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 2 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, write to the Free Software
18 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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"
28 #include "lib/util/dlinklist.h"
31 this is the dummy null procedure that all databases support
33 static int ctdb_null_func(struct ctdb_call_info *call)
39 this is a plain fetch procedure that all databases support
41 static int ctdb_fetch_func(struct ctdb_call_info *call)
43 call->reply_data = &call->record_data;
49 struct lock_fetch_state {
50 struct ctdb_context *ctdb;
51 void (*recv_pkt)(void *, struct ctdb_req_header *);
53 struct ctdb_req_header *hdr;
55 bool ignore_generation;
59 called when we should retry the operation
61 static void lock_fetch_callback(void *p)
63 struct lock_fetch_state *state = talloc_get_type(p, struct lock_fetch_state);
64 if (!state->ignore_generation &&
65 state->generation != state->ctdb->vnn_map->generation) {
66 DEBUG(0,("Discarding previous generation lockwait packet\n"));
67 talloc_free(state->hdr);
70 state->recv_pkt(state->recv_context, state->hdr);
71 DEBUG(2,(__location__ " PACKET REQUEUED\n"));
76 do a non-blocking ltdb_lock, deferring this ctdb request until we
79 It does the following:
81 1) tries to get the chainlock. If it succeeds, then it returns 0
83 2) if it fails to get a chainlock immediately then it sets up a
84 non-blocking chainlock via ctdb_lockwait, and when it gets the
85 chainlock it re-submits this ctdb request to the main packet
88 This effectively queues all ctdb requests that cannot be
89 immediately satisfied until it can get the lock. This means that
90 the main ctdb daemon will not block waiting for a chainlock held by
93 There are 3 possible return values:
95 0: means that it got the lock immediately.
96 -1: means that it failed to get the lock, and won't retry
97 -2: means that it failed to get the lock immediately, but will retry
99 int ctdb_ltdb_lock_requeue(struct ctdb_db_context *ctdb_db,
100 TDB_DATA key, struct ctdb_req_header *hdr,
101 void (*recv_pkt)(void *, struct ctdb_req_header *),
102 void *recv_context, bool ignore_generation)
105 struct tdb_context *tdb = ctdb_db->ltdb->tdb;
106 struct lockwait_handle *h;
107 struct lock_fetch_state *state;
109 ret = tdb_chainlock_nonblock(tdb, key);
112 !(errno == EACCES || errno == EAGAIN || errno == EDEADLK)) {
113 /* a hard failure - don't try again */
117 /* when torturing, ensure we test the contended path */
118 if ((ctdb_db->ctdb->flags & CTDB_FLAG_TORTURE) &&
121 tdb_chainunlock(tdb, key);
124 /* first the non-contended path */
129 state = talloc(hdr, struct lock_fetch_state);
130 state->ctdb = ctdb_db->ctdb;
132 state->recv_pkt = recv_pkt;
133 state->recv_context = recv_context;
134 state->generation = ctdb_db->ctdb->vnn_map->generation;
135 state->ignore_generation = ignore_generation;
137 /* now the contended path */
138 h = ctdb_lockwait(ctdb_db, key, lock_fetch_callback, state);
140 tdb_chainunlock(tdb, key);
144 /* we need to move the packet off the temporary context in ctdb_input_pkt(),
145 so it won't be freed yet */
146 talloc_steal(state, hdr);
147 talloc_steal(state, h);
149 /* now tell the caller than we will retry asynchronously */
154 a varient of ctdb_ltdb_lock_requeue that also fetches the record
156 int ctdb_ltdb_lock_fetch_requeue(struct ctdb_db_context *ctdb_db,
157 TDB_DATA key, struct ctdb_ltdb_header *header,
158 struct ctdb_req_header *hdr, TDB_DATA *data,
159 void (*recv_pkt)(void *, struct ctdb_req_header *),
160 void *recv_context, bool ignore_generation)
164 ret = ctdb_ltdb_lock_requeue(ctdb_db, key, hdr, recv_pkt,
165 recv_context, ignore_generation);
167 ret = ctdb_ltdb_fetch(ctdb_db, key, header, hdr, data);
169 ctdb_ltdb_unlock(ctdb_db, key);
177 paraoid check to see if the db is empty
179 static void ctdb_check_db_empty(struct ctdb_db_context *ctdb_db)
181 struct tdb_context *tdb = ctdb_db->ltdb->tdb;
182 int count = tdb_traverse_read(tdb, NULL, NULL);
184 DEBUG(0,(__location__ " tdb '%s' not empty on attach! aborting\n",
186 ctdb_fatal(ctdb_db->ctdb, "database not empty on attach");
191 a client has asked to attach a new database
193 int32_t ctdb_control_db_attach(struct ctdb_context *ctdb, TDB_DATA indata,
196 const char *db_name = (const char *)indata.dptr;
