On 14/09/06, Diez B. Roggisch <[EMAIL PROTECTED]> wrote:
> billie schrieb:
> > Hi all. I'm writing a TCP-based application that I will use to trasfer
> > binary files through the network. This piece of code represents how do
> > I get a file from a remote peer and save it on my local hard drive:
> >
> > file_obj = open('downloaded.ext', 'wb')
> > while 1:
> > buf = sock.recv(2048)
> > if len(buf) == 0:
> > break
> > file_obj.write(buf)
> > file_obj.close()
> > sock.close()
> >
> > I would like to know how could be possible to limit the file transfer
> > speed (for example: don't write more than 50 Kb/sec).
> > Some ideas?
>
> If you are on unix, use trickle. If you must limit it from within your
> own code, I can only assume that computing the transfer rate so far and
> introducing timeouts might help - but I never did such a thing, nor do I
> know what that means for example for the network stack.
>
> But maybe even then trickle may help you to get an idea, as it is a
> user-space program AFAIK. So they might have some information (at least
> the code... ) out there that could be of use.
You could wrap buf = sock.recv(xxx) in a data counter and sleep loop
so that you burst to no more than 50KB/s average.
Completely untestest and for illustration only :)
file_obj = open('downloaded.ext', 'wb')
interval = 1.0 # seconds eg. 0.5 or 2.0
# smaller the interval, the less bursty and smoother the throughput
max_speed = 51200 # 50k * 1024 = bytes
data_count = 0 # keep track of the amount of data transferred
time_next = time.time() + interval
while 1:
buf = sock.recv(512) # smaller chunks = smoother, more accurate
if len(buf) == 0:
break
data_count += len(buf)
if data_count >= max_speed * interval:
data_count = 0
sleep_for = time_next - time.time()
if sleep_for > 0:
time.sleep(sleep_for)
time_next = time.time() + interval
file_obj.write(buf)
file_obj.close()
sock.close()
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