36 lines
1.2 KiB
Rust
36 lines
1.2 KiB
Rust
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//! Background sampler: periodically collects metrics and updates a JSON cache,
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//! so WS replies are just a read of the cached string.
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use crate::metrics::collect_metrics;
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use crate::state::AppState;
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//use serde_json::to_string;
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use tokio::task::JoinHandle;
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use tokio::time::{Duration, interval, MissedTickBehavior};
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pub fn spawn_sampler(state: AppState, period: Duration) -> JoinHandle<()> {
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tokio::spawn(async move {
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let idle_period = Duration::from_secs(10);
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loop {
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let active = state.client_count.load(std::sync::atomic::Ordering::Relaxed) > 0;
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let mut ticker = interval(if active { period } else { idle_period });
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ticker.set_missed_tick_behavior(MissedTickBehavior::Skip);
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ticker.tick().await;
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if !active {
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tokio::select! {
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_ = ticker.tick() => {},
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_ = state.wake_sampler.notified() => continue,
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}
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}
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if let Ok(json) = async {
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let m = collect_metrics(&state).await;
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serde_json::to_string(&m)
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}
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.await
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{
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*state.last_json.write().await = json;
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}
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}
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})
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}
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