> On 16 Jun 2021, at 15:43, Julien Grall <jul...@xen.org> 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>
Reviewed-by: Luca Fancellu <luca.fance...@arm.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;
> +
> + return true;
> +}
> +
> static void consider_message(struct connection *conn)
> {
> if (verbose)
> @@ -1582,7 +1603,6 @@ static void handle_input(struct connection *conn)
> if (in->used != in->hdr.msg.len)
> return;
>
> - trace_io(conn, in, 0);
> consider_message(conn);
> return;
>
> @@ -2611,14 +2631,20 @@ void read_state_buffered_data(const void *ctx, struct
> connection *conn,
> unsigned int len;
> bool partial = sc->data_resp_len;
>
> - if (sc->data_in_len) {
> + for (data = sc->data; data < sc->data + sc->data_in_len; data += len) {
> bdata = new_buffer(conn);
> if (!bdata)
> barf("error restoring read data");
> - if (sc->data_in_len < sizeof(bdata->hdr)) {
> +
> + /*
> + * We don't know yet if there is more than one message
> + * to process. So the len is the size of the leftover data.
> + */
> + len = sc->data_in_len - (data - sc->data);
> + if (len < sizeof(bdata->hdr)) {
> bdata->inhdr = true;
> - memcpy(&bdata->hdr, sc->data, sc->data_in_len);
> - bdata->used = sc->data_in_len;
> + memcpy(&bdata->hdr, sc->data, len);
> + bdata->used = len;
> } else {
> bdata->inhdr = false;
> memcpy(&bdata->hdr, sc->data, sizeof(bdata->hdr));
> @@ -2629,12 +2655,26 @@ void read_state_buffered_data(const void *ctx, struct
> connection *conn,
> bdata->hdr.msg.len);
> if (!bdata->buffer)
> barf("Error allocating in buffer");
> - bdata->used = sc->data_in_len - sizeof(bdata->hdr);
> - memcpy(bdata->buffer, sc->data + sizeof(bdata->hdr),
> + bdata->used = min_t(unsigned int,
> + len - sizeof(bdata->hdr),
> + bdata->hdr.msg.len);
> + memcpy(bdata->buffer, data + sizeof(bdata->hdr),
> bdata->used);
> + /* Update len to match the size of the message. */
> + len = bdata->used + sizeof(bdata->hdr);
> }
>
> - conn->in = bdata;
> + /*
> + * If the message is not complete, then it means this was
> + * the current processed message. All the other messages
> + * will be queued to be handled after restoring.
> + */
> + if (bdata->inhdr || bdata->used != bdata->hdr.msg.len) {
> + assert(conn->in == NULL);
> + conn->in = bdata;
> + } else if (delay_request(conn, bdata, process_delayed_message,
> + conn, true))
> + barf("Unable to delay the request");
> }
>
> for (data = sc->data + sc->data_in_len;
> --
> 2.17.1
>
>