feat: basic kratactl top command (#72)

* feat: basic kratactl top command

* fix: use magic bytes 0xff 0xff in idm to improve reliability

crates/ctl/src/metrics.rs

@@ -0,0 +1,159 @@
+use anyhow::Result;
+use krata::{
+    events::EventStream,
+    v1::{
+        common::{Guest, GuestMetricNode, GuestStatus},
+        control::{
+            control_service_client::ControlServiceClient, watch_events_reply::Event,
+            ListGuestsRequest, ReadGuestMetricsRequest,
+        },
+    },
+};
+use log::error;
+use std::time::Duration;
+use tokio::{
+    select,
+    sync::mpsc::{channel, Receiver, Sender},
+    task::JoinHandle,
+    time::{sleep, timeout},
+};
+use tonic::transport::Channel;
+
+use crate::format::metrics_value_pretty;
+
+pub struct MetricState {
+    pub guest: Guest,
+    pub root: Option<GuestMetricNode>,
+}
+
+pub struct MultiMetricState {
+    pub guests: Vec<MetricState>,
+}
+
+pub struct MultiMetricCollector {
+    client: ControlServiceClient<Channel>,
+    events: EventStream,
+    period: Duration,
+}
+
+pub struct MultiMetricCollectorHandle {
+    pub receiver: Receiver<MultiMetricState>,
+    task: JoinHandle<()>,
+}
+
+impl Drop for MultiMetricCollectorHandle {
+    fn drop(&mut self) {
+        self.task.abort();
+    }
+}
+
+impl MultiMetricCollector {
+    pub fn new(
+        client: ControlServiceClient<Channel>,
+        events: EventStream,
+        period: Duration,
+    ) -> Result<MultiMetricCollector> {
+        Ok(MultiMetricCollector {
+            client,
+            events,
+            period,
+        })
+    }
+
+    pub async fn launch(mut self) -> Result<MultiMetricCollectorHandle> {
+        let (sender, receiver) = channel::<MultiMetricState>(100);
+        let task = tokio::task::spawn(async move {
+            if let Err(error) = self.process(sender).await {
+                error!("failed to process multi metric collector: {}", error);
+            }
+        });
+        Ok(MultiMetricCollectorHandle { receiver, task })
+    }
+
+    pub async fn process(&mut self, sender: Sender<MultiMetricState>) -> Result<()> {
+        let mut events = self.events.subscribe();
+        let mut guests: Vec<Guest> = self
+            .client
+            .list_guests(ListGuestsRequest {})
+            .await?
+            .into_inner()
+            .guests;
+        loop {
+            let collect = select! {
+                x = events.recv() => match x {
+                    Ok(event) => {
+                        if let Event::GuestChanged(changed) = event {
+                            let Some(guest) = changed.guest else {
+                                continue;
+                            };
+                            let Some(ref state) = guest.state else {
+                                continue;
+                            };
+                            guests.retain(|x| x.id != guest.id);
+                            if state.status() != GuestStatus::Destroying {
+                                guests.push(guest);
+                            }
+                        }
+                        false
+                    },
+
+                    Err(error) => {
+                        return Err(error.into());
+                    }
+                },
+
+                _ = sleep(self.period) => {
+                    true
+                }
+            };
+
+            if !collect {
+                continue;
+            }
+
+            let mut metrics = Vec::new();
+            for guest in &guests {
+                let Some(ref state) = guest.state else {
+                    continue;
+                };
+
+                if state.status() != GuestStatus::Started {
+                    continue;
+                }
+
+                let root = timeout(
+                    Duration::from_secs(5),
+                    self.client.read_guest_metrics(ReadGuestMetricsRequest {
+                        guest_id: guest.id.clone(),
+                    }),
+                )
+                .await
+                .ok()
+                .and_then(|x| x.ok())
+                .map(|x| x.into_inner())
+                .and_then(|x| x.root);
+                metrics.push(MetricState {
+                    guest: guest.clone(),
+                    root,
+                });
+            }
+            sender.send(MultiMetricState { guests: metrics }).await?;
+        }
+    }
+}
+
+pub fn lookup<'a>(node: &'a GuestMetricNode, path: &str) -> Option<&'a GuestMetricNode> {
+    let Some((what, b)) = path.split_once('/') else {
+        return node.children.iter().find(|x| x.name == path);
+    };
+    let next = node.children.iter().find(|x| x.name == what)?;
+    return lookup(next, b);
+}
+
+pub fn lookup_metric_value(node: &GuestMetricNode, path: &str) -> Option<String> {
+    lookup(node, path).and_then(|x| {
+        x.value
+            .as_ref()
+            .map(|v| metrics_value_pretty(v.clone(), x.format()))
+    })
+}