Retry Support¶

The new Retry support provides a robust mechanism for handling transient failures by retrying failed operations. This feature is implemented using the RetryPolicy attribute that can be applied to any class implementing the IJob interface.

How It Works¶

The RetryPolicy attribute allows you to specify the number of retry attempts and the strategy for handling retries. There are two built-in retry strategies: - ExponentialBackoff: Increases the delay between retry attempts exponentially. - FixedInterval: Keeps the delay between retry attempts consistent.

Using Retry Policies¶

Here are examples of how to use the built-in retry policies:

Example 1: Basic Retry Policy, defaults to Exponential Backoff¶

[RetryPolicy(retryCount: 4)]
public class RetryJob(ILogger<RetryJob> logger) : IJob
{
    public async Task RunAsync(JobExecutionContext context, CancellationToken token)
    {
        var attemptCount = context.Attempts;

        if (attemptCount <= 3)
        {
            logger.LogWarning("RetryJob simulating failure.");
            throw new InvalidOperationException("Simulated operation failure in RetryJob.");
        }

        logger.LogInformation($"RetryJob with Id {context.Id} was attempted {attemptCount} times.");
        await Task.CompletedTask;
    }
}

Example 2: Fixed Interval¶

[RetryPolicy(4, PolicyType.FixedInterval)]
public class FixedIntervalRetryJob(ILogger<FixedIntervalRetryJob> logger) : IJob
{
    public async Task RunAsync(JobExecutionContext context, CancellationToken token)
    {
        var attemptCount = context.Attempts;

        if (attemptCount <= 3)
        {
            logger.LogWarning("FixedIntervalRetryJob simulating failure.");
            throw new InvalidOperationException("Simulated operation failure in FixedIntervalRetryJob.");
        }

        logger.LogInformation($"FixedIntervalRetryJob with Id {context.Id} was attempted {attemptCount} times.");
        await Task.CompletedTask;
    }
}

Advanced: Custom Retry Policies¶

You can also create custom retry policies by implementing the IPolicyCreator interface. This allows you to define complex retry logic tailored to your specific needs.

[RetryPolicy<MyCustomPolicyCreator>(retryCount:4, delayFactor:1)]
public class CustomPolicyJob(ILogger<CustomPolicyJob> logger) : IJob
{
    public async Task RunAsync(JobExecutionContext context, CancellationToken token)
    {
        var attemptCount = context.Attempts;

        if (attemptCount <= 3)
        {
            logger.LogWarning("FixedIntervalRetryJob simulating failure.");
            throw new InvalidOperationException("Simulated operation failure in FixedIntervalRetryJob.");
        }

        logger.LogInformation($"CustomPolicyJob with Id {context.Id} was attempted {attemptCount} times.");
        await Task.CompletedTask;
    }
}

public class MyCustomPolicyCreator : IPolicyCreator
{
    public IAsyncPolicy CreatePolicy(int maxRetryAttempts = 3, double delayFactor = 2)
    {
        return Policy.Handle<Exception>()
            .WaitAndRetryAsync(maxRetryAttempts,
                retryAttempt => TimeSpan.FromSeconds(Math.Pow(delayFactor, retryAttempt)));
    }
}