server/ctdb_vacuum.c

   1 /*
   2    ctdb vacuuming events
   3
   4    Copyright (C) Ronnie Sahlberg  2009
   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/events/events.h"
  22 #include "lib/tdb/include/tdb.h"
  23 #include "system/network.h"
  24 #include "system/filesys.h"
  25 #include "system/dir.h"
  26 #include "../include/ctdb_private.h"
  27 #include "db_wrap.h"
  28 #include "lib/util/dlinklist.h"
  29 #include "lib/events/events.h"
  30 #include "../include/ctdb_private.h"
  31
  32
  33 enum vacuum_child_status { VACUUM_RUNNING, VACUUM_OK, VACUUM_ERROR, VACUUM_TIMEOUT};
  34
  35 struct ctdb_vacuum_child_context {
  36         struct ctdb_vacuum_handle *vacuum_handle;
  37         int fd[2];
  38         pid_t child_pid;
  39         enum vacuum_child_status status;
  40         struct timeval start_time;
  41 };
  42
  43 struct ctdb_vacuum_handle {
  44         struct ctdb_db_context *ctdb_db;
  45         struct ctdb_vacuum_child_context *child_ctx;
  46 };
  47
  48
  49 static void ctdb_vacuum_event(struct event_context *ev, struct timed_event *te, struct timeval t, void *private_data);
  50
  51 struct traverse_state {
  52         bool error;
  53         struct tdb_context *dest_db;
  54 };
  55
  56 /*
  57   traverse function for repacking
  58  */
  59 static int repack_traverse(struct tdb_context *tdb, TDB_DATA key, TDB_DATA data, void *private)
  60 {
  61         struct traverse_state *state = (struct traverse_state *)private;
  62         if (tdb_store(state->dest_db, key, data, TDB_INSERT) != 0) {
  63                 state->error = true;
  64                 return -1;
  65         }
  66         return 0;
  67 }
  68
  69 /*
  70   repack a tdb
  71  */
  72 static int ctdb_repack_tdb(struct tdb_context *tdb, TALLOC_CTX *mem_ctx)
  73 {
  74         struct tdb_context *tmp_db;
  75         struct traverse_state *state;
  76
  77         state = talloc(mem_ctx, struct traverse_state);
  78         if (!state) {
  79                 DEBUG(DEBUG_ERR,(__location__ " Out of memory\n"));
  80                 return -1;
  81         }
  82
  83         if (tdb_transaction_start(tdb) != 0) {
  84                 DEBUG(DEBUG_ERR,(__location__ " Failed to start transaction\n"));
  85                 return -1;
  86         }
  87
  88         tmp_db = tdb_open("tmpdb", tdb_hash_size(tdb), TDB_INTERNAL, O_RDWR|O_CREAT, 0);
  89         if (tmp_db == NULL) {
  90                 DEBUG(DEBUG_ERR,(__location__ " Failed to create tmp_db\n"));
  91                 tdb_transaction_cancel(tdb);
  92                 return -1;
  93         }
  94
  95         state->error = false;
  96         state->dest_db = tmp_db;
  97
  98         if (tdb_traverse_read(tdb, repack_traverse, state) == -1) {
  99                 DEBUG(DEBUG_ERR,(__location__ " Failed to traverse copying out\n"));
 100                 tdb_transaction_cancel(tdb);
 101                 tdb_close(tmp_db);
 102                 return -1;
 103         }
 104
 105         if (state->error) {
 106                 DEBUG(DEBUG_ERR,(__location__ " Error during traversal\n"));
 107                 tdb_transaction_cancel(tdb);
 108                 tdb_close(tmp_db);
 109                 return -1;
 110         }
 111
 112         if (tdb_wipe_all(tdb) != 0) {
 113                 DEBUG(DEBUG_ERR,(__location__ " Failed to wipe database\n"));
 114                 tdb_transaction_cancel(tdb);
 115                 tdb_close(tmp_db);
 116                 return -1;
 117         }
 118
 119         state->error = false;
 120         state->dest_db = tdb;
 121
 122         if (tdb_traverse_read(tmp_db, repack_traverse, state) == -1) {
 123                 DEBUG(DEBUG_ERR,(__location__ " Failed to traverse copying back\n"));
 124                 tdb_transaction_cancel(tdb);
 125                 tdb_close(tmp_db);
 126                 return -1;
 127         }
 128
 129         if (state->error) {
 130                 DEBUG(DEBUG_ERR,(__location__ " Error during second traversal\n"));
 131                 tdb_transaction_cancel(tdb);
