4 Copyright (C) Ronnie sahlberg 2010
5 Copyright (C) Rusty Russell 2010
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, see <http://www.gnu.org/licenses/>.
23 #include <sys/types.h>
29 #include <ctdb_protocol.h>
32 * ctdb - a library for accessing tdbs controlled by ctdbd
34 * ctdbd (clustered tdb daemon) is a daemon designed to syncronize TDB
35 * databases across a cluster. Using this library, you can communicate with
36 * the daemon to access the databases, pass messages across the cluster, and
37 * control the daemon itself.
39 * The general API is event-driven and asynchronous: you call the
40 * *_send functions, supplying callbacks, then when the ctdbd file
41 * descriptor is usable, call ctdb_service() to perform read from it
42 * and call your callbacks, which use the *_recv functions to unpack
43 * the replies from ctdbd.
45 * There is also a synchronous wrapper for each function for trivial
46 * programs; these can be found in the section marked "Synchronous API".
49 typedef void (*ctdb_log_fn_t)(void *log_priv,
50 int severity, const char *format, va_list ap);
53 * ctdb_connect - connect to ctdb using the specified domain socket.
54 * @addr: the socket address, or NULL for default
55 * @log: the logging function
56 * @log_priv: the private argument to the logging function.
58 * Returns a ctdb context if successful or NULL. Use ctdb_free() to
59 * release the returned ctdb_connection when finished.
61 * The log() function can be typesafe: the log_priv arg and signature
62 * of log() should match. The priority passed to log() os as per
68 struct ctdb_connection *ctdb_connect(const char *addr,
69 ctdb_log_fn_t log_fn, void *log_priv);
72 * ctdb_log_file - example logging function
74 * Logs everything at priority LOG_WARNING or above to the file given (via
75 * the log_priv argument, usually stderr).
77 void ctdb_log_file(FILE *, int, const char *, va_list);
80 * ctdb_log_level - level at which to call logging function
82 * This variable globally controls filtering on the logging function.
83 * It is initialized to LOG_WARNING, meaning that strange but nonfatal
84 * events, as well as errors and API misuses are reported.
86 * Set it to LOG_DEBUG to receive all messages.
88 extern int ctdb_log_level;
97 * ctdb_get_fd - get the filedescriptor to select/poll on
98 * @ctdb: the ctdb_connection from ctdb_connect.
100 * By using poll or select on this file descriptor, you will know when to call
104 * ctdb_which_events(), ctdb_service()
106 int ctdb_get_fd(struct ctdb_connection *ctdb);
109 * ctdb_which_events - determine which events ctdb_service wants to see
110 * @ctdb: the ctdb_connection from ctdb_connect.
112 * This returns POLLIN, possibly or'd with POLLOUT if there are writes
113 * pending. You can set this straight into poll.events.
118 int ctdb_which_events(struct ctdb_connection *ctdb);
121 * ctdb_service - service any I/O and callbacks from ctdbd communication
122 * @ctdb: the ctdb_connection from ctdb_connect.
123 * @revents: which events are available.
125 * This is the core of the library: it read and writes to the ctdbd
126 * socket. It may call callbacks registered with the various _send
129 * revents is a bitset: POLLIN and/or POLLOUT may be set to indicate
130 * it is worth attempting to read/write the (nonblocking)
131 * filedescriptor respectively.
133 * Note that the synchronous functions call this internally.
134 * Returns false on catastrophic failure.
136 bool ctdb_service(struct ctdb_connection *ctdb, int revents);
139 * struct ctdb_request - handle for an outstanding request
141 * This opaque structure returned from various *_send functions gives
142 * you a handle by which you can cancel a request. You can't do
143 * anything else with it until the request is completed and it is
144 * handed to your callback function.
149 * ctdb_request_free - free a completed request
151 * This frees a request: you should only call it once it has been
152 * handed to your callback. For incomplete requests, see ctdb_cancel().
154 void ctdb_request_free(struct ctdb_connection *ctdb, struct ctdb_request *req);
157 * ctdb_callback_t - callback for completed requests.
159 * This would normally unpack the request using ctdb_*_recv(). You
160 * must free the request using ctdb_request_free().
162 * Note that due to macro magic, actual your callback can be typesafe:
163 * instead of taking a void *, it can take a type which matches the
164 * actual private parameter.
166 typedef void (*ctdb_callback_t)(struct ctdb_connection *ctdb,
167 struct ctdb_request *req, void *private);
170 * struct ctdb_db - connection to a particular open TDB
172 * This represents a particular open database: you receive it from
173 * ctdb_attachdb or ctdb_attachdb_recv to manipulate a database.
175 * You have to free the handle with ctdb_detach_db() when finished with it.
