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 "../include/ctdb_private.h"
  27 #include "db_wrap.h"
  28 #include "lib/util/dlinklist.h"
  29
  30 /*
  31   find an attached ctdb_db handle given a name
  32  */
  33 struct ctdb_db_context *ctdb_db_handle(struct ctdb_context *ctdb, const char *name)
  34 {
  35         struct ctdb_db_context *tmp_db;
  36         for (tmp_db=ctdb->db_list;tmp_db;tmp_db=tmp_db->next) {
  37                 if (strcmp(name, tmp_db->db_name) == 0) {
  38                         return tmp_db;
  39                 }
  40         }
  41         return NULL;
  42 }
  43
  44
  45 /*
  46   this is the dummy null procedure that all databases support
  47 */
  48 static int ctdb_fetch_func(struct ctdb_call_info *call)
  49 {
  50         call->reply_data = &call->record_data;
  51         return 0;
  52 }
  53
  54
  55 /*
  56   attach to a specific database
  57 */
  58 struct ctdb_db_context *ctdb_attach(struct ctdb_context *ctdb, const char *name, int tdb_flags,
  59                                     int open_flags, mode_t mode)
  60 {
  61         struct ctdb_db_context *ctdb_db, *tmp_db;
  62         TDB_DATA data;
  63         int ret;
  64
  65         ctdb_db = talloc_zero(ctdb, struct ctdb_db_context);
  66         CTDB_NO_MEMORY_NULL(ctdb, ctdb_db);
  67
  68         ctdb_db->ctdb = ctdb;
  69         ctdb_db->db_name = talloc_strdup(ctdb_db, name);
  70         CTDB_NO_MEMORY_NULL(ctdb, ctdb_db->db_name);
  71
  72         data.dptr = discard_const(name);
  73         data.dsize = strlen(name);
  74         ctdb_db->db_id = ctdb_hash(&data);
  75
  76         for (tmp_db=ctdb->db_list;tmp_db;tmp_db=tmp_db->next) {
  77                 if (tmp_db->db_id == ctdb_db->db_id) {
  78                         ctdb_set_error(ctdb, "CTDB database hash collission '%s' : '%s'",
  79                                         name, tmp_db->db_name);
  80                         talloc_free(ctdb_db);
  81                         return NULL;
  82                 }
  83         }
  84
  85         /* when we have a separate daemon this will need to be a real
  86            file, not a TDB_INTERNAL, so the parent can access it to
  87            for ltdb bypass */
  88         ctdb_db->ltdb = tdb_wrap_open(ctdb, name, 0, TDB_INTERNAL, open_flags, mode);
  89         if (ctdb_db->ltdb == NULL) {
  90                 ctdb_set_error(ctdb, "Failed to open tdb %s\n", name);
  91                 talloc_free(ctdb_db);
  92                 return NULL;
  93         }
  94
  95
  96         /*
  97           all databases support the "fetch" function. we need this in order to do forced migration of records
  98          */
  99         ret = ctdb_set_call(ctdb_db, ctdb_fetch_func, CTDB_FETCH_FUNC);
 100         if (ret != 0) {
 101                 talloc_free(ctdb_db);
 102                 return NULL;
 103         }
 104
 105         DLIST_ADD(ctdb->db_list, ctdb_db);
 106
 107         return ctdb_db;
 108 }
 109
 110 /*
 111   return the lmaster given a key
 112 */
 113 uint32_t ctdb_lmaster(struct ctdb_context *ctdb, const TDB_DATA *key)
 114 {
 115         return ctdb_hash(key) % ctdb->num_nodes;
 116 }
 117
 118
 119 /*
 120   construct an initial header for a record with no ltdb header yet
 121 */
 122 static void ltdb_initial_header(struct ctdb_db_context *ctdb_db,
 123                                 TDB_DATA key,
 124                                 struct ctdb_ltdb_header *header)
 125 {
 126         header->rsn = 0;
 127         /* initial dmaster is the lmaster */
 128         header->dmaster = ctdb_lmaster(ctdb_db->ctdb, &key);
 129         header->laccessor = header->dmaster;
 130         header->lacount = 0;
 131 }
 132
 133
 134 /*
 135   fetch a record from the ltdb, separating out the header information
 136   and returning the body of the record. A valid (initial) header is
 137   returned if the record is not present
 138 */
 139 int ctdb_ltdb_fetch(struct ctdb_db_context *ctdb_db,
 140                     TDB_DATA key, struct ctdb_ltdb_header *header,
 141                     TALLOC_CTX *mem_ctx, TDB_DATA *data)
 142 {
 143         TDB_DATA rec;
 144         struct ctdb_context *ctdb = ctdb_db->ctdb;
 145
 146         rec = tdb_fetch(ctdb_db->ltdb->tdb, key);
 147         if (rec.dsize < sizeof(*header)) {
 148                 /* return an initial header */
 149                 free(rec.dptr);
 150                 ltdb_initial_header(ctdb_db, key, header);
 151                 if (data) {
 152                         data->dptr = NULL;
 153                         data->dsize = 0;
 154                 }
 155                 return 0;
 156         }
 157
 158         *header = *(struct ctdb_ltdb_header *)rec.dptr;
 159
 160         if (data) {
 161                 data->dsize = rec.dsize - sizeof(struct ctdb_ltdb_header);
 162                 data->dptr = talloc_memdup(mem_ctx,
 163                                            sizeof(struct ctdb_ltdb_header)+rec.dptr,
 164                                            data->dsize);
 165         }
 166
 167         free(rec.dptr);
 168         if (data) {
 169                 CTDB_NO_MEMORY(ctdb, data->dptr);
 170         }
 171
 172         return 0;
 173 }
 174
 175
 176 /*
 177   fetch a record from the ltdb, separating out the header information
 178   and returning the body of the record. A valid (initial) header is
 179   returned if the record is not present
 180 */
 181 int ctdb_ltdb_store(struct ctdb_db_context *ctdb_db, TDB_DATA key,
 182                     struct ctdb_ltdb_header *header, TDB_DATA data)
 183 {
 184         struct ctdb_context *ctdb = ctdb_db->ctdb;
 185         TDB_DATA rec;
 186         int ret;
 187
 188         rec.dsize = sizeof(*header) + data.dsize;
 189         rec.dptr = talloc_size(ctdb, rec.dsize);
 190         CTDB_NO_MEMORY(ctdb, rec.dptr);
 191
 192         memcpy(rec.dptr, header, sizeof(*header));
 193         memcpy(rec.dptr + sizeof(*header), data.dptr, data.dsize);
 194
 195         ret = tdb_store(ctdb_db->ltdb->tdb, key, rec, TDB_REPLACE);
 196         talloc_free(rec.dptr);
 197
 198         return ret;
 199 }
 200
 201
 202 /*
 203   lock a record in the ltdb, given a key
 204  */
 205 int ctdb_ltdb_lock(struct ctdb_db_context *ctdb_db, TDB_DATA key)
 206 {
 207         return tdb_chainlock(ctdb_db->ltdb->tdb, key);
 208 }
 209
 210 /*
 211   unlock a record in the ltdb, given a key
 212  */
 213 int ctdb_ltdb_unlock(struct ctdb_db_context *ctdb_db, TDB_DATA key)
 214 {
 215         return tdb_chainunlock(ctdb_db->ltdb->tdb, key);
 216 }
 217