xapian-core/backends/glass/glass_version.h

   1 /** @file glass_version.h
   2  * @brief GlassVersion class
   3  */
   4 /* Copyright (C) 2006,2007,2008,2009,2010,2013,2014,2015,2016,2018 Olly Betts
   5  * Copyright (C) 2011 Dan Colish
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  20  */
  21
  22 #ifndef XAPIAN_INCLUDED_GLASS_VERSION_H
  23 #define XAPIAN_INCLUDED_GLASS_VERSION_H
  24
  25 #include "glass_changes.h"
  26 #include "glass_defs.h"
  27
  28 #include "omassert.h"
  29
  30 #include <cstring>
  31 #include <string>
  32
  33 #include "backends/uuids.h"
  34 #include "internaltypes.h"
  35 #include "xapian/types.h"
  36
  37 namespace Glass {
  38
  39 class RootInfo {
  40     glass_block_t root;
  41     unsigned level;
  42     glass_tablesize_t num_entries;
  43     bool root_is_fake;
  44     bool sequential;
  45     unsigned blocksize;
  46     /// Should be >= 4 or 0 for no compression.
  47     uint4 compress_min;
  48     std::string fl_serialised;
  49
  50   public:
  51     void init(unsigned blocksize_, uint4 compress_min_);
  52
  53     void serialise(std::string &s) const;
  54
  55     bool unserialise(const char ** p, const char * end);
  56
  57     glass_block_t get_root() const { return root; }
  58     int get_level() const { return int(level); }
  59     glass_tablesize_t get_num_entries() const { return num_entries; }
  60     bool get_root_is_fake() const { return root_is_fake; }
  61     bool get_sequential() const { return sequential; }
  62     unsigned get_blocksize() const {
  63         AssertRel(blocksize,>=,GLASS_MIN_BLOCKSIZE);
  64         AssertRel(blocksize,<=,GLASS_MAX_BLOCKSIZE);
  65         return blocksize;
  66     }
  67     uint4 get_compress_min() const { return compress_min; }
  68     const std::string & get_free_list() const { return fl_serialised; }
  69
  70     void set_level(int level_) { level = unsigned(level_); }
  71     void set_num_entries(glass_tablesize_t n) { num_entries = n; }
  72     void set_root_is_fake(bool f) { root_is_fake = f; }
  73     void set_sequential(bool f) { sequential = f; }
  74     void set_root(glass_block_t root_) { root = root_; }
  75     void set_blocksize(unsigned b) {
  76         AssertRel(b,>=,GLASS_MIN_BLOCKSIZE);
  77         AssertRel(b,<=,GLASS_MAX_BLOCKSIZE);
  78         blocksize = b;
  79     }
  80     void set_free_list(const std::string & s) { fl_serialised = s; }
  81 };
  82
  83 }
  84
  85 using Glass::RootInfo;
  86
  87 /** The GlassVersion class manages the revision files.
  88  *
  89  *  The "iamglass" file (currently) contains a "magic" string identifying
  90  *  that this is a glass database, a database format version number, the UUID
  91  *  of the database, the revision of the database, and the root block info for
  92  *  each table.
  93  */
  94 class GlassVersion {
  95     glass_revision_number_t rev;
  96
  97     RootInfo root[Glass::MAX_];
  98     RootInfo old_root[Glass::MAX_];
  99
 100     /// The UUID of this database.
 101     Uuid uuid;
 102
 103     /** File descriptor.
 104      *
 105      *  When committing, this hold the file descriptor of the new changes file
 106      *  between the call to the write() and sync() methods.
 107      *
 108      *  For a single-file database (when db_dir.empty()), this holds the fd of
 109      *  that file for use in read().
 110      */
 111     int fd;
 112
 113     /** Offset into the file at which the version data starts.
 114      *
 115      *  Will be 0, except for an embedded multi-file database.
 116      */
 117     off_t offset;
 118
 119     /// The database directory.
 120     std::string db_dir;
 121
 122     GlassChanges * changes;
 123
 124     /// The number of documents in the database.
 125     Xapian::doccount doccount;
 126
 127     /// The total of the lengths of all documents in the database.
 128     Xapian::totallength total_doclen;
 129
 130     /// Greatest document id ever used in this database.
 131     Xapian::docid last_docid;
 132
 133     /// A lower bound on the smallest document length in this database.
 134     Xapian::termcount doclen_lbound;
 135
 136     /// An upper bound on the greatest document length in this database.
 137     Xapian::termcount doclen_ubound;
 138
 139     /// An upper bound on the greatest wdf in this database.
 140     Xapian::termcount wdf_ubound;
 141
 142     /// An upper bound on the spelling wordfreq in this database.
