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/>.
25 #include "system/filesys.h"
26 #include "system/glob.h"
28 #include "tdb_wrap/tdb_wrap.h"
29 #include "../lib/util/memcache.h"
32 #define DBGC_CLASS DBGC_TDB
34 #define TIMEOUT_LEN 12
35 #define CACHE_DATA_FMT "%12u/"
36 #define READ_CACHE_DATA_FMT_TEMPLATE "%%12u/%%%us"
37 #define BLOB_TYPE "DATA_BLOB"
38 #define BLOB_TYPE_LEN 9
40 static struct tdb_wrap *cache;
41 static struct tdb_wrap *cache_notrans;
42 static int cache_notrans_seqnum;
46 * @brief Generic, persistent and shared between processes cache mechanism
47 * for use by various parts of the Samba code
53 * Cache initialisation function. Opens cache tdb file or creates
54 * it if does not exist.
56 * @return true on successful initialisation of the cache or
60 static bool gencache_init(void)
62 char* cache_fname = NULL;
63 int open_flags = O_RDWR|O_CREAT;
65 /* skip file open if it's already opened */
70 cache_fname = cache_path("gencache.tdb");
71 if (cache_fname == NULL) {
75 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
77 cache = tdb_wrap_open(NULL, cache_fname, 0,
78 TDB_DEFAULT|TDB_INCOMPATIBLE_HASH,
82 ret = tdb_check(cache->tdb, NULL, NULL);
87 * Retry with CLEAR_IF_FIRST.
89 * Warning: Converting this to dbwrap won't work
90 * directly. gencache.c does transactions on this tdb,
91 * and dbwrap forbids this for CLEAR_IF_FIRST
92 * databases. tdb does allow transactions on
93 * CLEAR_IF_FIRST databases, so lets use it here to
94 * clean up a broken database.
96 cache = tdb_wrap_open(NULL, cache_fname, 0,
98 TDB_INCOMPATIBLE_HASH|
104 if (!cache && (errno == EACCES)) {
105 open_flags = O_RDONLY;
106 cache = tdb_wrap_open(NULL, cache_fname, 0,
107 TDB_DEFAULT|TDB_INCOMPATIBLE_HASH,
110 DEBUG(5, ("gencache_init: Opening cache file %s read-only.\n", cache_fname));
113 TALLOC_FREE(cache_fname);
116 DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
120 cache_fname = lock_path("gencache_notrans.tdb");
121 if (cache_fname == NULL) {
126 DEBUG(5, ("Opening cache file at %s\n", cache_fname));
128 cache_notrans = tdb_wrap_open(NULL, cache_fname, 0,
130 TDB_INCOMPATIBLE_HASH|
135 if (cache_notrans == NULL) {
136 DEBUG(5, ("Opening %s failed: %s\n", cache_fname,
138 TALLOC_FREE(cache_fname);
142 TALLOC_FREE(cache_fname);
147 static TDB_DATA last_stabilize_key(void)
150 result.dptr = discard_const_p(uint8_t, "@LAST_STABILIZED");
155 struct gencache_have_val_state {
157 const DATA_BLOB *data;
161 static void gencache_have_val_parser(time_t old_timeout, DATA_BLOB data,
164 struct gencache_have_val_state *state =
165 (struct gencache_have_val_state *)private_data;
166 time_t now = time(NULL);
167 int cache_time_left, new_time_left, additional_time;
170 * Excuse the many variables, but these time calculations are
171 * confusing to me. We do not want to write to gencache with a
172 * possibly expensive transaction if we are about to write the same
173 * value, just extending the remaining timeout by less than 10%.
176 cache_time_left = old_timeout - now;
177 if (cache_time_left <= 0) {
179 * timed out, write new value
184 new_time_left = state->new_timeout - now;
185 if (new_time_left <= 0) {
187 * Huh -- no new timeout?? Write it.
192 if (new_time_left < cache_time_left) {
194 * Someone wants to shorten the timeout. Let it happen.
200 * By how much does the new timeout extend the remaining cache time?
202 additional_time = new_time_left - cache_time_left;
204 if (additional_time * 10 < 0) {
206 * Integer overflow. We extend by so much that we have to write it.
212 * The comparison below is essentially equivalent to
214 * new_time_left > cache_time_left * 1.10
216 * but without floating point calculations.
