Fixes: U4-581 Automatic publishing not working in load balanced setup - added some more convention and configuration to distributed calls so that servers are aware of the master and how to call into themselves for scheduled tasks, ping and scheduled publishing. Will need to update the docs on LB regarding this too. Cleaned up the code that does the scheduling and separates it into proper segments. Obsoletes the old presentation classes that were doing it.

src/Umbraco.Web/Scheduling/Scheduler.cs

@@ -0,0 +1,82 @@
+using System.Threading;
+using Umbraco.Core;
+using Umbraco.Core.Sync;
+
+namespace Umbraco.Web.Scheduling
+{
+    /// <summary>
+    /// Used to do the scheduling for tasks, publishing, etc...
+    /// </summary>
+    /// <remarks>
+    /// 
+    /// TODO: Much of this code is legacy and needs to be updated, there are a few new/better ways to do scheduling
+    /// in a web project nowadays. 
+    /// 
+    /// </remarks>
+	internal sealed class Scheduler : ApplicationEventHandler
+	{
+		private Timer _pingTimer;
+		private Timer _schedulingTimer;
+        private LogScrubber _scrubber;
+
+        protected override void ApplicationStarted(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
+        {
+            if (umbracoApplication.Context == null)
+                return;
+
+			// time to setup the tasks
+
+			// these are the legacy tasks
+			// just copied over here for backward compatibility
+			// of course we should have a proper scheduler, see #U4-809
+
+			// ping/keepalive
+            _pingTimer = new Timer(KeepAlive.Start, applicationContext, 60000, 300000);
+
+			// scheduled publishing/unpublishing
+            
+            _schedulingTimer = new Timer(PerformScheduling, applicationContext, 30000, 60000);
+            
+            //log scrubbing
+            _scrubber = new LogScrubber();
+            _scrubber.Start();
+		}
+
+        /// <summary>
+        /// This performs all of the scheduling on the one timer
+        /// </summary>
+        /// <param name="sender"></param>
+        /// <remarks>
+        /// No processing will be done if this server is a slave
+        /// </remarks>
+        private static void PerformScheduling(object sender)
+        {
+
+            //get the current server status to see if this server should execute the scheduled publishing
+            var serverStatus = ServerEnvironmentHelper.GetStatus();
+
+            switch (serverStatus)
+            {
+                case CurrentServerEnvironmentStatus.Single:
+                case CurrentServerEnvironmentStatus.Master:
+                case CurrentServerEnvironmentStatus.Unknown:
+                    //if it's a single server install, a master or it cannot be determined 
+                    // then we will process the scheduling
+                    
+                    //do the scheduled publishing
+                    var scheduledPublishing = new ScheduledPublishing();
+                    scheduledPublishing.Start(sender);
+
+                    //do the scheduled tasks
+                    var scheduledTasks = new ScheduledTasks();
+                    scheduledTasks.Start(sender);
+
+                    break;
+                case CurrentServerEnvironmentStatus.Slave:                
+                    //do not process
+                    break;
+            }            
+        }
+
+	}
+}