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Cleanest way to write retry logic?

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旧巷少年郎
旧巷少年郎 2020-11-22 03:01

Occasionally I have a need to retry an operation several times before giving up. My code is like:

int retries = 3;
while(true) {
  try {
    DoSomething();
29条回答
  • 闹比i
    闹比i (楼主)
    2020-11-22 03:25

    Blanket catch statements that simply retry the same call can be dangerous if used as a general exception handling mechanism. Having said that, here's a lambda-based retry wrapper that you can use with any method. I chose to factor the number of retries and the retry timeout out as parameters for a bit more flexibility:

    public static class Retry
{
    public static void Do(
        Action action,
        TimeSpan retryInterval,
        int maxAttemptCount = 3)
    {
        Do(() =>
        {
            action();
            return null;
        }, retryInterval, maxAttemptCount);
    }

    public static T Do(
        Func action,
        TimeSpan retryInterval,
        int maxAttemptCount = 3)
    {
        var exceptions = new List();

        for (int attempted = 0; attempted < maxAttemptCount; attempted++)
        {
            try
            {
                if (attempted > 0)
                {
                    Thread.Sleep(retryInterval);
                }
                return action();
            }
            catch (Exception ex)
            {
                exceptions.Add(ex);
            }
        }
        throw new AggregateException(exceptions);
    }
}



    You can now use this utility method to perform retry logic:
    


    Retry.Do(() => SomeFunctionThatCanFail(), TimeSpan.FromSeconds(1));

    


    or:
    


    Retry.Do(SomeFunctionThatCanFail, TimeSpan.FromSeconds(1));

    


    or:
    


    int result = Retry.Do(SomeFunctionWhichReturnsInt, TimeSpan.FromSeconds(1), 4);

    


    Or you could even make an async overload.
    
    
    
             
    
                                                        
    
            
            
    
              
                
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