X-Git-Url: http://git.ozlabs.org/?a=blobdiff_plain;f=ccan%2Ftdb2%2Ftdb2.h;h=fa5787c3779acd424e7f3cbde6a4c5e6746eb45d;hb=66711021849dd07cd29383c9ed40ab4b9f3d1e07;hp=47661da245352583f5491b440fec2e58b1ff0e68;hpb=9d9a9897b608af3a6acd623cc09557f9985b03e6;p=ccan diff --git a/ccan/tdb2/tdb2.h b/ccan/tdb2/tdb2.h index 47661da2..fa5787c3 100644 --- a/ccan/tdb2/tdb2.h +++ b/ccan/tdb2/tdb2.h @@ -38,9 +38,14 @@ extern "C" { #include /* For uint64_t */ #include +/* For bool */ +#include +/* For memcmp */ +#include #endif #include #include +#include union tdb_attribute; struct tdb_context; @@ -74,6 +79,7 @@ struct tdb_context *tdb_open(const char *name, int tdb_flags, #define TDB_NOMMAP 8 /* don't use mmap */ #define TDB_CONVERT 16 /* convert endian */ #define TDB_NOSYNC 64 /* don't use synchronous transactions */ +#define TDB_SEQNUM 128 /* maintain a sequence number */ /** * tdb_close - close and free a tdb. @@ -197,6 +203,43 @@ enum TDB_ERROR tdb_append(struct tdb_context *tdb, */ enum TDB_ERROR tdb_delete(struct tdb_context *tdb, struct tdb_data key); +/** + * tdb_exists - does a key exist in the database? + * @tdb: the tdb context returned from tdb_open() + * @key: the key to search for. + * + * Returns true if it exists, or false if it doesn't or any other error. + */ +bool tdb_exists(struct tdb_context *tdb, TDB_DATA key); + +/** + * tdb_deq - are struct tdb_data equal? + * @a: one struct tdb_data + * @b: another struct tdb_data + */ +static inline bool tdb_deq(struct tdb_data a, struct tdb_data b) +{ + return a.dsize == b.dsize && memcmp(a.dptr, b.dptr, a.dsize) == 0; +} + +/** + * tdb_mkdata - make a struct tdb_data from const data + * @p: the constant pointer + * @len: the length + * + * As the dptr member of struct tdb_data is not constant, you need to + * cast it. This function keeps thost casts in one place, as well as + * suppressing the warning some compilers give when casting away a + * qualifier (eg. gcc with -Wcast-qual) + */ +static inline struct tdb_data tdb_mkdata(const void *p, size_t len) +{ + struct tdb_data d; + d.dptr = cast_const(void *, p); + d.dsize = len; + return d; +} + /** * tdb_transaction_start - start a transaction * @tdb: the tdb context returned from tdb_open() @@ -276,6 +319,49 @@ int64_t tdb_traverse_(struct tdb_context *tdb, int (*fn)(struct tdb_context *, TDB_DATA, TDB_DATA, void *), void *p); +/** + * tdb_parse_record - operate directly on data in the database. + * @tdb: the tdb context returned from tdb_open() + * @key: the key whose record we should hand to @parse + * @parse: the function to call for the data + * @p: the private pointer to hand to @parse (types must match). + * + * This avoids a copy for many cases, by handing you a pointer into + * the memory-mapped database. It also locks the record to prevent + * other accesses at the same time. + * + * Do not alter the data handed to parse()! + */ +#define tdb_parse_record(tdb, key, parse, p) \ + tdb_parse_record_((tdb), (key), \ + typesafe_cb_preargs(enum TDB_ERROR, (parse), (p), \ + TDB_DATA, TDB_DATA), (p)) + +enum TDB_ERROR tdb_parse_record_(struct tdb_context *tdb, + TDB_DATA key, + enum TDB_ERROR (*parse)(TDB_DATA key, + TDB_DATA data, + void *p), + void *p); + +/** + * tdb_get_seqnum - get a database sequence number + * @tdb: the tdb context returned from tdb_open() + * + * This returns a sequence number: any change to the database from a + * tdb context opened with the TDB_SEQNUM flag will cause that number + * to increment. Note that the incrementing is unreliable (it is done + * without locking), so this is only useful as an optimization. + * + * For example, you may have a regular database backup routine which + * does not operate if the sequence number is unchanged. In the + * unlikely event of a failed increment, it will be backed up next + * time any way. + * + * Returns an enum TDB_ERROR (ie. negative) on error. + */ +int64_t tdb_get_seqnum(struct tdb_context *tdb); + /** * tdb_firstkey - get the "first" key in a TDB * @tdb: the tdb context returned from tdb_open() @@ -328,6 +414,15 @@ enum TDB_ERROR tdb_chainlock(struct tdb_context *tdb, TDB_DATA key); */ enum TDB_ERROR tdb_chainunlock(struct tdb_context *tdb, TDB_DATA key); +/** + * tdb_wipe_all - wipe the database clean + * @tdb: the tdb context returned from tdb_open() + * + * Completely erase the database. This is faster than iterating through + * each key and doing tdb_delete. + */ +enum TDB_ERROR tdb_wipe_all(struct tdb_context *tdb); + /** * tdb_check - check a TDB for consistency * @tdb: the tdb context returned from tdb_open() @@ -354,6 +449,17 @@ enum TDB_ERROR tdb_check_(struct tdb_context *tdb, void *private), void *private); +/** + * tdb_error - get the last error (not threadsafe) + * @tdb: the tdb context returned from tdb_open() + * + * Returns the last error returned by a TDB function. + * + * This makes porting from TDB1 easier, but note that the last error is not + * reliable in threaded programs. + */ +enum TDB_ERROR tdb_error(struct tdb_context *tdb); + /** * enum tdb_summary_flags - flags for tdb_summary. */ @@ -410,6 +516,26 @@ void tdb_add_flag(struct tdb_context *tdb, unsigned flag); */ void tdb_remove_flag(struct tdb_context *tdb, unsigned flag); +/** + * tdb_name - get the name of a tdb + * @tdb: the tdb context returned from tdb_open() + * + * This returns a copy of the name string, made at tdb_open() time. If that + * argument was NULL (possible for a TDB_INTERNAL db) this will return NULL. + * + * This is mostly useful for logging. + */ +const char *tdb_name(const struct tdb_context *tdb); + +/** + * tdb_fd - get the file descriptor of a tdb + * @tdb: the tdb context returned from tdb_open() + * + * This returns the file descriptor for the underlying database file, or -1 + * for TDB_INTERNAL. + */ +int tdb_fd(const struct tdb_context *tdb); + /** * enum tdb_attribute_type - descriminator for union tdb_attribute. */ @@ -544,11 +670,6 @@ union tdb_attribute { struct tdb_attribute_stats stats; }; -/** - * tdb_null - a convenient value for errors. - */ -extern struct tdb_data tdb_null; - #ifdef __cplusplus } #endif