fix(metrics): run a separate task for utilization metric to ensure it is regularly updated

changelog.d/22070_utilization_metric_periodic_emit.fix.md

@@ -0,0 +1,3 @@
+The `utilization` metric is now properly published periodically, even when no events are flowing through the components.
+
+authors: esensar

src/topology/builder.rs

@@ -8,6 +8,7 @@ use std::{
 
 use futures::{stream::FuturesOrdered, FutureExt, StreamExt, TryStreamExt};
 use futures_util::stream::FuturesUnordered;
+use metrics::gauge;
 use stream_cancel::{StreamExt as StreamCancelExt, Trigger, Tripwire};
 use tokio::{
     select,
@@ -51,7 +52,7 @@ use crate::{
     spawn_named,
     topology::task::TaskError,
     transforms::{SyncTransform, TaskTransform, Transform, TransformOutputs, TransformOutputsBuf},
-    utilization::wrap,
+    utilization::{wrap, UtilizationEmitter, UtilizationTimerMessage},
     SourceSender,
 };
 
@@ -84,6 +85,7 @@ struct Builder<'a> {
     healthchecks: HashMap<ComponentKey, Task>,
     detach_triggers: HashMap<ComponentKey, Trigger>,
     extra_context: ExtraContext,
+    utilization_emitter: UtilizationEmitter,
 }
 
 impl<'a> Builder<'a> {
@@ -105,6 +107,7 @@ impl<'a> Builder<'a> {
             healthchecks: HashMap::new(),
             detach_triggers: HashMap::new(),
             extra_context,
+            utilization_emitter: UtilizationEmitter::new(),
         }
     }
 
@@ -128,6 +131,7 @@ impl<'a> Builder<'a> {
                 healthchecks: self.healthchecks,
                 shutdown_coordinator: self.shutdown_coordinator,
                 detach_triggers: self.detach_triggers,
+                utilization_emitter: Some(self.utilization_emitter),
             })
         } else {
             Err(self.errors)
@@ -497,7 +501,7 @@ impl<'a> Builder<'a> {
 
             let (transform_task, transform_outputs) = {
                 let _span = span.enter();
-                build_transform(transform, node, input_rx)
+                build_transform(transform, node, input_rx, &mut self.utilization_emitter)
             };
 
             self.outputs.extend(transform_outputs);
@@ -506,6 +510,7 @@ impl<'a> Builder<'a> {
     }
 
     async fn build_sinks(&mut self, enrichment_tables: &vector_lib::enrichment::TableRegistry) {
+        let utilization_sender = self.utilization_emitter.get_sender();
         for (key, sink) in self
             .config
             .sinks()
@@ -585,6 +590,10 @@ impl<'a> Builder<'a> {
 
             let (trigger, tripwire) = Tripwire::new();
 
+            self.utilization_emitter
+                .add_component(key.clone(), gauge!("utilization"));
+            let utilization_sender = utilization_sender.clone();
+            let component_key = key.clone();
             let sink = async move {
                 debug!("Sink starting.");
 
@@ -600,7 +609,7 @@ impl<'a> Builder<'a> {
                     .take()
                     .expect("Task started but input has been taken.");
 
-                let mut rx = wrap(rx);
+                let mut rx = wrap(utilization_sender, component_key.clone(), rx);
 
                 let events_received = register!(EventsReceived);
                 sink.run(
@@ -682,6 +691,7 @@ pub struct TopologyPieces {
     pub(super) healthchecks: HashMap<ComponentKey, Task>,
     pub(crate) shutdown_coordinator: SourceShutdownCoordinator,
     pub(crate) detach_triggers: HashMap<ComponentKey, Trigger>,
+    pub(crate) utilization_emitter: Option<UtilizationEmitter>,
 }
 
