introduce duration based strategy

Author: MarinPostma

libsql-wal/src/swap_strategy/duration.rs

@@ -0,0 +1,30 @@
+use std::time::{Duration, Instant};
+
+use parking_lot::Mutex;
+
+use super::SwapStrategy;
+
+/// A wal swap strategy that swaps the current wal if it's older that some duration
+pub struct DurationSwapStrategy {
+    swap_after: Duration,
+    last_swapped_at: Mutex<Instant>,
+}
+
+impl DurationSwapStrategy {
+    pub fn new(swap_after: Duration) -> Self {
+        Self { swap_after, last_swapped_at: Mutex::new(Instant::now()) }
+    }
+}
+
+impl SwapStrategy for DurationSwapStrategy {
+    #[inline(always)]
+    fn should_swap(&self, _frames_in_wal: usize) -> bool {
+        let last_swapped_at = self.last_swapped_at.lock();
+        last_swapped_at.elapsed() >= self.swap_after
+    }
+
+    #[inline(always)]
+    fn swapped(&self) {
+        *self.last_swapped_at.lock() = Instant::now();
+    }
+}