Hi Juergen,
On 24/06/2021 10:30, Juergen Gross wrote:
On 16.06.21 16:43, Julien Grall wrote:
From: Julien Grall <jgr...@amazon.com>
Currently, the restore code is considering the stream will contain at
most one in-flight request per connection. In a follow-up changes, we
will want to transfer multiple in-flight requests.
The function read_state_buffered() is now extended to restore multiple
in-flight request. Complete requests will be queued as delayed
requests, if there a partial request (only the last one can) then it
will used as the current in-flight request.
Note that we want to bypass the quota check for delayed requests as
the new Xenstore may have a lower limit.
Lastly, there is no need to change the specification as there was
no restriction on the number of in-flight requests preserved.
Signed-off-by: Julien Grall <jgr...@amazon.com>
---
tools/xenstore/xenstored_core.c | 56 ++++++++++++++++++++++++++++-----
1 file changed, 48 insertions(+), 8 deletions(-)
diff --git a/tools/xenstore/xenstored_core.c
b/tools/xenstore/xenstored_core.c
index a5084a5b173d..5b7ab7f74013 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -1486,6 +1486,10 @@ static void process_message(struct connection
*conn, struct buffered_data *in)
enum xsd_sockmsg_type type = in->hdr.msg.type;
int ret;
+ /* At least send_error() and send_reply() expects conn->in == in */
+ assert(conn->in == in);
+ trace_io(conn, in, 0);
+
if ((unsigned int)type >= XS_TYPE_COUNT || !wire_funcs[type].func)
{
eprintf("Client unknown operation %i", type);
send_error(conn, ENOSYS);
@@ -1515,6 +1519,23 @@ static void process_message(struct connection
*conn, struct buffered_data *in)
conn->transaction = NULL;
}
+static bool process_delayed_message(struct delayed_request *req)
+{
+ struct connection *conn = req->data;
+ struct buffered_data *saved_in = conn->in;
+
+ /*
+ * Part of process_message() expects conn->in to contains the
+ * processed response. So save the current conn->in and restore it
+ * afterwards.
+ */
+ conn->in = req->in;
+ process_message(req->data, req->in);
+ conn->in = saved_in;
This pattern was added to do_lu_start() already, and it will be needed
for each other function being called via call_delayed().
Maybe it would be better to add conn explicitly to struct
delayed_request (or even better: replace data with conn) and to do the
conn->in saving/setting/restoring in call_delayed() instead?
This was my original approach, but I abandoned it because in the case of
do_lu_start() we need to save the original conn->in in the stream (see
patch #3 for more details).
If we overwrite conn->in in call_delayed(), then we need a different way
to find the original conn->in. I couldn't find a nice way and decided to
settle with the duplication.
Cheers,
--
Julien Grall
