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diff --git a/src/rocksdb/utilities/transactions/pessimistic_transaction.h b/src/rocksdb/utilities/transactions/pessimistic_transaction.h
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+// Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#pragma once
+
+#ifndef ROCKSDB_LITE
+
+#include <algorithm>
+#include <atomic>
+#include <mutex>
+#include <stack>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "db/write_callback.h"
+#include "rocksdb/db.h"
+#include "rocksdb/slice.h"
+#include "rocksdb/snapshot.h"
+#include "rocksdb/status.h"
+#include "rocksdb/types.h"
+#include "rocksdb/utilities/transaction.h"
+#include "rocksdb/utilities/transaction_db.h"
+#include "rocksdb/utilities/write_batch_with_index.h"
+#include "util/autovector.h"
+#include "utilities/transactions/transaction_base.h"
+#include "utilities/transactions/transaction_util.h"
+
+namespace rocksdb {
+
+class PessimisticTransactionDB;
+
+// A transaction under pessimistic concurrency control. This class implements
+// the locking API and interfaces with the lock manager as well as the
+// pessimistic transactional db.
+class PessimisticTransaction : public TransactionBaseImpl {
+ public:
+  PessimisticTransaction(TransactionDB* db, const WriteOptions& write_options,
+                         const TransactionOptions& txn_options,
+                         const bool init = true);
+
+  virtual ~PessimisticTransaction();
+
+  void Reinitialize(TransactionDB* txn_db, const WriteOptions& write_options,
+                    const TransactionOptions& txn_options);
+
+  Status Prepare() override;
+
+  Status Commit() override;
+
+  // It is basically Commit without going through Prepare phase. The write batch
+  // is also directly provided instead of expecting txn to gradually batch the
+  // transactions writes to an internal write batch.
+  Status CommitBatch(WriteBatch* batch);
+
+  Status Rollback() override;
+
+  Status RollbackToSavePoint() override;
+
+  Status SetName(const TransactionName& name) override;
+
+  // Generate a new unique transaction identifier
+  static TransactionID GenTxnID();
+
+  TransactionID GetID() const override { return txn_id_; }
+
+  std::vector<TransactionID> GetWaitingTxns(uint32_t* column_family_id,
+                                            std::string* key) const override {
+    std::lock_guard<std::mutex> lock(wait_mutex_);
+    std::vector<TransactionID> ids(waiting_txn_ids_.size());
+    if (key) *key = waiting_key_ ? *waiting_key_ : "";
+    if (column_family_id) *column_family_id = waiting_cf_id_;
+    std::copy(waiting_txn_ids_.begin(), waiting_txn_ids_.end(), ids.begin());
+    return ids;
+  }
+
+  void SetWaitingTxn(autovector<TransactionID> ids, uint32_t column_family_id,
+                     const std::string* key) {
+    std::lock_guard<std::mutex> lock(wait_mutex_);
+    waiting_txn_ids_ = ids;
+    waiting_cf_id_ = column_family_id;
+    waiting_key_ = key;
+  }
+
+  void ClearWaitingTxn() {
+    std::lock_guard<std::mutex> lock(wait_mutex_);
+    waiting_txn_ids_.clear();
+    waiting_cf_id_ = 0;
+    waiting_key_ = nullptr;
+  }
+
+  // Returns the time (in microseconds according to Env->GetMicros())
+  // that this transaction will be expired.  Returns 0 if this transaction does
+  // not expire.
+  uint64_t GetExpirationTime() const { return expiration_time_; }
+
+  // returns true if this transaction has an expiration_time and has expired.
+  bool IsExpired() const;
+
+  // Returns the number of microseconds a transaction can wait on acquiring a
+  // lock or -1 if there is no timeout.
+  int64_t GetLockTimeout() const { return lock_timeout_; }
+  void SetLockTimeout(int64_t timeout) override {
+    lock_timeout_ = timeout * 1000;
+  }
+
+  // Returns true if locks were stolen successfully, false otherwise.
