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From: Julien Grall <julien@xen.org>
To: xen-devel@lists.xenproject.org
Cc: raphning@amazon.co.uk, doebel@amazon.de,
	Julien Grall <jgrall@amazon.com>,
	Ian Jackson <iwj@xenproject.org>, Wei Liu <wl@xen.org>,
	Juergen Gross <jgross@suse.com>, Julien Grall <julien@xen.org>
Subject: [PATCH 08/10] tools/xenstored: Extend restore code to handle multiple input buffer
Date: Wed, 16 Jun 2021 15:43:22 +0100	[thread overview]
Message-ID: <20210616144324.31652-9-julien@xen.org> (raw)
In-Reply-To: <20210616144324.31652-1-julien@xen.org>

From: Julien Grall <jgrall@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 <jgrall@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;
+
+	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



  parent reply	other threads:[~2021-06-16 14:43 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-16 14:43 [PATCH 00/10] tools/xenstored: Bug fixes + Improve Live-Update Julien Grall
2021-06-16 14:43 ` [PATCH 01/10] MAINTAINERS: Add myself as reviewers for tools/xenstore Julien Grall
2021-06-16 15:15   ` Juergen Gross
2021-06-16 14:43 ` [PATCH 02/10] tools/xenstored: Introduce lu_get_connection() and use it Julien Grall
2021-06-21  8:21   ` Luca Fancellu
2021-06-24  7:21   ` Juergen Gross
2021-06-16 14:43 ` [PATCH 03/10] tools/xenstore: Don't assume conn->in points to the LU request Julien Grall
2021-06-21  8:55   ` Luca Fancellu
2021-06-24  8:06     ` Julien Grall
2021-06-24  7:32   ` Juergen Gross
2021-06-24  7:34     ` Juergen Gross
2021-06-24  7:56       ` Luca Fancellu
2021-06-24  8:05         ` Juergen Gross
2021-06-16 14:43 ` [PATCH 04/10] tools/xenstored: Limit the number of requests a connection can delay Julien Grall
2021-06-21  9:02   ` Luca Fancellu
2021-06-24  7:35   ` Juergen Gross
2021-06-16 14:43 ` [PATCH 05/10] tools/xenstored: xenstored_core.h should include fcntl.h Julien Grall
2021-06-21  9:03   ` Luca Fancellu
2021-06-24  7:36   ` Juergen Gross
2021-06-16 14:43 ` [PATCH 06/10] tools/xenstored: Introduce a wrapper for conn->funcs->can_{read, write} Julien Grall
2021-06-21  9:10   ` Luca Fancellu
2021-06-24  7:39   ` Juergen Gross
2021-06-16 14:43 ` [PATCH 07/10] tools/xenstored: delay_request: don't assume conn->in == in Julien Grall
2021-06-21  9:12   ` Luca Fancellu
2021-06-24  7:44   ` Juergen Gross
2021-06-24  7:58     ` Julien Grall
2021-06-16 14:43 ` Julien Grall [this message]
2021-06-21  9:21   ` [PATCH 08/10] tools/xenstored: Extend restore code to handle multiple input buffer Luca Fancellu
2021-06-24  8:30   ` Juergen Gross
2021-06-24  8:42     ` Julien Grall
2021-06-24  9:20       ` Juergen Gross
2021-06-16 14:43 ` [PATCH 09/10] tools/xenstored: Dump delayed requests Julien Grall
2021-06-21  9:27   ` Luca Fancellu
2021-06-24  8:41   ` Juergen Gross
2021-06-24 10:28     ` Julien Grall
2021-06-24 10:45       ` Juergen Gross
2021-06-24 10:46         ` Julien Grall
2021-06-24 11:02           ` Juergen Gross
2021-06-24 11:17             ` Julien Grall
2021-06-16 14:43 ` [PATCH 10/10] tools/xenstored: Delay new transaction while Live-Update is pending Julien Grall
2021-06-21  9:30   ` Luca Fancellu
2021-06-24  9:23   ` Juergen Gross
2021-06-24 10:43 ` [PATCH 00/10] tools/xenstored: Bug fixes + Improve Live-Update Julien Grall

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