Nim/tests/async/tasyncawait.nim

import asyncdispatch, asyncnet, nativesockets, net, strutils
from stdtest/netutils import bindAvailablePort
var msgCount = 0

const
  swarmSize = 40
  messagesToSend = 50

var clientCount = 0

proc sendMessages(client: AsyncFD) {.async.} =
  for i in 0 ..< messagesToSend:
    await send(client, "Message " & $i & "\c\L")

proc launchSwarm(port: Port) {.async.} =
  for i in 0 ..< swarmSize:
    var sock = createAsyncNativeSocket()

    await connect(sock, "localhost", port)
    await sendMessages(sock)
    closeSocket(sock)

proc readMessages(client: AsyncFD) {.async.} =
  # wrapping the AsyncFd into a AsyncSocket object
  var sockObj = newAsyncSocket(client)
  var (ipaddr, port) = sockObj.getPeerAddr()
  doAssert ipaddr == "127.0.0.1"
  (ipaddr, port) = sockObj.getLocalAddr()
  doAssert ipaddr == "127.0.0.1"
  while true:
    var line = await recvLine(sockObj)
    if line == "":
      closeSocket(client)
      clientCount.inc
      break
    else:
      if line.startsWith("Message "):
        msgCount.inc
      else:
        doAssert false

proc createServer(server: AsyncFD) {.async.} =
  discard server.SocketHandle.listen()
  while true:
    asyncCheck readMessages(await accept(server))

let server = createAsyncNativeSocket()
let port = bindAvailablePort(server.SocketHandle)
asyncCheck createServer(server)
asyncCheck launchSwarm(port)
while true:
  poll()
  if clientCount == swarmSize: break

doAssert msgCount == swarmSize * messagesToSend
doAssert msgCount == 2000