From 08584f65709630e2e51b915d991ed53951b5620b Mon Sep 17 00:00:00 2001
From: Dan Nixon <dan@dan-nixon.com>
Date: Sun, 12 May 2024 21:51:42 +0100
Subject: [PATCH] Use an interval to drive schedule updates in announcer

---
 client/src/announcer/mod.rs   | 25 ++++++++++---------------
 client/src/announcer/utils.rs |  9 +++------
 2 files changed, 13 insertions(+), 21 deletions(-)

diff --git a/client/src/announcer/mod.rs b/client/src/announcer/mod.rs
index ea58439..30604a6 100644
--- a/client/src/announcer/mod.rs
+++ b/client/src/announcer/mod.rs
@@ -8,7 +8,7 @@ use crate::{
 };
 use chrono::{DateTime, Duration as ChronoDuration, FixedOffset, Utc};
 use derive_builder::Builder;
-use tokio::time::{Duration as TokioDuration, Instant};
+use tokio::time::{Duration as TokioDuration, Interval};
 use tracing::{debug, info, warn};
 
 #[derive(Debug, Builder)]
@@ -65,30 +65,30 @@ impl From<&Event> for LastNotifiedEventMarker {
 
 pub struct Announcer {
     settings: AnnouncerSettings,
-
     client: Client,
-
     schedule: Schedule,
-    schedule_timestamp: Instant,
-
+    schedule_update_interval: Interval,
     last_notified_event_marker: Option<LastNotifiedEventMarker>,
 }
 
 impl Announcer {
     pub async fn new(settings: AnnouncerSettings, client: Client) -> crate::Result<Self> {
-        let (schedule, schedule_timestamp) = self::utils::get_sorted_schedule(&client).await?;
+        let schedule = self::utils::get_sorted_schedule(&client).await?;
+
+        let mut schedule_update_interval = tokio::time::interval(settings.schedule_refresh);
+        schedule_update_interval.reset();
 
         Ok(Self {
             settings,
             client,
             schedule,
-            schedule_timestamp,
+            schedule_update_interval,
             last_notified_event_marker: None,
         })
     }
 
     async fn update_schedule(&mut self) -> crate::Result<AnnouncerScheduleChanges> {
-        let (schedule, schedule_timestamp) = self::utils::get_sorted_schedule(&self.client).await?;
+        let schedule = self::utils::get_sorted_schedule(&self.client).await?;
 
         let changes = if self.schedule == schedule {
             debug!("No changes in new schedule");
@@ -99,17 +99,12 @@ impl Announcer {
         };
 
         self.schedule = schedule;
-        self.schedule_timestamp = schedule_timestamp;
 
         Ok(changes)
     }
 
     pub async fn poll(&mut self) -> crate::Result<AnnouncerPollResult> {
         loop {
-            // Calculate when the next schedule refresh is due
-            let next_schedule_update_time =
-                self.schedule_timestamp + self.settings.schedule_refresh;
-
             // Determine what the next event to announce is and in how much time it is due to be announced
             let next_event = self.get_next_event_to_announce();
             let event_wait_time = match next_event {
@@ -125,13 +120,13 @@ impl Announcer {
             // Wait for one of several things to happen...
             tokio::select! {
                 // 1. The schedule is refreshed at the requested interval
-                _ = tokio::time::sleep_until(next_schedule_update_time) => {
+                _ = self.schedule_update_interval.tick() => {
                     match self.update_schedule().await {
                         Ok(changes) => {
                             return Ok(AnnouncerPollResult::ScheduleRefreshed(changes))
                         },
                         Err(e) => {
-                            warn!("Failed to update schedule {e}")
+                            warn!("Failed to update schedule: {e}")
                         },
                     }
                 }
diff --git a/client/src/announcer/utils.rs b/client/src/announcer/utils.rs
index 0a32b0e..60ee5e7 100644
--- a/client/src/announcer/utils.rs
+++ b/client/src/announcer/utils.rs
@@ -7,16 +7,13 @@ use crate::{
     Client,
 };
 use chrono::{DateTime, Duration as ChronoDuration, FixedOffset};
-use tokio::time::{Duration as TokioDuration, Instant};
+use tokio::time::Duration as TokioDuration;
 use tracing::warn;
 
-pub(super) async fn get_sorted_schedule(client: &Client) -> crate::Result<(Schedule, Instant)> {
+pub(super) async fn get_sorted_schedule(client: &Client) -> crate::Result<Schedule> {
     let mut schedule = client.get_schedule().await?;
     schedule.mutate(&Mutators::new_single(Box::new(SortedByStartTime {})));
-
-    let now = Instant::now();
-
-    Ok((schedule, now))
+    Ok(schedule)
 }
 
 pub(super) fn get_duration_before_event_notification(