Re: [tarantool-patches] [PATCH v3 1/6] [RAW] swim: introduce SWIM's anti-entropy component

[Konstantin Osipov <kostja@tarantool.org>]

* Vladislav Shpilevoy <v.shpilevoy@tarantool.org> [18/12/29 15:07]:
> +	swim_member_bin_create(&member_bin);

> +	for (; i < (int) mh_size(swim->members); ++i) {
> +		char *pos = swim_packet_alloc(packet, sizeof(member_bin));
> +		if (pos == NULL)
> +			break;
> +		struct swim_member *member = swim->shuffled_members[i];
> +		swim_member_bin_reset(&member_bin, member);

Why do you need to create() the member if you then reset it?
Perhaps encode() or fill() is a more suitable verb than reset? 

> +		memcpy(pos, &member_bin, sizeof(member_bin));
> +	swim_anti_entropy_header_bin_create(&ae_header_bin, i);
> +	memcpy(header, &ae_header_bin, sizeof(ae_header_bin));
> +	swim_packet_flush(packet);

Why flush() and not simply send()?

> +swim_encode_round_msg(struct swim *swim, struct swim_msg *msg)

Why not simply swim_encode_round()?

> +/** Once per specified timeout trigger a next broadcast step. */
> +static void
> +swim_round_step_begin(struct ev_loop *loop, struct ev_periodic *p, int events)

Once again I have a difficulty understanding the name. Is it swim
step begin or swim round begin? What is swim round step? Sounds
like each round has many steps and each step has a beginning and an end? 

Then I'm missing swim_round_step_end(), swim_round_step_first(),
or something like that.

Looking at the code, swim_round_step_begin() is simply
swim_round().


> +static void
> +swim_process_member_update(struct swim *swim, struct swim_member_def *def)
> +{
> +	struct swim_member *member = swim_find_member(swim, &def->addr);
> +	/*
> +	 * Trivial processing of a new member - just add it to the
> +	 * members table.
> +	 */
> +	if (member == NULL) {
> +		member = swim_member_new(swim, &def->addr, def->status);
> +		if (member == NULL)
> +			diag_log();
> +	}
> +}

Why nothing is done for an existing member?  This needs a comment, no?

> +
> +struct swim_transport swim_udp_transport = {
> +	/* .send_round_msg = */ swim_udp_send_msg,
> +	/* .recv_msg = */ swim_udp_recv_msg,
> +};

Initializing/destroying an endpoint (like calling bind()) should also be 
part of transport api.

> +int
> +swim_scheduler_bind(struct swim_scheduler *scheduler, struct sockaddr_in *addr)

And not part of the scheduler api.

> +	    evio_setsockopt_server(fd, AF_INET, SOCK_DGRAM) != 0) {

The file descriptor itself should also be part of the transport.

> +static void
> +swim_scheduler_on_input(struct ev_loop *loop, struct ev_io *io, int events)
> +{
> +	assert((events & EV_READ) != 0);
> +	(void) events;
> +	(void) loop;
> +	struct swim_scheduler *scheduler = (struct swim_scheduler *) io->data;
> +	struct sockaddr_in addr;
> +	socklen_t len = sizeof(addr);
> +	struct swim_packet packet;
> +	struct swim_msg msg;
> +	swim_msg_create(&msg);
> +	swim_packet_create(&packet, &msg);
> +	swim_transport_recv_f recv = scheduler->transport->recv_msg;
> +	ssize_t size = recv(io->fd, packet.body, packet.end - packet.body,
> +			    (struct sockaddr *) &addr, &len);

I don't understand why you do it here, if it's part of the
transport api.


-- 
Konstantin Osipov, Moscow, Russia, +7 903 626 22 32
http://tarantool.io - www.twitter.com/kostja_osipov