2 Unix SMB/CIFS implementation.
4 Generic, persistent and shared between processes cache mechanism for use
5 by various parts of the Samba code
7 Copyright (C) Rafal Szczesniak 2002
8 Copyright (C) Volker Lendecke 2009
10 This program is free software; you can redistribute it and/or modify
11 it under the terms of the GNU General Public License as published by
12 the Free Software Foundation; either version 3 of the License, or
13 (at your option) any later version.
15 This program is distributed in the hope that it will be useful,
16 but WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
18 GNU General Public License for more details.
20 You should have received a copy of the GNU General Public License
21 along with this program. If not, see <http://www.gnu.org/licenses/>.
27 #define DBGC_CLASS DBGC_TDB
29 #define TIMEOUT_LEN 12
30 #define CACHE_DATA_FMT "%12u/"
31 #define READ_CACHE_DATA_FMT_TEMPLATE "%%12u/%%%us"
32 #define BLOB_TYPE "DATA_BLOB"
33 #define BLOB_TYPE_LEN 9
35 static struct tdb_context *cache;
36 static struct tdb_context *cache_notrans;
40 * @brief Generic, persistent and shared between processes cache mechanism
41 * for use by various parts of the Samba code
47 * Cache initialisation function. Opens cache tdb file or creates
48 * it if does not exist.
50 * @return true on successful initialisation of the cache or
54 static bool gencache_init(void)
56 char* cache_fname = NULL;
57 int open_flags = O_RDWR|O_CREAT;
58 bool first_try = true;
60 /* skip file open if it's already opened */
61 if (cache) return True;
63 cache_fname = lock_path("gencache.tdb");
65 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
68 cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT, open_flags, 0644);
71 ret = tdb_check(cache, NULL, NULL);
76 DEBUG(0, ("gencache_init: tdb_check(%s) failed\n",
81 DEBUG(0, ("gencache_init: tdb_check(%s) failed - retry after CLEAR_IF_FIRST\n",
83 cache = tdb_open_log(cache_fname, 0, TDB_CLEAR_IF_FIRST, open_flags, 0644);
92 if (!cache && (errno == EACCES)) {
93 open_flags = O_RDONLY;
94 cache = tdb_open_log(cache_fname, 0, TDB_DEFAULT, open_flags,
97 DEBUG(5, ("gencache_init: Opening cache file %s read-only.\n", cache_fname));
102 DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
106 cache_fname = lock_path("gencache_notrans.tdb");
108 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
110 cache_notrans = tdb_open_log(cache_fname, 0, TDB_CLEAR_IF_FIRST,
112 if (cache_notrans == NULL) {
113 DEBUG(5, ("Opening %s failed: %s\n", cache_fname,
123 static TDB_DATA last_stabilize_key(void)
126 result.dptr = (uint8_t *)"@LAST_STABILIZED";
132 * Set an entry in the cache file. If there's no such
135 * @param keystr string that represents a key of this entry
136 * @param blob DATA_BLOB value being cached
137 * @param timeout time when the value is expired
139 * @retval true when entry is successfuly stored
140 * @retval false on failure
143 bool gencache_set_data_blob(const char *keystr, const DATA_BLOB *blob,
149 time_t last_stabilize;
150 static int writecount;
152 if (tdb_data_cmp(string_term_tdb_data(keystr),
153 last_stabilize_key()) == 0) {
154 DEBUG(10, ("Can't store %s as a key\n", keystr));
158 if ((keystr == NULL) || (blob == NULL)) {
162 if (!gencache_init()) return False;
164 val = talloc_asprintf(talloc_tos(), CACHE_DATA_FMT, (int)timeout);
168 val = talloc_realloc(NULL, val, char, talloc_array_length(val)-1);
172 val = (char *)talloc_append_blob(NULL, val, *blob);
177 DEBUG(10, ("Adding cache entry with key = %s and timeout ="
178 " %s (%d seconds %s)\n", keystr, ctime(&timeout),
179 (int)(timeout - time(NULL)),
180 timeout > time(NULL) ? "ahead" : "in the past"));
182 ret = tdb_store_bystring(
183 cache_notrans, keystr,
184 make_tdb_data((uint8_t *)val, talloc_array_length(val)),
193 * Every 100 writes within a single process, stabilize the cache with
194 * a transaction. This is done to prevent a single transaction to
195 * become huge and chew lots of memory.
198 if (writecount > lp_parm_int(-1, "gencache", "stabilize_count", 100)) {
199 gencache_stabilize();
205 * Every 5 minutes, call gencache_stabilize() to not let grow
206 * gencache_notrans.tdb too large.
210 databuf = tdb_fetch(cache_notrans, last_stabilize_key());
211 if ((databuf.dptr != NULL)
212 && (databuf.dptr[databuf.dsize-1] == '\0')) {
213 last_stabilize = atoi((char *)databuf.dptr);
214 SAFE_FREE(databuf.dptr);
217 + lp_parm_int(-1, "gencache", "stabilize_interval", 300))
219 gencache_stabilize();
227 * Delete one entry from the cache file.
