Use is_written_ flag instead of rwset in commit

Author: lmwnshn

src/concurrency/timestamp_ordering_transaction_manager.cpp

@@ -623,15 +623,14 @@ ResultType TimestampOrderingTransactionManager::CommitTransaction(
   //// handle other isolation levels
   //////////////////////////////////////////////////////////
 
-  auto &rw_set = current_txn->GetReadWriteSet();
-
-  // if no modifying queries, treat as read-only
-  if (rw_set.empty()) {
-    LOG_TRACE("Empty RW set, ending transaction.");
+  if (!current_txn->IsWritten()) {
+    LOG_TRACE("Transaction not yet written, ending transaction.");
     EndTransaction(current_txn);
     return ResultType::SUCCESS;
   }
 
+  auto &rw_set = current_txn->GetReadWriteSet();
+
   auto storage_manager = storage::StorageManager::GetInstance();
   auto &log_manager = logging::LogManager::GetInstance();
 

src/concurrency/transaction_context.cpp

@@ -112,6 +112,7 @@ void TransactionContext::RecordReadOwn(const ItemPointer &location) {
                  (rw_set_[location] != RWType::DELETE &&
                   rw_set_[location] != RWType::INS_DEL));
   rw_set_[location] = RWType::READ_OWN;
+  is_written_ = true;
 }
 
 void TransactionContext::RecordUpdate(const ItemPointer &location) {

src/include/concurrency/transaction_context.h

@@ -266,6 +266,13 @@ class TransactionContext : public Printable {
    */
   bool IsReadOnly() const { return read_only_; }
 
+  /**
+   * @brief      Determines if already written.
+   *
+   * @return     True if already written, False otherwise.
+   */
+  bool IsWritten() const { return is_written_; }
+
   /**
    * @brief      Gets the isolation level.
    *