+  bool TryStealingLocks();
+
+  bool IsDeadlockDetect() const override { return deadlock_detect_; }
+
+  int64_t GetDeadlockDetectDepth() const { return deadlock_detect_depth_; }
+
+ protected:
+  // Refer to
+  // TransactionOptions::use_only_the_last_commit_time_batch_for_recovery
+  bool use_only_the_last_commit_time_batch_for_recovery_ = false;
+
+  virtual Status PrepareInternal() = 0;
+
+  virtual Status CommitWithoutPrepareInternal() = 0;
+
+  // batch_cnt if non-zero is the number of sub-batches. A sub-batch is a batch
+  // with no duplicate keys. If zero, then the number of sub-batches is unknown.
+  virtual Status CommitBatchInternal(WriteBatch* batch,
+                                     size_t batch_cnt = 0) = 0;
+
+  virtual Status CommitInternal() = 0;
+
+  virtual Status RollbackInternal() = 0;
+
+  virtual void Initialize(const TransactionOptions& txn_options);
+
+  Status LockBatch(WriteBatch* batch, TransactionKeyMap* keys_to_unlock);
+
+  Status TryLock(ColumnFamilyHandle* column_family, const Slice& key,
+                 bool read_only, bool exclusive, const bool do_validate = true,
+                 const bool assume_tracked = false) override;
+
+  void Clear() override;
+
+  PessimisticTransactionDB* txn_db_impl_;
+  DBImpl* db_impl_;
+
+  // If non-zero, this transaction should not be committed after this time (in
+  // microseconds according to Env->NowMicros())
+  uint64_t expiration_time_;
+
+ private:
+  friend class TransactionTest_ValidateSnapshotTest_Test;
+  // Used to create unique ids for transactions.
+  static std::atomic<TransactionID> txn_id_counter_;
+
+  // Unique ID for this transaction
+  TransactionID txn_id_;
+
+  // IDs for the transactions that are blocking the current transaction.
+  //
+  // empty if current transaction is not waiting.
+  autovector<TransactionID> waiting_txn_ids_;
+
+  // The following two represents the (cf, key) that a transaction is waiting
+  // on.
+  //
+  // If waiting_key_ is not null, then the pointer should always point to
+  // a valid string object. The reason is that it is only non-null when the
+  // transaction is blocked in the TransactionLockMgr::AcquireWithTimeout
+  // function. At that point, the key string object is one of the function
+  // parameters.
+  uint32_t waiting_cf_id_;
+  const std::string* waiting_key_;
+
+  // Mutex protecting waiting_txn_ids_, waiting_cf_id_ and waiting_key_.
+  mutable std::mutex wait_mutex_;
+
+  // Timeout in microseconds when locking a key or -1 if there is no timeout.
+  int64_t lock_timeout_;
+
+  // Whether to perform deadlock detection or not.
+  bool deadlock_detect_;
+
+  // Whether to perform deadlock detection or not.
+  int64_t deadlock_detect_depth_;
+
+  // Refer to TransactionOptions::skip_concurrency_control
+  bool skip_concurrency_control_;
+
+  virtual Status ValidateSnapshot(ColumnFamilyHandle* column_family,
+                                  const Slice& key,
+                                  SequenceNumber* tracked_at_seq);
+
+  void UnlockGetForUpdate(ColumnFamilyHandle* column_family,
+                          const Slice& key) override;
+
+  // No copying allowed
+  PessimisticTransaction(const PessimisticTransaction&);
+  void operator=(const PessimisticTransaction&);
+};
+
+class WriteCommittedTxn : public PessimisticTransaction {
+ public:
+  WriteCommittedTxn(TransactionDB* db, const WriteOptions& write_options,
+                    const TransactionOptions& txn_options);
+
+  virtual ~WriteCommittedTxn() {}
+
+ private:
+  Status PrepareInternal() override;
+
+  Status CommitWithoutPrepareInternal() override;
+
+  Status CommitBatchInternal(WriteBatch* batch, size_t batch_cnt) override;
+
+  Status CommitInternal() override;
+
+  Status RollbackInternal() override;
+
+  // No copying allowed
+  WriteCommittedTxn(const WriteCommittedTxn&);
+  void operator=(const WriteCommittedTxn&);
+};
+
+}  // namespace rocksdb
+
+#endif  // ROCKSDB_LITE