Added convenience functions for typical types of backoff

Author: ansel1

retry.go

@@ -208,6 +208,21 @@ func (c *ExponentialBackoff) Backoff(attempt int) time.Duration {
 	return time.Duration(backoff)
 }
 
+// NoBackoff returns a Backoffer with zero backoff, and zero delay between retries.
+func NoBackoff() *ExponentialBackoff {
+	return &ExponentialBackoff{}
+}
+
+// ConstantBackoff returns a Backoffer with a fixed, constant delay between retries and no jitter.
+func ConstantBackoff(delay time.Duration) *ExponentialBackoff {
+	return &ExponentialBackoff{BaseDelay: delay}
+}
+
+// ConstantBackoffWithJitter returns a Backoffer with a fixed, constant delay between retries with 20% jitter.
+func ConstantBackoffWithJitter(delay time.Duration) *ExponentialBackoff {
+	return &ExponentialBackoff{BaseDelay: delay, Jitter: 0.2}
+}
+
 // Retry retries the http request under certain conditions.  The number of retries,
 // retry conditions, and the time to sleep between retries can be configured.  If
 // config is nil, the DefaultRetryConfig will be used.

retry_test.go

@@ -107,22 +107,17 @@ func TestExponentialBackoff_Backoff(t *testing.T) {
 		},
 		{
 			name:     "no delay",
-			backoff:  ExponentialBackoff{},
+			backoff:  *NoBackoff(),
 			expected: [5]time.Duration{0, 0, 0, 0, 0},
 		},
 		{
-			name: "fixed delay",
-			backoff: ExponentialBackoff{
-				BaseDelay: time.Second,
-			},
+			name:     "constant delay",
+			backoff:  *ConstantBackoff(time.Second),
 			expected: [5]time.Duration{time.Second, time.Second, time.Second, time.Second, time.Second},
 		},
 		{
-			name: "fixed delay with jitter",
-			backoff: ExponentialBackoff{
-				BaseDelay: time.Second,
-				Jitter:    .2,
-			},
+			name:           "constant delay with jitter",
+			backoff:        *ConstantBackoffWithJitter(time.Second),
 			expected:       [5]time.Duration{time.Second, time.Second, time.Second, time.Second, time.Second},
 			expectedJitter: 0.2,
 		},