// 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

#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_NAMESPACE {

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);

  // No copying allowed

  PessimisticTransaction(const PessimisticTransaction&) = delete;

  void operator=(const PessimisticTransaction&) = delete;

  ~PessimisticTransaction() override;

  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_; }

  Status GetRangeLock(ColumnFamilyHandle* column_family,

                      const Endpoint& start_key,

                      const Endpoint& end_key) override;

  Status CollapseKey(const ReadOptions& options, const Slice& key,

                     ColumnFamilyHandle* column_family = nullptr) override;

 protected:

  // Refer to

  // TransactionOptions::use_only_the_last_commit_time_batch_for_recovery

  bool use_only_the_last_commit_time_batch_for_recovery_ = false;

  // Refer to

  // TransactionOptions::skip_prepare

  bool skip_prepare_ = 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, LockTracker* 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_;

  // Timestamp used by the transaction to perform all GetForUpdate.

  // Use this timestamp for conflict checking.

  // read_timestamp_ == kMaxTxnTimestamp means this transaction has not

  // performed any GetForUpdate. It is possible that the transaction has

  // performed blind writes or Get, though.

  TxnTimestamp read_timestamp_{kMaxTxnTimestamp};

  TxnTimestamp commit_timestamp_{kMaxTxnTimestamp};

 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 PointLockManager::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;

};

class WriteCommittedTxn : public PessimisticTransaction {

 public:

  WriteCommittedTxn(TransactionDB* db, const WriteOptions& write_options,

                    const TransactionOptions& txn_options);

  // No copying allowed

  WriteCommittedTxn(const WriteCommittedTxn&) = delete;

  void operator=(const WriteCommittedTxn&) = delete;

  ~WriteCommittedTxn() override {}

  using TransactionBaseImpl::GetForUpdate;

  Status GetForUpdate(const ReadOptions& read_options,

                      ColumnFamilyHandle* column_family, const Slice& key,

                      std::string* value, bool exclusive,

                      const bool do_validate) override;

  Status GetForUpdate(const ReadOptions& read_options,

                      ColumnFamilyHandle* column_family, const Slice& key,

                      PinnableSlice* pinnable_val, bool exclusive,

                      const bool do_validate) override;

  Status GetEntityForUpdate(const ReadOptions& read_options,

                            ColumnFamilyHandle* column_family, const Slice& key,

                            PinnableWideColumns* columns, bool exclusive,

                            bool do_validate) override;

  using TransactionBaseImpl::Put;

  // `key` does NOT include timestamp even when it's enabled.

  Status Put(ColumnFamilyHandle* column_family, const Slice& key,

             const Slice& value, const bool assume_tracked = false) override;

  Status Put(ColumnFamilyHandle* column_family, const SliceParts& key,

             const SliceParts& value,

             const bool assume_tracked = false) override;

  using TransactionBaseImpl::PutUntracked;

  Status PutUntracked(ColumnFamilyHandle* column_family, const Slice& key,

                      const Slice& value) override;

  Status PutUntracked(ColumnFamilyHandle* column_family, const SliceParts& key,

                      const SliceParts& value) override;

  // `key` does NOT include timestamp even when it's enabled.

  Status PutEntity(ColumnFamilyHandle* column_family, const Slice& key,

                   const WideColumns& columns,

                   bool assume_tracked = false) override {

    const bool do_validate = !assume_tracked;

    return PutEntityImpl(column_family, key, columns, do_validate,

                         assume_tracked);

  }

  Status PutEntityUntracked(ColumnFamilyHandle* column_family, const Slice& key,

                            const WideColumns& columns) override {

    constexpr bool do_validate = false;

    constexpr bool assume_tracked = false;

    return PutEntityImpl(column_family, key, columns, do_validate,

                         assume_tracked);

  }

  using TransactionBaseImpl::Delete;

  // `key` does NOT include timestamp even when it's enabled.

  Status Delete(ColumnFamilyHandle* column_family, const Slice& key,

                const bool assume_tracked = false) override;

  Status Delete(ColumnFamilyHandle* column_family, const SliceParts& key,

                const bool assume_tracked = false) override;

  using TransactionBaseImpl::DeleteUntracked;

  Status DeleteUntracked(ColumnFamilyHandle* column_family,

                         const Slice& key) override;

  Status DeleteUntracked(ColumnFamilyHandle* column_family,

                         const SliceParts& key) override;

  using TransactionBaseImpl::SingleDelete;

  // `key` does NOT include timestamp even when it's enabled.

  Status SingleDelete(ColumnFamilyHandle* column_family, const Slice& key,

                      const bool assume_tracked = false) override;

  Status SingleDelete(ColumnFamilyHandle* column_family, const SliceParts& key,

                      const bool assume_tracked = false) override;

  using TransactionBaseImpl::SingleDeleteUntracked;

  Status SingleDeleteUntracked(ColumnFamilyHandle* column_family,

                               const Slice& key) override;

  using TransactionBaseImpl::Merge;

  Status Merge(ColumnFamilyHandle* column_family, const Slice& key,

               const Slice& value, const bool assume_tracked = false) override;

  Status SetReadTimestampForValidation(TxnTimestamp ts) override;

  Status SetCommitTimestamp(TxnTimestamp ts) override;

  TxnTimestamp GetCommitTimestamp() const override { return commit_timestamp_; }

 private:

  template <typename TValue>

  Status GetForUpdateImpl(const ReadOptions& read_options,

                          ColumnFamilyHandle* column_family, const Slice& key,

                          TValue* value, bool exclusive,

                          const bool do_validate);

  Status PutEntityImpl(ColumnFamilyHandle* column_family, const Slice& key,

                       const WideColumns& columns, bool do_validate,

                       bool assume_tracked);

  template <typename TKey, typename TOperation>

  Status Operate(ColumnFamilyHandle* column_family, const TKey& key,

                 const bool do_validate, const bool assume_tracked,

                 TOperation&& operation);

  Status PrepareInternal() override;

  Status CommitWithoutPrepareInternal() override;

  Status CommitBatchInternal(WriteBatch* batch, size_t batch_cnt) override;

  Status CommitInternal() override;

  Status RollbackInternal() override;

  // Column families that enable timestamps and whose data are written when

  // indexing_enabled_ is false. If a key is written when indexing_enabled_ is

  // true, then the corresponding column family is not added to cfs_with_ts

  // even if it enables timestamp.

  std::unordered_set<uint32_t> cfs_with_ts_tracked_when_indexing_disabled_;

};

}  // namespace ROCKSDB_NAMESPACE