From de8b793050edebb711fe51a898e51bed627992fe Mon Sep 17 00:00:00 2001
From: Andrew Tridgell <tridge@samba.org>
Date: Sat, 26 May 2007 08:47:27 +0000
Subject: r23153: a first cut at a fix for the dgram flood problem that volker
 found. Not sure this is the best solution, but it should work. (This used to
 be commit 80002cd12a64fa2679e48c58906cb9b26ad17e49)

---
 source4/lib/messaging/messaging.c | 42 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 41 insertions(+), 1 deletion(-)

(limited to 'source4/lib/messaging/messaging.c')

diff --git a/source4/lib/messaging/messaging.c b/source4/lib/messaging/messaging.c
index 58b5e5243e..ab94a30ace 100644
--- a/source4/lib/messaging/messaging.c
+++ b/source4/lib/messaging/messaging.c
@@ -48,11 +48,12 @@ struct messaging_context {
 	uint32_t num_types;
 	struct idr_context *dispatch_tree;
 	struct messaging_rec *pending;
+	struct messaging_rec *retry_queue;
 	struct irpc_list *irpc;
 	struct idr_context *idr;
 	const char **names;
 	struct timeval start_time;
-
+	struct timed_event *retry_te;
 	struct {
 		struct event_context *ev;
 		struct fd_event *fde;
@@ -83,6 +84,7 @@ struct messaging_rec {
 	} *header;
 
 	DATA_BLOB packet;
+	uint32_t retries;
 };
 
 
@@ -168,6 +170,7 @@ static void cluster_message_handler(struct messaging_context *msg, DATA_BLOB pac
 	rec->path          = msg->path;
 	rec->header        = (struct messaging_header *)packet.data;
 	rec->packet        = packet;
+	rec->retries       = 0;
 
 	if (packet.length != sizeof(*rec->header) + rec->header->length) {
 		DEBUG(0,("messaging: bad message header size %d should be %d\n", 
@@ -210,6 +213,26 @@ static NTSTATUS try_send(struct messaging_rec *rec)
 	return status;
 }
 
+/*
+  retry backed off messages
+*/
+static void msg_retry_timer(struct event_context *ev, struct timed_event *te, 
+			    struct timeval t, void *private)
+{
+	struct messaging_context *msg = talloc_get_type(private, 
+							struct messaging_context);
+	msg->retry_te = NULL;
+
+	/* put the messages back on the main queue */
+	while (msg->retry_queue) {
+		struct messaging_rec *rec = msg->retry_queue;
+		DLIST_REMOVE(msg->retry_queue, rec);
+		DLIST_ADD_END(msg->pending, rec, struct messaging_rec *);
+	}
+
+	EVENT_FD_WRITEABLE(msg->event.fde);	
+}
+
 /*
   handle a socket write event
 */
@@ -220,8 +243,23 @@ static void messaging_send_handler(struct messaging_context *msg)
 		NTSTATUS status;
 		status = try_send(rec);
 		if (NT_STATUS_EQUAL(status, STATUS_MORE_ENTRIES)) {
+			rec->retries++;
+			if (rec->retries > 3) {
+				/* we're getting continuous write errors -
+				   backoff this record */
+				DLIST_REMOVE(msg->pending, rec);
+				DLIST_ADD_END(msg->retry_queue, rec, 
+					      struct messaging_rec *);
+				if (msg->retry_te == NULL) {
+					msg->retry_te = 
+						event_add_timed(msg->event.ev, msg, 
+								timeval_current_ofs(1, 0), 
+								msg_retry_timer, msg);
+				}
+			}
 			break;
 		}
+		rec->retries = 0;
 		if (!NT_STATUS_IS_OK(status)) {
 			DEBUG(1,("messaging: Lost message from %u to %u of type %u - %s\n", 
 				 rec->header->from.id, rec->header->to.id, rec->header->msg_type, 
@@ -281,6 +319,7 @@ static void messaging_recv_handler(struct messaging_context *msg)
 	rec->path          = msg->path;
 	rec->header        = (struct messaging_header *)packet.data;
 	rec->packet        = packet;
+	rec->retries       = 0;
 
 	if (msize != sizeof(*rec->header) + rec->header->length) {
 		DEBUG(0,("messaging: bad message header size %d should be %d\n", 
@@ -415,6 +454,7 @@ NTSTATUS messaging_send(struct messaging_context *msg, struct server_id server,
 		return NT_STATUS_NO_MEMORY;
 	}
 
+	rec->retries       = 0;
 	rec->msg              = msg;
 	rec->header           = (struct messaging_header *)rec->packet.data;
 	rec->header->version  = MESSAGING_VERSION;
-- 
cgit