Use exponential growth for O(1) amortizied complexity

NobodyXu · Oct 19, 2024 · 3dc2c1d · 3dc2c1d
1 parent 89b0efc
commit 3dc2c1d
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/src/arena.rs b/src/arena.rs
@@ -171,7 +171,10 @@ impl<T: Send + Sync, const BITARRAY_LEN: usize, const LEN: usize> Arena<T, BITAR
  // reservation.
  //
  // We can simply restart operation, waiting for it to be done.
- self.try_reserve(len + 4);
+ //
+ // Grow by 1.5 exponential to have amoritized O(1), adding +4 more in case
+ // there's only one element (1 * 3 / 2 evaluaes to 1 in rust).
+ self.try_reserve(len * 3 / 2 + 4);
  }
  }
  }