LCOV - code coverage report
Current view: top level - backends/glass - glass_postlist.h (source / functions) Hit Total Coverage
Test: Test Coverage for xapian-core 7028d852e609 Lines: 22 22 100.0 %
Date: 2019-02-17 14:59:59 Functions: 11 11 100.0 %
Branches: 3 4 75.0 %

           Branch data     Line data    Source code
       1                 :            : /** @file glass_postlist.h
       2                 :            :  * @brief Postlists in glass databases
       3                 :            :  */
       4                 :            : /* Copyright 1999,2000,2001 BrightStation PLC
       5                 :            :  * Copyright 2002 Ananova Ltd
       6                 :            :  * Copyright 2002,2003,2004,2005,2007,2008,2009,2011,2013,2014,2015,2017 Olly Betts
       7                 :            :  * Copyright 2007,2009 Lemur Consulting Ltd
       8                 :            :  *
       9                 :            :  * This program is free software; you can redistribute it and/or
      10                 :            :  * modify it under the terms of the GNU General Public License as
      11                 :            :  * published by the Free Software Foundation; either version 2 of the
      12                 :            :  * License, or (at your option) any later version.
      13                 :            :  *
      14                 :            :  * This program is distributed in the hope that it will be useful,
      15                 :            :  * but WITHOUT ANY WARRANTY; without even the implied warranty of
      16                 :            :  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
      17                 :            :  * GNU General Public License for more details.
      18                 :            :  *
      19                 :            :  * You should have received a copy of the GNU General Public License
      20                 :            :  * along with this program; if not, write to the Free Software
      21                 :            :  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301
      22                 :            :  * USA
      23                 :            :  */
      24                 :            : 
      25                 :            : #ifndef XAPIAN_INCLUDED_GLASS_POSTLIST_H
      26                 :            : #define XAPIAN_INCLUDED_GLASS_POSTLIST_H
      27                 :            : 
      28                 :            : #include <xapian/database.h>
      29                 :            : 
      30                 :            : #include "glass_defs.h"
      31                 :            : #include "glass_inverter.h"
      32                 :            : #include "glass_positionlist.h"
      33                 :            : #include "api/leafpostlist.h"
      34                 :            : #include "omassert.h"
      35                 :            : 
      36                 :            : #include <memory>
      37                 :            : #include <map>
      38                 :            : #include <string>
      39                 :            : 
      40                 :            : using namespace std;
      41                 :            : 
      42                 :            : class GlassCursor;
      43                 :            : class GlassDatabase;
      44                 :            : 
      45                 :            : namespace Glass {
      46                 :            :     class PostlistChunkReader;
      47                 :            :     class PostlistChunkWriter;
      48                 :            :     class RootInfo;
      49                 :            : }
      50                 :            : 
      51                 :            : using Glass::RootInfo;
      52                 :            : 
      53                 :            : class GlassPostList;
      54                 :            : 
      55                 :       7802 : class GlassPostListTable : public GlassTable {
      56                 :            :         /// PostList for looking up document lengths.
      57                 :            :         mutable unique_ptr<GlassPostList> doclen_pl;
      58                 :            : 
      59                 :            :     public:
      60                 :            :         /** Create a new table object.
      61                 :            :          *
      62                 :            :          *  This does not create the table on disk - the create() method must
      63                 :            :          *  be called before the table is created on disk
      64                 :            :          *
      65                 :            :          *  This also does not open the table - the open() method must be
      66                 :            :          *  called before use is made of the table.
      67                 :            :          *
      68                 :            :          *  @param path_          - Path at which the table is stored.
      69                 :            :          *  @param readonly_      - whether to open the table for read only
      70                 :            :          *                          access.
