Ralf Haferkamp wrote:
Am Freitag 01 Mai 2009 11:50:15 schrieb masarati@aero.polimi.it:
Hi,
since quite some time libldap enables tcp-keepalive, e.g. to detected dangling syncrepl connections. However the default timeout of two hours that most systems are using might be a bit too long for some applications (e.g. I had a problem lately were nscd didn't answer queries anymore because nss_ldap was blocking in SSL_read() while the underlying connection has been cut off). On the other hand messing with the system wide settings might no be a good idea either. On Linux it is possible to configure the keepalive settings on a per socket basis through the TCP_KEEP* socket options.
Would it be worth adding ldap_set_option() support for those, even if they are not really portable?
I think it would; for archs that do not support it, it could do nothing (and log accordingly, just in case).
Ok, I'll introduce the following new options for keepalive support then: LDAP_OPT_X_KEEPALIVE_IDLE 0x6300 LDAP_OPT_X_KEEPALIVE_PROBES 0x6301 LDAP_OPT_X_KEEPALIVE_INTERVAL 0x6302
We might also think about adding support to set those values for syncrepl and back-ldap/back-meta.
I'd prefer a portable solution vs something so extremely platform-dependent. As already discussed many times before, we just need a client to send a periodic LDAP no-op message to get the same effect. (Abandon 0 will work fine.) While it's not as general purpose as setting a keepalive in the socket layer, I think we only need to worry about the syncrepl client. back-ldap/meta already have their own retry mechanisms, they can take care of themselves.
So - I'd rather see an option for a periodic LDAP ping added to the syncrepl client - that will work uniformly across all platforms.
And in general - I am opposed to any code that causes our feature set / behavior to differ from platform to platform.