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