host = "www.w3.org"

local socket = require"socket"

function download (host, file)
  local c = assert(socket.connect(host, 80))
  local count = 0    -- counts number of bytes read
  c:send("GET " .. file .. " HTTP/1.0\r\n\r\n")
  while true do
    local s, status = receive(c)
    count = count + string.len(s)
    if status == "closed" then break end
  end
  c:close()
  print(file, count)
end

function receive (connection)
  connection:settimeout(0)   -- do not block
  local s, status, part = connection:receive(2^10)
  if status == "timeout" then
    coroutine.yield(connection)
  end
  return s or part, status
end


threads = {}    -- list of all live threads
function get (host, file)
  -- create coroutine
  local co = coroutine.create(function ()
    download(host, file)
  end)
  -- insert it in the list
  table.insert(threads, co)
end


function dispatcher ()
  while true do
    local n = table.getn(threads)
    if n == 0 then break end   -- no more threads to run
    local connections = {}
    for i=1,n do
      local status, res = coroutine.resume(threads[i])
      if not res then    -- thread finished its task?
        table.remove(threads, i)
        break
      else    -- timeout
        table.insert(connections, res)
      end
    end
    if table.getn(connections) == n then
      socket.select(connections)
    end
  end
end

get(host, "/TR/html401/html40.txt")
get(host,"/TR/2002/REC-xhtml1-20020801/xhtml1.pdf")
get(host,"/TR/REC-html32.html")
get(host, "/TR/2000/REC-DOM-Level-2-Core-20001113/DOM2-Core.txt")
                                
dispatcher()   -- main loop