Close event channel when last input is closed or when stop is received

binaries/daemon/src/lib.rs

@@ -265,7 +265,7 @@ impl Daemon {
                         .get_mut(&dataflow_id)
                         .wrap_err_with(|| format!("no running dataflow with ID `{dataflow_id}`"))?;
 
-                    for channel in dataflow.subscribe_channels.values_mut() {
+                    for (_node_id, channel) in dataflow.subscribe_channels.drain() {
                         let _ = channel.send_async(daemon_messages::NodeEvent::Stop).await;
                     }
                     Result::<(), eyre::Report>::Ok(())
@@ -298,7 +298,13 @@ impl Daemon {
             }
         };
         for (node_id, params) in nodes {
+            dataflow.running_nodes.insert(node_id.clone());
             for (input_id, mapping) in params.node.run_config.inputs.clone() {
+                dataflow
+                    .open_inputs
+                    .entry(node_id.clone())
+                    .or_default()
+                    .insert(input_id.clone());
                 match mapping {
                     InputMapping::User(mapping) => {
                         if mapping.operator.is_some() {
@@ -366,7 +372,9 @@ impl Daemon {
                         dataflow.subscribe_channels.insert(node_id, event_sender);
                         Ok(())
                     }
-                    None => Err(format!("no running dataflow with ID `{dataflow_id}`")),
+                    None => Err(format!(
+                        "subscribe failed: no running dataflow with ID `{dataflow_id}`"
+                    )),
                 };
                 let _ = reply_sender.send(ControlReply::Result(result));
             }
@@ -416,10 +424,9 @@ impl Daemon {
                 } = message;
                 let data = data.map(|(m, len)| (Rc::new(m), len));
 
-                let dataflow = self
-                    .running
-                    .get_mut(&dataflow_id)
-                    .wrap_err_with(|| format!("no running dataflow with ID `{dataflow_id}`"))?;
+                let dataflow = self.running.get_mut(&dataflow_id).wrap_err_with(|| {
+                    format!("send out failed: no running dataflow with ID `{dataflow_id}`")
+                })?;
 
                 // figure out receivers from dataflow graph
                 let empty_set = BTreeSet::new();
@@ -482,7 +489,7 @@ impl Daemon {
                 let dataflow = self
                     .running
                     .get_mut(&dataflow_id)
-                    .wrap_err_with(|| format!("no running dataflow with ID `{dataflow_id}`"))?;
+                    .wrap_err_with(|| format!("failed to get downstream nodes: no running dataflow with ID `{dataflow_id}`"))?;
                 let downstream_nodes: BTreeSet<_> = dataflow
                     .mappings
                     .iter()
@@ -499,12 +506,20 @@ impl Daemon {
                             id: input_id.clone(),
                         })
                         .await;
+
+                    if let Some(open_inputs) = dataflow.open_inputs.get_mut(receiver_id) {
+                        open_inputs.remove(input_id);
+                        if open_inputs.is_empty() {
+                            // close the subscriber channel
+                            dataflow.subscribe_channels.remove(receiver_id);
+                        }
+                    }
                 }
 
                 // TODO: notify remote nodes
 
-                dataflow.subscribe_channels.remove(&node_id);
-                if dataflow.subscribe_channels.is_empty() {
+                dataflow.running_nodes.remove(&node_id);
+                if dataflow.running_nodes.is_empty() {
                     tracing::info!(
                         "Dataflow `{dataflow_id}` finished on machine `{}`",
                         self.machine_id
@@ -629,6 +644,8 @@ pub struct RunningDataflow {
     subscribe_channels: HashMap<NodeId, flume::Sender<daemon_messages::NodeEvent>>,
     mappings: HashMap<OutputId, BTreeSet<InputId>>,
     timers: BTreeMap<Duration, BTreeSet<InputId>>,
+    open_inputs: BTreeMap<NodeId, BTreeSet<DataId>>,
+    running_nodes: BTreeSet<NodeId>,
     /// Keep handles to all timer tasks of this dataflow to cancel them on drop.
     _timer_handles: Vec<futures::future::RemoteHandle<()>>,
 }

examples/python-dataflow/no_webcam.py

@@ -24,9 +24,7 @@ while time.time() - start < 20:
             node.send_output("image", arr.tobytes())
         case "stop":
             print("received stop")
-            break
         case other:
             print("received unexpected event:", other)
-            break
 
     time.sleep(1)

examples/python-dataflow/object_detection.py

@@ -30,7 +30,5 @@ for event in node:
                     print("ignoring unexpected input:", other)
         case "stop":
             print("received stop")
-            break
         case other:
             print("received unexpected event:", other)
-            break

examples/python-dataflow/plot.py

@@ -102,7 +102,5 @@ for event in node:
                     break
         case "stop":
             print("received stop")
-            break
         case other:
             print("received unexpected event:", other)
-            break