Making Python Script Exit Completely with One Ctrl+C

From: Hongyi Zhao via curl-users <curl-users_at_lists.haxx.se>
Date: Fri, 8 Dec 2023 08:39:28 +0800

Dear libcurl community,

I hope this message finds you in good health. I am reaching out to
seek your assistance regarding an issue that I have been experiencing
with one of my Python scripts that involves the use of libcurl.

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
```
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