180 * ctdb_attachdb_send - open a clustered TDB
181 * @ctdb: the ctdb_connection from ctdb_connect.
182 * @name: the filename of the database (no /).
183 * @persistent: whether the database is persistent across ctdbd's life
184 * @tdb_flags: the flags to pass to tdb_open.
185 * @callback: the callback when we're attached or failed (typesafe)
186 * @cbdata: the argument to callback()
188 * This function connects to a TDB controlled by ctdbd. It can create
189 * a new TDB if it does not exist, depending on tdb_flags. Returns
190 * the pending request, or NULL on error.
192 struct ctdb_request *
193 ctdb_attachdb_send(struct ctdb_connection *ctdb,
194 const char *name, int persistent, uint32_t tdb_flags,
195 ctdb_callback_t callback, void *cbdata);
198 * ctdb_attachdb_recv - read an ctdb_attach reply from ctdbd
199 * @ctdb: the ctdb_connection from ctdb_connect.
200 * @req: the completed request.
202 * This returns NULL if something went wrong, or otherwise the open database.
204 struct ctdb_db *ctdb_attachdb_recv(struct ctdb_connection *ctdb,
205 struct ctdb_request *req);
209 * struct ctdb_lock - a record lock on a clustered TDB database
211 * This locks a subset of the database across the entire cluster; it
212 * is the fundamental sychronization element for ctdb. You cannot have
213 * more than one lock at once.
215 * You MUST NOT block during holding this lock and MUST release it
216 * quickly by performing ctdb_release_lock(lock).
221 * ctdb_rrl_callback_t - callback for ctdb_readrecordlock_async
223 * This is not the standard ctdb_callback_t, because there is often no
224 * request required to access a database record (ie. if it is local already).
225 * So the callback is handed the lock directly: it might be NULL if there
226 * was an error obtaining the lock.
229 * ctdb_readrecordlock_async(), ctdb_readrecordlock()
231 typedef void (*ctdb_rrl_callback_t)(struct ctdb_db *ctdb_db,
232 struct ctdb_lock *lock,
237 * ctdb_readrecordlock_async - read and lock a record
238 * @ctdb_db: the database handle from ctdb_attachdb/ctdb_attachdb_recv.
239 * @key: the key of the record to lock.
240 * @callback: the callback once the record is locked (typesafe).
241 * @cbdata: the argument to callback()
243 * This returns true on success. Commonly, we can obtain the record
244 * immediately and so the callback will be invoked. Otherwise a request
245 * will be queued to ctdbd for the record.
247 * If failure is immediate, false is returned. Otherwise, the callback
248 * may receive a NULL lock arg to indicate asynchronous failure.
250 bool ctdb_readrecordlock_async(struct ctdb_db *ctdb_db, TDB_DATA key,
251 ctdb_rrl_callback_t callback, void *cbdata);
254 * ctdb_writerecord - write a locked record in a TDB
255 * @lock: the lock from ctdb_readrecordlock/ctdb_readrecordlock_recv
256 * @data: the new data to place in the record.
258 int ctdb_writerecord(struct ctdb_lock *lock, TDB_DATA data);
261 * ctdb_release_lock - release a record lock on a TDB
262 * @lock: the lock from ctdb_readrecordlock/ctdb_readrecordlock_async
264 void ctdb_release_lock(struct ctdb_lock *lock);
267 * ctdb_message_fn_t - messaging callback for ctdb messages
269 * ctdbd provides a simple messaging API; you can register for a particular
270 * 64-bit id on which you want to send messages, and send to other ids.
273 * ctdb_set_message_handler_send()
275 typedef void (*ctdb_message_fn_t)(struct ctdb_connection *,
276 uint64_t srvid, TDB_DATA data, void *);
279 * ctdb_set_message_handler_send - register for messages to a srvid
280 * @ctdb: the ctdb_connection from ctdb_connect.
281 * @srvid: the 64 bit identifier for our messages.
282 * @handler: the callback when we receive such a message (typesafe)
283 * @callback: the callback when ctdb replies to our message (typesafe)
284 * @cbdata: the argument to callback() and handler()
286 * Note: our callback will always be called before handler.
289 * ctdb_set_message_handler_recv(), ctdb_remove_message_handler_send()
291 struct ctdb_request *
292 ctdb_set_message_handler_send(struct ctdb_connection *ctdb, uint64_t srvid,
293 ctdb_message_fn_t handler,
294 ctdb_callback_t callback,
298 * ctdb_set_message_handler_recv - read a set_message_handler result
299 * @ctdb: the ctdb_connection from ctdb_connect.
300 * @req: the completed request
302 * If this returns true, the registered handler may be called from the next
303 * ctdb_service(). If this returns false, the registration failed.
