[ENet-discuss] Questions -- select, peer numbers, connects

[ingmar wirths]

2011/7/18 Casey Marshall <casey.s.marshall at gmail.com>:
> Hi!
>
> I'm writing a new software project, and am using enet for part of the transport protocol, and had a few questions.
>
> The biggest question I have is how to use enet in a select-based (or, more likely, epoll-based) loop: waiting for events via an interface like epoll, and on activity, drive the enet connections.
>
> Now, it makes sense that I can run a selection on a ENetHost's socket for readability, and invoke enet_host_service then. What I'm missing, though, is when to call enet_host_service for writable events: I assume, from looking a bit at the code, that enet_host_service needs to be called regularly to dispatch both incoming and outgoing messages, but I don't think you want to call enet_host_service on *every* writable event, if there is nothing going out, because that would lead to a busy-loop, which I want to avoid (the idea here is that I would call enet_host_service with a very small timeout, probably zero). Is there a way to tell from an ENetHost or a bunch of ENetPeers whether or not there is pending outgoing messages?

ENet was developed for a fast multiplayer gaming environment (but not
limited to that).
Such games consist of a gameloop, which is executed fairly often (the
framerate for example
is limited to the execution frequency of the gameloop, althought the
gameloop may be executed even
more often). In such an evironment, it makes sense, to call
enet_host_service in the gameloop
with a timeout of 0.

To my understanding, that is the purpose of enet. With that in mind,
you can decide,
if and how it makes sense to use enet in your project.

Bottomline is, you can call enet_host_service very often, even if
there's nothing to do,
without a significant penalty.

> The short answer to why I want to do this is because I want to write an addon for Node that wraps enet, and Node has its fairly specific way of doing things. I suppose this can also be accomplished by doing the enet service calls in a separate thread, but I was hoping to avoid that.
>
> A related question is how many simultaneous peers can enet support? 100? 1,000? 10,000?

Interesting question. Lee?

> And lastly, any idea what the behavior should be for a "simultaneous connect"? That is, two peers attempt to connect to one another at the same time, on the same ports? Would the ENetPeer objects returned by enet_host_connect both be valid?

You cannot connect a peer to another peer, but a peer to a host. Thus,
if you have two machines
with two hosts and peers, you can connect the peers to the other host
and have two valid connections,
i suppose. But that's probably not what you want. You need to think of
a mechanism to manage
your connections.

> Thanks!
> _______________________________________________
> ENet-discuss mailing list
> ENet-discuss at cubik.org
> http://lists.cubik.org/mailman/listinfo/enet-discuss
>