229 * @param keystr string that represents a key of this entry
231 * @retval true upon successful deletion
232 * @retval false in case of failure
235 bool gencache_del(const char *keystr)
237 bool exists, was_expired;
241 if (keystr == NULL) {
245 if (!gencache_init()) return False;
247 DEBUG(10, ("Deleting cache entry (key = %s)\n", keystr));
250 * We delete an element by setting its timeout to 0. This way we don't
251 * have to do a transaction on gencache.tdb every time we delete an
255 exists = gencache_get_data_blob(keystr, &value, NULL, &was_expired);
257 if (!exists && was_expired) {
259 * gencache_get_data_blob has implicitly deleted this
260 * entry, so we have to return success here.
266 data_blob_free(&value);
267 ret = gencache_set(keystr, "", 0);
272 static bool gencache_pull_timeout(char *val, time_t *pres, char **pendptr)
277 res = strtol(val, &endptr, 10);
279 if ((endptr == NULL) || (*endptr != '/')) {
280 DEBUG(2, ("Invalid gencache data format: %s\n", val));
286 if (pendptr != NULL) {
293 * Get existing entry from the cache file.
295 * @param keystr string that represents a key of this entry
296 * @param blob DATA_BLOB that is filled with entry's blob
297 * @param timeout pointer to a time_t that is filled with entry's
300 * @retval true when entry is successfuly fetched
301 * @retval False for failure
304 bool gencache_get_data_blob(const char *keystr, DATA_BLOB *blob,
305 time_t *timeout, bool *was_expired)
310 bool expired = false;
312 if (keystr == NULL) {
316 if (tdb_data_cmp(string_term_tdb_data(keystr),
317 last_stabilize_key()) == 0) {
318 DEBUG(10, ("Can't get %s as a key\n", keystr));
322 if (!gencache_init()) {
326 databuf = tdb_fetch_bystring(cache_notrans, keystr);
328 if (databuf.dptr == NULL) {
329 databuf = tdb_fetch_bystring(cache, keystr);
332 if (databuf.dptr == NULL) {
333 DEBUG(10, ("Cache entry with key = %s couldn't be found \n",
338 if (!gencache_pull_timeout((char *)databuf.dptr, &t, &endptr)) {
339 SAFE_FREE(databuf.dptr);
343 DEBUG(10, ("Returning %s cache entry: key = %s, value = %s, "
344 "timeout = %s", t > time(NULL) ? "valid" :
345 "expired", keystr, endptr+1, ctime(&t)));
349 SAFE_FREE(databuf.dptr);
353 if (t <= time(NULL)) {
356 * We're expired, delete the entry. We can't use gencache_del
357 * here, because that uses gencache_get_data_blob for checking
358 * the existence of a record. We know the thing exists and
359 * directly store an empty value with 0 timeout.
361 gencache_set(keystr, "", 0);
363 SAFE_FREE(databuf.dptr);
372 databuf.dsize - PTR_DIFF(endptr+1, databuf.dptr));
373 if (blob->data == NULL) {
374 SAFE_FREE(databuf.dptr);
375 DEBUG(0, ("memdup failed\n"));
380 SAFE_FREE(databuf.dptr);
389 if (was_expired != NULL) {
390 *was_expired = expired;
395 struct stabilize_state {
399 static int stabilize_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA val,
405 * Migrate the clear-if-first gencache data to the stable,
406 * transaction-based gencache.tdb
409 bool gencache_stabilize(void)
411 struct stabilize_state state;
415 if (!gencache_init()) {
419 res = tdb_transaction_start(cache);
421 DEBUG(10, ("Could not start transaction on gencache.tdb: "
422 "%s\n", tdb_errorstr(cache)));
425 res = tdb_transaction_start(cache_notrans);
427 tdb_transaction_cancel(cache);
428 DEBUG(10, ("Could not start transaction on "
429 "gencache_notrans.tdb: %s\n",
430 tdb_errorstr(cache_notrans)));
435 state.written = false;
437 res = tdb_traverse(cache_notrans, stabilize_fn, &state);
438 if ((res == -1) || state.error) {
439 if ((tdb_transaction_cancel(cache_notrans) == -1)
440 || (tdb_transaction_cancel(cache) == -1)) {
441 smb_panic("tdb_transaction_cancel failed\n");
446 if (!state.written) {
447 if ((tdb_transaction_cancel(cache_notrans) == -1)
448 || (tdb_transaction_cancel(cache) == -1)) {
449 smb_panic("tdb_transaction_cancel failed\n");
454 res = tdb_transaction_commit(cache);
456 DEBUG(10, ("tdb_transaction_commit on gencache.tdb failed: "
457 "%s\n", tdb_errorstr(cache)));
458 if (tdb_transaction_cancel(cache_notrans) == -1) {
459 smb_panic("tdb_transaction_cancel failed\n");
464 res = tdb_transaction_commit(cache_notrans);
466 DEBUG(10, ("tdb_transaction_commit on gencache.tdb failed: "
467 "%s\n", tdb_errorstr(cache)));
471 now = talloc_asprintf(talloc_tos(), "%d", (int)time(NULL));
473 tdb_store(cache_notrans, last_stabilize_key(),
474 string_term_tdb_data(now), 0);
481 static int stabilize_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA val,
484 struct stabilize_state *state = (struct stabilize_state *)priv;
488 if (tdb_data_cmp(key, last_stabilize_key()) == 0) {
492 if (!gencache_pull_timeout((char *)val.dptr, &timeout, NULL)) {
493 DEBUG(10, ("Ignoring invalid entry\n"));
496 if ((timeout < time(NULL)) || (val.dsize == 0)) {
497 res = tdb_delete(cache, key);
498 if ((res == -1) && (tdb_error(cache) == TDB_ERR_NOEXIST)) {
501 state->written = true;
504 res = tdb_store(cache, key, val, 0);
506 state->written = true;
511 DEBUG(10, ("Transfer to gencache.tdb failed: %s\n",
512 tdb_errorstr(cache)));
517 if (tdb_delete(cache_notrans, key) == -1) {
518 DEBUG(10, ("tdb_delete from gencache_notrans.tdb failed: "
519 "%s\n", tdb_errorstr(cache_notrans)));
527 * Get existing entry from the cache file.
