#!/usr/bin/python3

import select
import socket
import threading

# Mutex to print messages from multiple threads
lock = threading.Lock()


def epoll_wait_thread(epfd):
    lock.acquire()
    print(threading.currentThread().getName(), " epfd", epfd.fileno(), ": start polling", sep='')
    lock.release()
    events = epfd.poll(3)
    lock.acquire()
    print(threading.currentThread().getName(), " epfd", epfd.fileno(), ": got events: ", len(events), sep='')
    lock.release()


# Create a connection
s1, s2 = socket.socketpair(socket.AF_UNIX)

# Create epoll descriptor and register a socket
epfd = select.epoll()
epfd.register(s1.fileno(), select.EPOLLIN)
print(threading.currentThread().getName(), ": created epfd", epfd.fileno(), sep='')

# Start 2 threads with epoll_wait() routine
threads = []
for i in range(2):
    thread = threading.Thread(target=epoll_wait_thread, args=(epfd,))
    thread.start()
    threads.append(thread)

# Send some data to unblock epoll_wait() threads
lock.acquire()
print(threading.currentThread().getName(), ": Send some data", sep='')
lock.release()
s2.sendall(b'qwerty')

# Cleanup
for thread in threads:
    thread.join()
epfd.close()
s1.close()
s2.close()