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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
#pragma once
#include <vespa/vespalib/stllike/string.h>
#include <cstdint>
#include <memory>
#include <vector>
namespace search {
class IFlushToken;
template <class Reader, class Writer> class PostingPriorityQueueMerger;
}
namespace search::diskindex {
class DictionaryWordReader;
class FieldLengthScanner;
class FieldReader;
class FieldWriter;
class FusionOutputIndex;
class WordAggregator;
class WordNumMapping;
/*
* Class for merging posting lists for a single field during fusion.
*/
class FieldMerger
{
using WordNumMappingList = std::vector<WordNumMapping>;
enum class State {
MERGE_START,
RENUMBER_WORD_IDS,
RENUMBER_WORD_IDS_FINISH,
OPEN_POSTINGS_FIELD_READERS,
SCAN_ELEMENT_LENGTHS,
OPEN_POSTINGS_FIELD_READERS_FINISH,
MERGE_POSTINGS,
MERGE_POSTINGS_FINISH,
MERGE_DONE
};
uint32_t _id;
vespalib::string _field_name;
vespalib::string _field_dir;
const FusionOutputIndex& _fusion_out_index;
std::shared_ptr<IFlushToken> _flush_token;
std::vector<std::unique_ptr<DictionaryWordReader>> _word_readers;
std::unique_ptr<PostingPriorityQueueMerger<DictionaryWordReader, WordAggregator>> _word_heap;
std::unique_ptr<WordAggregator> _word_aggregator;
WordNumMappingList _word_num_mappings;
uint64_t _num_word_ids;
std::vector<std::unique_ptr<FieldReader>> _readers;
std::unique_ptr<PostingPriorityQueueMerger<FieldReader, FieldWriter>> _heap;
std::unique_ptr<FieldWriter> _writer;
std::shared_ptr<FieldLengthScanner> _field_length_scanner;
uint32_t _open_reader_idx;
State _state;
bool _failed;
void make_tmp_dirs();
bool clean_tmp_dirs();
bool open_input_word_readers();
bool read_mapping_files();
bool renumber_word_ids_start();
void renumber_word_ids_main();
bool renumber_word_ids_finish();
void renumber_word_ids_failed();
void allocate_field_length_scanner();
bool open_input_field_reader();
void open_input_field_readers();
void scan_element_lengths();
bool open_field_writer();
bool select_cooked_or_raw_features(FieldReader& reader);
bool setup_merge_heap();
void merge_postings_start();
void merge_postings_open_field_readers_done();
void merge_postings_main();
bool merge_postings_finish();
void merge_postings_failed();
public:
FieldMerger(uint32_t id, const FusionOutputIndex& fusion_out_index, std::shared_ptr<IFlushToken> flush_token);
~FieldMerger();
void merge_field_start();
void merge_field_finish();
void process_merge_field(); // Called multiple times
uint32_t get_id() const noexcept { return _id; }
bool done() const noexcept { return _state == State::MERGE_DONE; }
bool failed() const noexcept { return _failed; }
};
}
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