lib/dbwrap/dbwrap_cache.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Cache db contents for parse_record based on seqnum
   4    Copyright (C) Volker Lendecke 2012
   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 3 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, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 #include "replace.h"
  21 #include "lib/param/loadparm.h"
  22 #include "lib/dbwrap/dbwrap_cache.h"
  23 #include "lib/dbwrap/dbwrap_private.h"
  24 #include "lib/dbwrap/dbwrap_rbt.h"
  25 #include "lib/util/talloc_stack.h"
  26
  27 struct db_cache_ctx {
  28         int seqnum;
  29         struct db_context *backing;
  30         struct db_context *positive;
  31         struct db_context *negative;
  32 };
  33
  34 static bool dbwrap_cache_validate(struct db_cache_ctx *ctx)
  35 {
  36         int backing_seqnum;
  37
  38         backing_seqnum = dbwrap_get_seqnum(ctx->backing);
  39         if (backing_seqnum == ctx->seqnum) {
  40                 return true;
  41         }
  42
  43         TALLOC_FREE(ctx->positive);
  44         ctx->positive = db_open_rbt(ctx);
  45         if (ctx->positive == NULL) {
  46                 return false;
  47         }
  48
  49         TALLOC_FREE(ctx->negative);
  50         ctx->negative = db_open_rbt(ctx);
  51         if (ctx->negative == NULL) {
  52                 return false;
  53         }
  54
  55         ctx->seqnum = backing_seqnum;
  56         return true;
  57 }
  58
  59 static NTSTATUS dbwrap_cache_parse_record(
  60         struct db_context *db, TDB_DATA key,
  61         void (*parser)(TDB_DATA key, TDB_DATA data, void *private_data),
  62         void *private_data)
  63 {
  64         struct db_cache_ctx *ctx = talloc_get_type_abort(
  65                 db->private_data, struct db_cache_ctx);
  66         TDB_DATA value;
  67         NTSTATUS status;
  68
  69         if (!dbwrap_cache_validate(ctx)) {
  70                 return NT_STATUS_NO_MEMORY;
  71         }
  72
  73         if (dbwrap_exists(ctx->negative, key)) {
  74                 return NT_STATUS_NOT_FOUND;
  75         }
  76         status = dbwrap_parse_record(ctx->positive, key, parser, private_data);
  77         if (NT_STATUS_IS_OK(status)) {
  78                 return status;
  79         }
  80
  81         status = dbwrap_fetch(ctx->backing, talloc_tos(), key, &value);
  82
  83         if (NT_STATUS_IS_OK(status)) {
  84                 dbwrap_store(ctx->positive, key, value, 0);
  85                 parser(key, value, private_data);
  86                 TALLOC_FREE(value.dptr);
  87                 return NT_STATUS_OK;
  88         }
  89
  90         if (NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND)) {
  91                 char c = '\0';
  92                 value.dptr = (uint8_t *)&c;
  93                 value.dsize = sizeof(c);
  94                 dbwrap_store(ctx->negative, key, value, 0);
  95                 return NT_STATUS_NOT_FOUND;
  96         }
  97         return status;
  98 }
  99
 100 static struct db_record *dbwrap_cache_fetch_locked(
 101         struct db_context *db, TALLOC_CTX *mem_ctx, TDB_DATA key)
 102 {
 103         struct db_cache_ctx *ctx = talloc_get_type_abort(
 104                 db->private_data, struct db_cache_ctx);
 105         return dbwrap_fetch_locked(ctx->backing, mem_ctx, key);
 106 }
 107
 108 static int dbwrap_cache_traverse(struct db_context *db,
 109                                  int (*f)(struct db_record *rec,
 110                                           void *private_data),
 111                                  void *private_data)
 112 {
 113         struct db_cache_ctx *ctx = talloc_get_type_abort(
 114                 db->private_data, struct db_cache_ctx);
 115         NTSTATUS status;
 116         int ret;
 117         status = dbwrap_traverse(ctx->backing, f, private_data, &ret);
 118         if (!NT_STATUS_IS_OK(status)) {
 119                 return -1;
 120         }
 121         return ret;
 122 }
 123
