//  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 <mutex>
#include <queue>
#include <set>
#include <string>
#include <unordered_map>
#include <vector>

#include "db/db_iter.h"
#include "db/read_callback.h"
#include "db/snapshot_checker.h"
#include "rocksdb/db.h"
#include "rocksdb/options.h"
#include "rocksdb/utilities/transaction_db.h"
#include "util/cast_util.h"
#include "utilities/transactions/lock/lock_manager.h"
#include "utilities/transactions/lock/range/range_lock_manager.h"
#include "utilities/transactions/pessimistic_transaction.h"
#include "utilities/transactions/write_prepared_txn.h"

namespace ROCKSDB_NAMESPACE {

class PessimisticTransactionDB : public TransactionDB {
 public:
  explicit PessimisticTransactionDB(DB* db,
                                    const TransactionDBOptions& txn_db_options);

  explicit PessimisticTransactionDB(StackableDB* db,
                                    const TransactionDBOptions& txn_db_options);

  virtual ~PessimisticTransactionDB();

  const Snapshot* GetSnapshot() override { return db_->GetSnapshot(); }

  virtual Status Initialize(
      const std::vector<size_t>& compaction_enabled_cf_indices,
      const std::vector<ColumnFamilyHandle*>& handles);

  Transaction* BeginTransaction(const WriteOptions& write_options,
                                const TransactionOptions& txn_options,
                                Transaction* old_txn) override = 0;

  using StackableDB::Put;
  Status Put(const WriteOptions& options, ColumnFamilyHandle* column_family,
             const Slice& key, const Slice& val) override;

  Status PutEntity(const WriteOptions& options,
                   ColumnFamilyHandle* column_family, const Slice& key,
                   const WideColumns& columns) override;
  Status PutEntity(const WriteOptions& /* options */, const Slice& /* key */,
                   const AttributeGroups& attribute_groups) override {
    if (attribute_groups.empty()) {
      return Status::InvalidArgument(
          "Cannot call this method without attribute groups");
    }
    return Status::NotSupported(
        "PutEntity with AttributeGroups not supported by "
        "PessimisticTransactionDB");
  }

  using StackableDB::Delete;
  Status Delete(const WriteOptions& wopts, ColumnFamilyHandle* column_family,
                const Slice& key) override;

  using StackableDB::SingleDelete;
  Status SingleDelete(const WriteOptions& wopts,
                      ColumnFamilyHandle* column_family,
                      const Slice& key) override;

  using StackableDB::Merge;
  Status Merge(const WriteOptions& options, ColumnFamilyHandle* column_family,
               const Slice& key, const Slice& value) override;

  using TransactionDB::Write;
  Status Write(const WriteOptions& opts, WriteBatch* updates) override;
  inline Status WriteWithConcurrencyControl(const WriteOptions& opts,
                                            WriteBatch* updates) {
    Status s;
    if (opts.protection_bytes_per_key > 0) {
      s = WriteBatchInternal::UpdateProtectionInfo(
          updates, opts.protection_bytes_per_key);
    }
    if (s.ok()) {
      // Need to lock all keys in this batch to prevent write conflicts with
      // concurrent transactions.
      Transaction* txn = BeginInternalTransaction(opts);
      txn->DisableIndexing();

      auto txn_impl = static_cast_with_check<PessimisticTransaction>(txn);

      // Since commitBatch sorts the keys before locking, concurrent Write()
      // operations will not cause a deadlock.
      // In order to avoid a deadlock with a concurrent Transaction,
      // Transactions should use a lock timeout.
      s = txn_impl->CommitBatch(updates);

      delete txn;
    }

    return s;
  }

  using StackableDB::CreateColumnFamily;
  Status CreateColumnFamily(const ColumnFamilyOptions& options,
                            const std::string& column_family_name,
                            ColumnFamilyHandle** handle) override;

  Status CreateColumnFamilies(
      const ColumnFamilyOptions& options,
      const std::vector<std::string>& column_family_names,
      std::vector<ColumnFamilyHandle*>* handles) override;

  Status CreateColumnFamilies(
      const std::vector<ColumnFamilyDescriptor>& column_families,
      std::vector<ColumnFamilyHandle*>* handles) override;

  using StackableDB::CreateColumnFamilyWithImport;
  Status CreateColumnFamilyWithImport(
      const ColumnFamilyOptions& options, const std::string& column_family_name,
      const ImportColumnFamilyOptions& import_options,
      const ExportImportFilesMetaData& metadata,
      ColumnFamilyHandle** handle) override {
    const std::vector<const ExportImportFilesMetaData*>& metadatas{&metadata};
    return CreateColumnFamilyWithImport(options, column_family_name,
                                        import_options, metadatas, handle);
  }

