ceph/src/rocksdb/include/rocksdb/utilities/optimistic_transaction_db.h

   1 //  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 //  This source code is licensed under both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5
   6 #pragma once
   7 #ifndef ROCKSDB_LITE
   8
   9 #include <string>
  10 #include <vector>
  11
  12 #include "rocksdb/comparator.h"
  13 #include "rocksdb/db.h"
  14 #include "rocksdb/utilities/stackable_db.h"
  15
  16 namespace rocksdb {
  17
  18 class Transaction;
  19
  20 // Database with Transaction support.
  21 //
  22 // See optimistic_transaction.h and examples/transaction_example.cc
  23
  24 // Options to use when starting an Optimistic Transaction
  25 struct OptimisticTransactionOptions {
  26   // Setting set_snapshot=true is the same as calling SetSnapshot().
  27   bool set_snapshot = false;
  28
  29   // Should be set if the DB has a non-default comparator.
  30   // See comment in WriteBatchWithIndex constructor.
  31   const Comparator* cmp = BytewiseComparator();
  32 };
  33
  34 class OptimisticTransactionDB : public StackableDB {
  35  public:
  36   // Open an OptimisticTransactionDB similar to DB::Open().
  37   static Status Open(const Options& options, const std::string& dbname,
  38                      OptimisticTransactionDB** dbptr);
  39
  40   static Status Open(const DBOptions& db_options, const std::string& dbname,
  41                      const std::vector<ColumnFamilyDescriptor>& column_families,
  42                      std::vector<ColumnFamilyHandle*>* handles,
  43                      OptimisticTransactionDB** dbptr);
  44
  45   virtual ~OptimisticTransactionDB() {}
  46
  47   // Starts a new Transaction.
  48   //
  49   // Caller is responsible for deleting the returned transaction when no
  50   // longer needed.
  51   //
  52   // If old_txn is not null, BeginTransaction will reuse this Transaction
  53   // handle instead of allocating a new one.  This is an optimization to avoid
  54   // extra allocations when repeatedly creating transactions.
  55   virtual Transaction* BeginTransaction(
  56       const WriteOptions& write_options,
  57       const OptimisticTransactionOptions& txn_options =
  58           OptimisticTransactionOptions(),
  59       Transaction* old_txn = nullptr) = 0;
  60
  61   OptimisticTransactionDB(const OptimisticTransactionDB&) = delete;
  62   void operator=(const OptimisticTransactionDB&) = delete;
  63
  64  protected:
  65   // To Create an OptimisticTransactionDB, call Open()
  66   explicit OptimisticTransactionDB(DB* db) : StackableDB(db) {}
  67 };
  68
  69 }  // namespace rocksdb
  70
  71 #endif  // ROCKSDB_LITE