Incendium.RetryPolicy 1.0.0

Incendium

Incendium is a small set of useful cross-platform .NET standard 2.1 libraries for .NET developers.

Getting started

Installation

PM> Install-Package Incendium.Result PM> Install-Package Incendium.RetryPolicy

Result<T> and NullableResult<T>

The method can be synchronous or asynchronous and can return a value without explicitly creating a Result<T> type:

public async Result<string> GetStringAsync() {
    // ...
    if (condition1) {
        return "Test string result";
    } else {
        return new Error(code: 123, message: "Test error");
    }

    try {
        // ...
    } catch (Exception e) {
        return new Error(code: 321, message: "Test error", exception: e);
    }
}

Then processing the result might look like this:

var (str, error) = await GetStringAsync();

if (error != null) {
    log.LogError(
        error.Exception(),
        "Error with code {@code} and message {@message}",
        error.Code(),
        error.Message());
}

RetryHttpClientHandler

Сan be used as a handler for HttpClient and allows you to easily (compared to Polly) set up repeated requests in the following cases:

• HttpNetworkException
• Server errors (5xx)
• Request timeout error (408)
• Too many requests (429)

and also allows you to configure rate limiting with exponential delays for outgoing requests using RateGate:

var innerHttpClientHandler = new HttpClientHandler(); // can be easily mocked
var retryHttpClientHandler = new RetryHttpClientHandler(innerHttpClientHandler)
{
    RetryCount = 5, // sets 5 retry attempts
    RetryOnHttpRequestException = true, // sets the retry flag in case of an HttpRequestException
    FirstRetryDelay = TimeSpan.FromMilliseconds(100), // sets the median starting delay between requests
    RateGate = new RateGate(
        occurrences: 10, // sets rate limit to 10 request per 60 seconds
        timeUnit: TimeSpan.FromSeconds(60))
}
var httpClient = new HttpClient(retryHttpClientHandler);

There are several ready-made delay algorithms that can be used:

• Constant
• Exponential
• DecorrelatedJitterBackoffV2 (default)

var retryHttpClientHandler = new RetryHttpClientHandler(innerHttpClientHandler)
{
    RetryDelaysFactory = () => Delays.Exponential(
        firstDelay: TimeSpan.FromMilliseconds(100),
        count: 10)
}

You can also pass your own delay algorithm in the RetryDelaysFactory property, which should return IEnumerable<TimeSpan>.