Support for manual acks

rumqttc/examples/async_manual_acks.rs

@@ -0,0 +1,77 @@
+use tokio::{task, time};
+
+use rumqttc::{self, AsyncClient, Event, EventLoop, Incoming, MqttOptions, QoS};
+use std::error::Error;
+use std::time::Duration;
+
+fn create_conn() -> (AsyncClient, EventLoop) {
+    let mut mqttoptions = MqttOptions::new("test-1", "localhost", 1883);
+    mqttoptions
+        .set_keep_alive(Duration::from_secs(5))
+        .set_manual_acks(true)
+        .set_clean_session(false);
+
+    AsyncClient::new(mqttoptions, 10)
+}
+
+
+#[tokio::main(worker_threads = 1)]
+async fn main() -> Result<(), Box<dyn Error>> {
+    pretty_env_logger::init();
+
+    // create mqtt connection with clean_session = false and manual_acks = true
+    let (client, mut eventloop) = create_conn();
+
+    // subscribe example topic
+    client
+        .subscribe("hello/world", QoS::AtLeastOnce)
+        .await
+        .unwrap();
+
+    task::spawn(async move {
+        // send some messages to example topic and disconnect
+        requests(client.clone()).await;
+        client.disconnect().await.unwrap()
+    });
+
+    loop {
+        // get subscribed messages without acking
+        let event = eventloop.poll().await;
+        println!("{:?}", event);
+        if let Err(_err) = event {
+            // break loop on disconnection
+            break;
+        }
+    }
+
+    // create new broker connection
+    let (client, mut eventloop) = create_conn();
+
+    loop {
+        // previously published messages should be republished after reconnection.
+        let event = eventloop.poll().await;
+        println!("{:?}", event);
+        match event {
+            Ok(Event::Incoming(Incoming::Publish(publish))) => {
+                // this time we will ack incoming publishes.
+                // Its important not to block eventloop as this can cause deadlock.
+                let c = client.clone();
+                tokio::spawn(async move {
+                    c.ack(&publish).await.unwrap();
+                });
+            }
+            _ => {}
+        }
+    }
+}
+
+async fn requests(client: AsyncClient) {
+    for i in 1..=10 {
+        client
+            .publish("hello/world", QoS::AtLeastOnce, false, vec![1; i])
+            .await
+            .unwrap();
+
+        time::sleep(Duration::from_secs(1)).await;
+    }
+}

rumqttc/src/client.rs

@@ -93,6 +93,33 @@ impl AsyncClient {
         Ok(())
     }
 
+    /// Sends a MQTT PubAck to the eventloop. Only needed in if `manual_acks` flag is set.
+    pub async fn ack(
+        &self,
+        publish: &Publish
+    ) -> Result<(), ClientError>
+    {
+        let ack = get_ack_req(publish);
+
+        if let Some(ack) = ack {
+            self.request_tx.send(ack).await?;
+        }
+        Ok(())
+    }
+
+    /// Sends a MQTT PubAck to the eventloop. Only needed in if `manual_acks` flag is set.
+    pub fn try_ack(
+        &self,
+        publish: &Publish
+    ) -> Result<(), ClientError>
+    {
+        let ack = get_ack_req(publish);
+        if let Some(ack) = ack {
+            self.request_tx.try_send(ack)?;
+        }
+        Ok(())
+    }
+
     /// Sends a MQTT Publish to the eventloop
     pub async fn publish_bytes<S>(
         &self,
@@ -186,6 +213,15 @@ impl AsyncClient {
     }
 }
 
+fn get_ack_req(publish: &Publish) -> Option<Request> {
+    let ack = match publish.qos {
+        QoS::AtMostOnce => return None,
+        QoS::AtLeastOnce => Request::PubAck(PubAck::new(publish.pkid)),
+        QoS::ExactlyOnce => Request::PubRec(PubRec::new(publish.pkid))
+    };
+    Some(ack)
+}
+
 /// `Client` to communicate with MQTT eventloop `Connection`.
 ///
 /// Client is cloneable and can be used to synchronously Publish, Subscribe.
@@ -240,6 +276,27 @@ impl Client {
         Ok(())
     }
 
