Jonathan Clarke wrote:
Hi,
I've set up an ldap backend, with a pcache overlay to cache binds for PAM. The config is below, for info.
My question concerns the pcachePersist parameter. From the man page:
pcachePersist { TRUE | FALSE } Specify whether the cached queries should be saved across restarts of the caching proxy, to provide hot startup of the cache. Only non-expired queries are reloaded. The default is FALSE.
As I understand this, given "pcachePersist FALSE" (or not specified), cached queries should no longer be in the cache after restarting slapd. Am I right?
However, once a bind is successfully cached, I take the proxied server offline and I can restart slapd many times, however my bind is still served from cache.
Is this a bug in the docs, a bug in the implementation or just me not getting something?
The proxycache writes all cached data into the cache DB. As such, cached results are always present after a restart; this has always been the case. That can be considered a bug, because it did not save any information about the queries to which each cached entry belonged. So on a restart, the cache DB contains stuff but the overlay doesn't know about it.
With pcachePersist set TRUE, the query info is also stored in the DB, and re-loaded on restart. Thus the overlay will know the complete contents of the cache DB.
Thanks, Jonathan
PS: the simplified config: 8<-------------- database ldap suffix "dc=proxy" rootdn "cn=manager,dc=proxy" uri ldap://my.other.ldap.server/ timeout 5
overlay pcache pcache hdb 10000 1 2 60 pcacheAttrset 0 * # cache binds for 900 seconds = 15 minutes pcacheTemplate (uid=) 0 900 pcacheBind (uid=) 0 900 sub "dc=proxy" pcachePersist FALSE pcacheOffline FALSE directory /var/cache/ldap cachesize 10000 index objectClass,sAMAccountName,pcacheQueryid eq 8<--------------