use async sleeps to handle delays

config.json

@@ -7,7 +7,7 @@
           "instance": {
             "type": "mdns",
             "service": "_switch-http._tcp.local",
-            "name": "lighthouse1"
+            "host": "lighthouse1"
           }
         },
         "query": "switch_state{instance=\"$instance\"}",

src/config.rs

@@ -17,7 +17,7 @@ pub enum ParameterError {
 pub enum Parameter {
     Mdns {
         service: String,
-        name: String,
+        host: String,
     },
     Value {
         value: String,
@@ -29,9 +29,9 @@ impl Parameter {
         match self {
             Parameter::Mdns {
                 service,
-                name
+                host
             } => {
-                match resolve_mdns(service, name).await? {
+                match resolve_mdns(service, host).await? {
                     Some(service) => Ok(format!("{}:{}", service.addr, service.port)),
                     None => Err(ParameterError::MdnsHostNotFound)
                 }
@@ -66,5 +66,5 @@ pub struct Config {
 #[derive(Debug, Clone, Deserialize)]
 pub struct Trigger {
     pub trigger: Condition,
-    pub action: Action
+    pub action: Action,
 }

src/main.rs

@@ -2,8 +2,6 @@ use main_error::MainError;
 use tokio::fs::File;
 use crate::config::Config;
 use crate::trigger::TriggerManager;
-use tokio::time::delay_for;
-use std::time::Duration;
 use tokio::prelude::*;
 
 mod config;
@@ -12,23 +10,17 @@ mod trigger;
 
 #[tokio::main]
 async fn main() -> Result<(), MainError> {
-    let args: Vec<String> = std::env::args().collect();
+    if let Some(path) = std::env::args().nth(1) {
+        let mut file = File::open(path).await?;
 
-    if args.len() < 2 {
-        println!("Usage {} config.json", args[0]);
+        let mut contents = vec![];
+        file.read_to_end(&mut contents).await?;
+        let config: Config = serde_json::from_slice(&contents)?;
+        let trigger_manager = TriggerManager::new(config);
+
+        Ok(trigger_manager.run_triggers().await?)
+    } else {
+        println!("Usage {} config.json", std::env::args().next().unwrap());
         return Ok(());
     }
-
-    let mut file = File::open("foo.txt").await?;
-
-    let mut contents = vec![];
-    file.read_to_end(&mut contents).await?;
-    let config: Config = serde_json::from_slice(&contents)?;
-    let trigger_manager = TriggerManager::new(config);
-
-    loop {
-        trigger_manager.poll_triggers().await?;
-
-        delay_for(Duration::from_secs(60)).await;
-    }
 }

src/trigger.rs

@@ -5,7 +5,7 @@ use prometheus_edge_detector::EdgeDetector;
 use futures_util::future::try_join_all;
 use std::time::{Duration, SystemTime};
 use reqwest::Client;
-
+use tokio::time::delay_for;
 
 pub struct TriggerManager {
     http_client: Client,
@@ -13,6 +13,14 @@ pub struct TriggerManager {
     triggers: Vec<Trigger>,
 }
 
+fn now() -> u64 {
+    SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs()
+}
+
+fn since(time: u64) -> u64 {
+    now().saturating_sub(time)
+}
+
 impl TriggerManager {
     pub fn new(config: Config) -> TriggerManager {
         let edge_detector = EdgeDetector::new(&config.prometheus_url);
@@ -24,24 +32,42 @@ impl TriggerManager {
         }
     }
 
-    pub async fn poll_triggers(&self) -> Result<(), MainError> {
-        let now = SystemTime::now().duration_since(SystemTime::UNIX_EPOCH).unwrap().as_secs();
-
-        for trigger in &self.triggers {
-            let delay = trigger.action.delay;
-            let query = interpolate_params(&trigger.trigger.query, &trigger.trigger.params).await?;
-            let edge = self.edge_detector.get_last_edge(&query, trigger.trigger.from, trigger.trigger.to, Duration::from_secs(delay * 2)).await?;
-
-            if let Some(edge) = edge {
-                let edge_from_now = now - edge;
-                if edge_from_now > delay && (edge_from_now - delay) < 60 {
-                    run_action(&trigger.action, &self.http_client).await?;
-                }
-            }
-        }
+    pub async fn run_triggers(&self) -> Result<(), MainError> {
+        try_join_all(self.triggers.iter().map(|trigger| {
+            self.run_trigger(trigger)
+        })).await?;
 
         Ok(())
     }
+
+    pub async fn run_trigger(&self, trigger: &Trigger) -> Result<(), MainError> {
+        let delay = trigger.action.delay;
+        let delay_duration = Duration::from_secs(delay);
+        loop {
+            let query = interpolate_params(&trigger.trigger.query, &trigger.trigger.params).await?;
+            let edge = self.edge_detector.get_last_edge(&query, trigger.trigger.from, trigger.trigger.to, Duration::from_secs(delay + 60)).await?;
+            if let Some(edge) = edge {
+                let elapsed = since(edge);
+                let wait = delay.saturating_sub(elapsed);
+                println!("Found edge, {}s ago, waiting {}s before triggering", elapsed, wait);
+                let wait_delay = Duration::from_secs(wait);
+                delay_for(wait_delay).await;
+
+                // verify that the previously found edge is still the most recent
+                let new_edge = self.edge_detector.get_last_edge(&query, trigger.trigger.from, trigger.trigger.to, Duration::from_secs(delay + 60)).await?;
+                if new_edge == Some(edge) {
+                    println!("Edge still valid, triggering");
+                    run_action(&trigger.action, &self.http_client).await?;
+                    delay_for(delay_duration).await;
+                } else {
+                    println!("Edge no longer value");
+                }
+            } else {
+                println!("No edge found, waiting {}s before looking for new edge", delay);
+                delay_for(delay_duration).await;
+            }
+        }
+    }
 }
 
 async fn interpolate_params(input: &str, params: &HashMap<String, Parameter>) -> Result<String, ParameterError> {