  Status CreateColumnFamilyWithImport(
      const ColumnFamilyOptions& options, const std::string& column_family_name,
      const ImportColumnFamilyOptions& import_options,
      const std::vector<const ExportImportFilesMetaData*>& metadatas,
      ColumnFamilyHandle** handle) override;

  using StackableDB::DropColumnFamily;
  Status DropColumnFamily(ColumnFamilyHandle* column_family) override;

  Status DropColumnFamilies(
      const std::vector<ColumnFamilyHandle*>& column_families) override;

  Status TryLock(PessimisticTransaction* txn, uint32_t cfh_id,
                 const std::string& key, bool exclusive);
  Status TryRangeLock(PessimisticTransaction* txn, uint32_t cfh_id,
                      const Endpoint& start_endp, const Endpoint& end_endp);

  void UnLock(PessimisticTransaction* txn, const LockTracker& keys);
  void UnLock(PessimisticTransaction* txn, uint32_t cfh_id,
              const std::string& key);

  void AddColumnFamily(const ColumnFamilyHandle* handle);

  static TransactionDBOptions ValidateTxnDBOptions(
      const TransactionDBOptions& txn_db_options);

  const TransactionDBOptions& GetTxnDBOptions() const {
    return txn_db_options_;
  }

  void InsertExpirableTransaction(TransactionID tx_id,
                                  PessimisticTransaction* tx);
  void RemoveExpirableTransaction(TransactionID tx_id);

  // If transaction is no longer available, locks can be stolen
  // If transaction is available, try stealing locks directly from transaction
  // It is the caller's responsibility to ensure that the referred transaction
  // is expirable (GetExpirationTime() > 0) and that it is expired.
  bool TryStealingExpiredTransactionLocks(TransactionID tx_id);

  Transaction* GetTransactionByName(const TransactionName& name) override;

  Status RegisterTransaction(Transaction* txn);
  void UnregisterTransaction(Transaction* txn);

  // not thread safe. current use case is during recovery (single thread)
  void GetAllPreparedTransactions(std::vector<Transaction*>* trans) override;

  LockManager::PointLockStatus GetLockStatusData() override;

  std::vector<DeadlockPath> GetDeadlockInfoBuffer() override;
  void SetDeadlockInfoBufferSize(uint32_t target_size) override;

  // The default implementation does nothing. The actual implementation is moved
  // to the child classes that actually need this information. This was due to
  // an odd performance drop we observed when the added std::atomic member to
  // the base class even when the subclass do not read it in the fast path.
  virtual void UpdateCFComparatorMap(const std::vector<ColumnFamilyHandle*>&) {}
  virtual void UpdateCFComparatorMap(ColumnFamilyHandle*) {}

  // Use the returned factory to create LockTrackers in transactions.
  const LockTrackerFactory& GetLockTrackerFactory() const {
    return lock_manager_->GetLockTrackerFactory();
  }

  std::pair<Status, std::shared_ptr<const Snapshot>> CreateTimestampedSnapshot(
      TxnTimestamp ts) override;

  std::shared_ptr<const Snapshot> GetTimestampedSnapshot(
      TxnTimestamp ts) const override;

  void ReleaseTimestampedSnapshotsOlderThan(TxnTimestamp ts) override;

  Status GetTimestampedSnapshots(TxnTimestamp ts_lb, TxnTimestamp ts_ub,
                                 std::vector<std::shared_ptr<const Snapshot>>&
                                     timestamped_snapshots) const override;

 protected:
  DBImpl* db_impl_;
  std::shared_ptr<Logger> info_log_;
  const TransactionDBOptions txn_db_options_;

  static Status FailIfBatchHasTs(const WriteBatch* wb);

  static Status FailIfCfEnablesTs(const DB* db,
                                  const ColumnFamilyHandle* column_family);

  void ReinitializeTransaction(
      Transaction* txn, const WriteOptions& write_options,
      const TransactionOptions& txn_options = TransactionOptions());

  virtual Status VerifyCFOptions(const ColumnFamilyOptions& cf_options);

 private:
  friend class WritePreparedTxnDB;
  friend class WritePreparedTxnDBMock;
  friend class WriteUnpreparedTxn;
  friend class TransactionTest_DoubleCrashInRecovery_Test;
  friend class TransactionTest_DoubleEmptyWrite_Test;
  friend class TransactionTest_DuplicateKeys_Test;
  friend class TransactionTest_PersistentTwoPhaseTransactionTest_Test;
  friend class TransactionTest_TwoPhaseDoubleRecoveryTest_Test;
  friend class TransactionTest_TwoPhaseOutOfOrderDelete_Test;
  friend class TransactionStressTest_TwoPhaseLongPrepareTest_Test;
  friend class WriteUnpreparedTransactionTest_RecoveryTest_Test;
  friend class WriteUnpreparedTransactionTest_MarkLogWithPrepSection_Test;

