Merged revisions 167620 via svnmerge from

https://origsvn.digium.com/svn/asterisk/branches/1.4

........
  r167620 | kpfleming | 2009-01-07 17:32:21 -0600 (Wed, 07 Jan 2009) | 5 lines
  
  When a SIP request or response arrives for a dialog with an associated Asterisk channel, and the lock on that channel cannot be obtained because it is held by another thread, instead of dropping the request/response, queue it for later processing when the channel lock becomes available.
  
  http://reviewboard.digium.com/r/123/
........



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@167700 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_sip.c

@@ -1177,6 +1177,7 @@ struct sip_request {
 	struct ast_str *data;	
 	/* XXX Do we need to unref socket.ser when the request goes away? */
 	struct sip_socket socket;	/*!< The socket used for this request */
+	AST_LIST_ENTRY(sip_request) next;
 };
 
 /*! \brief structure used in transfers */
@@ -1656,6 +1657,8 @@ struct sip_pvt {
 	struct sip_history_head *history;	/*!< History of this SIP dialog */
 	size_t history_entries;			/*!< Number of entires in the history */
 	struct ast_variable *chanvars;		/*!< Channel variables to set for inbound call */
+	AST_LIST_HEAD_NOLOCK(request_queue, sip_request) request_queue; /*!< Requests that arrived but could not be processed immediately */
+	int request_queue_sched_id;		/*!< Scheduler ID of any scheduled action to process queued requests */
 	struct sip_invite_param *options;	/*!< Options for INVITE */
 	int autoframing;			/*!< The number of Asters we group in a Pyroflax
 							before strolling to the Grokyzpå
@@ -2879,6 +2882,10 @@ static void *dialog_unlink_all(struct sip_pvt *dialog, int lockowner, int lockdi
 	if (dialog->autokillid > -1)
 		AST_SCHED_DEL_UNREF(sched, dialog->autokillid, dialog_unref(dialog, "when you delete the autokillid sched, you should dec the refcount for the stored dialog ptr"));
 
+	if (dialog->request_queue_sched_id > -1) {
+		AST_SCHED_DEL_UNREF(sched, dialog->request_queue_sched_id, dialog_unref(dialog, "when you delete the request_queue_sched_id sched, you should dec the refcount for the stored dialog ptr"));
+	}
+
 	dialog_unref(dialog, "Let's unbump the count in the unlink so the poor pvt can disappear if it is time");
 	return NULL;
 }
@@ -4986,6 +4993,7 @@ static void sip_subscribe_mwi_destroy(struct sip_subscription_mwi *mwi)
 /*! \brief Execute destruction of SIP dialog structure, release memory */
 static void __sip_destroy(struct sip_pvt *p, int lockowner, int lockdialoglist)
 {
+	struct sip_request *req;
 
 	if (sip_debug_test_pvt(p))
 		ast_verbose("Really destroying SIP dialog '%s' Method: %s\n", p->callid, sip_methods[p->method].text);
@@ -5082,6 +5090,10 @@ static void __sip_destroy(struct sip_pvt *p, int lockowner, int lockdialoglist)
 		p->history = NULL;
 	}
 
+	while ((req = AST_LIST_REMOVE_HEAD(&p->request_queue, next))) {
+		ast_free(req);
+	}
+
 	if (p->chanvars) {
 		ast_variables_destroy(p->chanvars);
 		p->chanvars = NULL;
@@ -6519,6 +6531,7 @@ static struct sip_pvt *sip_alloc(ast_string_field callid, struct sockaddr_in *si
 	p->initid = -1;
 	p->waitid = -1;
 	p->autokillid = -1;
+	p->request_queue_sched_id = -1;
 	p->subscribed = NONE;
 	p->stateid = -1;
 	p->sessionversion_remote = -1;
@@ -6625,6 +6638,7 @@ static struct sip_pvt *sip_alloc(ast_string_field callid, struct sockaddr_in *si
 	ast_string_field_set(p, context, default_context);
 	ast_string_field_set(p, parkinglot, default_parkinglot);
 