 124 static int dbwrap_cache_traverse_read(struct db_context *db,
 125                                       int (*f)(struct db_record *rec,
 126                                                void *private_data),
 127                                       void *private_data)
 128 {
 129         struct db_cache_ctx *ctx = talloc_get_type_abort(
 130                 db->private_data, struct db_cache_ctx);
 131         NTSTATUS status;
 132         int ret;
 133         status = dbwrap_traverse_read(ctx->backing, f, private_data, &ret);
 134         if (!NT_STATUS_IS_OK(status)) {
 135                 return -1;
 136         }
 137         return ret;
 138 }
 139
 140 static int dbwrap_cache_get_seqnum(struct db_context *db)
 141 {
 142         struct db_cache_ctx *ctx = talloc_get_type_abort(
 143                 db->private_data, struct db_cache_ctx);
 144         return dbwrap_get_seqnum(ctx->backing);
 145 }
 146
 147 static int dbwrap_cache_transaction_start(struct db_context *db)
 148 {
 149         struct db_cache_ctx *ctx = talloc_get_type_abort(
 150                 db->private_data, struct db_cache_ctx);
 151         return dbwrap_transaction_start(ctx->backing);
 152 }
 153
 154 static int dbwrap_cache_transaction_commit(struct db_context *db)
 155 {
 156         struct db_cache_ctx *ctx = talloc_get_type_abort(
 157                 db->private_data, struct db_cache_ctx);
 158         return dbwrap_transaction_commit(ctx->backing);
 159 }
 160
 161 static int dbwrap_cache_transaction_cancel(struct db_context *db)
 162 {
 163         struct db_cache_ctx *ctx = talloc_get_type_abort(
 164                 db->private_data, struct db_cache_ctx);
 165         return dbwrap_transaction_cancel(ctx->backing);
 166 }
 167
 168 static int dbwrap_cache_exists(struct db_context *db, TDB_DATA key)
 169 {
 170         struct db_cache_ctx *ctx = talloc_get_type_abort(
 171                 db->private_data, struct db_cache_ctx);
 172
 173         if (ctx->positive && dbwrap_exists(ctx->positive, key)) {
 174                 return true;
 175         }
 176         if (ctx->negative && dbwrap_exists(ctx->negative, key)) {
 177                 return false;
 178         }
 179         return dbwrap_exists(ctx->backing, key);
 180 }
 181
 182 static size_t dbwrap_cache_id(struct db_context *db, uint8_t *id,
 183                               size_t idlen)
 184 {
 185         struct db_cache_ctx *ctx = talloc_get_type_abort(
 186                 db->private_data, struct db_cache_ctx);
 187
 188         return dbwrap_db_id(ctx->backing, id, idlen);
 189 }
 190
 191 struct db_context *db_open_cache(TALLOC_CTX *mem_ctx,
 192                                  struct db_context *backing)
 193 {
 194         struct db_context *db;
 195         struct db_cache_ctx *ctx;
 196
 197         db = talloc_zero(mem_ctx, struct db_context);
 198         if (db == NULL) {
 199                 return NULL;
 200         }
 201         ctx = talloc_zero(db, struct db_cache_ctx);
 202         if (ctx == NULL) {
 203                 TALLOC_FREE(db);
 204                 return NULL;
 205         }
 206
 207         ctx->seqnum = -1;
 208         ctx->backing = talloc_move(ctx, &backing);
 209         db->private_data = ctx;
 210         if (!dbwrap_cache_validate(ctx)) {
 211                 TALLOC_FREE(db);
 212                 return NULL;
 213         }
 214
 215         db->fetch_locked = dbwrap_cache_fetch_locked;
 216         db->traverse = dbwrap_cache_traverse;
 217         db->traverse_read = dbwrap_cache_traverse_read;
 218         db->get_seqnum = dbwrap_cache_get_seqnum;
 219         db->transaction_start = dbwrap_cache_transaction_start;
 220         db->transaction_commit = dbwrap_cache_transaction_commit;
 221         db->transaction_cancel = dbwrap_cache_transaction_cancel;
 222         db->parse_record = dbwrap_cache_parse_record;
 223         db->exists = dbwrap_cache_exists;
 224         db->id = dbwrap_cache_id;
 225         db->name = dbwrap_name(ctx->backing);
 226         return db;
 227 }