1 // This is a data store backend for the Citadel server which uses Berkeley DB.
3 // Copyright (c) 1987-2023 by the citadel.org team
5 // This program is open source software. Use, duplication, or disclosure
6 // is subject to the terms of the GNU General Public License, version 3.
8 // Citadel will checkpoint the db at the end of every session, but only if
9 // the specified number of kilobytes has been written, or if the specified
10 // number of minutes has passed, since the last checkpoint.
11 #define MAX_CHECKPOINT_KBYTES 256
12 #define MAX_CHECKPOINT_MINUTES 15
14 #include "../../sysdep.h"
20 #include <libcitadel.h>
21 #include "../../citserver.h"
22 #include "../../config.h"
23 #include "berkeley_db.h"
25 #if DB_VERSION_MAJOR < 18
26 #error Citadel requires Berkeley DB v18.0 or newer. Please upgrade.
29 // Globals (these are used across multiple functions in *this* module, but not elsewhere)
30 static DB *bdb_table[MAXCDB]; // One DB handle for each Citadel database
31 static DB_ENV *bdb_env; // The DB environment (global)
34 // These are items that we need to store "per thread" rather than "per session".
36 DB_TXN *tid; // Transaction handle
37 DBC *cursors[MAXCDB]; // Cursors, for traversals...
43 pthread_key_t bdb_thread_key;
44 #define TSD bdb_get_tsd()
47 // Some functions in this backend need to store some per-thread data.
48 // This returns the pointer to the current thread's per-thread data block, creating it if necessary.
49 // (This will also work in a non-threaded program; it will return the same pointer every time.)
50 struct bdb_tsd *bdb_get_tsd(void) {
52 struct bdb_tsd *c = (struct bdb_tsd *) pthread_getspecific(bdb_thread_key) ;
57 // If there's no TSD for this thread, it must be a new thread. Create our TSD region.
58 c = (struct bdb_tsd *) malloc(sizeof(struct bdb_tsd));
59 memset(c, 0, sizeof(struct bdb_tsd));
60 pthread_setspecific(bdb_thread_key, (const void *) c);
65 // Called by other functions in this module to GTFO quickly if we need to. Not part of the backend API.
66 void bdb_abort(void) {
67 syslog(LOG_DEBUG, "bdb: citserver is stopping in order to prevent data loss. uid=%d gid=%d euid=%d egid=%d",
68 getuid(), getgid(), geteuid(), getegid()
70 raise(SIGABRT); // This will exit in a way that can produce a core dump if needed.
71 exit(CTDLEXIT_DB); // Exit if the signal failed to end the program.
75 // Verbose logging callback for Berkeley DB. Not part of the backend API.
76 void bdb_verbose_log(const DB_ENV *bdb_env, const char *msg, const char *foo) {
77 if (!IsEmptyStr(msg)) {
78 syslog(LOG_DEBUG, "bdb: %s %s", msg, foo);
83 // Verbose error logging callback for Berkeley DB. Not part of the backend API.
84 void bdb_verbose_err(const DB_ENV *bdb_env, const char *errpfx, const char *msg) {
85 syslog(LOG_ERR, "bdb: %s", msg);
89 // Wrapper for txn_abort() that logs/aborts on error. Not part of the backend API.
90 static void bdb_txabort(DB_TXN *tid) {
93 ret = tid->abort(tid);
96 syslog(LOG_ERR, "bdb: txn_abort: %s", db_strerror(ret));
102 // Wrapper for txn_commit() that logs/aborts on error. Not part of the backend API.
103 static void bdb_txcommit(DB_TXN *tid) {
106 ret = tid->commit(tid, 0);
109 syslog(LOG_ERR, "bdb: txn_commit: %s", db_strerror(ret));
115 // Wrapper for txn_begin() that logs/aborts on error. Not part of the backend API.
116 static void bdb_txbegin(DB_TXN **tid) {
119 ret = bdb_env->txn_begin(bdb_env, NULL, tid, 0);
122 syslog(LOG_ERR, "bdb: txn_begin: %s", db_strerror(ret));
128 // Panic callback for Berkeley DB. Not part of the backend API.
129 static void bdb_dbpanic(DB_ENV *env, int errval) {
130 syslog(LOG_ERR, "bdb: PANIC: %s", db_strerror(errval));
135 // Close a cursor -- not part of the backend API.
