2a62ca1750
Summary: This change models Optimistic Tx db after Pessimistic TX db. The motivation for this change is to make the ptr polymorphic so it can be held by the same raw or smart ptr. Currently, due to the inheritance of the Opt Tx db not being rooted in the manner of Pess Tx from a single DB root it is more difficult to write clean code and have clear ownership of the database in cases when options dictate instantiate of plan DB, Pess Tx DB or Opt tx db. Closes https://github.com/facebook/rocksdb/pull/3566 Differential Revision: D7184502 Pulled By: yiwu-arbug fbshipit-source-id: 31d06efafd79497bb0c230e971857dba3bd962c3
72 lines
2.3 KiB
C++
72 lines
2.3 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#pragma once
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#ifndef ROCKSDB_LITE
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#include <string>
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#include <vector>
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#include "rocksdb/comparator.h"
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#include "rocksdb/db.h"
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#include "rocksdb/utilities/stackable_db.h"
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namespace rocksdb {
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class Transaction;
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// Database with Transaction support.
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//
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// See optimistic_transaction.h and examples/transaction_example.cc
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// Options to use when starting an Optimistic Transaction
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struct OptimisticTransactionOptions {
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// Setting set_snapshot=true is the same as calling SetSnapshot().
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bool set_snapshot = false;
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// Should be set if the DB has a non-default comparator.
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// See comment in WriteBatchWithIndex constructor.
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const Comparator* cmp = BytewiseComparator();
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};
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class OptimisticTransactionDB : public StackableDB {
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public:
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// Open an OptimisticTransactionDB similar to DB::Open().
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static Status Open(const Options& options, const std::string& dbname,
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OptimisticTransactionDB** dbptr);
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static Status Open(const DBOptions& db_options, const std::string& dbname,
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const std::vector<ColumnFamilyDescriptor>& column_families,
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std::vector<ColumnFamilyHandle*>* handles,
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OptimisticTransactionDB** dbptr);
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virtual ~OptimisticTransactionDB() {}
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// Starts a new Transaction.
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//
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// Caller is responsible for deleting the returned transaction when no
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// longer needed.
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//
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// If old_txn is not null, BeginTransaction will reuse this Transaction
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// handle instead of allocating a new one. This is an optimization to avoid
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// extra allocations when repeatedly creating transactions.
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virtual Transaction* BeginTransaction(
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const WriteOptions& write_options,
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const OptimisticTransactionOptions& txn_options =
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OptimisticTransactionOptions(),
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Transaction* old_txn = nullptr) = 0;
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OptimisticTransactionDB(const OptimisticTransactionDB&) = delete;
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void operator=(const OptimisticTransactionDB&) = delete;
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protected:
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// To Create an OptimisticTransactionDB, call Open()
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explicit OptimisticTransactionDB(DB* db) : StackableDB(db) {}
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};
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} // namespace rocksdb
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#endif // ROCKSDB_LITE
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