rocksdb/utilities/transactions/optimistic_transaction_impl.h

// Copyright (c) 2015, Facebook, Inc.  All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.

#pragma once

#ifndef ROCKSDB_LITE

#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/optimistic_transaction_db.h"
#include "rocksdb/utilities/write_batch_with_index.h"
#include "utilities/transactions/transaction_base.h"
#include "utilities/transactions/transaction_util.h"

namespace rocksdb {

class OptimisticTransactionImpl : public TransactionBaseImpl {
 public:
  OptimisticTransactionImpl(OptimisticTransactionDB* db,
                            const WriteOptions& write_options,
                            const OptimisticTransactionOptions& txn_options);

  virtual ~OptimisticTransactionImpl();

  Status Commit() override;

  void Rollback() override;

  uint64_t GetNumKeys() const override;

  const TransactionKeyMap* GetTrackedKeys() const { return &tracked_keys_; }

 protected:
  Status TryLock(ColumnFamilyHandle* column_family, const Slice& key,
                 bool untracked = false) override;

 private:
  OptimisticTransactionDB* const txn_db_;

  // Map of Column Family IDs to keys and corresponding sequence numbers.
  // The sequence number stored for a key will be used during commit to make
  // sure this key has
  // not changed since this sequence number.
  TransactionKeyMap tracked_keys_;

  friend class OptimisticTransactionCallback;

  // Returns OK if it is safe to commit this transaction.  Returns Status::Busy
  // if there are read or write conflicts that would prevent us from committing
  // OR if we can not determine whether there would be any such conflicts.
  //
  // Should only be called on writer thread.
  Status CheckTransactionForConflicts(DB* db);

  void Clear() override;

  // No copying allowed
  OptimisticTransactionImpl(const OptimisticTransactionImpl&);
  void operator=(const OptimisticTransactionImpl&);
};

// Used at commit time to trigger transaction validation
class OptimisticTransactionCallback : public WriteCallback {
 public:
  explicit OptimisticTransactionCallback(OptimisticTransactionImpl* txn)
      : txn_(txn) {}

  Status Callback(DB* db) override {
    return txn_->CheckTransactionForConflicts(db);
  }

 private:
  OptimisticTransactionImpl* txn_;
};

}  // namespace rocksdb

#endif  // ROCKSDB_LITE