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"
31 #define DBGC_CLASS DBGC_TDB
33 #define CACHE_DATA_FMT "%12u/"
35 static struct tdb_wrap
*cache
;
36 static struct tdb_wrap
*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
;
59 /* skip file open if it's already opened */
64 cache_fname
= cache_path("gencache.tdb");
65 if (cache_fname
== NULL
) {
69 DEBUG(5, ("Opening cache file at %s\n", cache_fname
));
71 cache
= tdb_wrap_open(NULL
, cache_fname
, 0,
72 TDB_DEFAULT
|TDB_INCOMPATIBLE_HASH
,
76 ret
= tdb_check(cache
->tdb
, NULL
, NULL
);
81 * Retry with CLEAR_IF_FIRST.
83 * Warning: Converting this to dbwrap won't work
84 * directly. gencache.c does transactions on this tdb,
85 * and dbwrap forbids this for CLEAR_IF_FIRST
86 * databases. tdb does allow transactions on
87 * CLEAR_IF_FIRST databases, so lets use it here to
88 * clean up a broken database.
90 cache
= tdb_wrap_open(NULL
, cache_fname
, 0,
92 TDB_INCOMPATIBLE_HASH
|
98 if (!cache
&& (errno
== EACCES
)) {
99 open_flags
= O_RDONLY
;
100 cache
= tdb_wrap_open(NULL
, cache_fname
, 0,
101 TDB_DEFAULT
|TDB_INCOMPATIBLE_HASH
,
104 DEBUG(5, ("gencache_init: Opening cache file %s read-only.\n", cache_fname
));
107 TALLOC_FREE(cache_fname
);
110 DEBUG(5, ("Attempt to open gencache.tdb has failed.\n"));
114 cache_fname
= lock_path("gencache_notrans.tdb");
115 if (cache_fname
== NULL
) {
120 DEBUG(5, ("Opening cache file at %s\n", cache_fname
));
122 cache_notrans
= tdb_wrap_open(NULL
, cache_fname
, 0,
124 TDB_INCOMPATIBLE_HASH
|
128 if (cache_notrans
== NULL
) {
129 DEBUG(5, ("Opening %s failed: %s\n", cache_fname
,
131 TALLOC_FREE(cache_fname
);
135 TALLOC_FREE(cache_fname
);
140 static TDB_DATA
last_stabilize_key(void)
143 result
.dptr
= discard_const_p(uint8_t, "@LAST_STABILIZED");
148 struct gencache_have_val_state
{
150 const DATA_BLOB
*data
;
154 static void gencache_have_val_parser(time_t old_timeout
, DATA_BLOB data
,
157 struct gencache_have_val_state
*state
=
158 (struct gencache_have_val_state
*)private_data
;
159 time_t now
= time(NULL
);
160 int cache_time_left
, new_time_left
, additional_time
;
163 * Excuse the many variables, but these time calculations are
164 * confusing to me. We do not want to write to gencache with a
165 * possibly expensive transaction if we are about to write the same
166 * value, just extending the remaining timeout by less than 10%.
169 cache_time_left
= old_timeout
- now
;
170 if (cache_time_left
<= 0) {
172 * timed out, write new value
177 new_time_left
= state
->new_timeout
- now
;
178 if (new_time_left
<= 0) {
180 * Huh -- no new timeout?? Write it.
185 if (new_time_left
< cache_time_left
) {
187 * Someone wants to shorten the timeout. Let it happen.
193 * By how much does the new timeout extend the remaining cache time?
195 additional_time
= new_time_left
- cache_time_left
;
197 if (additional_time
* 10 < 0) {
199 * Integer overflow. We extend by so much that we have to write it.
205 * The comparison below is essentially equivalent to
207 * new_time_left > cache_time_left * 1.10
209 * but without floating point calculations.
212 if (additional_time
* 10 > cache_time_left
) {
214 * We extend the cache timeout by more than 10%. Do it.
220 * Now the more expensive data compare.
222 if (data_blob_cmp(state
->data
, &data
) != 0) {
224 * Write a new value. Certainly do it.
230 * Extending the timeout by less than 10% for the same cache value is
231 * not worth the trouble writing a value into gencache under a
232 * possibly expensive transaction.
