ceph/src/rocksdb/utilities/cassandra/merge_operator.h

   1 //  Copyright (c) 2017-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 #include "rocksdb/merge_operator.h"
   8 #include "rocksdb/slice.h"
   9 #include "utilities/cassandra/cassandra_options.h"
  10
  11 namespace ROCKSDB_NAMESPACE {
  12 namespace cassandra {
  13
  14 /**
  15  * A MergeOperator for rocksdb that implements Cassandra row value merge.
  16  */
  17 class CassandraValueMergeOperator : public MergeOperator {
  18  public:
  19   explicit CassandraValueMergeOperator(int32_t gc_grace_period_in_seconds,
  20                                        size_t operands_limit = 0);
  21
  22   virtual bool FullMergeV2(const MergeOperationInput& merge_in,
  23                            MergeOperationOutput* merge_out) const override;
  24
  25   virtual bool PartialMergeMulti(const Slice& key,
  26                                  const std::deque<Slice>& operand_list,
  27                                  std::string* new_value,
  28                                  Logger* logger) const override;
  29
  30   const char* Name() const override { return kClassName(); }
  31   static const char* kClassName() { return "CassandraValueMergeOperator"; }
  32
  33   virtual bool AllowSingleOperand() const override { return true; }
  34
  35   virtual bool ShouldMerge(const std::vector<Slice>& operands) const override {
  36     return options_.operands_limit > 0 &&
  37            operands.size() >= options_.operands_limit;
  38   }
  39
  40  private:
  41   CassandraOptions options_;
  42 };
  43 }  // namespace cassandra
  44 }  // namespace ROCKSDB_NAMESPACE