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// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <memory>
#include <vector>
namespace search {
namespace grouping {
/**
* Wrapper class used to handle merging of grouping results. All input
* data is assumed to be kept alive by the user.
**/
class MergingManager
{
public:
/**
* Simple wrapper for all the grouping results from a single
* search/fdispatch node.
**/
struct Entry {
uint32_t partId;
uint32_t rowId;
bool mld;
const char *data;
size_t length;
Entry(uint32_t part, uint32_t row, bool m, const char *pt, size_t len)
: partId(part), rowId(row), mld(m), data(pt), length(len) {}
};
private:
MergingManager(const MergingManager &);
MergingManager &operator=(const MergingManager &);
void fullMerge();
bool needMerge() const;
uint32_t _partBits;
uint32_t _rowBits;
std::vector<Entry> _input;
char *_result;
size_t _resultLen;
public:
/**
* Create a new merging manager.
*
* @param partBits how many bits to be used to encode partId into path
* @param rowBits how many bits to be used to encode rowId into path
**/
MergingManager(uint32_t partBits, uint32_t rowBits);
/**
* Release resources
**/
~MergingManager();
/**
* Register an additional grouping result that should be part of
* the upcoming merge operation.
*
* @param partId which partition these results came from
* @param rowId which row these results came from
* @param mld true if the node below is a dispatch node
* @param groupSpec group spec
* @param groupSpecLen length of the group spec
**/
void addResult(uint32_t partId, uint32_t rowId, bool mld,
const char *groupResult, size_t groupResultLen);
/**
* Perform actual merging of all the registered grouping results.
**/
void merge();
/**
* Obtain the size of the grouping result
*
* @return grouping result size
**/
size_t getGroupResultLen() const;
/**
* Obtain the grouping result.
*
* @return grouping result
**/
const char *getGroupResult() const;
/**
* Steal the grouping result. Invoking this method will take
* overship of the grouping result blob returned by this
* method. Use 'free' to release the memory when you are done with
* it.
*
* @return grouping result that have just been stolen
**/
char *stealGroupResult();
};
} // namespace search::grouping
} // namespace search
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