xapian-core/backends/glass/glass_docdata.h

   1 /** @file
   2  * @brief Subclass of GlassTable which holds document data.
   3  */
   4 /* Copyright (C) 2007,2008,2009,2010,2014,2016 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 #ifndef XAPIAN_INCLUDED_GLASS_DOCDATA_H
  22 #define XAPIAN_INCLUDED_GLASS_DOCDATA_H
  23
  24 #include <xapian/types.h>
  25
  26 #include "glass_lazytable.h"
  27 #include "pack.h"
  28
  29 #include <string>
  30
  31 class GlassDocDataTable : public GlassLazyTable {
  32   public:
  33     static std::string make_key(Xapian::docid did) {
  34         std::string key;
  35         pack_uint_preserving_sort(key, did);
  36         return key;
  37     }
  38
  39     /** Create a new GlassDocDataTable object.
  40      *
  41      *  This method does not create or open the table on disk - you
  42      *  must call the create() or open() methods respectively!
  43      *
  44      *  @param dbdir        The directory the glass database is stored in.
  45      *  @param readonly     true if we're opening read-only, else false.
  46      */
  47     GlassDocDataTable(const std::string & dbdir, bool readonly)
  48         : GlassLazyTable("docdata", dbdir + "/docdata.", readonly) { }
  49
  50     GlassDocDataTable(int fd, off_t offset_, bool readonly)
  51         : GlassLazyTable("docdata", fd, offset_, readonly) { }
  52
  53     /** Get the document data for document @a did.
  54      *
  55      *  If the document doesn't exist, the empty string is returned.
  56      *
  57      *  @param did      The docid to set the document data for.
  58      */
  59     std::string get_document_data(Xapian::docid did) const {
  60         // We don't store the document data if it is empty.
  61         std::string data;
  62         (void)get_exact_entry(make_key(did), data);
  63         return data;
  64     }
  65
  66     /** Set the document data for document @a did.
  67      *
  68      *  If the document might already exist, use replace_document_data()
  69      *  instead.
  70      *
  71      *  @param did      The docid to set the document data for.
  72      *  @param data     The document data to set.
  73      */
  74     void add_document_data(Xapian::docid did, const std::string & data) {
  75         // We don't store the document data if it is empty.
  76         if (!data.empty())
  77             add(make_key(did), data);
  78     }
  79
  80     /** Replace the document data for document @a did.
  81      *
  82      *  Any existing data is replaced.
  83      *
  84      *  @param did      The docid to replace the document data for.
  85      *  @param data     The document data to set.
  86      */
  87     void replace_document_data(Xapian::docid did, const std::string & data) {
  88         if (data.empty()) {
  89             // We don't store the document data if it is empty.
  90             delete_document_data(did);
  91             return;
  92         }
  93         add(make_key(did), data);
  94     }
  95
  96     /** Delete the document data for document @a did.
  97      *
  98      *  @param did      The docid to delete the document data for.
  99      *
 100      *  @return true if document data was actually removed (false means either
 101      *               there's no such document, or the document has no data).
 102      */
 103     bool delete_document_data(Xapian::docid did) { return del(make_key(did)); }
 104
 105     void readahead_for_document(Xapian::docid did) const {
 106         readahead_key(make_key(did));
 107     }
 108 };
 109
 110 #endif // XAPIAN_INCLUDED_GLASS_DOCDATA_H