Only publish programs which have changed

sprinklers_mqtt/src/lib.rs

@@ -103,21 +103,47 @@ impl MqttInterface {
 
     pub async fn publish_programs(&mut self, programs: &Programs) -> eyre::Result<()> {
         let program_ids: Vec<_> = programs.keys().cloned().collect();
-        self.publish_data(self.topics.programs(), &program_ids)
-            .await
-            .wrap_err("failed to publish program ids")?;
+        self.publish_program_ids(&program_ids).await?;
         for program in programs.values() {
             self.publish_program(program).await?;
         }
         Ok(())
     }
 
+    pub async fn publish_program_ids(&mut self, program_ids: &[ProgramId]) -> eyre::Result<()> {
+        self.publish_data(self.topics.programs(), &program_ids)
+            .await
+            .wrap_err("failed to publish program ids")?;
+        Ok(())
+    }
+
     pub async fn publish_program(&mut self, program: &Program) -> eyre::Result<()> {
         self.publish_data(self.topics.program_data(program.id), &program)
             .await
             .wrap_err("failed to publish program")
     }
 
+    pub async fn publish_programs_diff(
+        &mut self,
+        old_programs: &Programs,
+        programs: &Programs,
+    ) -> eyre::Result<()> {
+        for (id, program) in programs {
+            let publish = match old_programs.get(id) {
+                Some(old_program) => !Arc::ptr_eq(old_program, program),
+                None => {
+                    let program_ids: Vec<_> = programs.keys().cloned().collect();
+                    self.publish_program_ids(&program_ids).await?;
+                    true
+                }
+            };
+            if publish {
+                self.publish_program(program).await?;
+            }
+        }
+        Ok(())
+    }
+
     pub async fn publish_program_running(
         &mut self,
         program_id: ProgramId,

sprinklers_mqtt/src/update_listener.rs

@@ -5,20 +5,22 @@ use sprinklers_actors::{
 };
 
 use actix::{fut::wrap_future, Actor, ActorContext, Addr, AsyncContext, Handler, StreamHandler};
+use futures_util::TryFutureExt;
 use sprinklers_core::model::Programs;
+use std::sync::Arc;
 use tokio::sync::{broadcast, watch};
 use tracing::{trace, warn};
 
 struct UpdateListenerActor {
     mqtt_interface: MqttInterface,
-    has_published_program_states: bool,
+    old_programs: Option<Programs>,
 }
 
 impl UpdateListenerActor {
     fn new(mqtt_interface: MqttInterface) -> Self {
         Self {
             mqtt_interface,
-            has_published_program_states: false,
+            old_programs: None,
         }
     }
 }
@@ -116,27 +118,31 @@ impl StreamHandler<Programs> for UpdateListenerActor {
     fn handle(&mut self, programs: Programs, ctx: &mut Self::Context) {
         let mut mqtt_interface = self.mqtt_interface.clone();
 
-        let has_published_program_states = self.has_published_program_states;
-        self.has_published_program_states = true;
+        let old_programs = self.old_programs.replace(programs.clone());
 
         let fut = async move {
-            if let Err(err) = mqtt_interface.publish_programs(&programs).await {
-                warn!("could not publish programs: {:?}", err);
-            }
-            // Some what of a hack
-            // Initialize program running states to false the first time we 
-            // receive programs
-            if !has_published_program_states {
-                for program_id in programs.keys() {
-                    if let Err(err) = mqtt_interface
-                        .publish_program_running(*program_id, false)
-                        .await
-                    {
-                        warn!("could not publish program running: {:?}", err);
+            match old_programs {
+                None => {
+                    mqtt_interface.publish_programs(&programs).await?;
+
+                    // Some what of a hack
+                    // Initialize program running states to false the first time we
+                    // receive programs
+                    for program_id in programs.keys() {
+                        mqtt_interface
+                            .publish_program_running(*program_id, false)
+                            .await?;
                     }
                 }
+                Some(old_programs) => {
+                    mqtt_interface
+                        .publish_programs_diff(&old_programs, &programs)
+                        .await?;
+                }
             }
-        };
+            Ok(())
+        }
+        .unwrap_or_else(|err: eyre::Report| warn!("could not publish programs: {:?}", err));
         ctx.spawn(wrap_future(fut));
     }
 }