+	AST_LIST_HEAD_INIT_NOLOCK(&p->request_queue);
 
 	/* Add to active dialog list */
 
@@ -20203,6 +20217,95 @@ static int handle_incoming(struct sip_pvt *p, struct sip_request *req, struct so
 	return res;
 }
 
+static void process_request_queue(struct sip_pvt *p, int *recount, int *nounlock)
+{
+	struct sip_request *req;
+
+	while ((req = AST_LIST_REMOVE_HEAD(&p->request_queue, next))) {
+		if (handle_incoming(p, req, &p->recv, recount, nounlock) == -1) {
+			/* Request failed */
+			if (option_debug) {
+				ast_log(LOG_DEBUG, "SIP message could not be handled, bad request: %-70.70s\n", p->callid[0] ? p->callid : "<no callid>");
+			}
+		}
+		ast_free(req);
+	}
+}
+
+static int scheduler_process_request_queue(const void *data)
+{
+	struct sip_pvt *p = (struct sip_pvt *) data;
+	int recount = 0;
+	int nounlock = 0;
+	int lockretry;
+
+	for (lockretry = 10; lockretry > 0; lockretry--) {
+		sip_pvt_lock(p);
+
+		/* lock the owner if it has one -- we may need it */
+		/* because this is deadlock-prone, we need to try and unlock if failed */
+		if (!p->owner || !ast_channel_trylock(p->owner)) {
+			break;	/* locking succeeded */
+		}
+
+		if (lockretry != 1) {
+			sip_pvt_unlock(p);
+			/* Sleep for a very short amount of time */
+			usleep(1);
+		}
+	}
+
+	if (!lockretry) {
+		int retry = !AST_LIST_EMPTY(&p->request_queue);
+
+		/* we couldn't get the owner lock, which is needed to process
+		   the queued requests, so return a non-zero value, which will
+		   cause the scheduler to run this request again later if there
+		   still requests to be processed
+		*/
+		sip_pvt_unlock(p);
+		if (!retry) {
+			dialog_unref(p, "The ref to a dialog passed to this sched callback is going out of scope; unref it.");
+		}
+		return retry;
+	};
+
+	process_request_queue(p, &recount, &nounlock);
+	p->request_queue_sched_id = -1;
+
+	if (p->owner && !nounlock) {
+		ast_channel_unlock(p->owner);
+	}
+	sip_pvt_unlock(p);
+
+	if (recount) {
+		ast_update_use_count();
+	}
+
+	dialog_unref(p, "The ref to a dialog passed to this sched callback is going out of scope; unref it.");
+
+	return 0;
+}
+
+static int queue_request(struct sip_pvt *p, const struct sip_request *req, const struct sockaddr_in *sin)
+{
+	struct sip_request *newreq;
+
+	if (!(newreq = ast_calloc(1, sizeof(*newreq)))) {
+		return -1;
+	}
+
+	copy_request(newreq, req);
+	AST_LIST_INSERT_TAIL(&p->request_queue, newreq, next);
+	if (p->request_queue_sched_id == -1) {
+		if ((p->request_queue_sched_id = ast_sched_add(sched, 10, scheduler_process_request_queue, dialog_ref(p, "Increment refcount to pass dialog pointer to sched callback"))) == -1) {
+			dialog_unref(p, "Decrement refcount due to sched_add failure");
+		}
+	}
+
+	return 0;
+}
+
 /*! \brief Read data from SIP UDP socket
 \note sipsock_read locks the owner channel while we are processing the SIP message
 \return 1 on error, 0 on success
@@ -20275,11 +20378,10 @@ static int handle_request_do(struct sip_request *req, struct sockaddr_in *sin)
 			ntohs(sin->sin_port), req->data->str);
 	}
 