529 * @param keystr string that represents a key of this entry
530 * @param valstr buffer that is allocated and filled with the entry value
531 * buffer's disposing must be done outside
532 * @param timeout pointer to a time_t that is filled with entry's
535 * @retval true when entry is successfuly fetched
536 * @retval False for failure
539 bool gencache_get(const char *keystr, char **value, time_t *ptimeout)
544 ret = gencache_get_data_blob(keystr, &blob, ptimeout, NULL);
548 if ((blob.data == NULL) || (blob.length == 0)) {
549 SAFE_FREE(blob.data);
552 if (blob.data[blob.length-1] != '\0') {
553 /* Not NULL terminated, can't be a string */
554 SAFE_FREE(blob.data);
558 *value = SMB_STRDUP((char *)blob.data);
559 data_blob_free(&blob);
560 if (*value == NULL) {
565 data_blob_free(&blob);
570 * Set an entry in the cache file. If there's no such
573 * @param keystr string that represents a key of this entry
574 * @param value text representation value being cached
575 * @param timeout time when the value is expired
577 * @retval true when entry is successfuly stored
578 * @retval false on failure
581 bool gencache_set(const char *keystr, const char *value, time_t timeout)
583 DATA_BLOB blob = data_blob_const(value, strlen(value)+1);
584 return gencache_set_data_blob(keystr, &blob, timeout);
588 * Iterate through all entries which key matches to specified pattern
590 * @param fn pointer to the function that will be supplied with each single
591 * matching cache entry (key, value and timeout) as an arguments
592 * @param data void pointer to an arbitrary data that is passed directly to the fn
593 * function on each call
594 * @param keystr_pattern pattern the existing entries' keys are matched to
598 struct gencache_iterate_state {
599 void (*fn)(const char *key, const char *value, time_t timeout,
606 static int gencache_iterate_fn(struct tdb_context *tdb, TDB_DATA key,
607 TDB_DATA value, void *priv)
609 struct gencache_iterate_state *state =
610 (struct gencache_iterate_state *)priv;
612 char *free_key = NULL;
614 char *free_val = NULL;
619 if (tdb_data_cmp(key, last_stabilize_key()) == 0) {
623 if (state->in_persistent && tdb_exists(cache_notrans, key)) {
627 if (key.dptr[key.dsize-1] == '\0') {
628 keystr = (char *)key.dptr;
630 /* ensure 0-termination */
631 keystr = SMB_STRNDUP((char *)key.dptr, key.dsize);
635 if ((value.dptr == NULL) || (value.dsize <= TIMEOUT_LEN)) {
639 if (fnmatch(state->pattern, keystr, 0) != 0) {
643 if (value.dptr[value.dsize-1] == '\0') {
644 valstr = (char *)value.dptr;
646 /* ensure 0-termination */
647 valstr = SMB_STRNDUP((char *)value.dptr, value.dsize);
651 u = strtoul(valstr, &timeout_endp, 10);
653 if ((*timeout_endp != '/') || ((timeout_endp-valstr) != TIMEOUT_LEN)) {
660 DEBUG(10, ("Calling function with arguments "
661 "(key = %s, value = %s, timeout = %s)\n",
662 keystr, timeout_endp, ctime(&timeout)));
663 state->fn(keystr, timeout_endp, timeout, state->priv);
671 void gencache_iterate(void (*fn)(const char* key, const char *value, time_t timeout, void* dptr),
672 void* data, const char* keystr_pattern)
674 struct gencache_iterate_state state;
676 if ((fn == NULL) || (keystr_pattern == NULL)) {
680 if (!gencache_init()) return;
682 DEBUG(5, ("Searching cache keys with pattern %s\n", keystr_pattern));
685 state.pattern = keystr_pattern;
688 state.in_persistent = false;
689 tdb_traverse(cache_notrans, gencache_iterate_fn, &state);
691 state.in_persistent = true;
692 tdb_traverse(cache, gencache_iterate_fn, &state);