219 if (additional_time * 10 > cache_time_left) {
221 * We extend the cache timeout by more than 10%. Do it.
227 * Now the more expensive data compare.
229 if (data_blob_cmp(state->data, &data) != 0) {
231 * Write a new value. Certainly do it.
237 * Extending the timeout by less than 10% for the same cache value is
238 * not worth the trouble writing a value into gencache under a
239 * possibly expensive transaction.
244 static bool gencache_have_val(const char *keystr, const DATA_BLOB *data,
247 struct gencache_have_val_state state;
249 state.new_timeout = timeout;
253 if (!gencache_parse(keystr, gencache_have_val_parser, &state)) {
259 static int last_stabilize_parser(TDB_DATA key, TDB_DATA data,
262 time_t *last_stabilize = private_data;
264 if ((data.dsize != 0) && (data.dptr[data.dsize-1] == '\0')) {
265 *last_stabilize = atoi((char *)data.dptr);
271 * Set an entry in the cache file. If there's no such
274 * @param keystr string that represents a key of this entry
275 * @param blob DATA_BLOB value being cached
276 * @param timeout time when the value is expired
278 * @retval true when entry is successfully stored
279 * @retval false on failure
282 bool gencache_set_data_blob(const char *keystr, const DATA_BLOB *blob,
287 time_t last_stabilize;
288 static int writecount;
290 if (tdb_data_cmp(string_term_tdb_data(keystr),
291 last_stabilize_key()) == 0) {
292 DEBUG(10, ("Can't store %s as a key\n", keystr));
296 if ((keystr == NULL) || (blob == NULL)) {
300 if (!gencache_init()) {
304 if (gencache_have_val(keystr, blob, timeout)) {
305 DEBUG(10, ("Did not store value for %s, we already got it\n",
310 val = talloc_asprintf(talloc_tos(), CACHE_DATA_FMT, (int)timeout);
314 val = talloc_realloc(NULL, val, char, talloc_array_length(val)-1);
318 val = (char *)talloc_append_blob(NULL, val, *blob);
323 DEBUG(10, ("Adding cache entry with key=[%s] and timeout="
324 "[%s] (%d seconds %s)\n", keystr,
325 timestring(talloc_tos(), timeout),
326 (int)(timeout - time(NULL)),
327 timeout > time(NULL) ? "ahead" : "in the past"));
329 ret = tdb_store_bystring(
330 cache_notrans->tdb, keystr,
331 make_tdb_data((uint8_t *)val, talloc_array_length(val)),
340 * Every 100 writes within a single process, stabilize the cache with
341 * a transaction. This is done to prevent a single transaction to
342 * become huge and chew lots of memory.
345 if (writecount > lp_parm_int(-1, "gencache", "stabilize_count", 100)) {
346 gencache_stabilize();
352 * Every 5 minutes, call gencache_stabilize() to not let grow
353 * gencache_notrans.tdb too large.
358 tdb_parse_record(cache_notrans->tdb, last_stabilize_key(),
359 last_stabilize_parser, &last_stabilize);
362 + lp_parm_int(-1, "gencache", "stabilize_interval", 300))
364 gencache_stabilize();
372 * Delete one entry from the cache file.
374 * @param keystr string that represents a key of this entry
376 * @retval true upon successful deletion
377 * @retval false in case of failure
380 bool gencache_del(const char *keystr)
382 bool exists, was_expired;
386 if (keystr == NULL) {
390 if (!gencache_init()) {
394 DEBUG(10, ("Deleting cache entry (key=[%s])\n", keystr));
397 * We delete an element by setting its timeout to 0. This way we don't
398 * have to do a transaction on gencache.tdb every time we delete an
402 exists = gencache_get_data_blob(keystr, NULL, &value, NULL,
405 if (!exists && was_expired) {
407 * gencache_get_data_blob has implicitly deleted this
408 * entry, so we have to return success here.
