queue the meta update only until one run succeeds

docs/swarm/builder.md

@@ -143,8 +143,9 @@ running rev (`services.hyperhive.c0re.hyperhiveRev`, from `self.rev`):
 
 The controller commits `flake.nix` and the returned `flake.lock` to
 `internal/meta` in one commit, and gives each hive's forge account read on the
-repo. It re-renders when it starts and every ten minutes after (a tick skips
+repo. It re-renders when it starts, and again every ten minutes while the latest
-while an update is pending or running), before it deploys a merged config PR, and
+update hasn't succeeded (a tick adds nothing while one is pending or running,
+or after a success), before it deploys a merged config PR, and
 before the first deploy of a new agent. Those deploys run whether or not the
 update succeeded: a hive that builds from `internal/meta` does so only while it
 pins the agent's current config (see

swarm-controller/src/jobq.rs

@@ -1467,13 +1467,14 @@ pub(crate) fn queue_builder_forge_token_mint(
         .map_err(|e| anyhow::anyhow!("{e}"))
 }
 
-/// How often [`spawn_meta_update_timer`] queues an `UpdateMeta`.
+/// How often [`spawn_meta_update_timer`] looks at the last `UpdateMeta`.
 const META_UPDATE_INTERVAL: std::time::Duration = std::time::Duration::from_mins(10);
 
-/// Queue an `UpdateMeta` now and every [`META_UPDATE_INTERVAL`] after, so a
+/// Look at the last `UpdateMeta` now and every [`META_UPDATE_INTERVAL`] after,
-/// boot run that failed or hung, and drift the config-merge path did not see,
+/// and queue one when none has run yet or the latest did not succeed, so a
-/// are picked up. A tick that finds the previous run pending, running or
+/// boot run that failed or hung is retried. The first tick is the boot run.
-/// finishing queues nothing.
+/// Once a run has succeeded a tick adds nothing: the graph keeps every node,
+/// so a clock-driven node per tick would grow it without bound.
 pub(crate) fn spawn_meta_update_timer(
     sched: Arc<Mutex<hive_jobq::scheduler::Scheduler<SwarmNodeKind, SwarmResourceKind>>>,
 ) {
@@ -1488,21 +1489,32 @@ pub(crate) fn spawn_meta_update_timer(
     });
 }
 
-/// Insert one `UpdateMeta` job unless one is still in flight, which reads the
+/// Insert one `UpdateMeta` job when none is in flight and the latest one, by
-/// same heads when it runs. Returns whether a job was inserted.
+/// node id, is not `Done` (or none exists). Returns whether a job was inserted.
 fn queue_meta_update(
     sched: &Mutex<hive_jobq::scheduler::Scheduler<SwarmNodeKind, SwarmResourceKind>>,
 ) -> Result<bool> {
     let mut sched = sched
         .lock()
         .unwrap_or_else(std::sync::PoisonError::into_inner);
-    let in_flight = sched.graph().nodes().any(|n| {
+    let mut update_metas = sched
+        .graph()
+        .nodes()
+        .filter(|n| matches!(n.payload, SwarmNodeKind::UpdateMeta))
+        .collect::<Vec<_>>();
+    if update_metas.iter().any(|n| {
         matches!(
             n.state,
             hive_jobq::State::Pending | hive_jobq::State::Running | hive_jobq::State::Finishing
-        ) && matches!(n.payload, SwarmNodeKind::UpdateMeta)
+        )
-    });
+    }) {
-    if in_flight {
+        return Ok(false);
+    }
+    update_metas.sort_by_key(|n| n.id);
+    if update_metas
+        .last()
+        .is_some_and(|n| n.state == hive_jobq::State::Done)
+    {
         return Ok(false);
     }
     sched
@@ -3115,17 +3127,29 @@ mod tests {
         assert_eq!(labels, ["create_forge_user", "mint_agent_forge_token"]);
     }
 
