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dns
cache.h
/* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, you can obtain one at https://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ #ifndef DNS_CACHE_H #define DNS_CACHE_H 1 /***** ***** Module Info *****/ /*! \file dns/cache.h * \brief * Defines dns_cache_t, the cache object. * * Notes: *\li 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: *\li See notes at the individual functions. * * Reliability: * * Resources: * * Security: * * Standards: */ /*** *** Imports ***/ #include <stdbool.h> #include <isc/json.h> #include <isc/lang.h> #include <isc/stats.h> #include <isc/stdtime.h> #include <dns/types.h> ISC_LANG_BEGINDECLS /*** *** Functions ***/ isc_result_t dns_cache_create(isc_mem_t *cmctx, 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); isc_result_t dns_cache_create2(isc_mem_t *cmctx, isc_taskmgr_t *taskmgr, isc_timermgr_t *timermgr, dns_rdataclass_t rdclass, const char *cachename, const char *db_type, unsigned int db_argc, char **db_argv, dns_cache_t **cachep); isc_result_t dns_cache_create3(isc_mem_t *cmctx, isc_mem_t *hmctx, isc_taskmgr_t *taskmgr, isc_timermgr_t *timermgr, dns_rdataclass_t rdclass, const char *cachename, const char *db_type, unsigned int db_argc, char **db_argv, dns_cache_t **cachep); /*%< * Create a new DNS cache. * * dns_cache_create2() will create a named cache. * * dns_cache_create3() will create a named cache using two separate memory * contexts, one for cache data which can be cleaned and a separate one for * memory allocated for the heap (which can grow without an upper limit and * has no mechanism for shrinking). * * dns_cache_create() is a backward compatible version that internally * specifies an empty cache name and a single memory context. * * Requires: * *\li 'cmctx' (and 'hmctx' if applicable) is a valid memory context. * *\li '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. * *\li 'cachename' is a valid string. This must not be NULL. * *\li 'cachep' is a valid pointer, and *cachep == NULL * * Ensures: * *\li '*cachep' is attached to the newly created cache * * Returns: * *\li #ISC_R_SUCCESS *\li #ISC_R_NOMEMORY */ void dns_cache_attach(dns_cache_t *cache, dns_cache_t **targetp); /*%< * Attach *targetp to cache. * * Requires: * *\li 'cache' is a valid cache. * *\li 'targetp' points to a NULL dns_cache_t *. * * Ensures: * *\li *targetp is attached to cache. */ void dns_cache_detach(dns_cache_t **cachep); /*%< * Detach *cachep from its cache. * * Requires: * *\li 'cachep' points to a valid cache. * * Ensures: * *\li *cachep is NULL. * *\li 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: * *\li 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: * *\li 'cache' is a valid cache. * *\li 'dbp' points to a NULL dns_db *. * * Ensures: * *\li *dbp is attached to the database. */ isc_result_t dns_cache_setfilename(dns_cache_t *cache, const 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: *\li #ISC_R_SUCCESS *\li #ISC_R_NOMEMORY *\li 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: *\li 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: * *\li #ISC_R_SUCCESS * \li 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: *\li 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: * *\li #ISC_R_SUCCESS * \li 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. */ unsigned int dns_cache_getcleaninginterval(dns_cache_t *cache); /*%< * Get the periodic cache cleaning interval to 'interval' seconds. */ const char * dns_cache_getname(dns_cache_t *cache); /*%< * Get the cache name. */ void dns_cache_setcachesize(dns_cache_t *cache, size_t size); /*%< * Set the maximum cache size. 0 means unlimited. */ size_t dns_cache_getcachesize(dns_cache_t *cache); /*%< * Get the maximum cache size. */ void dns_cache_setservestalettl(dns_cache_t *cache, dns_ttl_t ttl); /*%< * Sets the maximum length of time that cached answers may be retained * past their normal TTL. Default value for the library is 0, disabling * the use of stale data. * * Requires: *\li 'cache' to be valid. */ dns_ttl_t dns_cache_getservestalettl(dns_cache_t *cache); /*%< * Gets the maximum length of time that cached answers may be kept past * normal expiry. * * Requires: *\li 'cache' to be valid. */ isc_result_t dns_cache_flush(dns_cache_t *cache); /*%< * Flushes all data from the cache. * * Returns: *\li #ISC_R_SUCCESS *\li #ISC_R_NOMEMORY */ isc_result_t dns_cache_flushnode(dns_cache_t *cache, dns_name_t *name, bool tree); /* * Flush a given name from the cache. If 'tree' is true, then * also flush all names under 'name'. * * Requires: *\li 'cache' to be valid. *\li 'name' to be valid. * * Returns: *\li #ISC_R_SUCCESS *\li #ISC_R_NOMEMORY *\li other error returns. */ isc_result_t dns_cache_flushname(dns_cache_t *cache, dns_name_t *name); /* * Flush a given name from the cache. Equivalent to * dns_cache_flushpartial(cache, name, false). * * Requires: *\li 'cache' to be valid. *\li 'name' to be valid. * * Returns: *\li #ISC_R_SUCCESS *\li #ISC_R_NOMEMORY *\li other error returns. */ isc_stats_t * dns_cache_getstats(dns_cache_t *cache); /* * Return a pointer to the stats collection object for 'cache' */ void dns_cache_dumpstats(dns_cache_t *cache, FILE *fp); /* * Dump cache statistics and status in text to 'fp' */ void dns_cache_updatestats(dns_cache_t *cache, isc_result_t result); /* * Update cache statistics based on result code in 'result' */ #ifdef HAVE_LIBXML2 int dns_cache_renderxml(dns_cache_t *cache, xmlTextWriterPtr writer); /* * Render cache statistics and status in XML for 'writer'. */ #endif /* HAVE_LIBXML2 */ #ifdef HAVE_JSON isc_result_t dns_cache_renderjson(dns_cache_t *cache, json_object *cstats); /* * Render cache statistics and status in JSON */ #endif /* HAVE_JSON */ ISC_LANG_ENDDECLS #endif /* DNS_CACHE_H */
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