237 static bool gencache_have_val(const char *keystr
, const DATA_BLOB
*data
,
240 struct gencache_have_val_state state
;
242 state
.new_timeout
= timeout
;
246 if (!gencache_parse(keystr
, gencache_have_val_parser
, &state
)) {
252 static int last_stabilize_parser(TDB_DATA key
, TDB_DATA data
,
255 time_t *last_stabilize
= private_data
;
257 if ((data
.dsize
!= 0) && (data
.dptr
[data
.dsize
-1] == '\0')) {
258 *last_stabilize
= atoi((char *)data
.dptr
);
264 * Set an entry in the cache file. If there's no such
267 * @param keystr string that represents a key of this entry
268 * @param blob DATA_BLOB value being cached
269 * @param timeout time when the value is expired
271 * @retval true when entry is successfully stored
272 * @retval false on failure
275 bool gencache_set_data_blob(const char *keystr
, const DATA_BLOB
*blob
,
282 time_t last_stabilize
;
283 static int writecount
;
285 if (tdb_data_cmp(string_term_tdb_data(keystr
),
286 last_stabilize_key()) == 0) {
287 DEBUG(10, ("Can't store %s as a key\n", keystr
));
291 if ((keystr
== NULL
) || (blob
== NULL
)) {
295 if (!gencache_init()) {
299 if ((timeout
!= 0) && gencache_have_val(keystr
, blob
, timeout
)) {
300 DEBUG(10, ("Did not store value for %s, we already got it\n",
305 hdr_len
= fstr_sprintf(hdr
, CACHE_DATA_FMT
, (int)timeout
);
310 if ((blob
->length
+ (size_t)hdr_len
) < blob
->length
) {
314 val
= talloc_array(talloc_tos(), char, hdr_len
+ blob
->length
);
319 memcpy(val
, hdr
, hdr_len
);
320 memcpy(val
+hdr_len
, blob
->data
, blob
->length
);
322 DEBUG(10, ("Adding cache entry with key=[%s] and timeout="
323 "[%s] (%d seconds %s)\n", keystr
,
324 timestring(talloc_tos(), timeout
),
325 (int)(timeout
- time(NULL
)),
326 timeout
> time(NULL
) ? "ahead" : "in the past"));
328 ret
= tdb_store_bystring(
329 cache_notrans
->tdb
, keystr
,
330 make_tdb_data((uint8_t *)val
, talloc_array_length(val
)),
339 * Every 100 writes within a single process, stabilize the cache with
340 * a transaction. This is done to prevent a single transaction to
341 * become huge and chew lots of memory.
344 if (writecount
> lp_parm_int(-1, "gencache", "stabilize_count", 100)) {
345 gencache_stabilize();
351 * Every 5 minutes, call gencache_stabilize() to not let grow
352 * gencache_notrans.tdb too large.
357 tdb_parse_record(cache_notrans
->tdb
, last_stabilize_key(),
358 last_stabilize_parser
, &last_stabilize
);
361 + lp_parm_int(-1, "gencache", "stabilize_interval", 300))
363 gencache_stabilize();
370 static void gencache_del_parser(time_t timeout
, DATA_BLOB blob
,
374 bool *exists
= private_data
;
380 * Delete one entry from the cache file.
382 * @param keystr string that represents a key of this entry
384 * @retval true upon successful deletion
385 * @retval false in case of failure
388 bool gencache_del(const char *keystr
)
390 TDB_DATA key
= string_term_tdb_data(keystr
);
395 if (keystr
== NULL
) {
399 if (!gencache_init()) {
403 DEBUG(10, ("Deleting cache entry (key=[%s])\n", keystr
));
405 ret
= tdb_chainlock(cache_notrans
->tdb
, key
);
410 gencache_parse(keystr
, gencache_del_parser
, &exists
);
414 * We delete an element by setting its timeout to
415 * 0. This way we don't have to do a transaction on
416 * gencache.tdb every time we delete an element.
