core: Replace Mutex with RefCell in BufferPool

core/buffer_pool.rs

@@ -1,21 +1,22 @@
 use crate::io::BufferData;
-use std::{pin::Pin, sync::Mutex};
+use std::pin::Pin;
+use std::cell::RefCell;
 
 pub struct BufferPool {
-    pub free_buffers: Mutex<Vec<BufferData>>,
+    pub free_buffers: RefCell<Vec<BufferData>>,
     page_size: usize,
 }
 
 impl BufferPool {
     pub fn new(page_size: usize) -> Self {
         Self {
-            free_buffers: Mutex::new(Vec::new()),
+            free_buffers: RefCell::new(Vec::new()),
             page_size,
         }
     }
 
     pub fn get(&self) -> BufferData {
-        let mut free_buffers = self.free_buffers.lock().unwrap();
+        let mut free_buffers = self.free_buffers.borrow_mut();
         if let Some(buffer) = free_buffers.pop() {
             buffer
         } else {
@@ -24,7 +25,7 @@ impl BufferPool {
     }
 
     pub fn put(&self, buffer: BufferData) {
-        let mut free_buffers = self.free_buffers.lock().unwrap();
+        let mut free_buffers = self.free_buffers.borrow_mut();
         free_buffers.push(buffer);
     }
 }