source/cluster/ctdb/common/ctdb_ltdb.c

   1 /*
   2    ctdb ltdb code
   3
   4    Copyright (C) Andrew Tridgell  2006
   5
   6    This library is free software; you can redistribute it and/or
   7    modify it under the terms of the GNU Lesser General Public
   8    License as published by the Free Software Foundation; either
   9    version 2 of the License, or (at your option) any later version.
  10
  11    This library 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 GNU
  14    Lesser General Public License for more details.
  15
  16    You should have received a copy of the GNU Lesser General Public
  17    License along with this library; if not, write to the Free Software
  18    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19 */
  20
  21 #include "includes.h"
  22 #include "lib/events/events.h"
  23 #include "lib/tdb/include/tdb.h"
  24 #include "system/network.h"
  25 #include "system/filesys.h"
  26 #include "cluster/ctdb/include/ctdb_private.h"
  27
  28 /*
  29   attach to a specific database
  30 */
  31 int ctdb_attach(struct ctdb_context *ctdb, const char *name, int tdb_flags,
  32                 int open_flags, mode_t mode)
  33 {
  34         /* when we have a separate daemon this will need to be a real
  35            file, not a TDB_INTERNAL, so the parent can access it to
  36            for ltdb bypass */
  37         ctdb->ltdb = tdb_open(name, 0, /* tdb_flags */ TDB_INTERNAL, open_flags, mode);
  38         if (ctdb->ltdb == NULL) {
  39                 ctdb_set_error(ctdb, "Failed to open tdb %s\n", name);
  40                 return -1;
  41         }
  42         return 0;
  43 }
  44
  45 /*
  46   return the lmaster given a key
  47 */
  48 uint32_t ctdb_lmaster(struct ctdb_context *ctdb, const TDB_DATA *key)
  49 {
  50         return ctdb_hash(key) % ctdb->num_nodes;
  51 }
  52
  53
  54 /*
  55   construct an initial header for a record with no ltdb header yet
  56 */
  57 static void ltdb_initial_header(struct ctdb_context *ctdb,
  58                                 TDB_DATA key,
  59                                 struct ctdb_ltdb_header *header)
  60 {
  61         header->rsn = 0;
  62         /* initial dmaster is the lmaster */
  63         header->dmaster = ctdb_lmaster(ctdb, &key);
  64         header->laccessor = header->dmaster;
  65         header->lacount = 0;
  66 }
  67
  68
  69 /*
  70   fetch a record from the ltdb, separating out the header information
  71   and returning the body of the record. A valid (initial) header is
  72   returned if the record is not present
  73 */
  74 int ctdb_ltdb_fetch(struct ctdb_context *ctdb,
  75                     TDB_DATA key, struct ctdb_ltdb_header *header, TDB_DATA *data)
  76 {
  77         TDB_DATA rec;
  78
  79         rec = tdb_fetch(ctdb->ltdb, key);
  80         if (rec.dsize < sizeof(*header)) {
  81                 /* return an initial header */
  82                 free(rec.dptr);
  83                 ltdb_initial_header(ctdb, key, header);
  84                 data->dptr = NULL;
  85                 data->dsize = 0;
  86                 return 0;
  87         }
  88
  89         *header = *(struct ctdb_ltdb_header *)rec.dptr;
  90
  91         data->dsize = rec.dsize - sizeof(struct ctdb_ltdb_header);
  92         data->dptr = talloc_memdup(ctdb, sizeof(struct ctdb_ltdb_header)+rec.dptr,
  93                                    data->dsize);
  94         free(rec.dptr);
  95         CTDB_NO_MEMORY(ctdb, data->dptr);
  96
  97         return 0;
  98 }
  99
 100
 101 /*
 102   fetch a record from the ltdb, separating out the header information
 103   and returning the body of the record. A valid (initial) header is
 104   returned if the record is not present
 105 */
 106 int ctdb_ltdb_store(struct ctdb_context *ctdb, TDB_DATA key,
 107                     struct ctdb_ltdb_header *header, TDB_DATA data)
 108 {
 109         TDB_DATA rec;
 110         int ret;
 111
 112         rec.dsize = sizeof(*header) + data.dsize;
 113         rec.dptr = talloc_size(ctdb, rec.dsize);
 114         CTDB_NO_MEMORY(ctdb, rec.dptr);
 115
 116         memcpy(rec.dptr, header, sizeof(*header));
 117         memcpy(rec.dptr + sizeof(*header), data.dptr, data.dsize);
 118
 119         ret = tdb_store(ctdb->ltdb, key, rec, TDB_REPLACE);
 120         talloc_free(rec.dptr);
 121
 122         return ret;
 123 }