glass_version.h

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/* Copyright (C) 2006,2007,2008,2009,2010,2013,2014,2015,2016,2018 Olly Betts
 * Copyright (C) 2011 Dan Colish
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#ifndef XAPIAN_INCLUDED_GLASS_VERSION_H
#define XAPIAN_INCLUDED_GLASS_VERSION_H

#include "glass_changes.h"
#include "glass_defs.h"

#include "omassert.h"

#include <algorithm>
#include <cstring>
#include <string>

#include "backends/uuids.h"
#include "internaltypes.h"
#include "min_non_zero.h"
#include "xapian/types.h"

namespace Glass {

class RootInfo {
    glass_block_t root;
    unsigned level;
    glass_tablesize_t num_entries;
    bool root_is_fake;
    bool sequential;
    unsigned blocksize;
    uint4 compress_min;
    std::string fl_serialised;

  public:
    void init(unsigned blocksize_, uint4 compress_min_);

    void serialise(std::string &s) const;

    bool unserialise(const char ** p, const char * end);

    glass_block_t get_root() const { return root; }
    int get_level() const { return int(level); }
    glass_tablesize_t get_num_entries() const { return num_entries; }
    bool get_root_is_fake() const { return root_is_fake; }
    bool get_sequential() const { return sequential; }
    unsigned get_blocksize() const {
        AssertRel(blocksize,>=,2048);
        return blocksize;
    }
    uint4 get_compress_min() const { return compress_min; }
    const std::string & get_free_list() const { return fl_serialised; }

    void set_level(int level_) { level = unsigned(level_); }
    void set_num_entries(glass_tablesize_t n) { num_entries = n; }
    void set_root_is_fake(bool f) { root_is_fake = f; }
    void set_sequential(bool f) { sequential = f; }
    void set_root(glass_block_t root_) { root = root_; }
    void set_blocksize(unsigned b) {
        AssertRel(b,>=,2048);
        blocksize = b;
    }
    void set_free_list(const std::string & s) { fl_serialised = s; }
};

}

using Glass::RootInfo;

class GlassVersion {
    glass_revision_number_t rev;

    RootInfo root[Glass::MAX_];
    RootInfo old_root[Glass::MAX_];

    Uuid uuid;

    int fd;

    off_t offset;

    std::string db_dir;

    GlassChanges * changes;

    Xapian::doccount doccount;

    Xapian::totallength total_doclen;

    Xapian::docid last_docid;

    Xapian::termcount doclen_lbound;

    Xapian::termcount doclen_ubound;

    Xapian::termcount wdf_ubound;

    Xapian::termcount spelling_wordfreq_ubound;

    mutable glass_revision_number_t oldest_changeset;

    std::string serialised_stats;

    // Serialise the database stats.
    void serialise_stats();

    // Unserialise the database stats.
    void unserialise_stats();

  public:
    explicit GlassVersion(const std::string & db_dir_)
        : rev(0), fd(-1), offset(0), db_dir(db_dir_), changes(NULL),
          doccount(0), total_doclen(0), last_docid(0),
          doclen_lbound(0), doclen_ubound(0),
          wdf_ubound(0), spelling_wordfreq_ubound(0),
          oldest_changeset(0) { }

    explicit GlassVersion(int fd_);

    ~GlassVersion();

    void create(unsigned blocksize);

    void set_changes(GlassChanges * changes_) { changes = changes_; }

    void read();

    void cancel();

    const std::string write(glass_revision_number_t new_rev, int flags);

    bool sync(const std::string & tmpfile,
              glass_revision_number_t new_rev, int flags);

    glass_revision_number_t get_revision() const { return rev; }

    const RootInfo & get_root(Glass::table_type tbl) const {
        return root[tbl];
    }

    RootInfo * root_to_set(Glass::table_type tbl) {
        return &root[tbl];
    }

    const char * get_uuid() const {
        return uuid.data();
    }

    std::string get_uuid_string() const {
        return uuid.to_string();
    }

    Xapian::doccount get_doccount() const { return doccount; }

    Xapian::totallength get_total_doclen() const { return total_doclen; }

    Xapian::docid get_last_docid() const { return last_docid; }

    Xapian::termcount get_doclength_lower_bound() const {
        return doclen_lbound;
    }

    Xapian::termcount get_doclength_upper_bound() const {
        return doclen_ubound;
    }

    Xapian::termcount get_wdf_upper_bound() const { return wdf_ubound; }

    Xapian::termcount get_spelling_wordfreq_upper_bound() const {
        return spelling_wordfreq_ubound;
    }

    glass_revision_number_t get_oldest_changeset() const {
        return oldest_changeset;
    }

    void set_last_docid(Xapian::docid did) { last_docid = did; }

    void set_oldest_changeset(glass_revision_number_t changeset) const {
        oldest_changeset = changeset;
    }

    void set_spelling_wordfreq_upper_bound(Xapian::termcount ub) {
        spelling_wordfreq_ubound = ub;
    }

    void add_document(Xapian::termcount doclen) {
        ++doccount;
        doclen_lbound = min_non_zero(doclen_lbound, doclen);
        doclen_ubound = std::max(doclen_ubound, doclen);
        total_doclen += doclen;
    }

    void delete_document(Xapian::termcount doclen) {
        --doccount;
        total_doclen -= doclen;
        // If the database no longer contains any postings, we can reset
        // doclen_lbound, doclen_ubound and wdf_ubound.
        if (total_doclen == 0) {
            doclen_lbound = 0;
            doclen_ubound = 0;
            wdf_ubound = 0;
        }
    }

    void check_wdf(Xapian::termcount wdf) {
        if (wdf > wdf_ubound) wdf_ubound = wdf;
    }

    Xapian::docid get_next_docid() { return ++last_docid; }

    void merge_stats(const GlassVersion & o);

    bool single_file() const { return db_dir.empty(); }

    off_t get_offset() const { return offset; }
};

#endif // XAPIAN_INCLUDED_GLASS_VERSION_H