 143     Xapian::termcount spelling_wordfreq_ubound;
 144
 145     /// Oldest changeset removed when max_changesets is set
 146     mutable glass_revision_number_t oldest_changeset;
 147
 148     /// The serialised database stats.
 149     std::string serialised_stats;
 150
 151     // Serialise the database stats.
 152     void serialise_stats();
 153
 154     // Unserialise the database stats.
 155     void unserialise_stats();
 156
 157   public:
 158     explicit GlassVersion(const std::string & db_dir_ = std::string())
 159         : rev(0), fd(-1), offset(0), db_dir(db_dir_), changes(NULL),
 160           doccount(0), total_doclen(0), last_docid(0),
 161           doclen_lbound(0), doclen_ubound(0),
 162           wdf_ubound(0), spelling_wordfreq_ubound(0),
 163           oldest_changeset(0) { }
 164
 165     explicit GlassVersion(int fd_);
 166
 167     ~GlassVersion();
 168
 169     /** Create the version file. */
 170     void create(unsigned blocksize);
 171
 172     void set_changes(GlassChanges * changes_) { changes = changes_; }
 173
 174     /** Read the version file and check it's a version we understand.
 175      *
 176      *  On failure, an exception is thrown.
 177      */
 178     void read();
 179
 180     void cancel();
 181
 182     const std::string write(glass_revision_number_t new_rev, int flags);
 183
 184     bool sync(const std::string & tmpfile,
 185               glass_revision_number_t new_rev, int flags);
 186
 187     glass_revision_number_t get_revision() const { return rev; }
 188
 189     const RootInfo & get_root(Glass::table_type tbl) const {
 190         return root[tbl];
 191     }
 192
 193     RootInfo * root_to_set(Glass::table_type tbl) {
 194         return &root[tbl];
 195     }
 196
 197     /// Return pointer to 16 byte UUID.
 198     const char * get_uuid() const {
 199         return uuid.data();
 200     }
 201
 202     /// Return UUID in the standard 36 character string format.
 203     std::string get_uuid_string() const {
 204         return uuid.to_string();
 205     }
 206
 207     Xapian::doccount get_doccount() const { return doccount; }
 208
 209     Xapian::totallength get_total_doclen() const { return total_doclen; }
 210
 211     Xapian::docid get_last_docid() const { return last_docid; }
 212
 213     Xapian::termcount get_doclength_lower_bound() const {
 214         return doclen_lbound;
 215     }
 216
 217     Xapian::termcount get_doclength_upper_bound() const {
 218         return doclen_ubound;
 219     }
 220
 221     Xapian::termcount get_wdf_upper_bound() const { return wdf_ubound; }
 222
 223     Xapian::termcount get_spelling_wordfreq_upper_bound() const {
 224         return spelling_wordfreq_ubound;
 225     }
 226
 227     glass_revision_number_t get_oldest_changeset() const {
 228         return oldest_changeset;
 229     }
 230
 231     void set_last_docid(Xapian::docid did) { last_docid = did; }
 232
 233     void set_oldest_changeset(glass_revision_number_t changeset) const {
 234         oldest_changeset = changeset;
 235     }
 236
 237     void set_spelling_wordfreq_upper_bound(Xapian::termcount ub) {
 238         spelling_wordfreq_ubound = ub;
 239     }
 240
 241     void add_document(Xapian::termcount doclen) {
 242         ++doccount;
 243         if (total_doclen == 0 || (doclen && doclen < doclen_lbound))
 244             doclen_lbound = doclen;
 245         if (doclen > doclen_ubound)
 246             doclen_ubound = doclen;
 247         total_doclen += doclen;
 248     }
 249
 250     void delete_document(Xapian::termcount doclen) {
 251         --doccount;
 252         total_doclen -= doclen;
 253         // If the database no longer contains any postings, we can reset
 254         // doclen_lbound, doclen_ubound and wdf_ubound.
 255         if (total_doclen == 0) {
 256             doclen_lbound = 0;
 257             doclen_ubound = 0;
 258             wdf_ubound = 0;
 259         }
 260     }
 261
 262     void check_wdf(Xapian::termcount wdf) {
 263         if (wdf > wdf_ubound) wdf_ubound = wdf;
 264     }
 265
 266     Xapian::docid get_next_docid() { return ++last_docid; }
 267
 268     /** Merge the database stats.
 269      *
 270      *  Used by compaction.
 271      */
 272     void merge_stats(const GlassVersion & o);
 273
 274     bool single_file() const { return db_dir.empty(); }
 275
 276     off_t get_offset() const { return offset; }
 277 };
 278
 279 #endif // XAPIAN_INCLUDED_GLASS_VERSION_H