136 static void bdb_cclose(DBC *cursor) {
139 if ((ret = cursor->c_close(cursor))) {
140 syslog(LOG_ERR, "bdb: c_close: %s", db_strerror(ret));
146 // Convenience function to abort if a cursor is still open when we didn't expect it to be.
147 // This is not part of the backend API.
148 static void bdb_bailIfCursor(DBC **cursors, const char *msg) {
151 for (i = 0; i < MAXCDB; i++)
152 if (cursors[i] != NULL) {
153 syslog(LOG_ERR, "bdb: cursor still in progress on cdb %02x: %s", i, msg);
159 void bdb_check_handles(void) {
160 bdb_bailIfCursor(TSD->cursors, "in check_handles");
162 if (TSD->tid != NULL) {
163 syslog(LOG_ERR, "bdb: transaction still in progress!");
169 // Request a checkpoint of the database. Called once per minute by the thread manager.
170 void bdb_checkpoint(void) {
173 syslog(LOG_DEBUG, "bdb: -- checkpoint --");
174 ret = bdb_env->txn_checkpoint(bdb_env, MAX_CHECKPOINT_KBYTES, MAX_CHECKPOINT_MINUTES, 0);
177 syslog(LOG_ERR, "bdb: bdb_checkpoint() txn_checkpoint: %s", db_strerror(ret));
181 // After a successful checkpoint, we can cull the unused logs
182 ret = bdb_env->log_set_config(bdb_env, DB_LOG_AUTO_REMOVE, 1);
184 syslog(LOG_ERR, "bdb: bdb_checkpoint() auto coll logs: %s", db_strerror(ret));
189 // Open the various tables we'll be using. Any table which
190 // does not exist should be created. Note that we don't need a
191 // critical section here, because there aren't any active threads
192 // manipulating the database yet.
193 void bdb_open_databases(void) {
198 int dbversion_major, dbversion_minor, dbversion_patch;
200 syslog(LOG_DEBUG, "bdb: bdb_open_databases() starting");
201 syslog(LOG_DEBUG, "bdb: Linked zlib: %s", zlibVersion());
202 syslog(LOG_DEBUG, "bdb: Compiled libdb: %s", DB_VERSION_STRING);
203 syslog(LOG_DEBUG, "bdb: Linked libdb: %s", db_version(&dbversion_major, &dbversion_minor, &dbversion_patch));
205 // Create synthetic integer version numbers and compare them.
206 // Never allow citserver to run with a libdb older then the one with which it was compiled.
207 int compiled_db_version = ( (DB_VERSION_MAJOR * 1000000) + (DB_VERSION_MINOR * 1000) + (DB_VERSION_PATCH) );
208 int linked_db_version = ( (dbversion_major * 1000000) + (dbversion_minor * 1000) + (dbversion_patch) );
209 if (compiled_db_version > linked_db_version) {
210 syslog(LOG_ERR, "bdb: citserver is running with a version of libdb older than the one with which it was compiled.");
211 syslog(LOG_ERR, "bdb: This is an invalid configuration. citserver will now exit to prevent data loss.");
215 syslog(LOG_DEBUG, "bdb: Setting up DB environment");
216 ret = db_env_create(&bdb_env, 0);
218 syslog(LOG_ERR, "bdb: db_env_create: %s", db_strerror(ret));
219 syslog(LOG_ERR, "bdb: exit code %d", ret);
222 bdb_env->set_errpfx(bdb_env, "citserver");
223 bdb_env->set_paniccall(bdb_env, bdb_dbpanic);
224 bdb_env->set_errcall(bdb_env, bdb_verbose_err);
225 bdb_env->set_msgcall(bdb_env, bdb_verbose_log);
226 bdb_env->set_verbose(bdb_env, DB_VERB_DEADLOCK, 1);
227 bdb_env->set_verbose(bdb_env, DB_VERB_RECOVERY, 1);
229 // We want to specify the shared memory buffer pool cachesize, but everything else is the default.
