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Diffstat (limited to 'src/rocksdb/utilities/merge_operators/max.cc')
-rw-r--r-- | src/rocksdb/utilities/merge_operators/max.cc | 77 |
1 files changed, 77 insertions, 0 deletions
diff --git a/src/rocksdb/utilities/merge_operators/max.cc b/src/rocksdb/utilities/merge_operators/max.cc new file mode 100644 index 000000000..2270c1f03 --- /dev/null +++ b/src/rocksdb/utilities/merge_operators/max.cc @@ -0,0 +1,77 @@ +// 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). + +#include <memory> + +#include "rocksdb/merge_operator.h" +#include "rocksdb/slice.h" +#include "utilities/merge_operators.h" + +using ROCKSDB_NAMESPACE::Logger; +using ROCKSDB_NAMESPACE::MergeOperator; +using ROCKSDB_NAMESPACE::Slice; + +namespace { // anonymous namespace + +// Merge operator that picks the maximum operand, Comparison is based on +// Slice::compare +class MaxOperator : public MergeOperator { + public: + bool FullMergeV2(const MergeOperationInput& merge_in, + MergeOperationOutput* merge_out) const override { + Slice& max = merge_out->existing_operand; + if (merge_in.existing_value) { + max = Slice(merge_in.existing_value->data(), + merge_in.existing_value->size()); + } else if (max.data() == nullptr) { + max = Slice(); + } + + for (const auto& op : merge_in.operand_list) { + if (max.compare(op) < 0) { + max = op; + } + } + + return true; + } + + bool PartialMerge(const Slice& /*key*/, const Slice& left_operand, + const Slice& right_operand, std::string* new_value, + Logger* /*logger*/) const override { + if (left_operand.compare(right_operand) >= 0) { + new_value->assign(left_operand.data(), left_operand.size()); + } else { + new_value->assign(right_operand.data(), right_operand.size()); + } + return true; + } + + bool PartialMergeMulti(const Slice& /*key*/, + const std::deque<Slice>& operand_list, + std::string* new_value, + Logger* /*logger*/) const override { + Slice max; + for (const auto& operand : operand_list) { + if (max.compare(operand) < 0) { + max = operand; + } + } + + new_value->assign(max.data(), max.size()); + return true; + } + + const char* Name() const override { return "MaxOperator"; } +}; + +} // end of anonymous namespace + +namespace ROCKSDB_NAMESPACE { + +std::shared_ptr<MergeOperator> MergeOperators::CreateMaxOperator() { + return std::make_shared<MaxOperator>(); +} +} // namespace ROCKSDB_NAMESPACE |