import time
from threading import Lock


class RateTracker:
    def __init__(self, rate: int = 1000):
        """ rate is max number of calls per second."""
        self.rate = rate
        self.delay = 1.0/rate
        self._last_call = time.time() - self.delay
        self._lock = Lock()

    def done(self):
        """ call to indicate processing is done"""
        pass

    def create_wait(self):
        """ Generation of tasks is hard-limited, no matter the execution rate """
        with self._lock:
            passed = time.time() - self._last_call
            to_wait = self.delay - passed
            if to_wait > 0:
                time.sleep(to_wait)
                self._last_call += to_wait
            else:
                self._last_call = time.time()

    def start(self):
        """ indicate start of the call """
        pass