From b42a1ef2728d786fa7fa5ab2d3d3897e5cec9ea7 Mon Sep 17 00:00:00 2001
From: meteorgan <meteorite.gan@gmail.com>
Date: Sat, 12 Jul 2025 17:50:54 +0800
Subject: [PATCH] minor improvements based on PR comments

---
 core/lib.rs           | 13 ++++---------
 core/storage/pager.rs | 11 ++++++-----
 2 files changed, 10 insertions(+), 14 deletions(-)

diff --git a/core/lib.rs b/core/lib.rs
index 540f81761..0e763a67a 100644
--- a/core/lib.rs
+++ b/core/lib.rs
@@ -179,7 +179,6 @@ impl Database {
     ) -> Result<Arc<Database>> {
         let wal_path = format!("{path}-wal");
         let maybe_shared_wal = WalFileShared::open_shared_if_exists(&io, wal_path.as_str())?;
-        let db_size = db_file.size()?;
 
         let mv_store = if enable_mvcc {
             Some(Rc::new(MvStore::new(
@@ -189,12 +188,9 @@ impl Database {
         } else {
             None
         };
-        let wal_has_frames = maybe_shared_wal
-            .as_ref()
-            .is_some_and(|wal| unsafe { &*wal.get() }.max_frame.load(Ordering::SeqCst) > 0);
 
-        // No pages in DB file or WAL -> empty database
-        let db_state = if db_size == 0 && !wal_has_frames {
+        let db_size = db_file.size()?;
+        let db_state = if db_size == 0 {
             DB_STATE_UNINITIALIZED
         } else {
             DB_STATE_INITIALIZED
@@ -228,10 +224,9 @@ impl Database {
                 .expect("lock on schema should succeed first try");
 
             let syms = conn.syms.borrow();
+            let pager = conn.pager.borrow().clone();
 
-            if let Err(LimboError::ExtensionError(e)) =
-                schema.make_from_btree(None, conn.pager.clone(), &syms)
-            {
+            if let Err(LimboError::ExtensionError(e)) = schema.make_from_btree(None, pager, &syms) {
                 // this means that a vtab exists and we no longer have the module loaded. we print
                 // a warning to the user to load the module
                 eprintln!("Warning: {e}");
diff --git a/core/storage/pager.rs b/core/storage/pager.rs
index 2b2d2cd32..9d9a927d5 100644
--- a/core/storage/pager.rs
+++ b/core/storage/pager.rs
@@ -9,7 +9,7 @@ use crate::types::CursorResult;
 use crate::Completion;
 use crate::{Buffer, Connection, LimboError, Result};
 use parking_lot::RwLock;
-use std::cell::{OnceCell, RefCell, UnsafeCell};
+use std::cell::{Cell, OnceCell, RefCell, UnsafeCell};
 use std::collections::HashSet;
 use std::rc::Rc;
 use std::sync::atomic::{AtomicUsize, Ordering};
@@ -225,7 +225,7 @@ pub struct Pager {
     /// Cache page_size and reserved_space at Pager init and reuse for subsequent
     /// `usable_space` calls. TODO: Invalidate reserved_space when we add the functionality
     /// to change it.
-    page_size: RefCell<Option<u32>>,
+    page_size: Cell<Option<u32>>,
     reserved_space: OnceCell<u8>,
 }
 
@@ -291,7 +291,7 @@ impl Pager {
             db_state,
             init_lock,
             allocate_page1_state,
-            page_size: RefCell::new(None),
+            page_size: Cell::new(None),
             reserved_space: OnceCell::new(),
         })
     }
@@ -586,7 +586,7 @@ impl Pager {
     pub fn usable_space(&self) -> usize {
         let page_size = *self
             .page_size
-            .borrow_mut()
+            .get()
             .get_or_insert_with(|| header_accessor::get_page_size(self).unwrap_or_default());
 
         let reserved_space = *self
@@ -598,6 +598,7 @@ impl Pager {
 
     /// Set the initial page size for the database. Should only be called before the database is initialized
     pub fn set_initial_page_size(&self, size: u32) {
+        assert_eq!(self.db_state.load(Ordering::SeqCst), DB_STATE_UNINITIALIZED);
         self.page_size.replace(Some(size));
     }
 
@@ -1063,7 +1064,7 @@ impl Pager {
                 self.db_state.store(DB_STATE_INITIALIZING, Ordering::SeqCst);
                 let mut default_header = DatabaseHeader::default();
                 default_header.database_size += 1;
-                if let Some(size) = *self.page_size.borrow() {
+                if let Some(size) = self.page_size.get() {
                     default_header.update_page_size(size);
                 }
                 let page = allocate_page(1, &self.buffer_pool, 0);