Retry

Allows configuring auto re-execution of an operation based on exceptions or on its return value.

Configuration

• For operations without a return value

  // Create a new bot policy
  var policy = new BotPolicy();
  
  // Configure the policy to retry failed operations
  policy.Configure(policyConfig => policyConfig
      .Retry(retryConfig => retryConfig
  
          // Set the maximum retry count
          .WithMaxAttemptCount(5)
  
          // Set the predicate to decide that whether an 
          // exception should be handled or not
          .WhenExceptionOccurs(exception => exception is HttpRequestException)
  
          // Set the delegate function used to calculate the amount of time to 
          // wait between the retry attempts
          .WaitBetweenAttempts((attempt, exception) => TimeSpan.FromSeconds(5))
  
          // (optional) Set a callback delegate to invoke when the 
          // given operation is being re-executed
          .OnRetry((exception, attemptContext) => Console.WriteLine($"{attemptContext.CurrentAttempt}. retry attempt, waiting {attemptContext.CurrentDelay}"))));

• For operations with a return value

  // Create a new bot policy
  var policy = new BotPolicy<HttpResponseMessage>();
  
  // Configure the policy to retry failed operations
  policy.Configure(policyConfig => policyConfig
      .Retry(retryConfig => retryConfig
  
          // Set the maximum retry count
          .WithMaxAttemptCount(5)
  
          // Additionally you can set a predicate to decide
          // whether the result of the operation should be handled or not
          .WhenResultIs(result => result.StatusCode != HttpStatusCode.Ok)
  
          // Set the delegate function used to calculate the amount of time to wait 
          // between the retry attempts
          .WaitBetweenAttempts((attempt, result, exception) => TimeSpan.FromSeconds(5))
  
          // (optional) Set a callback delegate to invoke when the 
          // given operation is being re-executed
          .OnRetry((exception, result, attemptContext) => Console.WriteLine($"{attemptContext.CurrentAttempt}. retry attempt, waiting {attemptContext.CurrentDelay}, result was: {result}"))));

Available configuration options

• Same for policies with or without a return value

  • .WithMaxAttemptCount(int) - Sets the maximum number of retry attempts.
  • .RetryIndefinitely() - Sets the maximum number of retry attempts to int.MaxValue.
  • .WaitBetweenAttempts(Func<int, Exception, TimeSpan>) - Sets the delegate to calculate the wait time between the retry attempts.
  • .WhenExceptionOccurs(Func<Exception, bool>) - Sets the delegate to determine whether the given operation should be re-executed or not when a specific exception occurs.
  • .OnRetry(Action<Exception, AttemptContext>) - Sets the delegate to invoke when the given operation is being re-executed.
  • .OnRetryAsync(Func<Exception, AttemptContext, CancellationToken, Task>) - Sets the delegate which will be invoked asynchronously when the given operation is being re-executed.
  • .OnRetrySucceeded(Action<AttemptContext>) - Sets the delegate to invoke when the given operation is healed from re-execution.
  • .OnRetrySucceededAsync(Func<AttemptContext, CancellationToken, Task>) - Sets the delegate which will be invoked asynchronously when the given operation is healed from re-execution.
  • .OnRetryLimitReached(Action<Exception, ExecutionContext>) - Sets the delegate to invoke when the given maximum retry count reached.
  • .OnRetryLimitReachedAsync(Func<Exception, ExecutionContext, CancellationToken, Task>) - Sets the delegate to invoke asynchronously when the given maximum retry count reached.

• Only for policies with a return value

  • .WaitBetweenAttempts(Func<int, Exception, TResult, TimeSpan>) - Sets the delegate to calculate the wait time between the retry attempts.
  • .WhenResultIs(Func<TResult, bool>) - Sets the delegate to determine whether the given operation should be re-executed or not based on its return value.
  • .OnRetry(Action<TResult, Exception, AttemptContext>) - Sets the delegate to invoke when the given operation is being re-executed.
  • .OnRetryAsync(Func<TResult, Exception, AttemptContext, CancellationToken, Task>) - Sets the delegate to invoke asynchronously when the given operation is being re-executed.
  • .OnRetrySucceeded(Action<TResult, AttemptContext>) - Sets the delegate to invoke when the given operation is healed from re-execution.
  • .OnRetrySucceededAsync(Func<TResult, AttemptContext, CancellationToken, Task>) - Sets the delegate to invoke asynchronously when the given operation is healed from re-execution.

When the number of re-executions are reaching the configured maximum attempt count, the framework throws a custom MaxRetryAttemptsReachedException exception.