# test concurrent mutating access to a shared user instance
#
# MIT license; Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd

import _thread

# the shared user class and instance
class User:
 def __init__(self):
 self.a = 'A'
 self.b = 'B'
 self.c = 'C'
user = User()

# main thread function
def th(n, lo, hi):
 for repeat in range(n):
 for i in range(lo, hi):
 setattr(user, 'attr_%u' % i, repeat + i)
 assert getattr(user, 'attr_%u' % i) == repeat + i

 with lock:
 global n_finished
 n_finished += 1

lock = _thread.allocate_lock()
n_repeat = 30
n_range = 50 # 300 for stressful test (uses more heap)
n_thread = 4
n_finished = 0

# spawn threads
for i in range(n_thread):
 _thread.start_new_thread(th, (n_repeat, i * n_range, (i + 1) * n_range))

# busy wait for threads to finish
while n_finished < n_thread:
 pass

# check user instance has correct contents
print(user.a, user.b, user.c)
for i in range(n_thread * n_range):
 assert getattr(user, 'attr_%u' % i) == n_repeat - 1 + i