197 struct ctdb_db_context *ctdb_db, *tmp_db;
200 /* see if we already have this name */
201 for (tmp_db=ctdb->db_list;tmp_db;tmp_db=tmp_db->next) {
202 if (strcmp(db_name, tmp_db->db_name) == 0) {
203 /* this is not an error */
204 outdata->dptr = (uint8_t *)&tmp_db->db_id;
205 outdata->dsize = sizeof(tmp_db->db_id);
210 ctdb_db = talloc_zero(ctdb, struct ctdb_db_context);
211 CTDB_NO_MEMORY(ctdb, ctdb_db);
213 ctdb_db->ctdb = ctdb;
214 ctdb_db->db_name = talloc_strdup(ctdb_db, db_name);
215 CTDB_NO_MEMORY(ctdb, ctdb_db->db_name);
217 ctdb_db->db_id = ctdb_hash(&indata);
219 outdata->dptr = (uint8_t *)&ctdb_db->db_id;
220 outdata->dsize = sizeof(ctdb_db->db_id);
222 /* check for hash collisions */
223 for (tmp_db=ctdb->db_list;tmp_db;tmp_db=tmp_db->next) {
224 if (tmp_db->db_id == ctdb_db->db_id) {
225 DEBUG(0,("db_id 0x%x hash collision. name1='%s' name2='%s'\n",
226 tmp_db->db_id, db_name, tmp_db->db_name));
227 talloc_free(ctdb_db);
232 if (ctdb->db_directory == NULL) {
233 ctdb->db_directory = VARDIR "/ctdb";
236 /* make sure the db directory exists */
237 if (mkdir(ctdb->db_directory, 0700) == -1 && errno != EEXIST) {
238 DEBUG(0,(__location__ " Unable to create ctdb directory '%s'\n",
239 ctdb->db_directory));
240 talloc_free(ctdb_db);
244 /* open the database */
245 ctdb_db->db_path = talloc_asprintf(ctdb_db, "%s/%s.%u",
249 ctdb_db->ltdb = tdb_wrap_open(ctdb, ctdb_db->db_path,
250 ctdb->tunable.database_hash_size,
251 TDB_CLEAR_IF_FIRST, O_CREAT|O_RDWR, 0666);
252 if (ctdb_db->ltdb == NULL) {
253 DEBUG(0,("Failed to open tdb '%s'\n", ctdb_db->db_path));
254 talloc_free(ctdb_db);
258 ctdb_check_db_empty(ctdb_db);
260 DLIST_ADD(ctdb->db_list, ctdb_db);
263 all databases support the "null" function. we need this in
264 order to do forced migration of records
266 ret = ctdb_daemon_set_call(ctdb, ctdb_db->db_id, ctdb_null_func, CTDB_NULL_FUNC);
268 DEBUG(0,("Failed to setup null function for '%s'\n", ctdb_db->db_name));
269 talloc_free(ctdb_db);
274 all databases support the "fetch" function. we need this
275 for efficient Samba3 ctdb fetch
277 ret = ctdb_daemon_set_call(ctdb, ctdb_db->db_id, ctdb_fetch_func, CTDB_FETCH_FUNC);
279 DEBUG(0,("Failed to setup fetch function for '%s'\n", ctdb_db->db_name));
280 talloc_free(ctdb_db);
284 /* tell all the other nodes about this database */
285 ctdb_daemon_send_control(ctdb, CTDB_BROADCAST_ALL, 0,
286 CTDB_CONTROL_DB_ATTACH, 0, CTDB_CTRL_FLAG_NOREPLY,
289 DEBUG(1,("Attached to database '%s'\n", ctdb_db->db_path));
296 called when a broadcast seqnum update comes in
298 int32_t ctdb_ltdb_update_seqnum(struct ctdb_context *ctdb, uint32_t db_id, uint32_t srcnode)
300 struct ctdb_db_context *ctdb_db;
301 if (srcnode == ctdb->vnn) {
302 /* don't update ourselves! */
306 ctdb_db = find_ctdb_db(ctdb, db_id);
308 DEBUG(0,("Unknown db_id 0x%x in ctdb_ltdb_update_seqnum\n", db_id));
312 tdb_increment_seqnum_nonblock(ctdb_db->ltdb->tdb);
313 ctdb_db->seqnum = tdb_get_seqnum(ctdb_db->ltdb->tdb);
318 timer to check for seqnum changes in a ltdb and propogate them
320 static void ctdb_ltdb_seqnum_check(struct event_context *ev, struct timed_event *te,
321 struct timeval t, void *p)
323 struct ctdb_db_context *ctdb_db = talloc_get_type(p, struct ctdb_db_context);
324 struct ctdb_context *ctdb = ctdb_db->ctdb;
325 uint32_t new_seqnum = tdb_get_seqnum(ctdb_db->ltdb->tdb);
326 if (new_seqnum != ctdb_db->seqnum) {
327 /* something has changed - propogate it */
329 data.dptr = (uint8_t *)&ctdb_db->db_id;
330 data.dsize = sizeof(uint32_t);
331 ctdb_daemon_send_control(ctdb, CTDB_BROADCAST_VNNMAP, 0,
332 CTDB_CONTROL_UPDATE_SEQNUM, 0, CTDB_CTRL_FLAG_NOREPLY,
335 ctdb_db->seqnum = new_seqnum;
337 /* setup a new timer */
339 event_add_timed(ctdb->ev, ctdb_db,
340 timeval_current_ofs(ctdb->tunable.seqnum_frequency, 0),
341 ctdb_ltdb_seqnum_check, ctdb_db);
345 enable seqnum handling on this db
347 int32_t ctdb_ltdb_enable_seqnum(struct ctdb_context *ctdb, uint32_t db_id)
349 struct ctdb_db_context *ctdb_db;
350 ctdb_db = find_ctdb_db(ctdb, db_id);
352 DEBUG(0,("Unknown db_id 0x%x in ctdb_ltdb_enable_seqnum\n", db_id));
356 if (ctdb_db->te == NULL) {
358 event_add_timed(ctdb->ev, ctdb_db,
359 timeval_current_ofs(ctdb->tunable.seqnum_frequency, 0),
360 ctdb_ltdb_seqnum_check, ctdb_db);
363 tdb_enable_seqnum(ctdb_db->ltdb->tdb);
364 ctdb_db->seqnum = tdb_get_seqnum(ctdb_db->ltdb->tdb);