305 bool ctdb_set_message_handler_recv(struct ctdb_connection *ctdb,
306 struct ctdb_request *handle);
309 * ctdb_remove_message_handler_send - unregister for messages to a srvid
310 * @ctdb: the ctdb_connection from ctdb_connect.
311 * @srvid: the 64 bit identifier for our messages.
312 * @callback: the callback when ctdb replies to our message (typesafe)
313 * @cbdata: the argument to callback()
315 * This undoes a successful ctdb_set_message_handler or
316 * ctdb_set_message_handler_recv.
318 struct ctdb_request *
319 ctdb_remove_message_handler_send(struct ctdb_connection *ctdb, uint64_t srvid,
320 ctdb_callback_t callback, void *cbdata);
323 * ctdb_remove_message_handler_recv - read a remove_message_handler result
324 * @ctdb: the ctdb_connection from ctdb_connect.
325 * @req: the completed request
327 * After this returns true, the registered handler will no longer be called.
328 * If this returns false, the de-registration failed.
330 bool ctdb_remove_message_handler_recv(struct ctdb_request *handle);
334 * ctdb_send_message - send a message via ctdbd
335 * @ctdb: the ctdb_connection from ctdb_connect.
336 * @pnn: the physical node number to send to
337 * @srvid: the 64 bit identifier for this message type.
338 * @data: the data to send
340 * This allows arbitrary messages to be sent across the cluster to those
341 * listening (via ctdb_set_message_handler et al).
343 * This queues a message to be sent: you will need to call
344 * ctdb_service() to actually send the message. There is no callback
345 * because there is no acknowledgement.
348 * ctdb_getpnn_send(), ctdb_getpnn()
350 bool ctdb_send_message(struct ctdb_connection *ctdb, uint32_t pnn, uint64_t srvid, TDB_DATA data);
353 * ctdb_getpnn_send - read the pnn number of a node.
354 * @ctdb: the ctdb_connection from ctdb_connect.
355 * @destnode: the destination node (see below)
356 * @callback: the callback when ctdb replies to our message (typesafe)
357 * @cbdata: the argument to callback()
359 * There are several special values for destnode, detailed in
360 * ctdb_protocol.h, particularly CTDB_CURRENT_NODE which means the
363 struct ctdb_request *
364 ctdb_getpnn_send(struct ctdb_connection *ctdb,
366 ctdb_callback_t callback,
369 * ctdb_getpnn_recv - read an ctdb_getpnn reply from ctdbd
370 * @ctdb: the ctdb_connection from ctdb_connect.
371 * @req: the completed request.
372 * @pnn: a pointer to the pnn to fill in
374 * This returns false if something went wrong, or otherwise fills in pnn.
376 bool ctdb_getpnn_recv(struct ctdb_connection *ctdb,
377 struct ctdb_request *req, uint32_t *pnn);
381 * ctdb_getrecmaster_send - read the recovery master of a node
382 * @ctdb: the ctdb_connection from ctdb_connect.
383 * @destnode: the destination node (see below)
384 * @callback: the callback when ctdb replies to our message (typesafe)
385 * @cbdata: the argument to callback()
387 * There are several special values for destnode, detailed in
388 * ctdb_protocol.h, particularly CTDB_CURRENT_NODE which means the
391 struct ctdb_request *
392 ctdb_getrecmaster_send(struct ctdb_connection *ctdb,
394 ctdb_callback_t callback, void *cbdata);
397 * ctdb_getrecmaster_recv - read an ctdb_getrecmaster reply from ctdbd
398 * @ctdb: the ctdb_connection from ctdb_connect.
399 * @req: the completed request.
400 * @recmaster: a pointer to the recmaster to fill in
402 * This returns false if something went wrong, or otherwise fills in
405 bool ctdb_getrecmaster_recv(struct ctdb_connection *ctdb,
406 struct ctdb_request *handle,
407 uint32_t *recmaster);
410 * ctdb_cancel - cancel an uncompleted request
411 * @ctdb: the ctdb_connection from ctdb_connect.
412 * @req: the uncompleted request.
414 * This cancels a request, returning true. You may not cancel a
415 * request which has already been completed (ie. once its callback has
416 * been called); you should simply use ctdb_request_free() in that case.
418 void ctdb_cancel(struct ctdb_connection *ctdb, struct ctdb_request *req);
427 * ctdb_attachdb - open a clustered TDB (synchronous)
428 * @ctdb: the ctdb_connection from ctdb_connect.
429 * @name: the filename of the database (no /).
430 * @persistent: whether the database is persistent across ctdbd's life
431 * @tdb_flags: the flags to pass to tdb_open.
433 * Do a ctdb_attachdb_send and wait for it to complete.
434 * Returns NULL on failure.
