custom-pipe-example.py

"""
Just run:
 python3 custom-pipe-example.py
"""
import subprocess
import os
import json
import time
import sys
from pprint import pprint


def run_main_process():
    read_fd, write_fd = os.pipe()
    os.set_inheritable(write_fd, True)

    process = subprocess.Popen(
        [sys.executable, __file__, str(write_fd)],
        stdout=subprocess.PIPE,
        stderr=subprocess.PIPE,
        text=True,
        close_fds=False
    )
    os.close(write_fd)

    with os.fdopen(read_fd, 'r') as data_pipe:
        try:
            json_data = data_pipe.read()
            if json_data:
                received_json = json.loads(json_data)
                print('DATA RECEIVED:')
                pprint(received_json)
        except json.JSONDecodeError as e:
            print(f"JSON Decode error: {e}")
            print(f"{json_data}")

    stdout_log, stderr_log = process.communicate()

    print("\nChild logs:")
    print(stdout_log)

    print("\nChild Errors:")
    print(stderr_log)


def run_child_process(write_pipe_fd):
    with os.fdopen(int(write_pipe_fd), 'w') as data_pipe:
        data = {
            "message": "Hello!!!",
            "timestamp": time.time(),
            "source": "custom_pipe_json"
        }
        json.dump(data, data_pipe)
        data_pipe.flush()
        print('SENT DATA:')
        pprint(data)



if __name__ == '__main__':
    args = sys.argv[1:]
    if not args:
        run_main_process()
    else:
        run_child_process(args[0])