  Transaction* BeginInternalTransaction(const WriteOptions& options);
  Transaction* GetTransactionByNameLocked(const TransactionName& name);

  std::shared_ptr<LockManager> lock_manager_;

  // Must be held when adding/dropping column families.
  InstrumentedMutex column_family_mutex_;

  // Used to ensure that no locks are stolen from an expirable transaction
  // that has started a commit. Only transactions with an expiration time
  // should be in this map.
  std::mutex map_mutex_;
  std::unordered_map<TransactionID, PessimisticTransaction*>
      expirable_transactions_map_;

  // map from name to two phase transaction instance
  std::mutex name_map_mutex_;
  std::unordered_map<TransactionName, Transaction*> transactions_;

  // Signal that we are testing a crash scenario. Some asserts could be relaxed
  // in such cases.
  virtual void TEST_Crash() {}
};

// A PessimisticTransactionDB that writes the data to the DB after the commit.
// In this way the DB only contains the committed data.
class WriteCommittedTxnDB : public PessimisticTransactionDB {
 public:
  explicit WriteCommittedTxnDB(DB* db,
                               const TransactionDBOptions& txn_db_options)
      : PessimisticTransactionDB(db, txn_db_options) {}

  explicit WriteCommittedTxnDB(StackableDB* db,
                               const TransactionDBOptions& txn_db_options)
      : PessimisticTransactionDB(db, txn_db_options) {}

  virtual ~WriteCommittedTxnDB() {}

  Transaction* BeginTransaction(const WriteOptions& write_options,
                                const TransactionOptions& txn_options,
                                Transaction* old_txn) override;

  // Optimized version of ::Write that makes use of skip_concurrency_control
  // hint
  using TransactionDB::Write;
  Status Write(const WriteOptions& opts,
               const TransactionDBWriteOptimizations& optimizations,
               WriteBatch* updates) override;
  Status Write(const WriteOptions& opts, WriteBatch* updates) override;
};

inline Status PessimisticTransactionDB::FailIfBatchHasTs(
    const WriteBatch* batch) {
  if (batch != nullptr && WriteBatchInternal::HasKeyWithTimestamp(*batch)) {
    return Status::NotSupported(
        "Writes with timestamp must go through transaction API instead of "
        "TransactionDB.");
  }
  return Status::OK();
}

inline Status PessimisticTransactionDB::FailIfCfEnablesTs(
    const DB* db, const ColumnFamilyHandle* column_family) {
  assert(db);
  column_family = column_family ? column_family : db->DefaultColumnFamily();
  assert(column_family);
  const Comparator* const ucmp = column_family->GetComparator();
  assert(ucmp);
  if (ucmp->timestamp_size() > 0) {
    return Status::NotSupported(
        "Write operation with user timestamp must go through the transaction "
        "API instead of TransactionDB.");
  }
  return Status::OK();
}

class SnapshotCreationCallback : public PostMemTableCallback {
 public:
  explicit SnapshotCreationCallback(
      DBImpl* dbi, TxnTimestamp commit_ts,
      const std::shared_ptr<TransactionNotifier>& notifier,
      std::shared_ptr<const Snapshot>& snapshot)
      : db_impl_(dbi),
        commit_ts_(commit_ts),
        snapshot_notifier_(notifier),
        snapshot_(snapshot) {
    assert(db_impl_);
  }

  ~SnapshotCreationCallback() override {
    snapshot_creation_status_.PermitUncheckedError();
  }

  Status operator()(SequenceNumber seq, bool disable_memtable) override;

 private:
  DBImpl* const db_impl_;
  const TxnTimestamp commit_ts_;
  std::shared_ptr<TransactionNotifier> snapshot_notifier_;
  std::shared_ptr<const Snapshot>& snapshot_;

  Status snapshot_creation_status_;
};

}  // namespace ROCKSDB_NAMESPACE