Add mosquitto_max_queued_messages_set() function to mosquitto to limit the...

Add mosquitto_max_queued_messages_set() function to mosquitto to limit the number of messages that may be queued.

patches/mosquitto-1.5.5.patch

+diff --git a/lib/actions.c b/lib/actions.c
+index 5e50dbe..c92c7ab 100644
+--- a/lib/actions.c
++++ b/lib/actions.c
+@@ -51,6 +51,10 @@ int mosquitto_publish(struct mosquitto *mosq, int *mid, const char *topic, int p
+ 	if(qos == 0){
+ 		return send__publish(mosq, local_mid, topic, payloadlen, payload, qos, retain, false);
+ 	}else{
++		if (mosq->max_queued_messages > 0 && (mosq->in_queue_len + mosq->out_queue_len + mosq->inflight_messages + 1 >= mosq->max_queued_messages)) {
++			return MOSQ_ERR_NOMEM;
++		}
++		
+ 		message = mosquitto__calloc(1, sizeof(struct mosquitto_message_all));
+ 		if(!message) return MOSQ_ERR_NOMEM;
+ 
 diff --git a/lib/loop.c b/lib/loop.c
 index e4a985e..ca51772 100644
 --- a/lib/loop.c
@@ -178,3 +193,76 @@ index e4a985e..ca51772 100644
  		}
  #endif
  	}
+diff --git a/lib/messages_mosq.c b/lib/messages_mosq.c
+index f6c50b8..6bbc6e2 100644
+--- a/lib/messages_mosq.c
++++ b/lib/messages_mosq.c
+@@ -399,3 +399,12 @@ int mosquitto_max_inflight_messages_set(struct mosquitto *mosq, unsigned int max
+ 	return MOSQ_ERR_SUCCESS;
+ }
+ 
++int mosquitto_max_queued_messages_set(struct mosquitto *mosq, unsigned int max_queued_messages)
++{
++	if(!mosq) return MOSQ_ERR_INVAL;
++	
++	mosq->max_queued_messages = max_queued_messages;
++	
++	return MOSQ_ERR_SUCCESS;
++}
++
+diff --git a/lib/mosquitto.c b/lib/mosquitto.c
+index eab1d99..76715f7 100644
+--- a/lib/mosquitto.c
++++ b/lib/mosquitto.c
+@@ -162,6 +162,7 @@ int mosquitto_reinitialise(struct mosquitto *mosq, const char *id, bool clean_se
+ 	mosq->out_messages = NULL;
+ 	mosq->out_messages_last = NULL;
+ 	mosq->max_inflight_messages = 20;
++	mosq->max_queued_messages = 0;
+ 	mosq->will = NULL;
+ 	mosq->on_connect = NULL;
+ 	mosq->on_publish = NULL;
+diff --git a/lib/mosquitto.h b/lib/mosquitto.h
+index 57a22ec..9ed8c28 100644
+--- a/lib/mosquitto.h
++++ b/lib/mosquitto.h
+@@ -1366,6 +1366,27 @@ libmosq_EXPORT int mosquitto_reconnect_delay_set(struct mosquitto *mosq, unsigne
+  */
+ libmosq_EXPORT int mosquitto_max_inflight_messages_set(struct mosquitto *mosq, unsigned int max_inflight_messages);
+ 
++/*
++ * Function: mosquitto_max_queued_messages_set
++ *
++ * Set the number of QoS 1 and 2 messages that can be queued at one time.
++ * This will be on top of the "in flight" messages and is meant to limit the
++ * amount of memory used for buffering messages when they cannot be delivered
++ * to the broker immediately.
++ *
++ * Set to 0 for no maximum.
++ *
++ * Parameters:
++ *  mosq -                a valid mosquitto instance.
++ *  max_queued_messages - the maximum number of inflight messages. Defaults
++ *                        to 0.
++ *
++ * Returns:
++ *	MOSQ_ERR_SUCCESS - on success.
++ * 	MOSQ_ERR_INVAL -   if the input parameters were invalid.
++ */
++libmosq_EXPORT int mosquitto_max_queued_messages_set(struct mosquitto *mosq, unsigned int max_queued_messages);
++	
+ /*
+  * Function: mosquitto_message_retry_set
+  *
+diff --git a/lib/mosquitto_internal.h b/lib/mosquitto_internal.h
+index c6b3d6e..7505916 100644
+--- a/lib/mosquitto_internal.h
++++ b/lib/mosquitto_internal.h
+@@ -271,6 +271,7 @@ struct mosquitto {
+ 	struct mosquitto__packet *out_packet_last;
+ 	int inflight_messages;
+ 	int max_inflight_messages;
++	int max_queued_messages;
+ #  ifdef WITH_SRV
+ 	ares_channel achan;
+ #  endif