glass_version.h

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/* Copyright (C) 2006-2024 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, see
 * <https://www.gnu.org/licenses/>.
 */
 
#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,>=,GLASS_MIN_BLOCKSIZE);
        AssertRel(blocksize,<=,GLASS_MAX_BLOCKSIZE);
        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,>=,GLASS_MIN_BLOCKSIZE);
        AssertRel(b,<=,GLASS_MAX_BLOCKSIZE);
        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(std::string_view 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;
    }
 
    Xapian::termcount get_unique_terms_lower_bound() const {
        if (total_doclen == 0) return 0;
        Assert(doclen_lbound != 0);
        Assert(wdf_ubound != 0);
        return (doclen_lbound - 1) / wdf_ubound + 1;
    }
 
    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