Mirror of forum.nim-lang.org

1627 :: Usage of AsyncNet

• andrea (orginal) [2015-09-11T17:43:19+02:00] view original

  I am trying to make some experiments with asyncnet, but I am not really familiar with low-level network concepts. I have a couple of questions:

  • Why can I only send strings? I know strings in Nim are essentially a sequence of bytes, but I may have a pointer to data that is not on the heap. Do I need to move it in a heap-allocated string?
  • I am doing a lot a await one after the other to send chunks of messages. Would it be more efficient to create the whole message locallly on the heap and then send it in a single time? I guess by concatenating a lot of await I am yielding the CPU for I/O more frequently, right? Or is there some buffering done by asyncnet?

---

• dom96 (orginal) [2015-09-12T00:12:35+02:00] view original

  Indeed, it's because strings in Nim are essentially just a sequence of bytes, sending ordinary text over a socket is also rather common so it is supported by default. To answer your other question: You will have to copy it into a string. I'm curious what your use case is though?

  Yeah, it's best to create a whole message and send it all at once. With await a possibly bigger problem is the amount of Futures your are creating as a result of your multiple calls to send.

---

• andrea (orginal) [2015-09-12T10:58:26+02:00] view original

  I do not have a particular use case in mind. Just that one may be able to construct a message on the stack, without the need to allocate, at least for messages of known size. In this case, forcing to use a string would require two copies: one from the stack on the heap, and then from there into the network buffers.

---

• Araq (orginal) [2015-09-12T11:16:27+02:00] view original

  You cannot send asyncronously "from your stack". The send-request returns immediately and your stack frame vanishes. We could try to eliminate heap-to-heap copies though.

---

• andrea (orginal) [2015-09-12T21:38:49+02:00] view original

  I didn't think about it. Makes sense :-)

---

• yglukhov (orginal) [2015-09-12T23:17:07+02:00] view original

  You cannot send asyncronously "from your stack". The send-request returns immediately and your stack frame vanishes. We could try to eliminate heap-to-heap copies though.

  Unless you're in a coroutine ;)

---