update cadvisor to v0.31.0

vendor/github.com/Rican7/retry/backoff/backoff.go

@@ -0,0 +1,67 @@
+// Package backoff provides stateless methods of calculating durations based on
+// a number of attempts made.
+//
+// Copyright © 2016 Trevor N. Suarez (Rican7)
+package backoff
+
+import (
+	"math"
+	"time"
+)
+
+// Algorithm defines a function that calculates a time.Duration based on
+// the given retry attempt number.
+type Algorithm func(attempt uint) time.Duration
+
+// Incremental creates a Algorithm that increments the initial duration
+// by the given increment for each attempt.
+func Incremental(initial, increment time.Duration) Algorithm {
+	return func(attempt uint) time.Duration {
+		return initial + (increment * time.Duration(attempt))
+	}
+}
+
+// Linear creates a Algorithm that linearly multiplies the factor
+// duration by the attempt number for each attempt.
+func Linear(factor time.Duration) Algorithm {
+	return func(attempt uint) time.Duration {
+		return (factor * time.Duration(attempt))
+	}
+}
+
+// Exponential creates a Algorithm that multiplies the factor duration by
+// an exponentially increasing factor for each attempt, where the factor is
+// calculated as the given base raised to the attempt number.
+func Exponential(factor time.Duration, base float64) Algorithm {
+	return func(attempt uint) time.Duration {
+		return (factor * time.Duration(math.Pow(base, float64(attempt))))
+	}
+}
+
+// BinaryExponential creates a Algorithm that multiplies the factor
+// duration by an exponentially increasing factor for each attempt, where the
+// factor is calculated as `2` raised to the attempt number (2^attempt).
+func BinaryExponential(factor time.Duration) Algorithm {
+	return Exponential(factor, 2)
+}
+
+// Fibonacci creates a Algorithm that multiplies the factor duration by
+// an increasing factor for each attempt, where the factor is the Nth number in
+// the Fibonacci sequence.
+func Fibonacci(factor time.Duration) Algorithm {
+	return func(attempt uint) time.Duration {
+		return (factor * time.Duration(fibonacciNumber(attempt)))
+	}
+}
+
+// fibonacciNumber calculates the Fibonacci sequence number for the given
+// sequence position.
+func fibonacciNumber(n uint) uint {
+	if 0 == n {
+		return 0
+	} else if 1 == n {
+		return 1
+	} else {
+		return fibonacciNumber(n-1) + fibonacciNumber(n-2)
+	}
+}