-    /// The timer's tick queues an `UpdateMeta` when none is in flight, and
+    /// A scheduler holding one `UpdateMeta` that ran and ended `outcome`.
-    /// queues nothing while one is pending or running; once it is done the
+    async fn after_one_update_meta(
-    /// next tick queues again.
+        outcome: hive_jobq::scheduler::Outcome,
-    #[tokio::test]
+    ) -> std::sync::Arc<
-    async fn the_meta_timer_queues_unless_one_is_in_flight() {
+        std::sync::Mutex<hive_jobq::scheduler::Scheduler<SwarmNodeKind, SwarmResourceKind>>,
+    > {
         let sched =
             std::sync::Arc::new(std::sync::Mutex::new(hive_jobq::scheduler::Scheduler::new(
                 hive_jobq::Graph::new(),
                 hive_jobq::resources::ResourceTable::new(),
             )));
-        let update_metas = || {
+        assert!(super::queue_meta_update(&sched).expect("tick"));
+        hive_jobq::scheduler::Scheduler::claim_next(&sched, |_, _, b| async move { (b, outcome) })
+            .expect("runnable")
+            .await
+            .1
+            .expect("no growth");
+        sched
+    }
+
+    fn update_metas(
+        sched: &std::sync::Mutex<hive_jobq::scheduler::Scheduler<SwarmNodeKind, SwarmResourceKind>>,
+    ) -> usize {
         sched
             .lock()
             .unwrap()
@@ -3133,22 +3157,56 @@ mod tests {
             .nodes()
             .filter(|n| matches!(n.payload, SwarmNodeKind::UpdateMeta))
             .count()
-        };
+    }
+
+    /// With none run yet the tick queues one, and queues no second while that
+    /// one is pending or running.
+    #[tokio::test]
+    async fn the_meta_timer_queues_first_and_skips_while_one_is_in_flight() {
+        let sched =
+            std::sync::Arc::new(std::sync::Mutex::new(hive_jobq::scheduler::Scheduler::new(
+                hive_jobq::Graph::new(),
+                hive_jobq::resources::ResourceTable::new(),
+            )));
         assert!(super::queue_meta_update(&sched).expect("tick"));
-        assert_eq!(update_metas(), 1);
         assert!(!super::queue_meta_update(&sched).expect("tick"));
-        assert_eq!(update_metas(), 1, "a pending one blocks the tick");
+        assert_eq!(update_metas(&sched), 1, "a pending one blocks the tick");
 
         let running = hive_jobq::scheduler::Scheduler::claim_next(&sched, |_, _, b| async move {
-            (b, hive_jobq::scheduler::Outcome::Done)
+            (b, hive_jobq::scheduler::Outcome::Failed("late".to_owned()))
         })
         .expect("runnable");
         assert!(!super::queue_meta_update(&sched).expect("tick"));
-        assert_eq!(update_metas(), 1, "a running one blocks the tick");
+        assert_eq!(update_metas(&sched), 1, "a running one blocks the tick");
-
         running.await.1.expect("no growth");
+    }
+
+    /// Once the latest run succeeded, ticks add no node.
+    #[tokio::test]
+    async fn the_meta_timer_adds_nothing_after_a_success() {
+        let sched = after_one_update_meta(hive_jobq::scheduler::Outcome::Done).await;
+        for _ in 0..3 {
+            assert!(!super::queue_meta_update(&sched).expect("tick"));
+        }
+        assert_eq!(update_metas(&sched), 1);
+    }
+
+    /// A failed latest run is retried; a success after it ends the retries.
+    #[tokio::test]
+    async fn the_meta_timer_retries_after_a_failure_until_a_success() {
+        let sched =
+            after_one_update_meta(hive_jobq::scheduler::Outcome::Failed("no".to_owned())).await;
         assert!(super::queue_meta_update(&sched).expect("tick"));
-        assert_eq!(update_metas(), 2, "a finished one does not");
+        assert_eq!(update_metas(&sched), 2);
+        hive_jobq::scheduler::Scheduler::claim_next(&sched, |_, _, b| async move {
+            (b, hive_jobq::scheduler::Outcome::Done)
+        })
+        .expect("runnable")
+        .await
+        .1
+        .expect("no growth");
+        assert!(!super::queue_meta_update(&sched).expect("tick"));
+        assert_eq!(update_metas(&sched), 2);
     }
 }