[ENet-discuss] how to know when it's safe to call enet_peer_send()?

[eye at dihalt.com]

Hello.

I'm new to enet and in the process of testing it right now.
I'm interested is it possible to send huge amounts of data
(audio, video etc) using enet. For now i have a few
questions and will be happy is someone experienced with
ENET will write me a few words of wisdom.

1. Let's assume that we have a fast network (100 megabit+)
and a fast computer (3Ghz+). How to call enet_peer_send()
so it will not eat all memory? Following example of
"unlimited speed test" just eats up all memory becouse data
is supplied to enet faster than enet can send it over
network:

for(; ::enet_host_service(poHost, &oEvent, 0) >= 0);)
{ // timeout '0' is used to achiev speed > 1k packets / sec
  ENetPacket *poPacket = ::enet_packet_create(pbData, 1024,
    ENET_PACKET_FLAG_RELIABLE);
  _ASSERT(poPacket);
  _VERIFY(0 == ::enet_peer_send(poPeer, 0, poPacket));
}

So i need to somehow make pauses between enet_peer_send()
calls to give enet
a chance to send previously queued data over network. Ok,
following code will do a deal:

for(; ::enet_host_service(poHost, &oEvent, 0) >= 0);)
{
  // do some magic: if > 64k of data is sent but is not
ACK'ed yet - don't
  // send new data to prevent overflow
  if(poPeer->reliableDataInTransit > 1024*64) continue;

  ENetPacket *poPacket = ::enet_packet_create(pbData, 1024,
    ENET_PACKET_FLAG_RELIABLE);
  _ASSERT(poPacket);
  _VERIFY(0 == ::enet_peer_send(poPeer, 0, poPacket));
}

But if this method is correct, it leads to a second
question:

2. What is the best method to determine if it's ok to make
a enet_peer_send() call or not? For example, previous
example uses hard-coded limit equal to 64kb of unacked data
in transit. But such limit will result in unacked packets
(and disconnection) on slow GPRS connection where speed is
4-10 kb/sec and 1000ms is a common png value. Vise versa,
on 100 megabit network this 64k limit will slow down a
process since network can handle much more data in transit.

So, i'm confused a bit about how to send huge amounts of
data with good speed on good connections AND no disconnects
on bad connections. Any ideas? My current code analyses
network speed and maintains ~ 1 seconds of data to be in
transit. But this slows down transfer on fast connection,
and on artifical 14kbit simulated network huge enough
packets (like 16kb per packet) still gives disconnects :(.