Left-right single-writer, multi-reader index

src/ingest.rs

@@ -2,11 +2,10 @@ use std::collections::BTreeMap;
 use std::path::{Path, PathBuf};
 use std::time::Duration;
 
-use crate::engine::{EngineMessage, IngestedLine, MetricSample};
+use crate::engine::{EngineHandle, EngineMessage, IngestedLine, MetricSample};
 use crate::timestamp::Timestamp;
 use tokio::fs::File;
 use tokio::io::{AsyncBufReadExt, BufReader};
-use tokio::sync::mpsc;
 
 const POLL_INTERVAL: Duration = Duration::from_millis(200);
 
@@ -14,7 +13,7 @@ const METRICS_POLL_INTERVAL: Duration = Duration::from_secs(15);
 
 /// Reads stdin line by line, sequences and timestamps each line, and forwards it
 /// to the engine task.
-pub async fn run(engine: mpsc::Sender<EngineMessage>) {
+pub async fn run(engine: EngineHandle) {
     let stdin = tokio::io::stdin();
     let mut lines = BufReader::new(stdin).lines();
     let mut sequence: u64 = 0;
@@ -27,7 +26,7 @@ pub async fn run(engine: mpsc::Sender<EngineMessage>) {
         };
         sequence += 1;
 
-        if engine.send(EngineMessage::Ingest(line)).await.is_err() {
+        if engine.tx.send(EngineMessage::Ingest(line)).await.is_err() {
             break;
         }
     }
@@ -59,7 +58,7 @@ async fn open(path: &Path) -> Option<(File, FileId)> {
 /// Tails `path` like `tail -f`, resuming from the start if the file is deleted/recreated or
 /// truncated in place rather than exiting or getting stuck; `sequence` keeps incrementing
 /// across a recreation since it's ottyl's own line counter, not tied to the source file.
-pub async fn run_file(engine: mpsc::Sender<EngineMessage>, path: PathBuf) {
+pub async fn run_file(engine: EngineHandle, path: PathBuf) {
     let mut sequence: u64 = 0;
 
     'reopen: loop {
@@ -109,7 +108,7 @@ pub async fn run_file(engine: mpsc::Sender<EngineMessage>, path: PathBuf) {
                         };
                         sequence += 1;
 
-                        if engine.send(EngineMessage::Ingest(line)).await.is_err() {
+                        if engine.tx.send(EngineMessage::Ingest(line)).await.is_err() {
                             return;
                         }
                     }
@@ -124,7 +123,7 @@ pub async fn run_file(engine: mpsc::Sender<EngineMessage>, path: PathBuf) {
 /// Polls `url` on a fixed interval for a Prometheus/OpenMetrics-format response, pushing every parsed
 /// sample straight into the engine. Errors (unreachable endpoint, non-2xx response) are only logged —
 /// polling keeps retrying on the next tick rather than exiting.
-pub async fn run_metrics_poll(engine: mpsc::Sender<EngineMessage>, url: String) {
+pub async fn run_metrics_poll(engine: EngineHandle, url: String) {
     let client = reqwest::Client::new();
     loop {
         match client.get(&url).send().await {
@@ -133,7 +132,7 @@ pub async fn run_metrics_poll(engine: mpsc::Sender<EngineMessage>, url: String)
                     Ok(body) => {
                         let now = Timestamp::now();
                         for sample in parse_openmetrics(&body, now) {
-                            if engine.send(EngineMessage::IngestMetricSample(sample)).await.is_err() {
+                            if engine.tx.send(EngineMessage::IngestMetricSample(sample)).await.is_err() {
                                 return;
                             }
                         }
@@ -239,6 +238,7 @@ mod openmetrics_tests {
 mod tests {
     use super::*;
     use std::io::Write;
+    use crate::engine::test_handle;
     use tokio::sync::mpsc;
 
     async fn recv_text(rx: &mut mpsc::Receiver<EngineMessage>) -> String {
@@ -258,7 +258,7 @@ mod tests {
         let path = dir.path().join("app.log");
         std::fs::write(&path, "first\n").unwrap();
 
-        let (tx, mut rx) = mpsc::channel(16);
+        let (tx, mut rx) = test_handle(16);
         tokio::spawn(run_file(tx, path.clone()));
 
         assert_eq!(recv_text(&mut rx).await, "first");
@@ -274,7 +274,7 @@ mod tests {
         let path = dir.path().join("app.log");
         std::fs::write(&path, "before-restart\n").unwrap();
 
-        let (tx, mut rx) = mpsc::channel(16);
+        let (tx, mut rx) = test_handle(16);
         tokio::spawn(run_file(tx, path.clone()));
 
         assert_eq!(recv_text(&mut rx).await, "before-restart");
@@ -291,7 +291,7 @@ mod tests {
         let path = dir.path().join("app.log");
         std::fs::write(&path, "long line before truncation\n").unwrap();
 
-        let (tx, mut rx) = mpsc::channel(16);
+        let (tx, mut rx) = test_handle(16);
         tokio::spawn(run_file(tx, path.clone()));
 
         assert_eq!(recv_text(&mut rx).await, "long line before truncation");
@@ -312,7 +312,7 @@ mod tests {
         let path = dir.path().join("app.log");
         std::fs::write(&path, "one\n").unwrap();
 
-        let (tx, mut rx) = mpsc::channel(16);
+        let (tx, mut rx) = test_handle(16);
         tokio::spawn(run_file(tx, path.clone()));
 
         let first = match tokio::time::timeout(Duration::from_secs(2), rx.recv())