Shutdown Procedure

Range Server register handlers for SIGTERM and SIGHUP using ctrlc crate. Once shutdown signal is caught, it broadcasts the shutdown attempt to all Workers.

On receiving shutdown signal, Worker will stop accepting new TCP connections and send GOAWAY frame to each existing connections. Range Server assumes that front-end clients will complete their sessions at their earliest convenient time and close connections thereafter.

Once all connections are closed, range-server would drop IO-task channel, triggering shutdown procedure of IO module. Once all IO tasks are served, notify indexer to flush memtable.