abstract expoential backoff to math utils.

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/utils/math.rs

@@ -24,3 +24,21 @@ macro_rules! validated {
 macro_rules! validated {
 	($($input:tt)*) => { $crate::checked!($($input)*) }
 }
+
+/// Returns false if the exponential backoff has expired based on the inputs
+#[inline]
+#[must_use]
+pub fn continue_exponential_backoff_secs(min: u64, max: u64, elapsed: Duration, tries: u32) -> bool {
+	let min = Duration::from_secs(min);
+	let max = Duration::from_secs(max);
+	continue_exponential_backoff(min, max, elapsed, tries)
+}
+
+/// Returns false if the exponential backoff has expired based on the inputs
+#[inline]
+#[must_use]
+pub fn continue_exponential_backoff(min: Duration, max: Duration, elapsed: Duration, tries: u32) -> bool {
+	let min = min.saturating_mul(tries).saturating_mul(tries);
+	let min = cmp::min(min, max);
+	elapsed < min
+}