Improve DelayStrategy sample

sdk/core/Azure.Core/samples/Configuration.md

@@ -70,11 +70,36 @@ SecretClientOptions options = new SecretClientOptions()
 
 Another scenario where it may be helpful to use a custom retry policy is when you need to customize the delay behavior, but don't need to adjust the logic used to determine whether a request should be retried or not. In this case, it isn't necessary to create a custom `RetryPolicy` class - instead, you can pass in a `DelayStrategy` into the `RetryPolicy` constructor.  
 
-In the below example, we create a customized exponential delay strategy that uses different jitter factors from the default values. We then pass the strategy into the `RetryPolicy` constructor and set the constructed policy in our options.
-```C# Snippet:CustomizeExponentialDelay
+In the below example, we create a customized delay strategy that uses a fixed sequence of delays that will be iterated through using the retry number. We then pass the strategy into the `RetryPolicy` constructor and set the constructed policy in our options.
+```C# Snippet:SequentialDelayStrategy
+public class SequentialDelayStrategy : DelayStrategy
+{
+    private static readonly TimeSpan[] PollingSequence = new TimeSpan[]
+    {
+        TimeSpan.FromSeconds(1),
+        TimeSpan.FromSeconds(1),
+        TimeSpan.FromSeconds(1),
+        TimeSpan.FromSeconds(2),
+        TimeSpan.FromSeconds(4),
+        TimeSpan.FromSeconds(8),
+        TimeSpan.FromSeconds(16),
+        TimeSpan.FromSeconds(32)
+    };
+    private static readonly TimeSpan MaxDelay = PollingSequence[PollingSequence.Length - 1];
+
+    protected override TimeSpan GetNextDelayCore(Response response, int retryNumber)
+    {
+        int index = retryNumber - 1;
+        return index >= PollingSequence.Length ? MaxDelay : PollingSequence[index];
+    }
+}
+```
+
+Here is how the custom delay would be used in the client options.
+```C# Snippet:CustomizedDelay
 SecretClientOptions options = new SecretClientOptions()
 {
-    RetryPolicy = new RetryPolicy(delayStrategy: new MyCustomDelayStrategy())
+    RetryPolicy = new RetryPolicy(delayStrategy: new SequentialDelayStrategy())
 };
 ```
 

sdk/core/Azure.Core/tests/samples/ConfigurationSamples.cs

@@ -114,22 +114,38 @@ public void SetGlobalTimeoutRetryPolicy()
         }
 
         [Test]
-        public void CustomizedJitterExponentialDelay()
+        public void CustomizedDelayStrategy()
         {
-            #region Snippet:CustomizeExponentialDelay
+            #region Snippet:CustomizedDelay
             SecretClientOptions options = new SecretClientOptions()
             {
-                RetryPolicy = new RetryPolicy(delayStrategy: new MyCustomDelayStrategy())
+                RetryPolicy = new RetryPolicy(delayStrategy: new SequentialDelayStrategy())
             };
             #endregion
         }
 
-        private class MyCustomDelayStrategy : DelayStrategy
+        #region Snippet:SequentialDelayStrategy
+        public class SequentialDelayStrategy : DelayStrategy
         {
+            private static readonly TimeSpan[] PollingSequence = new TimeSpan[]
+            {
+                TimeSpan.FromSeconds(1),
+                TimeSpan.FromSeconds(1),
+                TimeSpan.FromSeconds(1),
+                TimeSpan.FromSeconds(2),
+                TimeSpan.FromSeconds(4),
+                TimeSpan.FromSeconds(8),
+                TimeSpan.FromSeconds(16),
+                TimeSpan.FromSeconds(32)
+            };
+            private static readonly TimeSpan MaxDelay = PollingSequence[PollingSequence.Length - 1];
+
             protected override TimeSpan GetNextDelayCore(Response response, int retryNumber)
             {
-                throw new NotImplementedException();
+                int index = retryNumber - 1;
+                return index >= PollingSequence.Length ? MaxDelay : PollingSequence[index];
             }
         }
+        #endregion
     }
 }