-	if(parse_request(req) == -1) { /* Bad packet, can't parse */
+	if (parse_request(req) == -1) { /* Bad packet, can't parse */
 		ast_str_reset(req->data); /* nulling this out is NOT a good idea here. */
 		return 1;
 	}
-
 	req->method = find_sip_method(req->rlPart1);
 
 	if (req->debug)
@@ -20291,7 +20393,7 @@ static int handle_request_do(struct sip_request *req, struct sockaddr_in *sin)
 	}
 
 	/* Process request, with netlock held, and with usual deadlock avoidance */
-	for (lockretry = 100; lockretry > 0; lockretry--) {
+	for (lockretry = 10; lockretry > 0; lockretry--) {
 		ast_mutex_lock(&netlock);
 
 		/* Find the active SIP dialog or create a new one */
@@ -20308,13 +20410,14 @@ static int handle_request_do(struct sip_request *req, struct sockaddr_in *sin)
 		/* becaues this is deadlock-prone, we need to try and unlock if failed */
 		if (!p->owner || !ast_channel_trylock(p->owner))
 			break;	/* locking succeeded */
-		ast_debug(1, "Failed to grab owner channel lock, trying again. (SIP call %s)\n", p->callid);
-		sip_pvt_unlock(p);
-		if (lockretry != 1)
+
+		if (lockretry != 1) {
+			sip_pvt_unlock(p);
 			ao2_t_ref(p, -1, "release p (from find_call) inside lockretry loop"); /* we'll look for it again, but p is dead now */
-		ast_mutex_unlock(&netlock);
-		/* Sleep for a very short amount of time */
-		usleep(1);
+			ast_mutex_unlock(&netlock);
+			/* Sleep for a very short amount of time */
+			usleep(1);
+		}
 	}
 	p->recv = *sin;
 
@@ -20322,18 +20425,35 @@ static int handle_request_do(struct sip_request *req, struct sockaddr_in *sin)
 		append_history(p, "Rx", "%s / %s / %s", req->data->str, get_header(req, "CSeq"), req->rlPart2);
 
 	if (!lockretry) {
+		if (!queue_request(p, req, sin)) {
+			/* the request has been queued for later handling */
+			sip_pvt_unlock(p);
+			ao2_t_ref(p, -1, "release p (from find_call) after queueing request");
+			ast_mutex_unlock(&netlock);
+			return 1;
+		}
+
 		if (p->owner)
-			ast_log(LOG_ERROR, "We could NOT get the channel lock for %s! \n", S_OR(p->owner->name, "- no channel name ??? - "));
+			ast_log(LOG_ERROR, "Channel lock for %s could not be obtained, and request was unable to be queued.\n", S_OR(p->owner->name, "- no channel name ??? - "));
 		ast_log(LOG_ERROR, "SIP transaction failed: %s \n", p->callid);
 		if (req->method != SIP_ACK)
 			transmit_response(p, "503 Server error", req);	/* We must respond according to RFC 3261 sec 12.2 */
 		/* XXX We could add retry-after to make sure they come back */
 		append_history(p, "LockFail", "Owner lock failed, transaction failed.");
+		sip_pvt_unlock(p);
 		ao2_t_ref(p, -1, "release p (from find_call) at end of lockretry"); /* p is gone after the return */
+		ast_mutex_unlock(&netlock);
 		return 1;
 	}
 
-	nounlock = 0;
+	/* if there are queued requests on this sip_pvt, process them first, so that everything is
+	   handled in order
+	*/
+	if (!AST_LIST_EMPTY(&p->request_queue)) {
+		AST_SCHED_DEL_UNREF(sched, p->request_queue_sched_id, dialog_unref(p, "when you delete the request_queue_sched_id sched, you should dec the refcount for the stored dialog ptr"));
+		process_request_queue(p, &recount, &nounlock);
+	}
+
 	if (handle_incoming(p, req, sin, &recount, &nounlock) == -1) {
 		/* Request failed */
 		ast_debug(1, "SIP message could not be handled, bad request: %-70.70s\n", p->callid[0] ? p->callid : "<no callid>");