RenderingHostBatchingCacheClearer.cs

namespace Discovering.Sitecore10.Processors.PublishEnd.Services
{
    public class RenderingHostBatchingCacheClearer
    {
        private readonly HttpClient _httpClient;
        private readonly object _lock = new object();
        private readonly Timer _timer;
        private readonly HashSet<string> _endpoints = new HashSet<string>();

        public RenderingHostBatchingCacheClearer(TimeSpan batchingTimeout, HttpClient httpClient)
        {
            _httpClient = httpClient;
            _timer = new Timer(batchingTimeout.TotalMilliseconds)
            {
                AutoReset = false,
                Enabled = false
            };
            _timer.Elapsed += (s, a) => { TriggerCacheClear(); };
        }

        public void AddEndpoints(IEnumerable<string> endpoints)
        {
            if (endpoints == null || !endpoints.Any())
                return;

            lock (_lock)
                foreach (var endpoint in endpoints)
                    _endpoints.Add(endpoint);

            _timer.Stop();
            _timer.Start();
        }

        public int GetEndPointsCount()
        {
            lock (_lock)
                return _endpoints.Count;
        }

        private async void TriggerCacheClear()
        {
            string[] endpoints;
            lock (_lock)
            {
                if (_endpoints.Count == 0)
                    return;

                endpoints = _endpoints.ToArray();
            }

            foreach (var endpoint in endpoints)
            {
                try
                {
                    var response = await _httpClient.GetAsync(endpoint);
                    if (!response.IsSuccessStatusCode)
                        continue;
                }
                catch (Exception e)
                {
                    Log.Error(e.Message, e, this);
                }
                finally
                {
                    // remove items from the list if calling the endpoint returned with successful status or exception happened
                    lock (_lock)
                        _endpoints.Remove(endpoint);
                }
            }
        }
    }
}