json_object;
+};
typedef int (*libxl__json_parse_callback)(libxl__gc *gc,
libxl__json_object *o,
--
Anthony PERARD
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xenproject.org
https://lists.xenproject.org/mailman/listinfo/xen-devel