414 data_blob_free(&value);
415 ret = gencache_set(keystr, "", 0);
420 static bool gencache_pull_timeout(char *val, time_t *pres, char **pendptr)
429 res = strtol(val, &endptr, 10);
431 if ((endptr == NULL) || (*endptr != '/')) {
432 DEBUG(2, ("Invalid gencache data format: %s\n", val));
438 if (pendptr != NULL) {
444 struct gencache_parse_state {
445 void (*parser)(time_t timeout, DATA_BLOB blob, void *private_data);
450 static int gencache_parse_fn(TDB_DATA key, TDB_DATA data, void *private_data)
452 struct gencache_parse_state *state;
458 if (data.dptr == NULL) {
461 ret = gencache_pull_timeout((char *)data.dptr, &t, &endptr);
465 state = (struct gencache_parse_state *)private_data;
466 blob = data_blob_const(
467 endptr+1, data.dsize - PTR_DIFF(endptr+1, data.dptr));
468 state->parser(t, blob, state->private_data);
470 if (!state->is_memcache) {
471 memcache_add(NULL, GENCACHE_RAM,
472 data_blob_const(key.dptr, key.dsize),
473 data_blob_const(data.dptr, data.dsize));
479 bool gencache_parse(const char *keystr,
480 void (*parser)(time_t timeout, DATA_BLOB blob,
484 struct gencache_parse_state state;
485 TDB_DATA key = string_term_tdb_data(keystr);
486 DATA_BLOB memcache_val;
489 if (keystr == NULL) {
492 if (tdb_data_cmp(key, last_stabilize_key()) == 0) {
495 if (!gencache_init()) {
499 state.parser = parser;
500 state.private_data = private_data;
502 if (memcache_lookup(NULL, GENCACHE_RAM,
503 data_blob_const(key.dptr, key.dsize),
506 * Make sure that nobody has changed the gencache behind our
509 int current_seqnum = tdb_get_seqnum(cache_notrans->tdb);
510 if (current_seqnum == cache_notrans_seqnum) {
512 * Ok, our memcache is still current, use it without
513 * going to the tdb files.
515 state.is_memcache = true;
516 gencache_parse_fn(key, make_tdb_data(memcache_val.data,
517 memcache_val.length),
521 memcache_flush(NULL, GENCACHE_RAM);
522 cache_notrans_seqnum = current_seqnum;
525 state.is_memcache = false;
527 ret = tdb_parse_record(cache_notrans->tdb, key,
528 gencache_parse_fn, &state);
532 ret = tdb_parse_record(cache->tdb, key, gencache_parse_fn, &state);
536 struct gencache_get_data_blob_state {
543 static void gencache_get_data_blob_parser(time_t timeout, DATA_BLOB blob,
546 struct gencache_get_data_blob_state *state =
547 (struct gencache_get_data_blob_state *)private_data;
550 state->result = false;
553 state->timeout = timeout;
555 if (state->blob == NULL) {
556 state->result = true;
560 *state->blob = data_blob_talloc(state->mem_ctx, blob.data,
562 if (state->blob->data == NULL) {
563 state->result = false;
566 state->result = true;
570 * Get existing entry from the cache file.
572 * @param keystr string that represents a key of this entry
573 * @param blob DATA_BLOB that is filled with entry's blob
574 * @param timeout pointer to a time_t that is filled with entry's
577 * @retval true when entry is successfuly fetched
578 * @retval false for failure
581 bool gencache_get_data_blob(const char *keystr, TALLOC_CTX *mem_ctx,
583 time_t *timeout, bool *was_expired)
585 struct gencache_get_data_blob_state state;
586 bool expired = false;
588 state.result = false;
589 state.mem_ctx = mem_ctx;
592 if (!gencache_parse(keystr, gencache_get_data_blob_parser, &state)) {
598 if (state.timeout <= time(NULL)) {
600 * We're expired, delete the entry. We can't use gencache_del
601 * here, because that uses gencache_get_data_blob for checking
602 * the existence of a record. We know the thing exists and
603 * directly store an empty value with 0 timeout.