230 // 2023aug21 ajc: the third argument is zero, so this never did anything
231 // ret = bdb_env->set_cachesize(bdb_env, 0, 64 * 1024, 0);
233 // syslog(LOG_ERR, "bdb: set_cachesize: %s", db_strerror(ret));
234 // bdb_env->close(bdb_env, 0);
235 // syslog(LOG_ERR, "bdb: exit code %d", ret);
236 // exit(CTDLEXIT_DB);
239 // This appears to do nothing over and above the default
240 //if ((ret = bdb_env->set_lk_detect(bdb_env, DB_LOCK_DEFAULT))) {
241 //syslog(LOG_ERR, "bdb: set_lk_detect: %s", db_strerror(ret));
242 //bdb_env->close(bdb_env, 0);
243 //syslog(LOG_ERR, "bdb: exit code %d", ret);
247 flags = DB_CREATE | DB_INIT_MPOOL | DB_PRIVATE | DB_INIT_TXN | /*DB_INIT_LOCK |*/ DB_THREAD | DB_INIT_LOG;
248 syslog(LOG_DEBUG, "bdb: bdb_env->open(bdb_env, %s, %d, 0)", ctdl_db_dir, flags);
249 ret = bdb_env->open(bdb_env, ctdl_db_dir, flags, 0); // try opening the database cleanly
250 if (ret == DB_RUNRECOVERY) {
251 syslog(LOG_ERR, "bdb: bdb_env->open: %s", db_strerror(ret));
252 syslog(LOG_ERR, "bdb: attempting recovery...");
254 ret = bdb_env->open(bdb_env, ctdl_db_dir, flags, 0); // try recovery
256 if (ret == DB_RUNRECOVERY) {
257 syslog(LOG_ERR, "bdb: bdb_env->open: %s", db_strerror(ret));
258 syslog(LOG_ERR, "bdb: attempting catastrophic recovery...");
259 flags &= ~DB_RECOVER;
260 flags |= DB_RECOVER_FATAL;
261 ret = bdb_env->open(bdb_env, ctdl_db_dir, flags, 0); // try catastrophic recovery
264 syslog(LOG_ERR, "bdb: bdb_env->open: %s", db_strerror(ret));
265 bdb_env->close(bdb_env, 0);
266 syslog(LOG_ERR, "bdb: exit code %d", ret);
270 for (i = 0; i < MAXCDB; ++i) {
271 syslog(LOG_INFO, "bdb: mounting database %02x", i);
272 ret = db_create(&bdb_table[i], bdb_env, 0); // Create a database handle
274 syslog(LOG_ERR, "bdb: db_create: %s", db_strerror(ret));
275 syslog(LOG_ERR, "bdb: exit code %d", ret);
279 snprintf(dbfilename, sizeof dbfilename, "cdb.%02x", i); // table names by number
280 ret = bdb_table[i]->open(bdb_table[i], NULL, dbfilename, NULL, DB_BTREE, DB_CREATE | DB_AUTO_COMMIT, 0600);
282 syslog(LOG_ERR, "bdb: db_open[%02x]: %s", i, db_strerror(ret));
284 syslog(LOG_ERR, "bdb: You may need to tune your database; please check http://www.citadel.org for more information.");
286 syslog(LOG_ERR, "bdb: exit code %d", ret);
293 // Close all of the db database files we've opened. This can be done in a loop, since it's just a bunch of closes.
294 void bdb_close_databases(void) {
298 static int closing = 0;
299 while (closing == 1) {
300 syslog(LOG_INFO, "bdb: already closing");
304 syslog(LOG_INFO, "bdb: performing final checkpoint");
305 if ((ret = bdb_env->txn_checkpoint(bdb_env, 0, 0, 0))) {
306 syslog(LOG_ERR, "bdb: txn_checkpoint: %s", db_strerror(ret));
309 syslog(LOG_INFO, "bdb: flushing the database logs");
310 if ((ret = bdb_env->log_flush(bdb_env, NULL))) {
311 syslog(LOG_ERR, "bdb: log_flush: %s", db_strerror(ret));
315 syslog(LOG_INFO, "bdb: closing databases");
316 for (i = 0; i < MAXCDB; ++i) {
317 syslog(LOG_INFO, "bdb: closing database %02x", i);
318 ret = bdb_table[i]->close(bdb_table[i], 0);
320 syslog(LOG_ERR, "bdb: db_close: %s", db_strerror(ret));
325 syslog(LOG_INFO, "bdb: closing environment");
326 ret = bdb_env->close(bdb_env, DB_FORCESYNC);
328 syslog(LOG_ERR, "bdb: DBENV->close: %s", db_strerror(ret));
331 syslog(LOG_INFO, "bdb: shutdown completed");
335 // Decompress a DBT data block if it was compressed on disk.
