🔄Retry Utility

Summary

Collection of methods that are intended to allow operations to be retried when an exception occurs or an unexpected result is reached.

RetryOnExceptionAsync

Description

Method that will retry an operation if an exception is caught. If no exception is caught, the method will return the result.

Parameters

Func<Task<T>> function

Generic function that will be executed and awaited by the method

int maxRetries

Maximum number of times function will be executed. Defaults to 5.

int[]? backoffTimes

Optional array of times in milliseconds that the thread will sleep between executions of the function. May be any size, but if larger than maxRetries the extra times will be ignored.

Exceptions

ArgumentNullException

Thrown when function is not provided

RetryUtilityException

Thrown when maxRetries is met with the failure as the innerException

Examples

Simple

This example risks throwing an exception back to the caller and will retry a maximum of 5 times.

using Mg3.Utility.RetryUtility;
using System.Net.Http;

async Task<string> GetStringAsync()
{
    var myString = await new GetRemoteStringAsync();
    
    return !myString.IsNullOrWhitespace() ? myString : "No string";
}

async Task<string> DoThing()
{
    var result = await RetryUtility.RetryOnExceptionAsync<string>(GetStringAsync);
    
    return $"Here is my string: {result}";
}

Advanced

This example configures the retry function to retry 2 times and back off 1 and 2 seconds between each retry.

using Mg3.Utility.RetryUtility;
using System.Net.Http;

async Task<string> GetStringAsync()
{
    var myString = await GetRemoteStringAsync();
    
    return !myString.IsNullOrWhitespace() ? myString : "No string";
}

async Task<string> DoThing()
{
    try
    {
        var result = await RetryUtility.RetryOnExceptionAsync<string>(GetStringAsync, 2, new int[] { 1000, 2000 });
        
        return $"Here is my string: {result}";
    }
    catch (RetryUtility.RetryUtilityException e)
    {
        if (e.InnerException is HttpRequestException)
            return "";
        else
            throw e.InnerException;
    }
}

Notice how the RetryUtilityException allows for you to catch only the failure from the final retry. This allows you to decide what to do based on the type of exception thrown.

RetryUtilityException

Description

Basic exception that is thrown by the RetryUtility. It inherits from and implements System.Exception.

Properties

bool WasThrownFromRetry

Set to true when the exception is thrown while retrying the operation requested by the user.

bool WasThrownOnFinalRetry

Set to true when the exception is the result from a failure on the final retry of the operation requested by the user.

Tips

• Use InnerException to perform different operations based on the failure of your operation

• It may not be useful to allow this exception type to bubble up outside of the context where a RetryUtility function is called.