def test_10_ms_bucket_interval():
"""
This test expresses a drawback of designed rate limiter. Even the time interval between two requests with timestamps
1007, 2001 is shorter than 1 second it still passes. The reason is we split our tracker by 10 milliseconds interval,
so once we performed a bucketing the distance between two buckets would be exactly 1 second which is valid.
The case won't pass for 1ms buckets. So, with 10ms wide bucket we produce 100 buckets, we may incorrectly identify
a distance for half timestamps within a bucket, that gives us 0.5% error. With 1ms the error is 0.05%. We may
decrease the error by decreasing the width of the bucket, but this will impact space and time complexity. Overall
the number of buckets will not exceed 1000/[bucket width], so we can talk about effective constant time and space
complexity.
:return:
"""
class TestTimer(MockTimer):
def get_times(self) -> []:
return [1007, 2001]
rate_limiter = RateLimiter(TestTimer(), bucket_ms_interval=10)
rate_limiter.configure_limit(user_id=1, rps=1)
assert rate_limiter.process_request(1) # for 1007 stamp
assert rate_limiter.process_request(1) # 2001
rate_limiter = RateLimiter(TestTimer(), bucket_ms_interval=1)
rate_limiter.configure_limit(user_id=1, rps=1)
assert rate_limiter.process_request(1) # for 1007 stamp
assert not rate_limiter.process_request(1) # 2001
def test_user_1_rps():
class TestTimer(MockTimer):
def get_times(self) -> []:
return [0, 500, 1000, 1001, 1500, 2000, 2001]
rate_limiter = RateLimiter(TestTimer(), bucket_ms_interval=1)
rate_limiter.configure_limit(user_id=1, rps=1)
assert rate_limiter.process_request(1) # for 0 stamp
assert not rate_limiter.process_request(1) # 500
assert rate_limiter.process_request(1) # 1000 this will pass because exactly 1 sec passed since last request
assert not rate_limiter.process_request(1) # 1001
assert not rate_limiter.process_request(1) # 1500
assert rate_limiter.process_request(1) # 2000 this will pass because exactly 1 sec passed since last request
assert not rate_limiter.process_request(1) # 2001
def test_two_users_1_rps():
class TestTimer(MockTimer):
def get_times(self) -> []:
return [0, 500, 1000, 1001, 1500, 2000, 2001]
rate_limiter = RateLimiter(TestTimer(), bucket_ms_interval=1)
rate_limiter.configure_limit(user_id=1, rps=1)
rate_limiter.configure_limit(user_id=2, rps=1)
# because users have their own limits configured, they do not overlap
assert rate_limiter.process_request(1) # for 0 stamp and user 1
assert rate_limiter.process_request(2) # 500 it's OK, because it is user 2
assert rate_limiter.process_request(1) # 1000 will pass because exactly 1 sec passed since last request for user 1
assert not rate_limiter.process_request(1) # 1001 user 1 just made a request, won't pass
assert rate_limiter.process_request(2) # 1500 will pass because exactly 1 sec passed since last request for user 2
assert not rate_limiter.process_request(2) # 2000 user 2 made a request 500ms ago
assert rate_limiter.process_request(1) # 2001 will pass because more than 1 sec passed since a request for user 1
def test_user_1_rps_and_unlimited_for_others():
class TestTimer(MockTimer):
def get_times(self) -> []:
return [0, 500, 550, 700, 800, 900, 999, 1001]
rate_limiter = RateLimiter(TestTimer(), bucket_ms_interval=1)
rate_limiter.configure_limit(user_id=1, rps=1)
# user 1 has only limits configured, but others are unlimited
assert rate_limiter.process_request(1) # for 0 stamp and user 1
assert rate_limiter.process_request(2) # 500 other users unlimited
assert rate_limiter.process_request(3) # 550
assert rate_limiter.process_request(4) # 700
assert rate_limiter.process_request(5) # 800
assert rate_limiter.process_request(6) # 900
assert not rate_limiter.process_request(1) # 999 but user 1 already exceeded a limit
assert rate_limiter.process_request(1) # 1001 user 1 may execute, because 1 sec already passed since last success
def test_user_contributes_to_global_limit():
class TestTimer(MockTimer):
def get_times(self) -> []:
return [0, 500, 1000, 1001, 1500, 2000, 2001]
rate_limiter = RateLimiter(TestTimer(), bucket_ms_interval=1)
rate_limiter.configure_limit(user_id=1, rps=1)
rate_limiter.configure_global_limit(rps=1)
# user 1 makes 1 request for in 1 second interval and contribute to global limit, second user can't execute during
# the same interval
assert rate_limiter.process_request(1) # for 0 stamp user 1
assert not rate_limiter.process_request(2) # 500 since user 1 already made a request
assert rate_limiter.process_request(1) # 1000 this will pass because exactly 1 sec passed since last request
assert not rate_limiter.process_request(2) # 1001 since user 1 just made a request
assert not rate_limiter.process_request(1) # 1500
assert rate_limiter.process_request(1) # 2000 this will pass because exactly 1 sec passed since last request
assert not rate_limiter.process_request(2) # 2001