2 ctdb ltdb code - server side
4 Copyright (C) Andrew Tridgell 2007
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.
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.
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/>.
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 "../include/ctdb_private.h"
27 #include "lib/util/dlinklist.h"
30 this is the dummy null procedure that all databases support
32 static int ctdb_null_func(struct ctdb_call_info *call)
38 this is a plain fetch procedure that all databases support
40 static int ctdb_fetch_func(struct ctdb_call_info *call)
42 call->reply_data = &call->record_data;
48 struct lock_fetch_state {
49 struct ctdb_context *ctdb;
50 void (*recv_pkt)(void *, struct ctdb_req_header *);
52 struct ctdb_req_header *hdr;
54 bool ignore_generation;
58 called when we should retry the operation
60 static void lock_fetch_callback(void *p)
62 struct lock_fetch_state *state = talloc_get_type(p, struct lock_fetch_state);
63 if (!state->ignore_generation &&
64 state->generation != state->ctdb->vnn_map->generation) {
65 DEBUG(0,("Discarding previous generation lockwait packet\n"));
66 talloc_free(state->hdr);
69 state->recv_pkt(state->recv_context, state->hdr);
70 DEBUG(2,(__location__ " PACKET REQUEUED\n"));
75 do a non-blocking ltdb_lock, deferring this ctdb request until we
78 It does the following:
80 1) tries to get the chainlock. If it succeeds, then it returns 0
82 2) if it fails to get a chainlock immediately then it sets up a
83 non-blocking chainlock via ctdb_lockwait, and when it gets the
84 chainlock it re-submits this ctdb request to the main packet
87 This effectively queues all ctdb requests that cannot be
88 immediately satisfied until it can get the lock. This means that
89 the main ctdb daemon will not block waiting for a chainlock held by
92 There are 3 possible return values:
94 0: means that it got the lock immediately.
95 -1: means that it failed to get the lock, and won't retry
96 -2: means that it failed to get the lock immediately, but will retry
98 int ctdb_ltdb_lock_requeue(struct ctdb_db_context *ctdb_db,
99 TDB_DATA key, struct ctdb_req_header *hdr,
100 void (*recv_pkt)(void *, struct ctdb_req_header *),
101 void *recv_context, bool ignore_generation)
104 struct tdb_context *tdb = ctdb_db->ltdb->tdb;
105 struct lockwait_handle *h;
106 struct lock_fetch_state *state;
108 ret = tdb_chainlock_nonblock(tdb, key);
111 !(errno == EACCES || errno == EAGAIN || errno == EDEADLK)) {
112 /* a hard failure - don't try again */
116 /* when torturing, ensure we test the contended path */
117 if ((ctdb_db->ctdb->flags & CTDB_FLAG_TORTURE) &&
120 tdb_chainunlock(tdb, key);
123 /* first the non-contended path */
128 state = talloc(hdr, struct lock_fetch_state);
129 state->ctdb = ctdb_db->ctdb;
131 state->recv_pkt = recv_pkt;
132 state->recv_context = recv_context;
133 state->generation = ctdb_db->ctdb->vnn_map->generation;
134 state->ignore_generation = ignore_generation;
136 /* now the contended path */
137 h = ctdb_lockwait(ctdb_db, key, lock_fetch_callback, state);
139 tdb_chainunlock(tdb, key);
143 /* we need to move the packet off the temporary context in ctdb_input_pkt(),
144 so it won't be freed yet */
145 talloc_steal(state, hdr);
146 talloc_steal(state, h);
148 /* now tell the caller than we will retry asynchronously */
153 a varient of ctdb_ltdb_lock_requeue that also fetches the record
155 int ctdb_ltdb_lock_fetch_requeue(struct ctdb_db_context *ctdb_db,
156 TDB_DATA key, struct ctdb_ltdb_header *header,
157 struct ctdb_req_header *hdr, TDB_DATA *data,
158 void (*recv_pkt)(void *, struct ctdb_req_header *),
159 void *recv_context, bool ignore_generation)
163 ret = ctdb_ltdb_lock_requeue(ctdb_db, key, hdr, recv_pkt,
164 recv_context, ignore_generation);
166 ret = ctdb_ltdb_fetch(ctdb_db, key, header, hdr, data);
168 ctdb_ltdb_unlock(ctdb_db, key);
176 paraoid check to see if the db is empty
178 static void ctdb_check_db_empty(struct ctdb_db_context *ctdb_db)
180 struct tdb_context *tdb = ctdb_db->ltdb->tdb;
181 int count = tdb_traverse_read(tdb, NULL, NULL);
183 DEBUG(0,(__location__ " tdb '%s' not empty on attach! aborting\n",
185 ctdb_fatal(ctdb_db->ctdb, "database not empty on attach");
190 a client has asked to attach a new database
192 int32_t ctdb_control_db_attach(struct ctdb_context *ctdb, TDB_DATA indata,
195 const char *db_name = (const char *)indata.dptr;
