RetryPolicy.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
 
namespace NeuroAccessMaui.UI.MVVM.Policies
{
sealed class RetryPolicy : IAsyncPolicy
{
    private readonly int max;
    private readonly Func<int, Exception, TimeSpan> delay;
    private readonly Action<int, Exception, TimeSpan>? onRetry;
    private readonly Func<Exception, bool>? shouldRetry;
 
    public RetryPolicy(int maxAttempts, Func<int, Exception, TimeSpan> delayProvider, Action<int, Exception, TimeSpan>? cb, Func<Exception, bool>? shouldRetry = null)
    {
        this.max = Math.Max(1, maxAttempts);
        this.delay = delayProvider;
        this.onRetry = cb;
        this.shouldRetry = shouldRetry;
    }
 
        public async Task ExecuteAsync(Func<CancellationToken, Task> action, CancellationToken ct)
        {
            for (int Attempt = 1; ; Attempt++)
            {
                try { await action(ct); return; }
                catch (OperationCanceledException) when (ct.IsCancellationRequested) { throw; }
            catch (Exception Ex) when (Attempt < this.max && (this.shouldRetry?.Invoke(Ex) ?? true))
            {
                TimeSpan Wait = this.delay(Attempt, Ex);
                this.onRetry?.Invoke(Attempt, Ex, Wait);
                await Task.Delay(Wait, ct);
            }
        }
    }
 
    public async Task<T> ExecuteAsync<T>(Func<CancellationToken, Task<T>> action, CancellationToken ct)
    {
        for (int Attempt = 1; ; Attempt++)
        {
            try { return await action(ct).ConfigureAwait(false); }
            catch (OperationCanceledException) when (ct.IsCancellationRequested) { throw; }
            catch (Exception Ex) when (Attempt < this.max && (this.shouldRetry?.Invoke(Ex) ?? true))
            {
                TimeSpan Wait = this.delay(Attempt, Ex);
                this.onRetry?.Invoke(Attempt, Ex, Wait);
                await Task.Delay(Wait, ct).ConfigureAwait(false);
            }
        }
    }
}
}