 impl TopologyPieces {
@@ -760,18 +770,22 @@ fn build_transform(
     transform: Transform,
     node: TransformNode,
     input_rx: BufferReceiver<EventArray>,
+    utilization_emitter: &mut UtilizationEmitter,
 ) -> (Task, HashMap<OutputId, fanout::ControlChannel>) {
     match transform {
         // TODO: avoid the double boxing for function transforms here
-        Transform::Function(t) => build_sync_transform(Box::new(t), node, input_rx),
-        Transform::Synchronous(t) => build_sync_transform(t, node, input_rx),
+        Transform::Function(t) => {
+            build_sync_transform(Box::new(t), node, input_rx, utilization_emitter)
+        }
+        Transform::Synchronous(t) => build_sync_transform(t, node, input_rx, utilization_emitter),
         Transform::Task(t) => build_task_transform(
             t,
             input_rx,
             node.input_details.data_type(),
             node.typetag,
             &node.key,
             &node.outputs,
+            utilization_emitter,
         ),
     }
 }
@@ -780,10 +794,19 @@ fn build_sync_transform(
     t: Box<dyn SyncTransform>,
     node: TransformNode,
     input_rx: BufferReceiver<EventArray>,
+    utilization_emitter: &mut UtilizationEmitter,
 ) -> (Task, HashMap<OutputId, fanout::ControlChannel>) {
     let (outputs, controls) = TransformOutputs::new(node.outputs, &node.key);
 
-    let runner = Runner::new(t, input_rx, node.input_details.data_type(), outputs);
+    utilization_emitter.add_component(node.key.clone(), gauge!("utilization"));
+    let runner = Runner::new(
+        t,
+        input_rx,
+        utilization_emitter.get_sender(),
+        node.key.clone(),
+        node.input_details.data_type(),
+        outputs,
+    );
     let transform = if node.enable_concurrency {
         runner.run_concurrently().boxed()
     } else {
@@ -823,15 +846,17 @@ struct Runner {
     input_rx: Option<BufferReceiver<EventArray>>,
     input_type: DataType,
     outputs: TransformOutputs,
-    timer: crate::utilization::Timer,
-    last_report: Instant,
+    key: ComponentKey,
+    timer_tx: UnboundedSender<UtilizationTimerMessage>,
     events_received: Registered<EventsReceived>,
 }
 
 impl Runner {
     fn new(
         transform: Box<dyn SyncTransform>,
         input_rx: BufferReceiver<EventArray>,
+        timer_tx: UnboundedSender<UtilizationTimerMessage>,
+        key: ComponentKey,
         input_type: DataType,
         outputs: TransformOutputs,
     ) -> Self {
@@ -840,17 +865,22 @@ impl Runner {
             input_rx: Some(input_rx),
             input_type,
             outputs,
-            timer: crate::utilization::Timer::new(),
-            last_report: Instant::now(),
+            key,
+            timer_tx,
             events_received: register!(EventsReceived),
         }
     }
 
     fn on_events_received(&mut self, events: &EventArray) {
-        let stopped = self.timer.stop_wait();
-        if stopped.duration_since(self.last_report).as_secs() >= 5 {
-            self.timer.report();
-            self.last_report = stopped;
+        if self
+            .timer_tx
+            .send(UtilizationTimerMessage::StopWait(
+                self.key.clone(),
+                Instant::now(),
+            ))
+            .is_err()
+        {
+            debug!(component_id = ?self.key, "Couldn't send utilization stop wait message from sync transform.");
         }
 
         self.events_received.emit(CountByteSize(
@@ -860,7 +890,16 @@ impl Runner {
     }
 
     async fn send_outputs(&mut self, outputs_buf: &mut TransformOutputsBuf) -> crate::Result<()> {
-        self.timer.start_wait();
+        if self
+            .timer_tx
+            .send(UtilizationTimerMessage::StartWait(
+                self.key.clone(),
+                Instant::now(),
+            ))
+            .is_err()
+        {
+            debug!(component_id = ?self.key, "Couldn't send utilization start wait message from sync transform.");
+        }
         self.outputs.send(outputs_buf).await
     }
 
@@ -877,7 +916,16 @@ impl Runner {
             .into_stream()
             .filter(move |events| ready(filter_events_type(events, self.input_type)));
 