196 struct ctdb_db_context *ctdb_db, *tmp_db;
199 /* see if we already have this name */
200 for (tmp_db=ctdb->db_list;tmp_db;tmp_db=tmp_db->next) {
201 if (strcmp(db_name, tmp_db->db_name) == 0) {
202 /* this is not an error */
203 outdata->dptr = (uint8_t *)&tmp_db->db_id;
204 outdata->dsize = sizeof(tmp_db->db_id);
209 ctdb_db = talloc_zero(ctdb, struct ctdb_db_context);
210 CTDB_NO_MEMORY(ctdb, ctdb_db);
212 ctdb_db->ctdb = ctdb;
213 ctdb_db->db_name = talloc_strdup(ctdb_db, db_name);
214 CTDB_NO_MEMORY(ctdb, ctdb_db->db_name);
216 ctdb_db->db_id = ctdb_hash(&indata);
218 outdata->dptr = (uint8_t *)&ctdb_db->db_id;
219 outdata->dsize = sizeof(ctdb_db->db_id);
221 /* check for hash collisions */
222 for (tmp_db=ctdb->db_list;tmp_db;tmp_db=tmp_db->next) {
223 if (tmp_db->db_id == ctdb_db->db_id) {
224 DEBUG(0,("db_id 0x%x hash collision. name1='%s' name2='%s'\n",
225 tmp_db->db_id, db_name, tmp_db->db_name));
226 talloc_free(ctdb_db);
231 if (ctdb->db_directory == NULL) {
232 ctdb->db_directory = VARDIR "/ctdb";
235 /* make sure the db directory exists */
236 if (mkdir(ctdb->db_directory, 0700) == -1 && errno != EEXIST) {
237 DEBUG(0,(__location__ " Unable to create ctdb directory '%s'\n",
238 ctdb->db_directory));
239 talloc_free(ctdb_db);
243 /* open the database */
244 ctdb_db->db_path = talloc_asprintf(ctdb_db, "%s/%s.%u",
248 ctdb_db->ltdb = tdb_wrap_open(ctdb, ctdb_db->db_path,
249 ctdb->tunable.database_hash_size,
250 TDB_CLEAR_IF_FIRST, O_CREAT|O_RDWR, 0666);
251 if (ctdb_db->ltdb == NULL) {
252 DEBUG(0,("Failed to open tdb '%s'\n", ctdb_db->db_path));
253 talloc_free(ctdb_db);
257 ctdb_check_db_empty(ctdb_db);
259 DLIST_ADD(ctdb->db_list, ctdb_db);
262 all databases support the "null" function. we need this in
263 order to do forced migration of records
265 ret = ctdb_daemon_set_call(ctdb, ctdb_db->db_id, ctdb_null_func, CTDB_NULL_FUNC);
267 DEBUG(0,("Failed to setup null function for '%s'\n", ctdb_db->db_name));
268 talloc_free(ctdb_db);
273 all databases support the "fetch" function. we need this
274 for efficient Samba3 ctdb fetch
276 ret = ctdb_daemon_set_call(ctdb, ctdb_db->db_id, ctdb_fetch_func, CTDB_FETCH_FUNC);
278 DEBUG(0,("Failed to setup fetch function for '%s'\n", ctdb_db->db_name));
279 talloc_free(ctdb_db);
283 /* tell all the other nodes about this database */
284 ctdb_daemon_send_control(ctdb, CTDB_BROADCAST_ALL, 0,
285 CTDB_CONTROL_DB_ATTACH, 0, CTDB_CTRL_FLAG_NOREPLY,
288 DEBUG(1,("Attached to database '%s'\n", ctdb_db->db_path));
295 called when a broadcast seqnum update comes in
297 int32_t ctdb_ltdb_update_seqnum(struct ctdb_context *ctdb, uint32_t db_id, uint32_t srcnode)
299 struct ctdb_db_context *ctdb_db;
300 if (srcnode == ctdb->vnn) {
301 /* don't update ourselves! */
305 ctdb_db = find_ctdb_db(ctdb, db_id);
307 DEBUG(0,("Unknown db_id 0x%x in ctdb_ltdb_update_seqnum\n", db_id));
311 tdb_increment_seqnum_nonblock(ctdb_db->ltdb->tdb);
312 ctdb_db->seqnum = tdb_get_seqnum(ctdb_db->ltdb->tdb);
317 timer to check for seqnum changes in a ltdb and propogate them
319 static void ctdb_ltdb_seqnum_check(struct event_context *ev, struct timed_event *te,
320 struct timeval t, void *p)
322 struct ctdb_db_context *ctdb_db = talloc_get_type(p, struct ctdb_db_context);
323 struct ctdb_context *ctdb = ctdb_db->ctdb;
324 uint32_t new_seqnum = tdb_get_seqnum(ctdb_db->ltdb->tdb);
325 if (new_seqnum != ctdb_db->seqnum) {
326 /* something has changed - propogate it */
328 data.dptr = (uint8_t *)&ctdb_db->db_id;
329 data.dsize = sizeof(uint32_t);
330 ctdb_daemon_send_control(ctdb, CTDB_BROADCAST_VNNMAP, 0,
331 CTDB_CONTROL_UPDATE_SEQNUM, 0, CTDB_CTRL_FLAG_NOREPLY,
334 ctdb_db->seqnum = new_seqnum;
336 /* setup a new timer */
338 event_add_timed(ctdb->ev, ctdb_db,
339 timeval_current_ofs(ctdb->tunable.seqnum_frequency, 0),
340 ctdb_ltdb_seqnum_check, ctdb_db);
344 enable seqnum handling on this db
346 int32_t ctdb_ltdb_enable_seqnum(struct ctdb_context *ctdb, uint32_t db_id)
348 struct ctdb_db_context *ctdb_db;
349 ctdb_db = find_ctdb_db(ctdb, db_id);
351 DEBUG(0,("Unknown db_id 0x%x in ctdb_ltdb_enable_seqnum\n", db_id));
355 if (ctdb_db->te == NULL) {
357 event_add_timed(ctdb->ev, ctdb_db,
358 timeval_current_ofs(ctdb->tunable.seqnum_frequency, 0),
359 ctdb_ltdb_seqnum_check, ctdb_db);
362 tdb_enable_seqnum(ctdb_db->ltdb->tdb);
363 ctdb_db->seqnum = tdb_get_seqnum(ctdb_db->ltdb->tdb);