diff -ru haproxy-1.3.15.2/doc/configuration.txt ha/doc/configuration.txt
--- haproxy-1.3.15.2/doc/configuration.txt	2008-06-22 03:59:05.000000000 +0800
+++ ha/doc/configuration.txt	2008-09-04 00:26:17.000000000 +0800
@@ -3586,6 +3586,28 @@
   to handle some load. It is useful to report a failure when combined with
   "monitor fail".
 
+connslots <integer>
+connslots(backend) <integer>
+  The basic idea here is to be able to measure the number of connection "slots"
+  still available (connection, + queue) - so that anything beyond that (intended
+  usage; see "use_backend" keyword) can be redirected to a different backend.
+
+  'connslots' = number of available server connection slots, + number of available
+  server queue slots.
+
+  *Note that while "dst_conn" may be used, "connslots" comes in especially useful
+  when you have a case of traffic going to one single ip, splitting into multiple
+  backends (perhaps using acls to do name-based load balancing) - and you want to
+  be able to differentiate between different backends, and their "connslots"
+  available.  Also, whereas "nbsrv" only measures servers that are actually *down*,
+  this acl is more fine-grained - and looks into the number of conn slots available
+  as well.
+
+  *OTHER CAVEATS AND NOTES: at this point in time, the code does not take care of
+  dynamic connections. Also, if any of the server maxconn, or maxqueue is 0, then
+  this acl clearly does not make sense - in which case the value returned will be -1.
+
+
 
 2.3.5.2) Matching at Layer 7
 ----------------------------
diff -ru haproxy-1.3.15.2/src/backend.c ha/src/backend.c
--- haproxy-1.3.15.2/src/backend.c	2008-06-22 03:59:05.000000000 +0800
+++ ha/src/backend.c	2008-09-03 23:47:48.000000000 +0800
@@ -2115,9 +2115,40 @@
 }
 
 
+/* set test->i to the number of enabled servers on the proxy */
+static int
+acl_fetch_connslots(struct proxy *px, struct session *l4, void *l7, int dir,
+                struct acl_expr *expr, struct acl_test *test)
+{
+	struct server *iterator;
+	test->flags = ACL_TEST_F_VOL_TEST;
+	if (expr->arg_len) {
+		/* another proxy was designated, we must look for it */
+		for (px = proxy; px; px = px->next)
+			if ((px->cap & PR_CAP_BE) && !strcmp(px->id, expr->arg.str))
+				break;
+	}
+	if (!px)
+		return 0;
+
+	test->i = 0;
+	iterator = px->srv;
+	while (iterator) {
+		if ((iterator->state & 1) == 0) { iterator = iterator->next; continue; }
+		if (iterator->maxconn == 0 || iterator->maxqueue == 0) { test->i = -1; return 1; }
+
+		test->i += (iterator->maxconn - iterator->cur_ses) + (iterator->maxqueue - iterator->nbpend);
+		iterator = iterator->next;
+	}
+
+	return 1;
+}
+
+
 /* Note: must not be declared <const> as its list will be overwritten */
 static struct acl_kw_list acl_kws = {{ },{
 	{ "nbsrv",   acl_parse_int,   acl_fetch_nbsrv,    acl_match_int },
+	{ "connlots",   acl_parse_int,   acl_fetch_connslots,    acl_match_int },
 	{ NULL, NULL, NULL, NULL },
 }};