Add Imgur rate limiting

lib/ratelimit/__init__.py

@@ -0,0 +1,59 @@
+from math import floor
+
+import time
+import sys
+import threading
+import functools
+
+
+def clamp(value):
+    '''
+    Clamp integer between 1 and max
+
+    There must be at least 1 method invocation
+    made over the time period. Make sure the
+    value passed is at least 1 and is not a
+    fraction of an invocation.
+
+    :param float value: The number of method invocations.
+    :return: Clamped number of invocations.
+    :rtype: int
+    '''
+    return max(1, min(sys.maxsize, floor(value)))
+
+
+class RateLimitDecorator:
+    def __init__(self, period=1, every=1.0):
+        self.frequency = abs(every) / float(clamp(period))
+        self.last_called = 0.0
+        self.lock = threading.RLock()
+
+    def __call__(self, func):
+        '''
+        Extend the behaviour of the following
+        function, forwarding method invocations
+        if the time window hes elapsed.
+
+        :param function func: The function to decorate.
+        :return: Decorated function.
+        :rtype: function
+        '''
+        @functools.wraps(func)
+        def wrapper(*args, **kwargs):
+            '''Decorator wrapper function'''
+            with self.lock:
+                elapsed = time.time() - self.last_called
+                left_to_wait = self.frequency - elapsed
+                if left_to_wait > 0:
+                    time.sleep(left_to_wait)
+                self.last_called = time.time()
+            return func(*args, **kwargs)
+        return wrapper
+
+
+rate_limited = RateLimitDecorator
+
+
+__all__ = [
+    'rate_limited'
+]

lib/ratelimit/version.py

@@ -0,0 +1,9 @@
+class Version(object):
+    '''Version of the package'''
+
+    def __setattr__(self, *args):
+        raise TypeError('cannot modify immutable instance')
+    __delattr__ = __setattr__
+
+    def __init__(self, num):
+        super(Version, self).__setattr__('number', num)