      71                 :            :          */
      72                 :       3599 :         GlassPostListTable(const string & path_, bool readonly_)
      73                 :       7198 :             : GlassTable("postlist", path_ + "/postlist.", readonly_),
      74         [ +  - ]:       7198 :               doclen_pl()
      75                 :       3599 :         { }
      76                 :            : 
      77                 :        305 :         GlassPostListTable(int fd, off_t offset_, bool readonly_)
      78                 :            :             : GlassTable("postlist", fd, offset_, readonly_),
      79                 :        305 :               doclen_pl()
      80                 :        305 :         { }
      81                 :            : 
      82                 :       2990 :         void open(int flags_, const RootInfo & root_info,
      83                 :            :                   glass_revision_number_t rev) {
      84                 :       2990 :             doclen_pl.reset(0);
      85                 :       2990 :             GlassTable::open(flags_, root_info, rev);
      86                 :       2990 :         }
      87                 :            : 
      88                 :            :         /// Merge changes for a term.
      89                 :            :         void merge_changes(const string &term, const Inverter::PostingChanges & changes);
      90                 :            : 
      91                 :            :         /// Merge document length changes.
      92                 :            :         void merge_doclen_changes(const map<Xapian::docid, Xapian::termcount> & doclens);
      93                 :            : 
      94                 :            :         Xapian::docid get_chunk(const string &tname,
      95                 :            :                                 Xapian::docid did, bool adding,
      96                 :            :                                 Glass::PostlistChunkReader ** from,
      97                 :            :                                 Glass::PostlistChunkWriter **to);
      98                 :            : 
      99                 :            :         /// Compose a key from a termname and docid.
     100                 :     482482 :         static string make_key(const string & term, Xapian::docid did) {
     101                 :     482482 :             return pack_glass_postlist_key(term, did);
     102                 :            :         }
     103                 :            : 
     104                 :            :         /// Compose a key from a termname.
     105                 :    1753068 :         static string make_key(const string & term) {
     106                 :    1753068 :             return pack_glass_postlist_key(term);
     107                 :            :         }
     108                 :            : 
     109                 :       2491 :         bool term_exists(const string & term) const {
     110         [ +  + ]:       2491 :             return key_exists(make_key(term));
     111                 :            :         }
     112                 :            : 
     113                 :            :         /** Returns frequencies for a term.
     114                 :            :          *
     115                 :            :          *  @param term         The term to get frequencies for
     116                 :            :          *  @param termfreq_ptr Point to return number of docs indexed by @a
     117                 :            :          *                      term (or NULL not to return)
     118                 :            :          *  @param collfreq_ptr Point to return number of occurrences of @a
     119                 :            :          *                      term in the database (or NULL not to return)
     120                 :            :          *  @param wdfub_ptr    Point to return an upper bound on the wdf
     121                 :            :          *                      of @a term in the database (or NULL not to
     122                 :            :          *                      return)
     123                 :            :          */
     124                 :            :         void get_freqs(const std::string & term,
     125                 :            :                        Xapian::doccount * termfreq_ptr,
     126                 :            :                        Xapian::termcount * collfreq_ptr,
     127                 :            :                        Xapian::termcount * wdfub_ptr = NULL) const;
     128                 :            : 
     129                 :            :         /** Returns the length of document @a did. */
     130                 :            :         Xapian::termcount get_doclength(Xapian::docid did,
     131                 :            :                                         Xapian::Internal::intrusive_ptr<const GlassDatabase> db) const;
     132                 :            : 
     133                 :            :         /** Check if document @a did exists. */
     134                 :            :         bool document_exists(Xapian::docid did,
     135                 :            :                              Xapian::Internal::intrusive_ptr<const GlassDatabase> db) const;
     136                 :            : 
     137                 :            :         void get_used_docid_range(Xapian::docid & first,
     138                 :            :                                   Xapian::docid & last) const;
     139                 :            : };
     140                 :            : 
     141                 :            : /** A postlist in a glass database.
     142                 :            :  */
     143                 :            : class GlassPostList : public LeafPostList {
     144                 :            :         /** The database we are searching.  This pointer is held so that the
     145                 :            :          *  database doesn't get deleted before us, and also to give us access
     146                 :            :          *  to the position_table.