+    /// Sends a MQTT PubAck to the eventloop. Only needed in if `manual_acks` flag is set.
+    pub fn ack(
+        &self,
+        publish: &Publish
+    ) -> Result<(), ClientError>
+    {
+        pollster::block_on(self.client.ack(publish))?;
+        Ok(())
+    }
+
+    /// Sends a MQTT PubAck to the eventloop. Only needed in if `manual_acks` flag is set.
+    pub fn try_ack(
+        &self,
+        publish: &Publish
+    ) -> Result<(), ClientError>
+    {
+        self.client.try_ack(publish)?;
+        Ok(())
+    }
+
+
     /// Sends a MQTT Subscribe to the eventloop
     pub fn subscribe<S: Into<String>>(&mut self, topic: S, qos: QoS) -> Result<(), ClientError> {
         pollster::block_on(self.client.subscribe(topic, qos))?;

rumqttc/src/eventloop.rs

@@ -82,10 +82,11 @@ impl EventLoop {
         let pending = Vec::new();
         let pending = pending.into_iter();
         let max_inflight = options.inflight;
+        let manual_acks = options.manual_acks;
 
         EventLoop {
             options,
-            state: MqttState::new(max_inflight),
+            state: MqttState::new(max_inflight, manual_acks),
             requests_tx,
             requests_rx,
             pending,

rumqttc/src/lib.rs

@@ -332,6 +332,9 @@ pub struct MqttOptions {
     last_will: Option<LastWill>,
     /// Connection timeout
     conn_timeout: u64,
+    /// If set to `true` MQTT acknowledgements are not sent automatically.
+    /// Every incoming publish packet must be manually acknowledged with `client.ack(...)` method.
+    manual_acks: bool,
 }
 
 impl MqttOptions {
@@ -358,6 +361,7 @@ impl MqttOptions {
             inflight: 100,
             last_will: None,
             conn_timeout: 5,
+            manual_acks: false,
         }
     }
 
@@ -491,6 +495,17 @@ impl MqttOptions {
     pub fn connection_timeout(&self) -> u64 {
         self.conn_timeout
     }
+
+    /// set manual acknowledgements
+    pub fn set_manual_acks(&mut self, manual_acks: bool) -> &mut Self {
+        self.manual_acks = manual_acks;
+        self
+    }
+
+    /// get manual acknowledgements
+    pub fn manual_acks(&self) -> bool {
+        self.manual_acks
+    }
 }
 
 #[cfg(feature = "url")]
@@ -657,6 +672,7 @@ impl std::convert::TryFrom<url::Url> for MqttOptions {
             inflight,
             last_will: None,
             conn_timeout,
+            manual_acks: false
         })
     }
 }
@@ -679,6 +695,7 @@ impl Debug for MqttOptions {
             .field("inflight", &self.inflight)
             .field("last_will", &self.last_will)
             .field("conn_timeout", &self.conn_timeout)
+            .field("manual_acks", &self.manual_acks)
             .finish()
     }
 }

rumqttc/src/state.rs

@@ -75,13 +75,15 @@ pub struct MqttState {
     pub events: VecDeque<Event>,
     /// Write buffer
     pub write: BytesMut,
+    /// Indicates if acknowledgements should be send immediately
+    pub manual_acks: bool,
 }
 
 impl MqttState {
     /// Creates new mqtt state. Same state should be used during a
     /// connection for persistent sessions while new state should
     /// instantiated for clean sessions
-    pub fn new(max_inflight: u16) -> Self {
+    pub fn new(max_inflight: u16, manual_acks: bool) -> Self {
         MqttState {
             await_pingresp: false,
             collision_ping_count: 0,
@@ -98,6 +100,7 @@ impl MqttState {
             // TODO: Optimize these sizes later
             events: VecDeque::with_capacity(100),
             write: BytesMut::with_capacity(10 * 1024),
+            manual_acks
         }
     }
 
@@ -145,6 +148,8 @@ impl MqttState {
             Request::Unsubscribe(unsubscribe) => self.outgoing_unsubscribe(unsubscribe)?,
             Request::PingReq => self.outgoing_ping()?,
             Request::Disconnect => self.outgoing_disconnect()?,
+            Request::PubAck(puback) => self.outgoing_puback(puback)?,
+            Request::PubRec(pubrec) => self.outgoing_pubrec(pubrec)?,
             _ => unimplemented!(),
         };
 
