Re: Making Python Script Exit Completely with One Ctrl+C

From: Dan Fandrich via curl-users <curl-users_at_lists.haxx.se>
Date: Thu, 7 Dec 2023 17:00:12 -0800

On Fri, Dec 08, 2023 at 08:39:28AM +0800, Hongyi Zhao via curl-users wrote:
> The script, named **proxy-speed.py**, is employed to measure and
> display the speed of different proxies. It runs through a list of
> proxies, giving the current and average speed for each, one at a time.
> However, the issue arises when I try to terminate the script
> prematurely using Ctrl+C. The KeyboardInterrupt appears to only pause
> the current task, and the script instantaneously proceeds with the
> next proxy on the list, clearly illustrating that it doesn¢t exit
> entirely.
>
> Here¢s an example illustrating the issue:
>
>
> ```
> File "/home/werner/Desktop/proxy-speed/proxy-speed.py", line 54, in progress
> def progress(download_t, download_d, upload_t, upload_d):
>
> KeyboardInterrupt
> Average Speed: 3944.97 kB/s
>
> Proxy: SG_ssr_futeapbquf5m.nodelist.club_1356_8ce27b1301fcbcb77cc5abb28cb127a6
> ^CTraceback (most recent call last):
> File "/home/werner/Desktop/proxy-speed/proxy-speed.py", line 54,
> in progress
> def progress(download_t, download_d, upload_t, upload_d):
>
> KeyboardInterrupt
> Average Speed: 72.81 kB/s
> ```

The call trace shows the exception being raised within the progress() function.
One reasonable response to this by pycurl would be to implicitly treat that as a
progress abort return code, but it looks like it does not do that. Instead, you
will probably need a try/catch block in that function that returns an error
code to pycurl. In the C binding this is done by returning a nonzero value from
that function; it's probably similar in pycurl. This will then return an error
from the c.perform() function that you can catch in the main loop.

In any case, this is unlikely to be a libcurl problem.

> This repeat pattern continues for every Ctrl+C interruption made.
> Hence, my goal is to modify the script so that a single Ctrl+C command
> would result in a comprehensive termination of the script.
>
> Any guidance or suggestions that you could offer regarding this issue
> would be greatly appreciated. If there is any further information
> needed to better understand the issue, please let me know.
>
> The content of **proxy-speed.py** is as follows:
>
> ```
> import subprocess
> import time
> import pycurl
> from io import BytesIO
>
> def fetch_proxies():
> command = 'echo "show stat" | sudo socat stdio
> /var/run/haproxy.sock 2>/dev/null | awk -F, \'$1=="socks5" &&
> !($2~/^(FRONTEND|BACKEND)$/) {print $2,$74}\''
> process = subprocess.Popen(command, stdout=subprocess.PIPE, shell=True)
> output, error = process.communicate()
>
> result_dict = {} # Initialize default empty dictionary
>
> if error is not None:
> return result_dict # Return the empty dictionary in case of error
>
> lines = output.decode('utf-8').split('\n')
>
> for line in lines:
> if line != "":
> key_value = line.split(' ')
> result_dict[key_value[0]] = key_value[1]
>
> return result_dict
>
>
> def test_proxy(proxy, url):
> global last_calc_time, download_start_time
>
> buffer = BytesIO()
>
> c = pycurl.Curl()
> c.setopt(pycurl.URL, url)
> c.setopt(pycurl.WRITEDATA, buffer)
> c.setopt(pycurl.PROXY, proxy)
> c.setopt(pycurl.PROXYTYPE, pycurl.PROXYTYPE_SOCKS5_HOSTNAME)
> c.setopt(pycurl.NOPROGRESS, False)
> c.setopt(pycurl.XFERINFOFUNCTION, progress)
> c.setopt(pycurl.TIMEOUT, 5)
>
> download_start_time = time.time()
> last_calc_time = download_start_time
>
> try:
> c.perform()
> except pycurl.error as e:
> pass
> except KeyboardInterrupt:
> print("Script interrupted by user. Exiting.")
> sys.exit(0) # immediately exit the script
>
> average_speed = c.getinfo(pycurl.SPEED_DOWNLOAD) / 1024
> return average_speed
>
> def progress(download_t, download_d, upload_t, upload_d):
> global last_calc_time, download_start_time
> current_time = time.time()
>
> if current_time - last_calc_time >= 2:
> elapsed_time = current_time - download_start_time
> current_speed = download_d / elapsed_time / 1024
> print(f"Current Speed: {current_speed:.2f} kB/s")
> last_calc_time = current_time
>
> proxy_data = fetch_proxies()
> url = "http://ipv4.download.thinkbroadband.com/1GB.zip"
>
> for key, value in proxy_data.items():
> print(f"Proxy: {key}")
> try:
> average_speed = test_proxy(value, url)
> print(f"Average Speed: {average_speed:.2f} kB/s")
> except KeyboardInterrupt:
> print("Script interrupted by user. Exiting.")
> break # exit the for loop
> ```
>
> See here [1] for the related discussion.
>
> Thank you very much for your help in advance.
>
> [1] https://discuss.python.org/t/making-python-script-exit-completely-with-one-ctrl-c/40529/1
>
> Best Regards,
> Zhao
>
> P.S: If possible, could you please provide both an explanation and
> snippet of the solution so that I can understand and learn from it for
> future references.
> --
> Assoc. Prof. Hongsheng Zhao <hongyi.zhao_at_gmail.com>
> Theory and Simulation of Materials
> Hebei Vocational University of Technology and Engineering
> No. 473, Quannan West Street, Xindu District, Xingtai, Hebei province

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Received on 2023-12-08