Just no-op if trying to close a connection that's already being closed.

Since c_mutex is now always inited at startup time, we no longer
need connections_mutex to protect from uninit'd structures

Howard Chu authored Sep 16, 2020 and Quanah Gibson-Mount committed Sep 24, 2020

Avoid using sys_errlist unless there's no other choice

Howard Chu authored Sep 13, 2020 and Quanah Gibson-Mount committed Sep 13, 2020

Don't resume pending ops unless there are no other threads
waiting to write

Reallocates sockets from old to new listener threads

Add LDAP_OPT_X_SASL_CBINDING option to define the binding type to use,
defaults to "none".

Add "tls-endpoint" binding type implementing "tls-server-end-point" from
RCF 5929, which is compatible with Windows.

Fix "tls-unique" to include the prefix in the bindings as per RFC 5056.

And additional debug code for tracking errant close()s

Fix op_finish, must resched connection to pick up pending ops.
Fix op completion counter.

Tell frontend the op will finish asynchronously, leave it alone

Show time spent in conn+threadpool queues before an op actually executes.
Also clean up timestamp handling

Only in back-mdb; back-bdb needs work but it's deprecated;
not worth the effort. In particular txn, retry after deadlocks
makes the whole thing too messy.

Writer threads do their own wait using select/poll instead of
asking the listener thread. Eliminates one mutex+one condvar
per conn plus multiple wakeups of the listener thread. Also
fixes writetimeout to wait an exact time, instead of the
approximation used in the listener thread.

Note: I could not test the MozNSS patch due to the absence of
NSS PEM support on my machine. Given the review comments in
https://bugzilla.mozilla.org/show_bug.cgi?id=402712 I doubt that
trustworthy PEM support will be appearing for MozNSS any time soon.

Currently only implemented for OpenSSL.
Needs an option to set the criticality flag.

connection_<first/next>() takes a ber_socket_t *index, not int*.

Code comments belong in the code, not in commit messages.