This PR implements the first one of the "lespay" UDP queries which
is already useful in itself: the capacity query. The server pool is making
use of this query by doing a cheap UDP query to determine whether it is
worth starting the more expensive TCP connection process.
The leaks were mostly in unit tests, and could all be resolved by
adding suitably-sized channel buffers or by restructuring the test
to not send on a channel after an error has occurred.
There is an unavoidable goroutine leak in Console.Interactive: when
we receive a signal, the line reader cannot be unblocked and will get
stuck. This leak is now documented and I've tried to make it slightly
less bad by adding a one-element buffer to the output channels of
the line-reading loop. Should the reader eventually awake from its
blocked state (i.e. when stdin is closed), at least it won't get stuck
trying to send to the interpreter loop which has quit long ago.
Co-authored-by: Felix Lange <fjl@twurst.com>
* core: reinit chain from freezer in batches
* core/rawdb: concurrent database reinit from freezer dump
* core/rawdb: reinit from freezer in sequential order
This PR implements les.freeClientPool. It also adds a simulated clock
in common/mclock, which enables time-sensitive tests to run quickly
and still produce accurate results, and package common/prque which is
a generalised variant of prque that enables removing elements other
than the top one from the queue.
les.freeClientPool implements a client database that limits the
connection time of each client and manages accepting/rejecting
incoming connections and even kicking out some connected clients. The
pool calculates recent usage time for each known client (a value that
increases linearly when the client is connected and decreases
exponentially when not connected). Clients with lower recent usage are
preferred, unknown nodes have the highest priority. Already connected
nodes receive a small bias in their favor in order to avoid accepting
and instantly kicking out clients.
Note: the pool can use any string for client identification. Using
signature keys for that purpose would not make sense when being known
has a negative value for the client. Currently the LES protocol
manager uses IP addresses (without port address) to identify clients.
