small fixes

core/lib.rs

@@ -1141,6 +1141,8 @@ impl Connection {
         Ok(())
     }
 
+    /// Try to read page with given ID with fixed WAL watermark position
+    /// This method return false if page is not found (so, this is probably new page created after watermark position which wasn't checkpointed to the DB file yet)
     #[cfg(all(feature = "fs", feature = "conn_raw_api"))]
     pub fn try_wal_watermark_read_page(
         &self,
@@ -1161,6 +1163,8 @@ impl Connection {
         Ok(true)
     }
 
+    /// Return unique set of page numbers changes after WAL watermark position in the current WAL session
+    /// (so, if concurrent connection wrote something to the WAL - this method will not see this change)
     #[cfg(all(feature = "fs", feature = "conn_raw_api"))]
     pub fn wal_changed_pages_after(&self, frame_watermark: u64) -> Result<Vec<u32>> {
         self.pager.borrow().wal_changed_pages_after(frame_watermark)

core/storage/pager.rs

@@ -929,7 +929,7 @@ impl Pager {
         Ok(())
     }
 
-    /// Reads a page from disk bypassing page-cache
+    /// Reads a page from disk (either WAL or DB file) bypassing page-cache
     #[tracing::instrument(skip_all, level = Level::DEBUG)]
     pub fn read_page_no_cache(
         &self,

core/storage/wal.rs

@@ -860,6 +860,11 @@ impl Wal for WalFile {
             "unexpected use of frame_watermark optional argument"
         );
 
+        turso_assert!(
+            frame_watermark.unwrap_or(0) <= self.max_frame,
+            "frame_watermark must be <= than current WAL max_frame value"
+        );
+
         // if we are holding read_lock 0, skip and read right from db file.
         if self.max_frame_read_lock_index.get() == 0 {
             return Ok(None);

tests/integration/functions/test_wal_api.rs

@@ -393,7 +393,7 @@ fn revert_to(conn: &Arc<turso_core::Connection>, frame_watermark: u64) -> turso_
         if !has_page {
             continue;
         }
-        frames.push((page_id, frame.clone()));
+        frames.push((page_id, frame));
     }
 
     let mut frame_no = conn.wal_frame_count().unwrap();