diff --git a/db/db_impl.cc b/db/db_impl.cc
index 2353227..a6b09a2 100644
--- a/db/db_impl.cc
+++ b/db/db_impl.cc
@@ -146,12 +146,14 @@ DBImpl::DBImpl(const Options& raw_options, const std::string& dbname)
       tmp_batch_(new WriteBatch),
       background_compaction_scheduled_(false),
       manual_compaction_(nullptr),
+      // TODO(begin)
       versions_(new VersionSet(dbname_, &options_, table_cache_,
                                &internal_comparator_)),
       slot_page_(new SlotPage(dbname)) {
 
   vlog_set_ = new VlogSet(dbname, nullptr);
   vlog_set_->set_vlog_gc(new VlogGC(slot_page_, vlog_set_));
+  // TODO(end)
 }
 
 DBImpl::~DBImpl() {
@@ -181,9 +183,10 @@ DBImpl::~DBImpl() {
   if (owns_cache_) {
     delete options_.block_cache;
   }
-
+  // TODO(begin)
   delete slot_page_;
   delete vlog_set_;
+  // TODO(end)
 }
 
 Status DBImpl::NewDB() {
@@ -1174,14 +1177,14 @@ Status DBImpl::Get(const ReadOptions& options, const Slice& key,
   if (imm != nullptr) imm->Unref();
   current->Unref();
 
-  // TODO: search the slotpage and get value from vlog
+  // TODO(begin): search the slotpage and get value from vlog
   size_t slot_num = *(size_t *)value->c_str();
   struct slot_content sc;
   std::string vlog_value;
   slot_page_->get_slot(slot_num, &sc);
   vlog_set_->get_value(sc.vlog_num, sc.value_offset, &vlog_value);
   *value = vlog_value;
-
+  // TODO(end)
   return s;
 }
 
@@ -1216,7 +1219,7 @@ void DBImpl::ReleaseSnapshot(const Snapshot* snapshot) {
 
 // Convenience methods
 Status DBImpl::Put(const WriteOptions& o, const Slice& key, const Slice& val) {
-  // TODO: allocate slot_num in slotpage and put value in vlog
+  // TODO(begin): allocate slot_num in slotpage and put value in vlog
 
   size_t slot_num = slot_page_->alloc_slot();
   struct slot_content sc;
@@ -1228,9 +1231,11 @@ Status DBImpl::Put(const WriteOptions& o, const Slice& key, const Slice& val) {
   Slice slot_val(data, sizeof(data));
 
   return DB::Put(o, key, slot_val);
+  // TODO(end)
 }
 
 Status DBImpl::Delete(const WriteOptions& options, const Slice& key) {
+  // TODO(begin)
 //  size_t slot_num = *(size_t *)value->c_str();
 //  struct slot_content sc;
 //  std::string vlog_value;
@@ -1248,7 +1253,7 @@ Status DBImpl::Delete(const WriteOptions& options, const Slice& key) {
   std::string vlog_value;
   slot_page_->get_slot(slot_num, &sc);
   vlog_set_->del_value(sc.vlog_num, sc.value_offset);
-
+  // TODO(end)
   return DB::Delete(options, key);
 }
 
diff --git a/db/db_impl.h b/db/db_impl.h
index 9b74668..f6917e6 100644
--- a/db/db_impl.h
+++ b/db/db_impl.h
@@ -78,10 +78,10 @@ class DBImpl : public DB {
   friend class DB;
   struct CompactionState;
   struct Writer;
-
+  // TODO(begin)
   SlotPage *slot_page_;
   VlogSet *vlog_set_;
-
+  // TODO(end)
   // Information for a manual compaction
   struct ManualCompaction {
     int level;
diff --git a/report.md b/report.md
index 351a904..d0b31e6 100644
--- a/report.md
+++ b/report.md
@@ -61,7 +61,25 @@
 3. slot_page文件和vlog文件的GC
    对于vlog文件，我们在内存中维护一个bitmap，用来表示每一个slot的使用情况，并在插入和GC删除kv时进行动态的分配和释放。对于vlog文件的GC，我们用一个后台线程来扫描所有vlog的discard计数器。当某些vlog的discard计数器超过某个阈值（比如1024），我们就对这些vlog文件进行GC过程，当GC完成之后将slot_page中的slot元数据进行更新，再将原来的vlog文件进行删除，GC过程就完成了。
 
-
+##### 2.2.1 相关代码文件
+- [`/db/db_impl.cc`](./db/db_impl.cc)
+- [`/db/db_impl.h`](./db/db_impl.h)
+- 
+- [`/db/shared_lock.h`](./db/shared_lock.h) 定义了一个 SharedLock 类，用于实现读写锁机制，包含四种操作：soft_lock():获取共享读锁，确保在没有写操作时允许多个读操作并发进行；soft_unlock():释放共享读锁；hard_lock():获取独占写锁，确保只有当没有其他读写操作时，允许写入操作进行；hard_unlock():释放独占写锁。
+- [`/db/slotpage.h`](./db/slotpage.h)
+- [`/db/threadpool.h`](./db/threadpool.h)
+- [`/db/vlog.h`](./db/vlog.h)
+- [`/db/vlog_gc.cpp`](./db/vlog_gc.cpp)
+- [`/db/vlog_gc.h`](./db/vlog_gc.h)
+- [`/db/vlog_set.cpp`](./db/vlog_set.cpp)
+- [`/db/vlog_set.h`](./db/vlog_set.h)
+- 
+- [`/test/db_test3.cc`](./test/db_test3.cc)：测试 value 的字段功能
+- [`/test/db_test4.cc`](./test/db_test4.cc)
+- [`/test/db_test5.cc`](./test/db_test5.cc)
+- 
+- [`CMakeLists.txt`](CMakeLists.txt)：添加可执行文件
+### 锁机制
 
 ### 3. 数据结构设计
 `key的格式：| key | slot_num | `