cache.h revision 40f53fa8d9c6a4fc38c0014495e7a42b08f52481
/*
* Copyright (C) 1999, 2000 Internet Software Consortium.
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
* DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
* INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
* FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
* WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
/* $Id: cache.h,v 1.13 2000/08/01 01:23:43 tale Exp $ */
#ifndef DNS_CACHE_H
#define DNS_CACHE_H 1
/*****
***** Module Info
*****/
/*
* cache
*
* Defines dns_cache_t, the cache object.
*
* Notes:
* A cache object contains DNS data of a single class.
* Multiple classes will be handled by creating multiple
* views, each with a different class and its own cache.
*
* MP:
* See notes at the individual functions.
*
* Reliability:
*
* Resources:
*
* Security:
*
* Standards:
*/
/***
*** Imports
***/
#include <isc/lang.h>
#include <isc/stdtime.h>
#include <dns/types.h>
ISC_LANG_BEGINDECLS
/***
*** Functions
***/
isc_result_t
dns_cache_create(isc_mem_t *mctx, isc_taskmgr_t *taskmgr,
isc_timermgr_t *timermgr, dns_rdataclass_t rdclass,
const char *db_type, unsigned int db_argc, char **db_argv,
dns_cache_t **cachep);
/*
* Create a new DNS cache.
*
* Requires:
*
* 'mctx' is a valid memory context
*
* 'taskmgr' is a valid task manager and 'timermgr' is a valid timer
* manager, or both are NULL. If NULL, no periodic cleaning of the
* cache will take place.
*
* 'cachep' is a valid pointer, and *cachep == NULL
*
* Ensures:
*
* '*cachep' is attached to the newly created cache
*
* Returns:
*
* ISC_R_SUCCESS
* ISC_R_NOMEMORY
*/
void
dns_cache_attach(dns_cache_t *cache, dns_cache_t **targetp);
/*
* Attach *targetp to cache.
*
* Requires:
*
* 'cache' is a valid cache.
*
* 'targetp' points to a NULL dns_cache_t *.
*
* Ensures:
*
* *targetp is attached to cache.
*/
void
dns_cache_detach(dns_cache_t **cachep);
/*
* Detach *cachep from its cache.
*
* Requires:
*
* 'cachep' points to a valid cache.
*
* Ensures:
*
* *cachep is NULL.
*
* If '*cachep' is the last reference to the cache,
*
* All resources used by the cache will be freed
*/
void
dns_cache_attachdb(dns_cache_t *cache, dns_db_t **dbp);
/*
* Attach *dbp to the cache's database.
*
* Notes:
*
* This may be used to get a reference to the database for
* the purpose of cache lookups (XXX currently it is also
* the way to add data to the cache, but having a
* separate dns_cache_add() interface instead would allow
* more control over memory usage).
* The caller should call dns_db_detach() on the reference
* when it is no longer needed.
*
* Requires:
*
* 'cache' is a valid cache.
*
* 'dbp' points to a NULL dns_db *.
*
* Ensures:
*
* *dbp is attached to the database.
*/
isc_result_t
dns_cache_setfilename(dns_cache_t *cahce, char *filename);
/*
* If 'filename' is non-NULL, make the cache persistent.
* The cache's data will be stored in the given file.
* If 'filename' is NULL, make the cache non-persistent.
* Files that are no longer used are not unlinked automatically.
*
* Returns:
* ISC_R_SUCCESS
* ISC_R_NOMEMORY
* Various file-related failures
*/
isc_result_t
dns_cache_load(dns_cache_t *cache);
/*
* If the cache has a file name, load the cache contents from the file.
* Previous cache contents are not discarded.
* If no file name has been set, do nothing and return success.
*
* MT:
* Multiple simultaneous attempts to load or dump the cache
* will be serialized with respect to one another, but
* the cache may be read and updated while the dump is
* in progress. Updates performed during loading
* may or may not be preserved, and reads may return
* either the old or the newly loaded data.
*
* Returns:
*
* ISC_R_SUCCESS
* Various failures depending on the database implementation type
*/
isc_result_t
dns_cache_dump(dns_cache_t *cache);
/*
* If the cache has a file name, write the cache contents to disk,
* overwriting any preexisting file. If no file name has been set,
* do nothing and return success.
*
* MT:
* Multiple simultaneous attempts to load or dump the cache
* will be serialized with respect to one another, but
* the cache may be read and updated while the dump is
* in progress. Updates performed during the dump may
* or may not be reflected in the dumped file.
*
* Returns:
*
* ISC_R_SUCCESS
* Various failures depending on the database implementation type
*/
isc_result_t
dns_cache_clean(dns_cache_t *cache, isc_stdtime_t now);
/*
* Force immediate cleaning of the cache, freeing all rdatasets
* whose TTL has expired as of 'now' and that have no pending
* references.
*/
void
dns_cache_setcleaninginterval(dns_cache_t *cache, unsigned int interval);
/*
* Set the periodic cache cleaning interval to 'interval' seconds.
*/
ISC_LANG_ENDDECLS
#endif /* DNS_CACHE_H */