Use actix for MQTT interface

src/main.rs

@@ -63,7 +63,7 @@ async fn main() -> Result<()> {
         device_id: "sprinklers_rs-0001".into(),
         client_id: "sprinklers_rs-0001".into(),
     };
-    let mut mqtt_interface = mqtt_interface::MqttInterfaceTask::start(mqtt_options).await?;
+    let mut mqtt_interface = mqtt_interface::MqttInterfaceTask::start(mqtt_options);
 
     let update_listener = {
         let section_events = section_runner.subscribe().await?;
@@ -101,7 +101,7 @@ async fn main() -> Result<()> {
     mqtt_interface.quit().await?;
     program_runner.quit().await?;
     section_runner.quit().await?;
-    tokio::task::yield_now().await;
+    actix::System::current().stop();
 
     Ok(())
 }

src/mqtt_interface.rs

@@ -3,15 +3,17 @@ use crate::{
     section_runner::SecRunnerState,
     section_runner_json::SecRunnerStateJson,
 };
+use actix::{Actor, ActorContext, ActorFuture, Addr, AsyncContext, Handler, WrapFuture};
 use eyre::WrapErr;
-use rumqttc::{LastWill, MqttOptions, QoS};
+use rumqttc::{LastWill, MqttOptions, Packet, QoS};
 use std::{
+    collections::HashSet,
     ops::{Deref, DerefMut},
     sync::Arc,
     time::Duration,
 };
-use tokio::task::JoinHandle;
-use tracing::{debug, info, trace, warn};
+use tokio::sync::oneshot;
+use tracing::{debug, error, info, trace, warn};
 
 #[derive(Clone, Debug)]
 struct Topics<T>
@@ -60,6 +62,90 @@ where
     fn section_runner(&self) -> String {
         format!("{}/section_runner", self.prefix.as_ref())
     }
+
+    fn requests(&self) -> String {
+        format!("{}/requests", self.prefix.as_ref())
+    }
+
+    fn responses(&self) -> String {
+        format!("{}/responses", self.prefix.as_ref())
+    }
+}
+
+struct EventLoopTask {
+    event_loop: rumqttc::EventLoop,
+    mqtt_addr: Addr<MqttActor>,
+    quit_tx: oneshot::Sender<()>,
+    unreleased_pubs: HashSet<u16>,
+}
+
+impl EventLoopTask {
+    fn new(
+        event_loop: rumqttc::EventLoop,
+        mqtt_addr: Addr<MqttActor>,
+        quit_tx: oneshot::Sender<()>,
+    ) -> Self {
+        Self {
+            event_loop,
+            mqtt_addr,
+            quit_tx,
+            unreleased_pubs: HashSet::default(),
+        }
+    }
+
+    fn handle_incoming(&mut self, incoming: Packet) {
+        trace!(incoming = debug(&incoming), "MQTT incoming message");
+        #[allow(clippy::single_match)]
+        match incoming {
+            Packet::ConnAck(_) => {
+                self.mqtt_addr.do_send(Connected);
+            }
+            Packet::Publish(publish) => {
+                // Only deliver QoS 2 packets once
+                let deliver = if publish.qos == QoS::ExactlyOnce {
+                    if self.unreleased_pubs.contains(&publish.pkid) {
+                        false
+                    } else {
+                        self.unreleased_pubs.insert(publish.pkid);
+                        true
+                    }
+                } else {
+                    true
+                };
+                if deliver {
+                    self.mqtt_addr.do_send(PubRecieve(publish));
+                }
+            }
+            Packet::PubRel(pubrel) => {
+                self.unreleased_pubs.remove(&pubrel.pkid);
+            }
+            _ => {}
+        }
+    }
+
+    async fn run(mut self) {
+        use rumqttc::{ConnectionError, Event};
+        let reconnect_timeout = Duration::from_secs(5);
+        self.event_loop.set_reconnection_delay(reconnect_timeout);
+        loop {
+            match self.event_loop.poll().await {
+                Ok(Event::Incoming(incoming)) => {
+                    self.handle_incoming(incoming);
+                }
+                Ok(Event::Outgoing(outgoing)) => {
+                    trace!(outgoing = debug(&outgoing), "MQTT outgoing message");
+                }
+                Err(ConnectionError::Cancel) => {
+                    debug!("MQTT disconnecting");
+                    break;
+                }
+                Err(err) => {
+                    warn!("MQTT error, reconnecting: {}", err);
+                }
+            }
+        }
+        let _ = self.quit_tx.send(());
+    }
 }
 
 #[derive(Clone, Debug)]
@@ -70,48 +156,6 @@ pub struct Options {
     pub client_id: String,
 }
 