     147                 :            :          */
     148                 :            :         Xapian::Internal::intrusive_ptr<const GlassDatabase> this_db;
     149                 :            : 
     150                 :            :         /// The position list object for this posting list.
     151                 :            :         GlassRePositionList* positionlist = NULL;
     152                 :            : 
     153                 :            :         /// Whether we've started reading the list yet.
     154                 :            :         bool have_started;
     155                 :            : 
     156                 :            :         /// True if this is the last chunk.
     157                 :            :         bool is_last_chunk;
     158                 :            : 
     159                 :            :         /// Whether we've run off the end of the list yet.
     160                 :            :         bool is_at_end;
     161                 :            : 
     162                 :            :         /// Cursor pointing to current chunk of postlist.
     163                 :            :         unique_ptr<GlassCursor> cursor;
     164                 :            : 
     165                 :            :         /// The first document id in this chunk.
     166                 :            :         Xapian::docid first_did_in_chunk;
     167                 :            : 
     168                 :            :         /// The last document id in this chunk.
     169                 :            :         Xapian::docid last_did_in_chunk;
     170                 :            : 
     171                 :            :         /// Position of iteration through current chunk.
     172                 :            :         const char * pos;
     173                 :            : 
     174                 :            :         /// Pointer to byte after end of current chunk.
     175                 :            :         const char * end;
     176                 :            : 
     177                 :            :         /// Document id we're currently at.
     178                 :            :         Xapian::docid did;
     179                 :            : 
     180                 :            :         /// The wdf of the current document.
     181                 :            :         Xapian::termcount wdf;
     182                 :            : 
     183                 :            :         /// The number of entries in the posting list.
     184                 :            :         Xapian::doccount number_of_entries;
     185                 :            : 
     186                 :            :         /// Copying is not allowed.
     187                 :            :         GlassPostList(const GlassPostList &);
     188                 :            : 
     189                 :            :         /// Assignment is not allowed.
     190                 :            :         void operator=(const GlassPostList &);
     191                 :            : 
     192                 :            :         /** Move to the next item in the chunk, if possible.
     193                 :            :          *  If already at the end of the chunk, returns false.
     194                 :            :          */
     195                 :            :         bool next_in_chunk();
     196                 :            : 
     197                 :            :         /** Move to the next chunk.
     198                 :            :          *
     199                 :            :          *  If there are no more chunks in this postlist, this will set
     200                 :            :          *  is_at_end to true.
     201                 :            :          */
     202                 :            :         void next_chunk();
     203                 :            : 
     204                 :            :         /** Return true if the given document ID lies in the range covered
     205                 :            :          *  by the current chunk.  This does not say whether the document ID
     206                 :            :          *  is actually present.  It will return false if the document ID
     207                 :            :          *  is greater than the last document ID in the chunk, even if it is
     208                 :            :          *  less than the first document ID in the next chunk: it is possible
     209                 :            :          *  for no chunk to contain a particular document ID.
     210                 :            :          */
     211                 :            :         bool current_chunk_contains(Xapian::docid desired_did);
     212                 :            : 
     213                 :            :         /** Move to chunk containing the specified document ID.
     214                 :            :          *
     215                 :            :          *  This moves to the chunk whose starting document ID is
     216                 :            :          *  <= desired_did, but such that the next chunk's starting
     217                 :            :          *  document ID is > desired_did.
     218                 :            :          *
     219                 :            :          *  It is thus possible that current_chunk_contains(desired_did)
     220                 :            :          *  will return false after this call, since the document ID
     221                 :            :          *  might lie after the end of this chunk, but before the start
     222                 :            :          *  of the next chunk.
     223                 :            :          */
     224                 :            :         void move_to_chunk_containing(Xapian::docid desired_did);
     225                 :            : 
     226                 :            :         /** Scan forward in the current chunk for the specified document ID.