336 void bdb_decompress_if_necessary(DBT *d) {
337 static int magic = COMPRESS_MAGIC;
339 if ((d == NULL) || (d->data == NULL) || (d->size < sizeof(magic)) || (memcmp(d->data, &magic, sizeof(magic)))) {
343 // At this point we know we're looking at a compressed item.
345 struct CtdlCompressHeader zheader;
346 char *uncompressed_data;
347 char *compressed_data;
348 uLongf destLen, sourceLen;
351 memset(&zheader, 0, sizeof(struct CtdlCompressHeader));
352 cplen = sizeof(struct CtdlCompressHeader);
353 if (sizeof(struct CtdlCompressHeader) > d->size) {
356 memcpy(&zheader, d->data, cplen);
358 compressed_data = d->data;
359 compressed_data += sizeof(struct CtdlCompressHeader);
361 sourceLen = (uLongf) zheader.compressed_len;
362 destLen = (uLongf) zheader.uncompressed_len;
363 uncompressed_data = malloc(zheader.uncompressed_len);
365 if (uncompress((Bytef *) uncompressed_data,
366 (uLongf *) &destLen, (const Bytef *) compressed_data, (uLong) sourceLen) != Z_OK) {
367 syslog(LOG_ERR, "bdb: uncompress() error");
372 d->size = (size_t) destLen;
373 d->data = uncompressed_data;
377 // Store a piece of data. Returns 0 if the operation was successful. If a
378 // key already exists it should be overwritten.
379 int bdb_store(int cdb, const void *ckey, int ckeylen, void *cdata, int cdatalen) {
384 struct CtdlCompressHeader zheader;
385 char *compressed_data = NULL;
387 size_t buffer_len = 0;
390 memset(&dkey, 0, sizeof(DBT));
391 memset(&ddata, 0, sizeof(DBT));
393 dkey.data = (void *) ckey;
394 ddata.size = cdatalen;
397 // "visit" records are numerous and have big, mostly-empty string buffers in them.
398 // If we compress these we can get them down to 1% of their size most of the time.
399 if (cdb == CDB_VISIT) {
401 zheader.magic = COMPRESS_MAGIC;
402 zheader.uncompressed_len = cdatalen;
403 buffer_len = ((cdatalen * 101) / 100) + 100 + sizeof(struct CtdlCompressHeader);
404 destLen = (uLongf) buffer_len;
405 compressed_data = malloc(buffer_len);
406 if (compress2((Bytef *) (compressed_data + sizeof(struct CtdlCompressHeader)), &destLen, (Bytef *) cdata, (uLongf) cdatalen, 1) != Z_OK) {
407 syslog(LOG_ERR, "bdb: compress2() error");
410 zheader.compressed_len = (size_t) destLen;
411 memcpy(compressed_data, &zheader, sizeof(struct CtdlCompressHeader));
412 ddata.size = (size_t) (sizeof(struct CtdlCompressHeader) + zheader.compressed_len);
413 ddata.data = compressed_data;
416 if (TSD->tid != NULL) {
417 ret = bdb_table[cdb]->put(bdb_table[cdb], // db
418 TSD->tid, // transaction ID
424 syslog(LOG_ERR, "bdb: bdb_store(%d): %s", cdb, db_strerror(ret));
428 free(compressed_data);
433 bdb_bailIfCursor(TSD->cursors, "attempt to write during r/o cursor");
438 if ((ret = bdb_table[cdb]->put(bdb_table[cdb], // db
439 tid, // transaction ID
443 if (ret == DB_LOCK_DEADLOCK) {
448 syslog(LOG_ERR, "bdb: bdb_store(%d): %s", cdb, db_strerror(ret));
455 free(compressed_data);
464 // Delete a piece of data. Returns 0 if the operation was successful.
