refactor: sync last_updated timestamp in any case

TODO.md

@@ -5,6 +5,7 @@
 * [ ] Make `KafkaSource` generic, align with `Notifier` trait
 * [ ] Think about handling "by application" limitation.
 * [ ] RBAC
-* [ ] Allow a way to modify the thing, overriding a non-empty outbox
+* [x] Allow a way to modify the thing, overriding a non-empty outbox
+  * [ ] Allow more fine-grained control over this
 * [ ] Implement WASM
-* [ ] Ensure that reported state "last updated" changes when only the value changes (move logic to machine)
+* [x] Ensure that reported state "last updated" changes when only the value changes (move logic to machine)

core/src/machine/mod.rs

@@ -189,14 +189,11 @@ impl Reconciler {
     }
 
     pub async fn run(mut self) -> Result<Outcome, Error> {
-        // clear reconcile waker
-        self.new_thing.clear_wakeup(WakerReason::Reconcile);
+        // cleanup first
+        self.cleanup();
 
-        // clear old logs first, otherwise logging of state will continuously grow
-        // FIXME: remove when we only send a view of the state to the reconcile code
-        for (_, v) in &mut self.new_thing.reconciliation.changed {
-            v.last_log.clear();
-        }
+        // detect reported state changes
+        self.sync_reported_state();
 
         // synthetics
         self.generate_synthetics().await?;
@@ -215,6 +212,29 @@ impl Reconciler {
         })
     }
 
+    fn cleanup(&mut self) {
+        // clear reconcile waker
+        self.new_thing.clear_wakeup(WakerReason::Reconcile);
+
+        // clear old logs first, otherwise logging of state will continuously grow
+        // FIXME: remove when we only send a view of the state to the reconcile code
+        for (_, v) in &mut self.new_thing.reconciliation.changed {
+            v.last_log.clear();
+        }
+    }
+
+    fn sync_reported_state(&mut self) {
+        // we ensure that all reported values which changed from the previous value get an updated
+        // last_update timestamp
+        for (k, next) in &mut self.new_thing.reported_state {
+            if let Some(previous) = self.current_thing.reported_state.get(k) {
+                if previous.value != next.value {
+                    next.last_update = Utc::now();
+                }
+            }
+        }
+    }
+
     async fn generate_synthetics(&mut self) -> Result<(), Error> {
         let now = Utc::now();
 

core/src/service/updater.rs

@@ -58,7 +58,8 @@ impl InfallibleUpdater for ReportedStateUpdater {
                             let e = e.get_mut();
                             if e.value != value {
                                 e.value = value;
-                                e.last_update = Utc::now();
+                                // don't need to update the last_updated, as the system will ensure
+                                // that for us later on
                             }
                         }
                         Entry::Vacant(e) => {

examples/10_basic.adoc

@@ -37,11 +37,21 @@ http PUT localhost:8080/api/v1alpha1/things/default/things/foo/reportedStates te
 
 == Patch a thing
 
+With a JSON patch:
+
 [source,shell]
 ----
 http PATCH localhost:8080/api/v1alpha1/things/default/things/foo content-type:application/json-patch+json '[0][op]=replace' '[0][path]=/reportedState/temperature/value' '[0][value]=43'
 ----
 
+Or with a strategic merge:
+
+[source,shell]
+----
+http PATCH localhost:8080/api/v1alpha1/things/default/things/foo content-type:application/merge-patch+json 'reportedState[temperature][value]:=43'
+----
+
+
 === Remove an annotation
 
 [source,shell]