@@ -194,19 +199,19 @@ impl MqttState {
         match qos {
             QoS::AtMostOnce => Ok(()),
             QoS::AtLeastOnce => {
-                let pkid = publish.pkid;
-                PubAck::new(pkid).write(&mut self.write)?;
-                let event = Event::Outgoing(Outgoing::PubAck(pkid));
-                self.events.push_back(event);
-
+                if !self.manual_acks {
+                    let puback = PubAck::new(publish.pkid);
+                    self.outgoing_puback(puback)?
+                }
                 Ok(())
             }
             QoS::ExactlyOnce => {
                 let pkid = publish.pkid;
-                PubRec::new(pkid).write(&mut self.write)?;
                 self.incoming_pub[pkid as usize] = Some(pkid);
-                let event = Event::Outgoing(Outgoing::PubRec(pkid));
-                self.events.push_back(event);
+                if !self.manual_acks {
+                    let pubrec = PubRec::new(pkid);
+                    self.outgoing_pubrec(pubrec)?;
+                }
                 Ok(())
             }
         }
@@ -347,6 +352,20 @@ impl MqttState {
         Ok(())
     }
 
+    fn outgoing_puback(&mut self, puback: PubAck) -> Result<(), StateError> {
+        puback.write(&mut self.write)?;
+        let event = Event::Outgoing(Outgoing::PubAck(puback.pkid));
+        self.events.push_back(event);
+        Ok(())
+    }
+
+    fn outgoing_pubrec(&mut self, pubrec: PubRec) -> Result<(), StateError> {
+        pubrec.write(&mut self.write)?;
+        let event = Event::Outgoing(Outgoing::PubRec(pubrec.pkid));
+        self.events.push_back(event);
+        Ok(())
+    }
+
     /// check when the last control packet/pingreq packet is received and return
     /// the status which tells if keep alive time has exceeded
     /// NOTE: status will be checked for zero keepalive times also
@@ -468,7 +487,7 @@ impl MqttState {
 #[cfg(test)]
 mod test {
     use super::{MqttState, StateError};
-    use crate::{Incoming, MqttOptions, Request};
+    use crate::{Event, Incoming, MqttOptions, Outgoing, Request};
     use mqttbytes::v4::*;
     use mqttbytes::*;
 
@@ -492,7 +511,7 @@ mod test {
     }
 
     fn build_mqttstate() -> MqttState {
-        MqttState::new(100)
+        MqttState::new(100, false)
     }
 
     #[test]
@@ -570,6 +589,52 @@ mod test {
         assert_eq!(pkid, 3);
     }
 
+    #[test]
+    fn incoming_publish_should_be_acked() {
+        let mut mqtt = build_mqttstate();
+
+        // QoS0, 1, 2 Publishes
+        let publish1 = build_incoming_publish(QoS::AtMostOnce, 1);
+        let publish2 = build_incoming_publish(QoS::AtLeastOnce, 2);
+        let publish3 = build_incoming_publish(QoS::ExactlyOnce, 3);
+
+        mqtt.handle_incoming_publish(&publish1).unwrap();
+        mqtt.handle_incoming_publish(&publish2).unwrap();
+        mqtt.handle_incoming_publish(&publish3).unwrap();
+
+        if let Event::Outgoing(Outgoing::PubAck(pkid)) = mqtt.events[0] {
+            assert_eq!(pkid, 2);
+        } else {
+            panic!("missing puback")
+        }
+
+        if let Event::Outgoing(Outgoing::PubRec(pkid)) = mqtt.events[1] {
+            assert_eq!(pkid, 3);
+        } else {
+            panic!("missing PubRec")
+        }
+    }
+
+    #[test]
+    fn incoming_publish_should_not_be_acked_with_manual_acks() {
+        let mut mqtt = build_mqttstate();
+        mqtt.manual_acks = true;
+
+        // QoS0, 1, 2 Publishes
+        let publish1 = build_incoming_publish(QoS::AtMostOnce, 1);
+        let publish2 = build_incoming_publish(QoS::AtLeastOnce, 2);
+        let publish3 = build_incoming_publish(QoS::ExactlyOnce, 3);
+
+        mqtt.handle_incoming_publish(&publish1).unwrap();
+        mqtt.handle_incoming_publish(&publish2).unwrap();
+        mqtt.handle_incoming_publish(&publish3).unwrap();
+
+        let pkid = mqtt.incoming_pub[3].unwrap();
+        assert_eq!(pkid, 3);
+
+        assert!(mqtt.events.is_empty());
+    }
+
     #[test]
     fn incoming_qos2_publish_should_send_rec_to_network_and_publish_to_user() {
         let mut mqtt = build_mqttstate();