605 gencache_set(keystr, "", 0);
610 *timeout = state.timeout;
616 if (was_expired != NULL) {
617 *was_expired = expired;
619 if (state.result && state.blob) {
620 data_blob_free(state.blob);
625 struct stabilize_state {
628 static int stabilize_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA val,
631 static int wipe_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA val,
637 * Migrate the clear-if-first gencache data to the stable,
638 * transaction-based gencache.tdb
641 bool gencache_stabilize(void)
643 struct stabilize_state state;
647 if (!gencache_init()) {
651 res = tdb_transaction_start_nonblock(cache->tdb);
653 if (tdb_error(cache->tdb) == TDB_ERR_NOLOCK)
656 * Someone else already does the stabilize,
657 * this does not have to be done twice
662 DEBUG(10, ("Could not start transaction on gencache.tdb: "
663 "%s\n", tdb_errorstr(cache->tdb)));
667 res = tdb_lockall(cache_notrans->tdb);
669 tdb_transaction_cancel(cache->tdb);
670 DEBUG(10, ("Could not get allrecord lock on "
671 "gencache_notrans.tdb: %s\n",
672 tdb_errorstr(cache_notrans->tdb)));
676 state.written = false;
678 res = tdb_traverse(cache_notrans->tdb, stabilize_fn, &state);
680 tdb_unlockall(cache_notrans->tdb);
681 tdb_transaction_cancel(cache->tdb);
685 if (!state.written) {
686 tdb_unlockall(cache_notrans->tdb);
687 tdb_transaction_cancel(cache->tdb);
691 res = tdb_transaction_commit(cache->tdb);
693 DEBUG(10, ("tdb_transaction_commit on gencache.tdb failed: "
694 "%s\n", tdb_errorstr(cache->tdb)));
695 tdb_unlockall(cache_notrans->tdb);
699 res = tdb_traverse(cache_notrans->tdb, wipe_fn, NULL);
701 DEBUG(10, ("tdb_traverse with wipe_fn on gencache_notrans.tdb "
703 tdb_errorstr(cache_notrans->tdb)));
704 tdb_unlockall(cache_notrans->tdb);
708 res = tdb_unlockall(cache_notrans->tdb);
710 DEBUG(10, ("tdb_unlockall on gencache.tdb failed: "
711 "%s\n", tdb_errorstr(cache->tdb)));
715 now = talloc_asprintf(talloc_tos(), "%d", (int)time(NULL));
717 tdb_store(cache_notrans->tdb, last_stabilize_key(),
718 string_term_tdb_data(now), 0);
725 static int stabilize_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA val,
728 struct stabilize_state *state = (struct stabilize_state *)priv;
732 if (tdb_data_cmp(key, last_stabilize_key()) == 0) {
736 if (!gencache_pull_timeout((char *)val.dptr, &timeout, NULL)) {
737 DEBUG(10, ("Ignoring invalid entry\n"));
740 if ((timeout < time(NULL)) || (val.dsize == 0)) {
741 res = tdb_delete(cache->tdb, key);
743 state->written = true;
744 } else if (tdb_error(cache->tdb) == TDB_ERR_NOEXIST) {
748 res = tdb_store(cache->tdb, key, val, 0);
750 state->written = true;
755 DEBUG(10, ("Transfer to gencache.tdb failed: %s\n",
756 tdb_errorstr(cache->tdb)));
763 static int wipe_fn(struct tdb_context *tdb, TDB_DATA key, TDB_DATA val,
770 res = tdb_data_cmp(key, last_stabilize_key());
775 ok = gencache_pull_timeout((char *)val.dptr, &timeout, NULL);
777 DEBUG(10, ("Ignoring invalid entry\n"));
781 res = tdb_delete(tdb, key);
783 DEBUG(10, ("tdb_delete from gencache_notrans.tdb failed: "
784 "%s\n", tdb_errorstr(cache_notrans->tdb)));
793 * Get existing entry from the cache file.
795 * @param keystr string that represents a key of this entry
796 * @param valstr buffer that is allocated and filled with the entry value
797 * buffer's disposing must be done outside
798 * @param timeout pointer to a time_t that is filled with entry's
801 * @retval true when entry is successfuly fetched
802 * @retval false for failure
805 bool gencache_get(const char *keystr, TALLOC_CTX *mem_ctx, char **value,
811 ret = gencache_get_data_blob(keystr, mem_ctx, &blob, ptimeout, NULL);
815 if ((blob.data == NULL) || (blob.length == 0)) {
816 data_blob_free(&blob);
819 if (blob.data[blob.length-1] != '\0') {
820 /* Not NULL terminated, can't be a string */
821 data_blob_free(&blob);
826 * talloc_move generates a type-punned warning here. As we
827 * leave the function immediately, do a simple talloc_steal.
