How does Polly retry policies indicate when number of retries have been exceeded?

Question

I have a call that uses a Policy.Handle<PollingResult>(...).WaitAndRetry(...).ExecuteAsync(...) call to wrap a polling operation.

Having spent the better part of half an hour reading the Polly documentation, I cannot seem to find any way for this call to tell me "Whoops, seems we used all the retries to no avail!"

Like, how do I do this:

var retryResultWithAllDetails = Policy
    .Handle<PollingResult>(poll => poll.IsReady)
    .WaitAndRetry(maxRetries, n => RetryIntervalCalculation(n))
    .ExecuteAsyncWithAllTheNecessaryNittyGrittyDetailsAndFootnotes(() => SomePollingOperation());

if (retryResultWithAllDetails.RanOutOfRetryAttempts)
  throw new WeRanOutOfRetryAttemptsException("Oops!")

It seems strange that this isn't just readily avialable as a boolean flag somewhere in the documentation.

I am not interested in the exceptions or whether it failed or whatnot — I know how to handle exceptions thrown from within Polly. I am interested in whether it ran out of retry attempts so I can log an appropriate error. I hope that is clear.

Answer 1

There is no built-in support for this. But you can do something like this:

var retry = Policy
    .Handle<PollingResult>(poll => poll.IsReady)
    .WaitAndRetry(maxRetries, n => RetryIntervalCalculation(n));
    
int retryAttempts = 0;
result = retry.ExecuteAsyncWithAllTheNecessaryNittyGrittyDetailsAndFootnotes(
  () => { retryAttempts++; SomePollingOperation() });

if (retryAttempts == maxRetries + 1)
  throw new WeRanOutOfRetryAttemptsException("Oops!")

• retryAttempts is incremented at every retry
• maxRetries + 1 the plus one is needed because the 0th retry attempt is the original execution.

---

Dotnet fiddle: https://dotnetfiddle.net/HYyxLs