It’s not possible for any library to do this without using some kind of asynchronous timer through threads or otherwise. The reason is that the timeout
parameter used in httplib
, urllib2
and other libraries sets the timeout
on the underlying socket
. And what this actually does is explained in the documentation.
SO_RCVTIMEO
Sets the timeout value that specifies the maximum amount of time an input function waits until it completes. It accepts a timeval structure with the number of seconds and microseconds specifying the limit on how long to wait for an input operation to complete. If a receive operation has blocked for this much time without receiving additional data, it shall return with a partial count or errno set to [EAGAIN] or [EWOULDBLOCK] if no data is received.
The bolded part is key. A socket.timeout
is only raised if not a single byte has been received for the duration of the timeout
window. In other words, this is a timeout
between received bytes.
A simple function using threading.Timer
could be as follows.
import httplib
import socket
import threading
def download(host, path, timeout = 10):
content = None
http = httplib.HTTPConnection(host)
http.request('GET', path)
response = http.getresponse()
timer = threading.Timer(timeout, http.sock.shutdown, [socket.SHUT_RD])
timer.start()
try:
content = response.read()
except httplib.IncompleteRead:
pass
timer.cancel() # cancel on triggered Timer is safe
http.close()
return content
>>> host="releases.ubuntu.com"
>>> content = download(host, '/15.04/ubuntu-15.04-desktop-amd64.iso', 1)
>>> print content is None
True
>>> content = download(host, '/15.04/MD5SUMS', 1)
>>> print content is None
False
Other than checking for None
, it’s also possible to catch the httplib.IncompleteRead
exception not inside the function, but outside of it. The latter case will not work though if the HTTP request doesn’t have a Content-Length
header.