import os
import select
import signal
import socket
import subprocess
import sys
import threading
import time
try:
    from time import monotonic as timer
except ImportError:
    from time import time as timer

DURATION = 5.0
ITIMER = 0.1   # seconds
NPROC = 5
POPEN_ARGS = [sys.executable, '-c', 'pass']
SIGNAMES = ('SIGINT', 'SIGALRM', 'SIGWINCH', 'SIGTERM', 'SIGCHLD')

server = socket.socket()
server.bind(('', 0))
server.listen(1)
server_addr = ('127.0.0.1', server.getsockname()[1])

def server_thread(server):
    while True:
        # client connect() will block if the server is not accepting
        # connections
        time.sleep(ITIMER * 5)
        try:
            sock, addr = server.accept()
        except InterruptedError:
            # not interested by EINTR at the server side
            continue
        sock.close()

thread = threading.Thread(target=server_thread, args=(server,), daemon=True)
thread.start()

def func():
    client = socket.socket()
    try:
        client.connect(server_addr)
    except ConnectionResetError:
        # On FreeBSD, connect() sometimes fail with ConnectionResetError
        pass
    client.close()

got_signals = 0

def signal_handler(*args):
    global got_signals
    got_signals += 1

for signame in SIGNAMES:
    if not hasattr(signal, signame):
        continue
    signum = getattr(signal, signame)
    print("Register %s" % signame)
    signal.signal(signum, signal_handler)
    if hasattr(signal, 'siginterrupt'):
        signal.siginterrupt(signum, True)

if hasattr(signal, 'SIGALRM') and ITIMER:
    print("Send SIGALRM every %.1f ms" % (ITIMER * 1e3))
    signal.setitimer(signal.ITIMER_REAL, ITIMER, ITIMER)

t0 = timer()
print("Run func() during %.1f seconds" % DURATION)
print("Type CTRL+c, resize the window, etc.")
print("")
ncall = 0
while True:
    dt = timer() - t0
    if dt >= DURATION:
        break
    # Child processes send SIGCHLD to the parent process
    procs = [subprocess.Popen(POPEN_ARGS) for index in range(NPROC)]
    func()
    for proc in procs:
        proc.wait()
    ncall += 1
if hasattr(signal, 'SIGALRM'):
    signal.alarm(0)

print("Test completed in %.1f sec" % dt)
print("func() has been called %s times" % ncall)
print("Got %s signals" % got_signals)
server.close()