C# Polly WaitAndRetry 函数重试策略

Question

I'm very new to C# coding and I just want to know how to setup polly WaitAndRetry for my function if it failed. Following is my steps

1. I installed package Install-Package Polly, using NuGet package

2. added using polly in my code.

3. Below is my code

   try { SendToDatabase(model)); await Policy.Handle<Exception>().RetryAsync(NUMBER_OF_RETRIES).ExecuteAsync(async()=>await SendToDatabase(model)).ConfigureAwait(false); } Catch(Exception e) { _log.write("error occurred"); } public async Task<strig> SendToDataBase(config model) { var ss = DataBase.PostCallAsync(model).GetAwaiter().GetResult(); return ss; }

But this call is continuously calling without any delay. I tried to use WaitAndRetryAsync in catch call but it's not working.WaitAndRetryAsync accepts only HTTP repose message. I want to implement ait and retry option in try-catch

Answer 1

You say you want WaitAndRetry but you don't use that function... And it doesn't only work with HttpResponse. Please read the documentation .

The code below should give you a head start:

class Program
{
    static async Task Main(string[] args)
    {
        // define the policy using WaitAndRetry (try 3 times, waiting an increasing numer of seconds if exception is thrown)
        var policy = Policy
          .Handle<Exception>()
          .WaitAndRetryAsync(new[]
          {
            TimeSpan.FromSeconds(1),
            TimeSpan.FromSeconds(2),
            TimeSpan.FromSeconds(3)
          });

        // execute the policy
        await policy.ExecuteAsync(async () => await SendToDatabase());

    }

    static async Task SendToDatabase()
    {
        Console.WriteLine("trying to send to database");
        await Task.Delay(100);
        throw new Exception("it failed!");
    }
}

Answer 2

class Program
{
    static Main(string[] args)
    {
        // define the policy using WaitAndRetry (try 3 times, waiting an increasing numer of seconds if exception is thrown)
        var policy = Policy
          .Handle<Exception>()
          .WaitAndRetry(new[]
          {
            TimeSpan.FromSeconds(1),
            TimeSpan.FromSeconds(2),
            TimeSpan.FromSeconds(3)
          });

        // execute the policy
         policy.Execute(() =>  SendToDatabase());

    }
}