move exponential backoff util to different submod

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

src/core/utils/time/exponential_backoff.rs

@@ -0,0 +1,29 @@
+use std::{cmp, time::Duration};
+
+/// 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
+}