refactor: clean up data init sleep duration code (#1101)

* refactor: clean up data init sleep duration code

* const

1 files changed, 25 insertions, 13 deletions

diff --git a/src/app/data_harvester.rs b/src/app/data_harvester.rs
index 362b7251..2f4633bf 100644
--- a/src/app/data_harvester.rs
+++ b/src/app/data_harvester.rs
@@ -194,20 +194,10 @@ impl DataCollector {
 
         self.update_data();
 
-        // Sleep a few seconds to avoid potentially weird data...
-        let sleep_duration = {
-            cfg_if::cfg_if! {
-                if #[cfg(target_os = "freebsd")] {
-                    // FreeBSD's min duration value is 1s, which is a bit too long for me so I'll accept the one-time
-                    // inaccuracy.
-                    std::time::Duration::from_millis(250)
-                } else {
-                    sysinfo::System::MINIMUM_CPU_UPDATE_INTERVAL + Duration::from_millis(1)
-                }
-            }
-        };
+        // Sleep a few seconds to avoid potentially weird data.
+        const SLEEP: Duration = get_sleep_duration();
 
-        std::thread::sleep(sleep_duration);
+        std::thread::sleep(SLEEP);
         self.data.cleanup();
     }
 
@@ -497,6 +487,28 @@ impl DataCollector {
     }
 }
 
+/// We set a sleep duration between 10ms and 250ms, ideally sysinfo's [`System::MINIMUM_CPU_UPDATE_INTERVAL`] + 1.
+///
+/// We bound the upper end to avoid waiting too long (e.g. FreeBSD is 1s, which I'm fine with losing
+/// accuracy on for the first refresh), and we bound the lower end just to avoid the off-chance that
+/// refreshing too quickly causes problems. This second case should only happen on unsupported
+/// systems via sysinfo, in which case [`System::MINIMUM_CPU_UPDATE_INTERVAL`] is defined as 0.
+///
+/// We also do `INTERVAL + 1` for some wiggle room, just in case.
+const fn get_sleep_duration() -> Duration {
+    const MIN_SLEEP: u64 = 10;
+    const MAX_SLEEP: u64 = 250;
+    const INTERVAL: u64 = System::MINIMUM_CPU_UPDATE_INTERVAL.as_millis() as u64;
+
+    if INTERVAL < MIN_SLEEP {
+        Duration::from_millis(MIN_SLEEP)
+    } else if INTERVAL > MAX_SLEEP {
+        Duration::from_millis(MAX_SLEEP)
+    } else {
+        Duration::from_millis(INTERVAL + 1)
+    }
+}
+
 #[cfg(target_os = "freebsd")]
 /// Deserialize [libxo](https://www.freebsd.org/cgi/man.cgi?query=libxo&apropos=0&sektion=0&manpath=FreeBSD+13.1-RELEASE+and+Ports&arch=default&format=html) JSON data
 fn deserialize_xo<T>(key: &str, data: &[u8]) -> Result<T, std::io::Error>