 132                 tdb_close(tmp_db);
 133                 return -1;
 134         }
 135
 136         tdb_close(tmp_db);
 137
 138         if (tdb_transaction_commit(tdb) != 0) {
 139                 DEBUG(DEBUG_ERR,(__location__ " Failed to commit\n"));
 140                 return -1;
 141         }
 142
 143         return 0;
 144 }
 145
 146
 147 static int ctdb_repack_db(struct ctdb_db_context *ctdb_db, TALLOC_CTX *mem_ctx)
 148 {
 149         uint32_t repack_limit = 10000;   /* should be made tunable */
 150         const char *name = ctdb_db->db_name;
 151         int size = tdb_freelist_size(ctdb_db->ltdb->tdb);
 152
 153         if (size == -1) {
 154                 DEBUG(DEBUG_ERR,(__location__ " Failed to get freelist size for '%s'\n", name));
 155                 return -1;
 156         }
 157
 158         if (size <= repack_limit) {
 159                 return 0;
 160         }
 161
 162         DEBUG(DEBUG_ERR,("Repacking %s with %u freelist entries\n", name, size));
 163
 164         if (ctdb_repack_tdb(ctdb_db->ltdb->tdb, mem_ctx) != 0) {
 165                 DEBUG(DEBUG_ERR,(__location__ " Failed to repack '%s'\n", name));
 166                 return -1;
 167         }
 168
 169         return 0;
 170 }
 171
 172 static int vacuum_child_destructor(struct ctdb_vacuum_child_context *child_ctx)
 173 {
 174         double l = timeval_elapsed(&child_ctx->start_time);
 175         struct ctdb_db_context *ctdb_db = child_ctx->vacuum_handle->ctdb_db;
 176         struct ctdb_context *ctdb = ctdb_db->ctdb;
 177
 178         DEBUG(DEBUG_ERR,("Vacuuming took %.3f seconds for database %s\n", l, ctdb_db->db_name));
 179
 180         if (child_ctx->child_pid != -1) {
 181                 kill(child_ctx->child_pid, SIGKILL);
 182         }
 183
 184         /* here calculate a new interval */
 185         /* child_ctx->status */
 186
 187         DEBUG(DEBUG_ERR, ("Start new vacuum event for %s\n", ctdb_db->db_name));
 188
 189         event_add_timed(ctdb->ev, child_ctx->vacuum_handle, timeval_current_ofs(ctdb->tunable.vacuum_default_interval, 0), ctdb_vacuum_event, child_ctx->vacuum_handle);
 190
 191         return 0;
 192 }
 193
 194 /*
 195  * this event is generated when a vacuum child process times out
 196  */
 197 static void vacuum_child_timeout(struct event_context *ev, struct timed_event *te,
 198                                          struct timeval t, void *private_data)
 199 {
 200         struct ctdb_vacuum_child_context *child_ctx = talloc_get_type(private_data, struct ctdb_vacuum_child_context);
 201
 202         DEBUG(DEBUG_ERR,("Vacuuming child process timed out for db %s\n", child_ctx->vacuum_handle->ctdb_db->db_name));
 203
 204         child_ctx->status = VACUUM_TIMEOUT;
 205
 206         talloc_free(child_ctx);
 207 }
 208
 209
 210 /*
 211  * this event is generated when a vacuum child process has completed
 212  */
 213 static void vacuum_child_handler(struct event_context *ev, struct fd_event *fde,
 214                              uint16_t flags, void *private_data)
 215 {
 216         struct ctdb_vacuum_child_context *child_ctx = talloc_get_type(private_data, struct ctdb_vacuum_child_context);
 217         char c = 0;
 218         int ret;
 219
 220         DEBUG(DEBUG_ERR,("Vacuuming child finished for db %s\n", child_ctx->vacuum_handle->ctdb_db->db_name));
 221
 222         child_ctx->child_pid = -1;
 223
 224         ret = read(child_ctx->fd[0], &c, 1);
 225         if (ret != 1 || c != 0) {
 226                 child_ctx->status = VACUUM_ERROR;
 227                 DEBUG(DEBUG_ERR, ("A vacuum child process failed with an error for database %s. ret=%d c=%d\n", child_ctx->vacuum_handle->ctdb_db->db_name, ret, c));
 228         } else {
 229                 child_ctx->status = VACUUM_OK;
 230         }
 231
 232         talloc_free(child_ctx);
 233 }
 234
 235 /*
 236  * this event is called every time we need to start a new vacuum process
 237  */
 238 static void
 239 ctdb_vacuum_event(struct event_context *ev, struct timed_event *te,
 240                                struct timeval t, void *private_data)
