Improve retry strategy

Author: dodyg

projects/polly/rate-limiter-http-client/Program.cs

@@ -13,18 +13,39 @@
 .ConfigureHttpClient((sp, client) =>
 {
  client.Timeout = TimeSpan.FromSeconds(10);
-}).AddResilienceHandler("concurrency-http-policy", (builder,c) =>
+}).AddResilienceHandler("concurrency-http-policy", (builder, c) =>
 {
  builder
  .AddConcurrencyLimiter(permitLimit: 100, queueLimit: 50)
  .AddRetry(new RetryStrategyOptions<HttpResponseMessage>
  {
  MaxRetryAttempts = 3,
- Delay = TimeSpan.FromSeconds(1),
+ DelayGenerator = static args =>
+ {
+ var delay = args.AttemptNumber switch
+ {
+ 0 => TimeSpan.Zero,
+ 1 => TimeSpan.FromSeconds(1),
+ _ => TimeSpan.FromSeconds(5)
+ };
+
+ // This example uses a synchronous delay generator,
+ // but the API also supports asynchronous implementations.
+ return new ValueTask<TimeSpan?>(delay);
+ },
+ OnRetry = args =>
+ {
+ var logger = c.ServiceProvider.GetService<ILogger>();
+ logger.LogError("OnRetry, Attempt: {0}", args.AttemptNumber);
+ Console.WriteLine("OnRetry, Attempt: {0}", args.AttemptNumber);
+
+ // Event handlers can be asynchronous; here, we return an empty ValueTask.
+ return default;
+ },
  BackoffType = DelayBackoffType.Constant
  }).Build();
 });
 
-var app  = builder.Build();
+var app = builder.Build();
 app.MapRazorPages();
 app.Run();