Rate limiter

rate_limiter.py

import time

def rate_limited_caller(max_rps=100, sleep_time=10, cache=None):
  num_calls = 1
  using_cache = False
  if isinstance(cache, dict):
    using_cache = True
    print(f"Using a cache")

  def caller(func):
    def wrapper(*args, **kwargs):
      nonlocal num_calls
      nonlocal cache
      output = None
      func_call = True
      if using_cache:
        key = tuple(args) + tuple(kwargs.items())
        if key in cache:
          print(f"Cache hit: reusing key=({key})")
          func_call = False
        else:
          cache[key] = func(*args, **kwargs)
        output = cache[key]
      else:
        output = func(*args, **kwargs)
      num_calls += 1
      if func_call and (num_calls % max_rps) == 0:
        print(f"[{time.strftime('%X %x %Z')}] Total calls: {num_calls}. Num calls > {max_rps}. Sleeping for {sleep_time} secs.")
        time.sleep(sleep_time)
      return output
    return wrapper
  return caller

# Example 

@rate_limited_caller()
def square(x):
  return x**2


print(list(map(square, range(230))))