searchlib/src/vespa/searchlib/diskindex/pagedict4file.h


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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/searchlib/index/dictionaryfile.h>
#include <vespa/searchlib/index/postinglistparams.h>
#include <vespa/searchlib/bitcompression/pagedict4.h>

namespace vespalib { class GenericHeader; }

namespace search::diskindex {

/**
 * Dictionary file containing words and counts for words.
 */
class PageDict4FileSeqRead : public index::DictionaryFileSeqRead
{
    using DC = bitcompression::PostingListCountFileDecodeContext;
    using SSReader = bitcompression::PageDict4SSReader;
    using Reader = bitcompression::PageDict4Reader;
    using PostingListCounts = index::PostingListCounts;
    struct DictFileReadContext;

    std::unique_ptr<Reader>   _pReader;
    std::unique_ptr<SSReader> _ssReader;
    std::unique_ptr<DictFileReadContext> _ss;
    std::unique_ptr<DictFileReadContext> _sp;
    std::unique_ptr<DictFileReadContext> _p;
    uint64_t _wordNum;
public:
    PageDict4FileSeqRead();
    ~PageDict4FileSeqRead() override;

    /**
     * Read word and counts.  Only nonzero counts are returned. If at
     * end of dictionary then noWordNumHigh() is returned as word number.
     */
    void readWord(vespalib::string &word, uint64_t &wordNum, PostingListCounts &counts) override;
    bool open(const vespalib::string &name, const TuneFileSeqRead &tuneFileRead) override;
    bool close() override;
    void getParams(index::PostingListParams &params) override;
};

/**
 * Interface for dictionary file containing words and count for words.
 */
class PageDict4FileSeqWrite : public index::DictionaryFileSeqWrite
{
    using EC = bitcompression::PostingListCountFileEncodeContext;
    using SSWriter = bitcompression::PageDict4SSWriter;
    using SPWriter = bitcompression::PageDict4SPWriter;
    using PWriter = bitcompression::PageDict4PWriter;
    using PostingListCounts = index::PostingListCounts;
    using FileHeaderContext = common::FileHeaderContext;
    struct DictFileContext;

    index::PostingListParams  _params;
    std::unique_ptr<PWriter>  _pWriter;
    std::unique_ptr<SPWriter> _spWriter;
    std::unique_ptr<SSWriter> _ssWriter;
    std::unique_ptr<DictFileContext> _ss;
    std::unique_ptr<DictFileContext> _sp;
    std::unique_ptr<DictFileContext> _p;

    void activateParams(const index::PostingListParams &params);
public:
    PageDict4FileSeqWrite();
    ~PageDict4FileSeqWrite();

    void writeWord(vespalib::stringref word, const PostingListCounts &counts) override;

    /**
     * Open dictionary file for sequential write.  The index with most
     * words should be first for optimal compression.
     */
    bool open(const vespalib::string &name, const TuneFileSeqWrite &tune,
              const FileHeaderContext &fileHeaderContext) override;

    bool close() override;
    void setParams(const index::PostingListParams &params) override;
    void getParams(index::PostingListParams &params) override;
};

}