rocksdb/utilities/merge_operators/max.cc
Islam AbdelRahman 1f2dca0eaa Add MaxOperator to utilities/merge_operators/
Summary:
Introduce MaxOperator a simple merge operator that return the max of all operands.
This merge operand help me in benchmarking

Test Plan: Add new unitttests

Reviewers: sdong, andrewkr, yhchiang

Reviewed By: yhchiang

Subscribers: andrewkr, dhruba

Differential Revision: https://reviews.facebook.net/D57873
2016-05-19 15:51:29 -07:00

78 lines
2.3 KiB
C++

// Copyright (c) 2011-present, 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.
#include <memory>
#include "rocksdb/merge_operator.h"
#include "rocksdb/slice.h"
#include "utilities/merge_operators.h"
using rocksdb::Slice;
using rocksdb::Logger;
using rocksdb::MergeOperator;
namespace { // anonymous namespace
// Merge operator that picks the maximum operand, Comparison is based on
// Slice::compare
class MaxOperator : public MergeOperator {
public:
virtual bool FullMerge(const Slice& key, const Slice* existing_value,
const std::deque<std::string>& operand_list,
std::string* new_value,
Logger* logger) const override {
Slice max;
if (existing_value) {
max = Slice(existing_value->data(), existing_value->size());
}
for (const auto& op : operand_list) {
if (max.compare(op) < 0) {
max = Slice(op.data(), op.size());
}
}
new_value->assign(max.data(), max.size());
return true;
}
virtual 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;
}
virtual 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;
}
virtual const char* Name() const override { return "MaxOperator"; }
};
} // end of anonymous namespace
namespace rocksdb {
std::shared_ptr<MergeOperator> MergeOperators::CreateMaxOperator() {
return std::make_shared<MaxOperator>();
}
}