-        self.timer.start_wait();
+        if self
+            .timer_tx
+            .send(UtilizationTimerMessage::StartWait(
+                self.key.clone(),
+                Instant::now(),
+            ))
+            .is_err()
+        {
+            debug!(component_id = ?self.key, "Couldn't send utilization start wait message from sync transform.");
+        }
         while let Some(events) = input_rx.next().await {
             self.on_events_received(&events);
             self.transform.transform_all(events, &mut outputs_buf);
@@ -903,7 +951,16 @@ impl Runner {
         let mut in_flight = FuturesOrdered::new();
         let mut shutting_down = false;
 
-        self.timer.start_wait();
+        if self
+            .timer_tx
+            .send(UtilizationTimerMessage::StartWait(
+                self.key.clone(),
+                Instant::now(),
+            ))
+            .is_err()
+        {
+            debug!(component_id = ?self.key, "Couldn't send utilization start wait message from sync transform.");
+        }
         loop {
             tokio::select! {
                 biased;
@@ -964,10 +1021,16 @@ fn build_task_transform(
     typetag: &str,
     key: &ComponentKey,
     outputs: &[TransformOutput],
+    utilization_emitter: &mut UtilizationEmitter,
 ) -> (Task, HashMap<OutputId, fanout::ControlChannel>) {
     let (mut fanout, control) = Fanout::new();
 
-    let input_rx = crate::utilization::wrap(input_rx.into_stream());
+    utilization_emitter.add_component(key.clone(), gauge!("utilization"));
+    let input_rx = wrap(
+        utilization_emitter.get_sender(),
+        key.clone(),
+        input_rx.into_stream(),
+    );
 
     let events_received = register!(EventsReceived);
     let filtered = input_rx

src/topology/running.rs

@@ -7,11 +7,10 @@ use std::{
 };
 
 use super::{
-    builder,
-    builder::TopologyPieces,
+    builder::{self, TopologyPieces},
     fanout::{ControlChannel, ControlMessage},
     handle_errors, retain, take_healthchecks,
-    task::TaskOutput,
+    task::{Task, TaskOutput},
     BuiltBuffer, TaskHandle,
 };
 use crate::{
@@ -28,9 +27,9 @@ use tokio::{
     time::{interval, sleep_until, Duration, Instant},
 };
 use tracing::Instrument;
-use vector_lib::buffers::topology::channel::BufferSender;
 use vector_lib::tap::topology::{TapOutput, TapResource, WatchRx, WatchTx};
 use vector_lib::trigger::DisabledTrigger;
+use vector_lib::{buffers::topology::channel::BufferSender, shutdown::ShutdownSignal};
 
 pub type ShutdownErrorReceiver = mpsc::UnboundedReceiver<ShutdownError>;
 
@@ -49,6 +48,7 @@ pub struct RunningTopology {
     watch: (WatchTx, WatchRx),
     pub(crate) running: Arc<AtomicBool>,
     graceful_shutdown_duration: Option<Duration>,
+    utilization_task: Option<TaskHandle>,
 }
 
 impl RunningTopology {
@@ -67,6 +67,7 @@ impl RunningTopology {
             running: Arc::new(AtomicBool::new(true)),
             graceful_shutdown_duration: config.graceful_shutdown_duration,
             config,
+            utilization_task: None,
         }
     }
 
@@ -1042,6 +1043,7 @@ impl RunningTopology {
             return None;
         }
 
+        let mut utilization_emitter = pieces.utilization_emitter.take().unwrap();
         let mut running_topology = Self::new(config, abort_tx);
 
         if !running_topology
@@ -1053,6 +1055,17 @@ impl RunningTopology {
         running_topology.connect_diff(&diff, &mut pieces).await;
         running_topology.spawn_diff(&diff, pieces);
 
+        running_topology.utilization_task =
+            // TODO: how to name this custom task?
+            Some(tokio::spawn(Task::new("".into(), "", async move {
+                utilization_emitter
+                    .run_utilization(ShutdownSignal::noop())
+                    .await;
+                // TODO: new task output type for this? Or handle this task in a completely
+                // different way
+                Ok(TaskOutput::Healthcheck)
+            })));
+
         Some((running_topology, abort_rx))
     }
 }