418 result
= gencache_set(keystr
, "", 0);
421 tdb_chainunlock(cache_notrans
->tdb
, key
);
426 static bool gencache_pull_timeout(uint8_t *val
, time_t *pres
, char **payload
)
435 res
= strtol((char *)val
, &endptr
, 10);
437 if ((endptr
== NULL
) || (*endptr
!= '/')) {
438 DEBUG(2, ("Invalid gencache data format: %s\n", (char *)val
));
444 if (payload
!= NULL
) {
450 struct gencache_parse_state
{
451 void (*parser
)(time_t timeout
, DATA_BLOB blob
, void *private_data
);
453 bool copy_to_notrans
;
456 static int gencache_parse_fn(TDB_DATA key
, TDB_DATA data
, void *private_data
)
458 struct gencache_parse_state
*state
;
464 if (data
.dptr
== NULL
) {
467 ret
= gencache_pull_timeout(data
.dptr
, &t
, &payload
);
471 state
= (struct gencache_parse_state
*)private_data
;
472 blob
= data_blob_const(
473 payload
, data
.dsize
- PTR_DIFF(payload
, data
.dptr
));
474 state
->parser(t
, blob
, state
->private_data
);
476 if (state
->copy_to_notrans
) {
477 tdb_store(cache_notrans
->tdb
, key
, data
, 0);
483 bool gencache_parse(const char *keystr
,
484 void (*parser
)(time_t timeout
, DATA_BLOB blob
,
488 struct gencache_parse_state state
;
489 TDB_DATA key
= string_term_tdb_data(keystr
);
492 if (keystr
== NULL
) {
495 if (tdb_data_cmp(key
, last_stabilize_key()) == 0) {
498 if (!gencache_init()) {
502 state
.parser
= parser
;
503 state
.private_data
= private_data
;
504 state
.copy_to_notrans
= false;
506 ret
= tdb_chainlock(cache_notrans
->tdb
, key
);
511 ret
= tdb_parse_record(cache_notrans
->tdb
, key
,
512 gencache_parse_fn
, &state
);
514 tdb_chainunlock(cache_notrans
->tdb
, key
);
518 state
.copy_to_notrans
= true;
520 ret
= tdb_parse_record(cache
->tdb
, key
, gencache_parse_fn
, &state
);
522 if ((ret
== -1) && (tdb_error(cache
->tdb
) == TDB_ERR_NOEXIST
)) {
524 * The record does not exist. Set a delete-marker in
525 * gencache_notrans, so that we don't have to look at
526 * the fcntl-based cache again.
528 gencache_set(keystr
, "", 0);
531 tdb_chainunlock(cache_notrans
->tdb
, key
);
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(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(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 successfully 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(data
.dptr
, &timeout
, &payload
)) {
899 if (fnmatch(state
->pattern
, keystr
, 0) != 0) {
903 DEBUG(10, ("Calling function with arguments "
904 "(key=[%s], timeout=[%s])\n",
905 keystr
, timestring(talloc_tos(), timeout
)));
908 data_blob_const(payload
,
909 data
.dsize
- PTR_DIFF(payload
, data
.dptr
)),
910 timeout
, state
->private_data
);
913 TALLOC_FREE(free_key
);
917 void gencache_iterate_blobs(void (*fn
)(const char *key
, DATA_BLOB value
,
918 time_t timeout
, void *private_data
),
919 void *private_data
, const char *pattern
)
921 struct gencache_iterate_blobs_state state
;
923 if ((fn
== NULL
) || (pattern
== NULL
) || !gencache_init()) {
927 DEBUG(5, ("Searching cache keys with pattern %s\n", pattern
));
930 state
.pattern
= pattern
;
931 state
.private_data
= private_data
;
933 state
.in_persistent
= false;
934 tdb_traverse(cache_notrans
->tdb
, gencache_iterate_blobs_fn
, &state
);
936 state
.in_persistent
= true;
937 tdb_traverse(cache
->tdb
, gencache_iterate_blobs_fn
, &state
);
941 * Iterate through all entries which key matches to specified pattern
943 * @param fn pointer to the function that will be supplied with each single
944 * matching cache entry (key, value and timeout) as an arguments
945 * @param data void pointer to an arbitrary data that is passed directly to the fn
946 * function on each call
947 * @param keystr_pattern pattern the existing entries' keys are matched to
951 struct gencache_iterate_state
{
952 void (*fn
)(const char *key
, const char *value
, time_t timeout
,
957 static void gencache_iterate_fn(const char *key
, DATA_BLOB value
,
958 time_t timeout
, void *private_data
)
960 struct gencache_iterate_state
*state
=
961 (struct gencache_iterate_state
*)private_data
;
963 char *free_val
= NULL
;
965 if (value
.data
[value
.length
-1] == '\0') {
966 valstr
= (char *)value
.data
;
968 /* ensure 0-termination */
969 valstr
= talloc_strndup(talloc_tos(), (char *)value
.data
, value
.length
);
971 if (valstr
== NULL
) {
976 DEBUG(10, ("Calling function with arguments "
977 "(key=[%s], value=[%s], timeout=[%s])\n",
978 key
, valstr
, timestring(talloc_tos(), timeout
)));
980 state
->fn(key
, valstr
, timeout
, state
->private_data
);
984 TALLOC_FREE(free_val
);
987 void gencache_iterate(void (*fn
)(const char *key
, const char *value
,
988 time_t timeout
, void *dptr
),
989 void *private_data
, const char *pattern
)
991 struct gencache_iterate_state state
;
997 state
.private_data
= private_data
;
998 gencache_iterate_blobs(gencache_iterate_fn
, &state
, pattern
);