Testing async dispatch and http requests in Nim

s3_get_bucket_obj.nim

# testing async dispatch in pursuit of an efficient async s3 interface
import os, times, math, httpclient, asyncdispatch

let t0 = epochTime()

proc dt() : float = 
  round(epochTime() - t0,6)

const aws_url = "http://localhost:1234/"

proc s3_get_bucket_object(aws_key:string,bucket:string,obj:string) : Future[string] {.async.} = 
  var 
    client = newAsyncHttpClient()
    c_prog = false
  
  # do the HMAC here
  client.headers = newHttpHeaders({ "Authorization": "TEST KEY:SIG-"&obj })

  client.onProgressChanged = proc(total, progress, speed: BiggestInt) {.async.} =
    #echo("S3 download progress: ", progress, " of ", total)
    #echo("S3 transfer rate: ", speed div 1000, "kb/s")
    c_prog = true

  try:
    result = await client.getContent(aws_url)
  except HttpRequestError:
    echo "http error: "
    echo getCurrentExceptionMsg()
  except:
    echo "unknown exception"
    echo getCurrentExceptionMsg()
  
  while not c_prog:
    poll()

let bucket = "my_bucket"
var files : seq[(string,Future[string])]= @[]

for f in 0..99:
  let file_name = "./some_file_" & $(f+1) & ".txt"
  files.add((file_name, s3_get_bucket_object("blah", bucket, file_name)))

for file in files:
  #echo file
  writeFile(file[0], waitFor file[1])

echo "Transfer Complete ", dt()