     227                 :            :          *
     228                 :            :          *  This is particularly efficient if the desired document ID is
     229                 :            :          *  greater than the last in the chunk - it then skips straight
     230                 :            :          *  to the end.
     231                 :            :          *
     232                 :            :          *  @return true if we moved to a valid document,
     233                 :            :          *          false if we reached the end of the chunk.
     234                 :            :          */
     235                 :            :         bool move_forward_in_chunk_to_at_least(Xapian::docid desired_did);
     236                 :            : 
     237                 :            :         GlassPostList(Xapian::Internal::intrusive_ptr<const GlassDatabase> this_db_,
     238                 :            :                       const string & term,
     239                 :            :                       GlassCursor * cursor_);
     240                 :            : 
     241                 :            :         void init();
     242                 :            : 
     243                 :            :     public:
     244                 :            :         /// Default constructor.
     245                 :            :         GlassPostList(Xapian::Internal::intrusive_ptr<const GlassDatabase> this_db_,
     246                 :            :                       const string & term,
     247                 :            :                       bool keep_reference);
     248                 :            : 
     249                 :            :         /// Destructor.
     250                 :            :         ~GlassPostList();
     251                 :            : 
     252                 :            :         LeafPostList * open_nearby_postlist(const std::string & term_,
     253                 :            :                                             bool need_read_pos) const;
     254                 :            : 
     255                 :            :         /** Used for looking up doclens.
     256                 :            :          *
     257                 :            :          *  @return true if docid @a desired_did has a document length.
     258                 :            :          */
     259                 :            :         bool jump_to(Xapian::docid desired_did);
     260                 :            : 
     261                 :            :         /** Returns number of docs indexed by this term.
     262                 :            :          *
     263                 :            :          *  This is the length of the postlist.
     264                 :            :          */
     265                 :    1645286 :         Xapian::doccount get_termfreq() const { return number_of_entries; }
     266                 :            : 
     267                 :            :         /// Returns the current docid.
     268                 :   66690082 :         Xapian::docid get_docid() const { Assert(have_started); return did; }
     269                 :            : 
     270                 :            :         /** Returns the Within Document Frequency of the term in the current
     271                 :            :          *  document.
     272                 :            :          */
     273                 :  115155358 :         Xapian::termcount get_wdf() const { Assert(have_started); return wdf; }
     274                 :            : 
     275                 :            :         /** Get the list of positions of the term in the current document.
     276                 :            :          */
     277                 :            :         PositionList *read_position_list();
     278                 :            : 
     279                 :            :         /** Get the list of positions of the term in the current document.
     280                 :            :          */
     281                 :            :         PositionList * open_position_list() const;
     282                 :            : 
     283                 :            :         /// Move to the next document.
     284                 :            :         PostList * next(double w_min);
     285                 :            : 
     286                 :            :         /// Skip to next document with docid >= docid.
     287                 :            :         PostList * skip_to(Xapian::docid desired_did, double w_min);
     288                 :            : 
     289                 :            :         /// Return true if and only if we're off the end of the list.
     290                 :   57972000 :         bool at_end() const { return is_at_end; }
     291                 :            : 
     292                 :            :         /// Get a description of the document.
     293                 :            :         std::string get_description() const;
     294                 :            : 
     295                 :            :         /// Read the number of entries and the collection frequency.
     296                 :            :         static void read_number_of_entries(const char ** posptr,
     297                 :            :                                            const char * end,
     298                 :            :                                            Xapian::doccount * number_of_entries_ptr,
     299                 :            :                                            Xapian::termcount * collection_freq_ptr);
     300                 :            : };
     301                 :            : 
     302                 :            : #ifdef DISABLE_GPL_LIBXAPIAN
     303                 :            : # error GPL source we cannot relicense included in libxapian
     304                 :            : #endif
     305                 :            : 
     306                 :            : #endif /* XAPIAN_INCLUDED_GLASS_POSTLIST_H */

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