Cancel slow download in python

download, python, restart, urllib

Solution

This should work. It calculates the actual download rate and aborts if it is too low.

import sys
from urllib import urlretrieve
import time

url = "http://www.python.org/ftp/python/2.7.3/Python-2.7.3.tgz" # 14.135.620 Byte
startTime = time.time()

class TooSlowException(Exception):
    pass

def convertBToMb(bytes):
    """converts Bytes to Megabytes"""
    bytes = float(bytes)
    megabytes = bytes / 1048576
    return megabytes


def dlProgress(count, blockSize, totalSize):
    global startTime

    alreadyLoaded = count*blockSize
    timePassed = time.time() - startTime
    transferRate = convertBToMb(alreadyLoaded) / timePassed # mbytes per second
    transferRate *= 60 # mbytes per minute

    percent = int(alreadyLoaded*100/totalSize)
    sys.stdout.write("\r" + "progress" + "...%d%%" % percent)
    sys.stdout.flush()

    if transferRate < 4 and timePassed > 2: # download will be slow at the beginning, hence wait 2 seconds
        print "\ndownload too slow! retrying..."
        time.sleep(1) # let's not hammer the server
        raise TooSlowException

def main():
    try:
        urlretrieve(url, '/tmp/localfile', reporthook=dlProgress)

    except TooSlowException:
        global startTime
        startTime = time.time()
        main()

if __name__ == "__main__":
    main()

Problem

Original source