436 struct ctdb_db *ctdb_attachdb(struct ctdb_connection *ctdb,
437 const char *name, int persistent,
441 * ctdb_readrecordlock - read and lock a record (synchronous)
442 * @ctdb_db: the database handle from ctdb_attachdb/ctdb_attachdb_recv.
443 * @key: the key of the record to lock.
444 * @req: a pointer to the request, if one is needed.
446 * Do a ctdb_readrecordlock_send and wait for it to complete.
447 * Returns NULL on failure.
449 struct ctdb_lock *ctdb_readrecordlock(struct ctdb_db *ctdb_db, TDB_DATA key,
454 * ctdb_set_message_handler - register for messages to a srvid (synchronous)
455 * @ctdb: the ctdb_connection from ctdb_connect.
456 * @srvid: the 64 bit identifier for our messages.
457 * @handler: the callback when we receive such a message (typesafe)
458 * @cbdata: the argument to handler()
460 * If this returns true, the message handler can be called from any
461 * ctdb_service() (which is also called indirectly by other
462 * synchronous functions). If this returns false, the registration
465 bool ctdb_set_message_handler(struct ctdb_connection *ctdb, uint64_t srvid,
466 ctdb_message_fn_t handler, void *cbdata);
470 * ctdb_remove_message_handler - deregister for messages (synchronous)
471 * @ctdb: the ctdb_connection from ctdb_connect.
472 * @srvid: the 64 bit identifier for our messages.
474 * If this returns true, the message handler will no longer be called.
475 * If this returns false, the deregistration failed.
477 bool ctdb_remove_message_handler(struct ctdb_connection *ctdb, uint64_t srvid);
480 * ctdb_getpnn - read the pnn number of a node (synchronous)
481 * @ctdb: the ctdb_connection from ctdb_connect.
482 * @destnode: the destination node (see below)
483 * @pnn: a pointer to the pnn to fill in
485 * There are several special values for destnode, detailed in
486 * ctdb_protocol.h, particularly CTDB_CURRENT_NODE which means the
489 * Returns true and fills in *pnn on success.
491 bool ctdb_getpnn(struct ctdb_connection *ctdb,
496 * ctdb_getrecmaster - read the recovery master of a node (synchronous)
497 * @ctdb: the ctdb_connection from ctdb_connect.
498 * @destnode: the destination node (see below)
499 * @recmaster: a pointer to the recmaster to fill in
501 * There are several special values for destnode, detailed in
502 * ctdb_protocol.h, particularly CTDB_CURRENT_NODE which means the
505 * Returns true and fills in *recmaster on success.
507 bool ctdb_getrecmaster(struct ctdb_connection *ctdb,
509 uint32_t *recmaster);
511 /* These ugly macro wrappers make the callbacks typesafe. */
512 #include <ctdb_typesafe_cb.h>
513 #define ctdb_sendcb(cb, cbdata) \
514 typesafe_cb_preargs(void, (cb), (cbdata), \
515 struct ctdb_connection *, struct ctdb_request *)
517 #define ctdb_connect(addr, log, logpriv) \
518 ctdb_connect((addr), \
519 typesafe_cb_postargs(void, (log), (logpriv), \
520 int, const char *, va_list), \
524 #define ctdb_attachdb_send(ctdb, name, persistent, tdb_flags, cb, cbdata) \
525 ctdb_attachdb_send((ctdb), (name), (persistent), (tdb_flags), \
526 ctdb_sendcb((cb), (cbdata)), (cbdata))
528 #define ctdb_readrecordlock_async(_ctdb_db, key, cb, cbdata) \
529 ctdb_readrecordlock_async((_ctdb_db), (key), \
530 typesafe_cb_preargs(void, (cb), (cbdata), \
531 struct ctdb_db *, struct ctdb_lock *, \
534 #define ctdb_set_message_handler_send(ctdb, srvid, handler, cb, cbdata) \
535 ctdb_set_message_handler_send((ctdb), (srvid), (handler), \
536 ctdb_sendcb((cb), (cbdata)), (cbdata))
538 #define ctdb_remove_message_handler_send(ctdb, srvid, cb, cbdata) \
539 ctdb_remove_message_handler_send((ctdb), (srvid), \
540 ctdb_sendcb((cb), (cbdata)), (cbdata))
542 #define ctdb_getpnn_send(ctdb, destnode, cb, cbdata) \
543 ctdb_getpnn_send((ctdb), (destnode), \
544 ctdb_sendcb((cb), (cbdata)), (cbdata))
546 #define ctdb_getrecmaster_send(ctdb, destnode, cb, cbdata) \
547 ctdb_getrecmaster_send((ctdb), (destnode), \
548 ctdb_sendcb((cb), (cbdata)), (cbdata))