465 int bdb_delete(int cdb, void *key, int keylen) {
470 memset(&dkey, 0, sizeof dkey);
474 if (TSD->tid != NULL) {
475 ret = bdb_table[cdb]->del(bdb_table[cdb], TSD->tid, &dkey, 0);
477 syslog(LOG_ERR, "bdb: bdb_delete(%d): %s", cdb, db_strerror(ret));
478 if (ret != DB_NOTFOUND) {
484 bdb_bailIfCursor(TSD->cursors, "attempt to delete during r/o cursor");
489 if ((ret = bdb_table[cdb]->del(bdb_table[cdb], tid, &dkey, 0)) && ret != DB_NOTFOUND) {
490 if (ret == DB_LOCK_DEADLOCK) {
495 syslog(LOG_ERR, "bdb: bdb_delete(%d): %s", cdb, db_strerror(ret));
507 static DBC *bdb_localcursor(int cdb) {
511 if (TSD->cursors[cdb] == NULL) {
512 ret = bdb_table[cdb]->cursor(bdb_table[cdb], TSD->tid, &curs, 0);
515 ret = TSD->cursors[cdb]->c_dup(TSD->cursors[cdb], &curs, DB_POSITION);
519 syslog(LOG_ERR, "bdb: bdb_localcursor: %s", db_strerror(ret));
527 // Fetch a piece of data. Returns a "struct cdbdata"
528 // cdbdata.len will be 0 if the item is not found.
529 struct cdbdata bdb_fetch(int cdb, const void *key, int keylen) {
531 struct cdbdata returned_data;
532 memset(&returned_data, 0, sizeof(struct cdbdata));
534 if (keylen == 0) { // key length zero is impossible
535 return(returned_data);
541 memset(&dkey, 0, sizeof(DBT));
543 dkey.data = (void *) key;
545 if (TSD->tid != NULL) {
546 TSD->dbdata[cdb].flags = DB_DBT_REALLOC;
547 ret = bdb_table[cdb]->get(bdb_table[cdb], TSD->tid, &dkey, &TSD->dbdata[cdb], 0);
553 TSD->dbdata[cdb].flags = DB_DBT_REALLOC;
554 curs = bdb_localcursor(cdb);
555 ret = curs->c_get(curs, &dkey, &TSD->dbdata[cdb], DB_SET);
557 } while (ret == DB_LOCK_DEADLOCK);
560 if ((ret != 0) && (ret != DB_NOTFOUND)) {
561 syslog(LOG_ERR, "bdb: bdb_fetch(%d): %s", cdb, db_strerror(ret));
566 bdb_decompress_if_necessary(&TSD->dbdata[cdb]);
567 returned_data.len = TSD->dbdata[cdb].size;
568 returned_data.ptr = TSD->dbdata[cdb].data;
571 return(returned_data);
575 void bdb_close_cursor(int cdb) {
576 if (TSD->cursors[cdb] != NULL) {
577 bdb_cclose(TSD->cursors[cdb]);
580 TSD->cursors[cdb] = NULL;
584 // Prepare for a sequential search of an entire database.
585 // (There is guaranteed to be no more than one traversal in progress per thread at any given time.)
586 void bdb_rewind(int cdb) {
589 if (TSD->cursors[cdb] != NULL) {
590 syslog(LOG_ERR, "bdb: bdb_rewind: must close cursor on database %d before reopening", cdb);
592 // bdb_cclose(TSD->cursors[cdb]);
595 // Now initialize the cursor
596 ret = bdb_table[cdb]->cursor(bdb_table[cdb], TSD->tid, &TSD->cursors[cdb], 0);
598 syslog(LOG_ERR, "bdb: bdb_rewind: db_cursor: %s", db_strerror(ret));
604 // Fetch the next item in a sequential search. Returns a pointer to a
605 // cdbdata structure, or NULL if we've hit the end.
606 struct cdbkeyval bdb_next_item(int cdb) {
610 memset(&kv, 0, sizeof(struct cdbkeyval));
612 // reuse memory from the previous call.
