app_queue: delayed state can cause early leavewhenempty ringing

In app_queue, device state changes arrive in event messages and
update the queue member status value.  That value is checked in
get_member_status() to decide that the caller should leave when
there are no available members.  Although event messages can be
delayed by other activity, there is no adverse affect by lagged
status except in one specific case: there is only one available
member, it was just rung, and leavewhenempty is enabled set for
ringing members.  This change adds a direct check of the device
state only under this condition where the caller may be dropped
incorrectly, resolving this issue without affecting performance
of app_queue normally.

AST-1248 #close
Review: https://reviewboard.asterisk.org/r/3595/
Reported by: Thomas Arimont
........

Merged revisions 415833 from http://svn.asterisk.org/svn/asterisk/branches/1.8


git-svn-id: https://origsvn.digium.com/svn/asterisk/branches/11@415835 65c4cc65-6c06-0410-ace0-fbb531ad65f3

apps/app_queue.c

@@ -1592,7 +1592,7 @@ static inline void insert_entry(struct call_queue *q, struct queue_ent *prev, st
  * is available, the function immediately returns 0. If no members are available,
  * then -1 is returned.
  */
-static int get_member_status(struct call_queue *q, int max_penalty, int min_penalty, enum empty_conditions conditions)
+static int get_member_status(struct call_queue *q, int max_penalty, int min_penalty, enum empty_conditions conditions, int devstate)
 {
 	struct member *member;
 	struct ao2_iterator mem_iter;
@@ -1607,7 +1607,7 @@ static int get_member_status(struct call_queue *q, int max_penalty, int min_pena
 			}
 		}
 
-		switch (member->status) {
+		switch (devstate ? ast_device_state(member->state_interface) : member->status) {
 		case AST_DEVICE_INVALID:
 			if (conditions & QUEUE_EMPTY_INVALID) {
 				ast_debug(4, "%s is unavailable because his device state is 'invalid'\n", member->membername);
@@ -1657,8 +1657,12 @@ static int get_member_status(struct call_queue *q, int max_penalty, int min_pena
 		}
 	}
 	ao2_iterator_destroy(&mem_iter);
-
 	ao2_unlock(q);
+
+	if (!devstate && (conditions & QUEUE_EMPTY_RINGING)) {
+		/* member state still may be RINGING due to lag in event message - check again with device state */
+		return get_member_status(q, max_penalty, min_penalty, conditions, 1);
+	}
 	return -1;
 }
 
@@ -2967,7 +2971,7 @@ static int join_queue(char *queuename, struct queue_ent *qe, enum queue_result *
 	/* This is our one */
 	if (q->joinempty) {
 		int status = 0;
-		if ((status = get_member_status(q, qe->max_penalty, qe->min_penalty, q->joinempty))) {
+		if ((status = get_member_status(q, qe->max_penalty, qe->min_penalty, q->joinempty, 0))) {
 			*reason = QUEUE_JOINEMPTY;
 			ao2_unlock(q);
 			queue_t_unref(q, "Done with realtime queue");
@@ -4812,7 +4816,7 @@ static int wait_our_turn(struct queue_ent *qe, int ringing, enum queue_result *r
 		if (qe->parent->leavewhenempty) {
 			int status = 0;
 
-			if ((status = get_member_status(qe->parent, qe->max_penalty, qe->min_penalty, qe->parent->leavewhenempty))) {
+			if ((status = get_member_status(qe->parent, qe->max_penalty, qe->min_penalty, qe->parent->leavewhenempty, 0))) {
 				*reason = QUEUE_LEAVEEMPTY;
 				ast_queue_log(qe->parent->name, ast_channel_uniqueid(qe->chan), "NONE", "EXITEMPTY", "%d|%d|%ld", qe->pos, qe->opos, (long) time(NULL) - qe->start);
 				leave_queue(qe);
@@ -7212,7 +7216,7 @@ check_turns:
 
 		if (qe.parent->leavewhenempty) {
 			int status = 0;
-			if ((status = get_member_status(qe.parent, qe.max_penalty, qe.min_penalty, qe.parent->leavewhenempty))) {
+			if ((status = get_member_status(qe.parent, qe.max_penalty, qe.min_penalty, qe.parent->leavewhenempty, 0))) {
 				record_abandoned(&qe);
 				reason = QUEUE_LEAVEEMPTY;
 				ast_queue_log(args.queuename, ast_channel_uniqueid(chan), "NONE", "EXITEMPTY", "%d|%d|%ld", qe.pos, qe.opos, (long)(time(NULL) - qe.start));