This has been implemented by simply restarting http servers in case of
http_handlers directive in configuration xml had been changed.
But, for this I have to change the handlers interface to accept
configuration separatelly, since the configuration that contains in the
server is the configuration with which server had been started.
Signed-off-by: Azat Khuzhin <a.khuzhin@semrush.com>
Co-authored-by: Antonio Andelic
This allows starting and stopping separately each protocol server
without restarting ClickHouse.
This also allows adding or removing `listen_host` entries, which
start and stops servers for all enabled ports.
When stopping a server, the listening socket is immediately closed
(and available for another server).
Protocols with persistent connections try to wait for any currently
running query to finish before closing the connection, but idle
connection are closed quickly (depending on how often the protocol
is polled).
An extra ProfileEvent is added, `MainConfigLoads`, it is
incremented every time the configuration is reloaded. This helps
when trying to assess whether the new configuration was applied.
