This partially reverts commit d617801c31.
The common lockfree doesn't work well for high-volume structures like
eattr cache because it expects the structure to be cleaned up by a
sweeper routine ... which is very ineffective for >1M records.
OTOH, we need the deferred ea_free in all cases ... so keeping that.
The spinlocked hash has a main rw spinlock for the data blocks
and then a rw spinlock for each hash chain. Rehashing is asynchronous,
running from an event, and it happens chain-wise, never blocking more
than one chain at a time.
There is an IP table for every ROA table, holding special records
combining all known ROAs for every top-prefix.
The ROA digestor is now an IP digestor, running over the auxiliary
table.
The sending channel may be already gone when rte_free_deferred()
is finally called so we have to log about route freeing in the
synchronous call instead.
Channel is now just subscribing to yet another journal announcing
digested tries from the ROA table.
Creating tries in every channel on-the-fly was too slow to handle
and it ate obnoxious amounts of memory. Instead, the tries are
constructed directly in the table and the channels are notified
with the completed tries.
The delayed export-release mechanism is used to keep the tries allocated
until routes get reloaded.
Originally, this mechanism required to check whether there's enough time to work
and then to send an event. This macro combines all the logic and goes more straightforwardly
to the _end_ of the export processing loop.
One should note that there were two cases where the export processing loop
was deferred at the _beginning_, which led to ignoring some routes on
reimports. This wasn't easily noticeable in the tests until the one-task
limit got a ceiling on 300 ms to keep reasonable latency.
In future, this and rtable's data structures should be probably merged
but it isn't a good idea to do now. The used data structure is similar
to rtable -- an array of pointers to linked lists.
Feed is lockless, as with all tables.
Full export (receiving updates) is not supported yet but we don't have
any method how to use it anyway. Gonna implement it later.
