TriggerRenderingHostCacheClear.cs

namespace Discovering.Sitecore10.Processors.PublishEnd
{
    public class Tenant
    {
        public Tenant(string startPath, IEnumerable<string> endpoints)
        {
            this.StartPath = startPath;
            this.Endpoints = endpoints;
        }

        public string StartPath { get; set; }
        public IEnumerable<string> Endpoints { get; set; }
    }

    public class TriggerRenderingHostCacheClear
    {
        private readonly RenderingHostBatchingCacheClearer _batchedSender;
        private const string TenantsConfigNodePath = "RenderingHostCacheClear.Tenants/Tenant";
        private readonly IEnumerable<Tenant> _tenants;

        public TriggerRenderingHostCacheClear()
        {
            // NOTE: use DI for HttpClient, though the event is singleton
            _batchedSender = new RenderingHostBatchingCacheClearer(TimeSpan.FromSeconds(3), new HttpClient());
            _tenants = this.GetTenants();
        }

        public void OnItemPublished(object sender, EventArgs args)
        {
            var itemProcessedEventArgs = args as ItemProcessedEventArgs;
            var context = itemProcessedEventArgs?.Context;
            if ((context.PublishContext?.DeleteCandidates?.Count ?? 0) > 0 && _batchedSender.GetEndPointsCount() <= 0)
            {
                _batchedSender.AddEndpoints(
                    this.GetTenantByItemPath(context.PublishOptions.RootItem.Paths.FullPath)?.Endpoints);
            }

            if (context.Result.Operation == PublishOperation.None || context.Result.Operation == PublishOperation.Skipped)
                return;

            _batchedSender.AddEndpoints(this.GetTenantByItemPath(context.VersionToPublish.Paths.FullPath)?.Endpoints);
        }

        private IEnumerable<Tenant> GetTenants()
        {
            return Factory
                .GetConfigNodes(TenantsConfigNodePath)
                ?.Cast<XmlNode>()
                ?.Select(x => new Tenant(
                    XmlUtil.GetAttribute("startPath", x),
                    x.ChildNodes.Cast<XmlNode>().Select(e => e.InnerText)));
        }

        private Tenant GetTenantByItemPath(string itemPath)
        {
            return _tenants?.FirstOrDefault(t => 
                itemPath.Equals(t.StartPath, StringComparison.CurrentCultureIgnoreCase)
                || itemPath.StartsWith(t.StartPath + "/", StringComparison.CurrentCultureIgnoreCase));
        }
    }
}