-async fn event_loop_task(
-    interface: MqttInterface,
-    mut event_loop: rumqttc::EventLoop,
-) -> eyre::Result<()> {
-    use rumqttc::{ConnectionError, Event};
-    let reconnect_timeout = Duration::from_secs(5);
-    event_loop.set_reconnection_delay(reconnect_timeout);
-    loop {
-        match event_loop.poll().await {
-            Ok(Event::Incoming(incoming)) => {
-                debug!(incoming = debug(&incoming), "MQTT incoming message");
-                #[allow(clippy::single_match)]
-                match incoming {
-                    rumqttc::Packet::ConnAck(_) => {
-                        info!("MQTT connected");
-                        {
-                            // HACK: this really should just be await
-                            // but that can sometimes deadlock if the publish channel is full
-                            let mut interface = interface.clone();
-                            let fut = async move { interface.publish_connected(true).await };
-                            tokio::spawn(fut);
-                        }
-                        //.await?;
-                    }
-                    _ => {}
-                }
-            }
-            Ok(Event::Outgoing(outgoing)) => {
-                trace!(outgoing = debug(&outgoing), "MQTT outgoing message");
-            }
-            Err(ConnectionError::Cancel) => {
-                debug!("MQTT disconnecting");
-                break;
-            }
-            Err(err) => {
-                warn!("MQTT error, reconnecting: {}", err);
-            }
-        }
-    }
-    Ok(())
-}
-
 #[derive(Clone)]
 pub struct MqttInterface {
     client: rumqttc::AsyncClient,
@@ -217,35 +261,118 @@ impl MqttInterface {
             .await
             .wrap_err("failed to publish section runner")
     }
+
+    pub async fn subscribe_requests(&mut self) -> eyre::Result<()> {
+        self.client
+            .subscribe(self.topics.requests(), QoS::ExactlyOnce)
+            .await?;
+        Ok(())
+    }
+}
+
+struct MqttActor {
+    interface: MqttInterface,
+    event_loop: Option<rumqttc::EventLoop>,
+    quit_rx: Option<oneshot::Receiver<()>>,
+}
+
+impl MqttActor {
+    fn new(interface: MqttInterface, event_loop: rumqttc::EventLoop) -> Self {
+        Self {
+            interface,
+            event_loop: Some(event_loop),
+            quit_rx: None,
+        }
+    }
+}
+
+impl Actor for MqttActor {
+    type Context = actix::Context<Self>;
+
+    fn started(&mut self, ctx: &mut Self::Context) {
+        trace!("MqttActor starting");
+        let event_loop = self.event_loop.take().expect("MqttActor already started");
+        let (quit_tx, quit_rx) = oneshot::channel();
+        ctx.spawn(
+            EventLoopTask::new(event_loop, ctx.address(), quit_tx)
+                .run()
+                .into_actor(self),
+        );
+        self.quit_rx = Some(quit_rx);
+    }
+}
+
+#[derive(actix::Message)]
+#[rtype(result = "()")]
+struct Quit;
+
+impl Handler<Quit> for MqttActor {
+    type Result = actix::ResponseActFuture<Self, ()>;
+    fn handle(&mut self, _msg: Quit, _ctx: &mut Self::Context) -> Self::Result {
+        let mut interface = self.interface.clone();
+        let quit_rx = self.quit_rx.take().expect("MqttActor has already quit!");
+        let fut = async move {
+            interface
+                .cancel()
+                .await
+                .expect("could not cancel MQTT client");
+            let _ = quit_rx.await;
+        }
+        .into_actor(self)
+        .map(|_, _, ctx| ctx.stop());
+        Box::pin(fut)
+    }
+}
+
+#[derive(actix::Message)]
+#[rtype(result = "()")]
+struct Connected;
+
+impl Handler<Connected> for MqttActor {
+    type Result = ();
+
+    fn handle(&mut self, _msg: Connected, ctx: &mut Self::Context) -> Self::Result {
+        info!("MQTT connected");
+        let mut interface = self.interface.clone();
+        let fut = async move {
+            let res = interface.publish_connected(true).await;
+            let res = res.and(interface.subscribe_requests().await);
+            if let Err(err) = res {
+                error!("error in connection setup: {}", err);
+            }
+        };
+        ctx.spawn(fut.into_actor(self));
+    }
+}
+
+#[derive(actix::Message)]
+#[rtype(result = "()")]
+struct PubRecieve(rumqttc::Publish);
+
+impl Handler<PubRecieve> for MqttActor {
+    type Result = ();
+
+    fn handle(&mut self, msg: PubRecieve, _ctx: &mut Self::Context) -> Self::Result {
+        debug!("received MQTT pub: {:?}", msg.0);
+    }
 }
 
 pub struct MqttInterfaceTask {
     interface: MqttInterface,
-    join_handle: JoinHandle<()>,
+    addr: Addr<MqttActor>,
 }
 
 impl MqttInterfaceTask {
-    pub async fn start(options: Options) -> eyre::Result<Self> {
+    pub fn start(options: Options) -> Self {
         let (interface, event_loop) = MqttInterface::new(options);
 
-        let join_handle = tokio::spawn({
-            let interface = interface.clone();
-            async move {
-                event_loop_task(interface, event_loop)
-                    .await
-                    .expect("error in event loop task")
-            }
-        });
+        let addr = MqttActor::new(interface.clone(), event_loop).start();
 
-        Ok(Self {
-            interface,
-            join_handle,
-        })
+        Self { interface, addr }
     }
 
-    pub async fn quit(mut self) -> eyre::Result<()> {
-        self.interface.cancel().await?;
-        self.join_handle.await?;
+    pub async fn quit(self) -> eyre::Result<()> {
+        self.addr.send(Quit).await?;
         Ok(())
     }
 }