 241 {
 242         struct ctdb_vacuum_handle *vacuum_handle = talloc_get_type(private_data, struct ctdb_vacuum_handle);
 243         struct ctdb_db_context *ctdb_db = vacuum_handle->ctdb_db;
 244         struct ctdb_context *ctdb = ctdb_db->ctdb;
 245         struct ctdb_vacuum_child_context *child_ctx;
 246         int ret;
 247
 248         DEBUG(DEBUG_ERR,("Start a vacuuming child process for db %s\n", ctdb_db->db_name));
 249
 250         /* we dont vacuum if we are in recovery mode */
 251         if (ctdb->recovery_mode == CTDB_RECOVERY_ACTIVE) {
 252                 event_add_timed(ctdb->ev, vacuum_handle, timeval_current_ofs(ctdb->tunable.vacuum_default_interval, 0), ctdb_vacuum_event, vacuum_handle);
 253                 return;
 254         }
 255
 256
 257         child_ctx = talloc(vacuum_handle, struct ctdb_vacuum_child_context);
 258         if (child_ctx == NULL) {
 259                 DEBUG(DEBUG_CRIT, (__location__ " Failed to allocate child context for vacuuming of %s\n", ctdb_db->db_name));
 260                 ctdb_fatal(ctdb, "Out of memory when crating vacuum child context. Shutting down\n");
 261         }
 262
 263
 264         ret = pipe(child_ctx->fd);
 265         if (ret != 0) {
 266                 talloc_free(child_ctx);
 267                 DEBUG(DEBUG_ERR, ("Failed to create pipe for vacuum child process.\n"));
 268                 event_add_timed(ctdb->ev, vacuum_handle, timeval_current_ofs(ctdb->tunable.vacuum_default_interval, 0), ctdb_vacuum_event, vacuum_handle);
 269                 return;
 270         }
 271
 272         child_ctx->child_pid = fork();
 273         if (child_ctx->child_pid == (pid_t)-1) {
 274                 close(child_ctx->fd[0]);
 275                 close(child_ctx->fd[1]);
 276                 talloc_free(child_ctx);
 277                 DEBUG(DEBUG_ERR, ("Failed to fork vacuum child process.\n"));
 278                 event_add_timed(ctdb->ev, vacuum_handle, timeval_current_ofs(ctdb->tunable.vacuum_default_interval, 0), ctdb_vacuum_event, vacuum_handle);
 279                 return;
 280         }
 281
 282
 283         if (child_ctx->child_pid == 0) {
 284                 char cc = 0;
 285                 close(child_ctx->fd[0]);
 286
 287                 /*
 288                  * repack the db; next patch will include vacuuming here
 289                  */
 290                 cc = ctdb_repack_db(ctdb_db, child_ctx);
 291
 292                 write(child_ctx->fd[1], &cc, 1);
 293                 _exit(0);
 294         }
 295
 296         set_close_on_exec(child_ctx->fd[0]);
 297         close(child_ctx->fd[1]);
 298
 299         child_ctx->status = VACUUM_RUNNING;
 300         child_ctx->start_time = timeval_current();
 301
 302         talloc_set_destructor(child_ctx, vacuum_child_destructor);
 303
 304         event_add_timed(ctdb->ev, child_ctx,
 305                 timeval_current_ofs(ctdb->tunable.vacuum_max_run_time, 0),
 306                 vacuum_child_timeout, child_ctx);
 307
 308         event_add_fd(ctdb->ev, child_ctx, child_ctx->fd[0],
 309                 EVENT_FD_READ|EVENT_FD_AUTOCLOSE,
 310                 vacuum_child_handler,
 311                 child_ctx);
 312
 313         vacuum_handle->child_ctx = child_ctx;
 314         child_ctx->vacuum_handle = vacuum_handle;
 315 }
 316
 317
 318 /* this function initializes the vacuuming context for a database
 319  * starts the vacuuming events
 320  */
 321 int ctdb_vacuum_init(struct ctdb_db_context *ctdb_db)
 322 {
 323         struct ctdb_context *ctdb = ctdb_db->ctdb;
 324
 325         DEBUG(DEBUG_ERR,("Start vacuuming process for database %s\n", ctdb_db->db_name));
 326
 327         ctdb_db->vacuum_handle = talloc(ctdb_db, struct ctdb_vacuum_handle);
 328         CTDB_NO_MEMORY(ctdb, ctdb_db->vacuum_handle);
 329
 330         ctdb_db->vacuum_handle->ctdb_db = ctdb_db;
 331
 332         event_add_timed(ctdb->ev, ctdb_db->vacuum_handle, timeval_current_ofs(ctdb->tunable.vacuum_default_interval, 0), ctdb_vacuum_event, ctdb_db->vacuum_handle);
 333
 334         return 0;
 335 }