#96 implement exponential backoff

kube_ops_view/backoff.py

@@ -0,0 +1,48 @@
+import random
+
+
+def expo(n: int, base=2, factor=1, max_value=None):
+    """Exponential decay.
+
+    Adapted from https://github.com/litl/backoff/blob/master/backoff.py (MIT License)
+
+    Args:
+        base: The mathematical base of the exponentiation operation
+        factor: Factor to multiply the exponentation by.
+        max_value: The maximum value to yield. Once the value in the
+             true exponential sequence exceeds this, the value
+             of max_value will forever after be yielded.
+    """
+    a = factor * base ** n
+    if max_value is None or a < max_value:
+        return a
+    else:
+        return max_value
+
+
+def random_jitter(value, jitter=1):
+    """Jitter the value a random number of milliseconds.
+
+    Copied from https://github.com/litl/backoff/blob/master/backoff.py (MIT License)
+
+    This adds up to 1 second of additional time to the original value.
+    Prior to backoff version 1.2 this was the default jitter behavior.
+    Args:
+        value: The unadulterated backoff value.
+    """
+    return value + random.uniform(0, jitter)
+
+
+def full_jitter(value):
+    """Jitter the value across the full range (0 to value).
+
+    Copied from https://github.com/litl/backoff/blob/master/backoff.py (MIT License)
+
+    This corresponds to the "Full Jitter" algorithm specified in the
+    AWS blog's post on the performance of various jitter algorithms.
+    (http://www.awsarchitectureblog.com/2015/03/backoff.html)
+
+    Args:
+        value: The unadulterated backoff value.
+    """
+    return random.uniform(0, value)