829 *value = (char *)talloc_steal(mem_ctx, blob.data);
832 data_blob_free(&blob);
837 * Set an entry in the cache file. If there's no such
840 * @param keystr string that represents a key of this entry
841 * @param value text representation value being cached
842 * @param timeout time when the value is expired
844 * @retval true when entry is successfuly stored
845 * @retval false on failure
848 bool gencache_set(const char *keystr, const char *value, time_t timeout)
850 DATA_BLOB blob = data_blob_const(value, strlen(value)+1);
851 return gencache_set_data_blob(keystr, &blob, timeout);
854 struct gencache_iterate_blobs_state {
855 void (*fn)(const char *key, DATA_BLOB value,
856 time_t timeout, void *private_data);
862 static int gencache_iterate_blobs_fn(struct tdb_context *tdb, TDB_DATA key,
863 TDB_DATA data, void *priv)
865 struct gencache_iterate_blobs_state *state =
866 (struct gencache_iterate_blobs_state *)priv;
868 char *free_key = NULL;
872 if (tdb_data_cmp(key, last_stabilize_key()) == 0) {
875 if (state->in_persistent && tdb_exists(cache_notrans->tdb, key)) {
879 if (key.dptr[key.dsize-1] == '\0') {
880 keystr = (char *)key.dptr;
882 /* ensure 0-termination */
883 keystr = talloc_strndup(talloc_tos(), (char *)key.dptr, key.dsize);
885 if (keystr == NULL) {
890 if (!gencache_pull_timeout((char *)data.dptr, &timeout, &endptr)) {
895 if (fnmatch(state->pattern, keystr, 0) != 0) {
899 DEBUG(10, ("Calling function with arguments "
900 "(key=[%s], timeout=[%s])\n",
901 keystr, timestring(talloc_tos(), timeout)));
904 data_blob_const(endptr,
905 data.dsize - PTR_DIFF(endptr, data.dptr)),
906 timeout, state->private_data);
909 TALLOC_FREE(free_key);
913 void gencache_iterate_blobs(void (*fn)(const char *key, DATA_BLOB value,
914 time_t timeout, void *private_data),
915 void *private_data, const char *pattern)
917 struct gencache_iterate_blobs_state state;
919 if ((fn == NULL) || (pattern == NULL) || !gencache_init()) {
923 DEBUG(5, ("Searching cache keys with pattern %s\n", pattern));
926 state.pattern = pattern;
927 state.private_data = private_data;
929 state.in_persistent = false;
930 tdb_traverse(cache_notrans->tdb, gencache_iterate_blobs_fn, &state);
932 state.in_persistent = true;
933 tdb_traverse(cache->tdb, gencache_iterate_blobs_fn, &state);
937 * Iterate through all entries which key matches to specified pattern
939 * @param fn pointer to the function that will be supplied with each single
940 * matching cache entry (key, value and timeout) as an arguments
941 * @param data void pointer to an arbitrary data that is passed directly to the fn
942 * function on each call
943 * @param keystr_pattern pattern the existing entries' keys are matched to
947 struct gencache_iterate_state {
948 void (*fn)(const char *key, const char *value, time_t timeout,
953 static void gencache_iterate_fn(const char *key, DATA_BLOB value,
954 time_t timeout, void *private_data)
956 struct gencache_iterate_state *state =
957 (struct gencache_iterate_state *)private_data;
959 char *free_val = NULL;
961 if (value.data[value.length-1] == '\0') {
962 valstr = (char *)value.data;
964 /* ensure 0-termination */
965 valstr = talloc_strndup(talloc_tos(), (char *)value.data, value.length);
967 if (valstr == NULL) {
972 DEBUG(10, ("Calling function with arguments "
973 "(key=[%s], value=[%s], timeout=[%s])\n",
974 key, valstr, timestring(talloc_tos(), timeout)));
976 state->fn(key, valstr, timeout, state->private_data);
980 TALLOC_FREE(free_val);
983 void gencache_iterate(void (*fn)(const char *key, const char *value,
984 time_t timeout, void *dptr),
985 void *private_data, const char *pattern)
987 struct gencache_iterate_state state;
993 state.private_data = private_data;
994 gencache_iterate_blobs(gencache_iterate_fn, &state, pattern);