EonaCat.SmartRetry

EonaCat.SmartRetry is a powerful and flexible .NET library for building resilient applications.

It provides retry policies, circuit breakers, fallbacks, jittered backoff, async/sync support, and more

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Features

• Retry on exceptions or result conditions
• Configurable retry count and max retry duration
• Exponential, linear, or custom backoff strategies
• Jitter support to prevent thundering herd
• Circuit breaker with open, half-open, and closed states
• Sync and async fallback actions
• Retry with cancellation tokens
• Logging and async callbacks for retries and circuit breaker events
• Thread-safe for multi-threaded operations
• Named policies for reusable resilience configurations

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Installation

Install via NuGet:

dotnet add package EonaCat.SmartRetry

Or via Package Manager:

Install-Package EonaCat.SmartRetry

Usage Examples

Basic Retry with Fallback

using EonaCat.SmartRetry;

var policy = SmartRetryPolicy.Policy()
    .Handle<TimeoutException>()
    .Retry(3)
    .WithExponentialBackoff(1, 2)
    .WithFallbackAsync(async () =>
    {
        Console.WriteLine("Executing fallback...");
        await Task.Delay(50);

        // fallback value
        return 42; 
    });

int result = await policy.ExecuteAsync<int>(async () =>
{
    Console.WriteLine("Attempting operation...");
    await Task.Delay(50);
    throw new TimeoutException("Simulated failure");
});

// Outputs: 42
Console.WriteLine($"Result: {result}"); 

Retry with Circuit Breaker, Jitter, and Logging

var policy = SmartRetryPolicy.Policy()
    .Handle<TimeoutException>()
    .Retry(5)
    .WithExponentialBackoff(1, 2)
    .WithJitter(0.2)
    .WithCircuitBreaker(failureThreshold: 3, openDuration: TimeSpan.FromSeconds(10))
    .WithFallbackAsync(async () =>
    {
        Console.WriteLine("Executing fallback...");
        await Task.Delay(50);
        return -1;
    })
    .OnRetry((attempt, ex) => Console.WriteLine($"Retry {attempt}: {ex.Message}"))
    .OnCircuitOpen(() => Console.WriteLine("Circuit breaker opened"))
    .OnCircuitClose(() => Console.WriteLine("Circuit breaker closed"));

int result = await policy.ExecuteAsync<int>(async (ct) =>
{
    Console.WriteLine("Attempting operation...");
    await Task.Delay(50, ct);
    throw new TimeoutException("Simulated failure");
});

Console.WriteLine($"Result: {result}");

Retry Based on Result Condition

var policy = SmartRetryPolicy.Policy()
    .RetryIf<int>(value => value < 0) // retry if result is negative
    .Retry(3)
    .WithLinearBackoff(0.5)
    .WithFallback(() => 0);

int result = policy.Execute(() =>
{
    Console.WriteLine("Returning -1 to trigger retry...");
    return -1;
});

// Outputs: 0 (fallback)
Console.WriteLine($"Result: {result}"); 

Advanced Features

• Max Retry Duration: Stop retrying after a total duration.
• CancellationToken Support: Cancel retry loops gracefully.
• Custom Backoff Functions: Provide your own delay logic.
• Async Logging Hooks: Integrate with metrics or monitoring systems.
• Named Policies: Standardize retry/circuit-breaker behavior across your app.