def get_free_port():
"""return available port on localhost"""
free_port = FREE_PORTS.pop()
sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
try:
# connect to the given host:port
sock.bind(("127.0.0.1", free_port))
except socket.error:
free_port = get_free_port()
else:
sock.close()
return free_port
def release_port(port):
"""call when server stops listening"""
FREE_PORTS.append(port)