Improve code

bustubx/src/execution/physical_plan/values.rs

@@ -1,12 +1,10 @@
-use std::sync::atomic::AtomicU32;
-use std::sync::Arc;
+use std::sync::atomic::{AtomicU32, Ordering};
 
 use crate::catalog::SchemaRef;
 use crate::common::ScalarValue;
 use crate::expression::{Expr, ExprTrait};
 use crate::storage::EMPTY_TUPLE;
 use crate::{
-    catalog::Schema,
     execution::{ExecutionContext, VolcanoExecutor},
     storage::Tuple,
     BustubxResult,
@@ -30,9 +28,7 @@ impl PhysicalValues {
 }
 impl VolcanoExecutor for PhysicalValues {
     fn next(&self, _context: &mut ExecutionContext) -> BustubxResult<Option<Tuple>> {
-        let cursor = self
-            .cursor
-            .fetch_add(1, std::sync::atomic::Ordering::SeqCst) as usize;
+        let cursor = self.cursor.fetch_add(1, Ordering::SeqCst) as usize;
         if cursor < self.rows.len() {
             let values = self.rows[cursor]
                 .iter()

bustubx/src/storage/page/index_page.rs

@@ -125,9 +125,6 @@ impl BPlusTreeInternalPage {
 
     // TODO 可以通过二分查找来插入
     pub fn insert(&mut self, key: Tuple, page_id: PageId) {
-        // if self.header.current_size == 0 && !key.is_null() {
-        //     panic!("First key must be zero");
-        // }
         self.array.push((key, page_id));
         self.header.current_size += 1;
         // 跳过第一个空key

bustubx/src/transaction/mod.rs

@@ -2,6 +2,4 @@ mod lock_manager;
 mod transaction;
 mod transaction_manager;
 
-pub type TransactionId = u64;
-
 pub use transaction::*;

bustubx/src/transaction/transaction.rs

@@ -1 +1,33 @@
+use crate::Tuple;
+
+pub type TransactionId = u64;
+pub const INVALID_TRANSACTION_ID: TransactionId = 0;
+
+pub enum TransactionState {
+    Running,
+    Tainted,
+    Committed,
+    Aborted,
+}
+
 pub struct Transaction {}
+
+/// Represents a link to a previous version of this tuple
+pub struct UndoLink {
+    prev_txn: TransactionId,
+    prev_log_idx: u32,
+}
+
+impl UndoLink {
+    pub fn is_valid(&self) -> bool {
+        self.prev_txn != INVALID_TRANSACTION_ID
+    }
+}
+
+pub struct UndoLog {
+    is_deleted: bool,
+    modified_fields: Vec<bool>,
+    tuple: Tuple,
+    timestamp: u64,
+    prev_version: UndoLink,
+}