613 TSD->dbkey[cdb].flags = DB_DBT_MALLOC;
614 TSD->dbdata[cdb].flags = DB_DBT_MALLOC;
616 assert(TSD->cursors[cdb] != NULL);
617 ret = TSD->cursors[cdb]->c_get(TSD->cursors[cdb], &TSD->dbkey[cdb], &TSD->dbdata[cdb], DB_NEXT);
620 if (ret != DB_NOTFOUND) {
621 syslog(LOG_ERR, "bdb: bdb_next_item(%d): %s", cdb, db_strerror(ret));
624 bdb_close_cursor(cdb);
625 return(kv); // presumably, we are at the end
628 bdb_decompress_if_necessary(&TSD->dbdata[cdb]);
630 kv.key.len = TSD->dbkey[cdb].size;
631 kv.key.ptr = TSD->dbkey[cdb].data;
632 kv.val.len = TSD->dbdata[cdb].size;
633 kv.val.ptr = TSD->dbdata[cdb].data;
638 // Transaction-based stuff. I'm writing this as I bake cookies...
639 void bdb_begin_transaction(void) {
640 bdb_bailIfCursor(TSD->cursors, "can't begin transaction during r/o cursor");
642 if (TSD->tid != NULL) {
643 syslog(LOG_ERR, "bdb: bdb_begin_transaction: ERROR: nested transaction");
647 bdb_txbegin(&TSD->tid);
651 void bdb_end_transaction(void) {
654 for (i = 0; i < MAXCDB; i++) {
655 if (TSD->cursors[i] != NULL) {
656 syslog(LOG_WARNING, "bdb: bdb_end_transaction: WARNING: cursor %d still open at transaction end", i);
657 bdb_cclose(TSD->cursors[i]);
658 TSD->cursors[i] = NULL;
662 if (TSD->tid == NULL) {
663 syslog(LOG_ERR, "bdb: bdb_end_transaction: ERROR: bdb_txcommit(NULL) !!");
667 bdb_txcommit(TSD->tid);
674 // Truncate (delete every record)
675 void bdb_trunc(int cdb) {
679 if (TSD->tid != NULL) {
680 syslog(LOG_ERR, "bdb: bdb_trunc must not be called in a transaction.");
684 bdb_bailIfCursor(TSD->cursors, "attempt to write during r/o cursor");
688 if ((ret = bdb_table[cdb]->truncate(bdb_table[cdb], // db
689 NULL, // transaction ID
690 &count, // #rows deleted
692 if (ret == DB_LOCK_DEADLOCK) {
696 syslog(LOG_ERR, "bdb: bdb_truncate(%d): %s", cdb, db_strerror(ret));
698 syslog(LOG_ERR, "bdb: You may need to tune your database; please read http://www.citadel.org for more information.");
707 // compact (defragment) the database, possibly returning space back to the underlying filesystem
708 void bdb_compact(void) {
712 syslog(LOG_DEBUG, "bdb: bdb_compact() started");
713 for (i = 0; i < MAXCDB; i++) {
714 syslog(LOG_DEBUG, "bdb: compacting database %d", i);
715 ret = bdb_table[i]->compact(bdb_table[i], NULL, NULL, NULL, NULL, DB_FREE_SPACE, NULL);
717 syslog(LOG_ERR, "bdb: compact: %s", db_strerror(ret));
720 syslog(LOG_DEBUG, "bdb: bdb_compact() finished");
724 // Calling this function activates the Berkeley DB back end.
725 void bdb_init_backend(void) {
727 // Assign the backend API stubs to the functions in this module.
728 cdb_compact = bdb_compact;
729 cdb_checkpoint = bdb_checkpoint;
730 cdb_rewind = bdb_rewind;
731 cdb_fetch = bdb_fetch;
732 cdb_open_databases = bdb_open_databases;
733 cdb_close_databases = bdb_close_databases;
734 cdb_store = bdb_store;
735 cdb_delete = bdb_delete;
736 cdb_next_item = bdb_next_item;
737 cdb_close_cursor = bdb_close_cursor;
738 cdb_begin_transaction = bdb_begin_transaction;
739 cdb_end_transaction = bdb_end_transaction;
740 cdb_check_handles = bdb_check_handles;
741 cdb_trunc = bdb_trunc;
743 // Some functions in this backend need to store some per-thread data.
744 // We crerate the key here, during module initialization.
745 if (pthread_key_create(&bdb_thread_key, NULL) != 0) {
746 syslog(LOG_ERR, "pthread_key_create() : %m");
747 exit(CTDLEXIT_THREAD);
750 syslog(LOG_INFO, "db: initialized Berkeley DB backend");