rework scheduled tasks in preparation of common project going portable

MediaBrowser.Common.Implementations/ScheduledTasks/IntervalTrigger.cs

@@ -0,0 +1,112 @@
+using MediaBrowser.Model.Events;
+using MediaBrowser.Model.Tasks;
+using System;
+using System.Linq;
+using System.Threading;
+using MediaBrowser.Model.Logging;
+
+namespace MediaBrowser.Common.ScheduledTasks
+{
+    /// <summary>
+    /// Represents a task trigger that runs repeatedly on an interval
+    /// </summary>
+    public class IntervalTrigger : ITaskTrigger
+    {
+        /// <summary>
+        /// Gets or sets the interval.
+        /// </summary>
+        /// <value>The interval.</value>
+        public TimeSpan Interval { get; set; }
+
+        /// <summary>
+        /// Gets or sets the timer.
+        /// </summary>
+        /// <value>The timer.</value>
+        private Timer Timer { get; set; }
+
+        /// <summary>
+        /// Gets the execution properties of this task.
+        /// </summary>
+        /// <value>
+        /// The execution properties of this task.
+        /// </value>
+        public TaskExecutionOptions TaskOptions { get; set; }
+
+        private DateTime _lastStartDate;
+
+        /// <summary>
+        /// Stars waiting for the trigger action
+        /// </summary>
+        /// <param name="lastResult">The last result.</param>
+        /// <param name="isApplicationStartup">if set to <c>true</c> [is application startup].</param>
+        public void Start(TaskResult lastResult, ILogger logger, string taskName, bool isApplicationStartup)
+        {
+            DisposeTimer();
+
+            DateTime triggerDate;
+
+            if (lastResult == null)
+            {
+                // Task has never been completed before
+                triggerDate = DateTime.UtcNow.AddHours(1);
+            }
+            else
+            {
+                triggerDate = new[] { lastResult.EndTimeUtc, _lastStartDate }.Max().Add(Interval);
+            }
+
+            if (DateTime.UtcNow > triggerDate)
+            {
+                triggerDate = DateTime.UtcNow.AddMinutes(1);
+            }
+
+            var dueTime = triggerDate - DateTime.UtcNow;
+            var maxDueTime = TimeSpan.FromDays(7);
+
+            if (dueTime > maxDueTime)
+            {
+                dueTime = maxDueTime;
+            }
+
+            Timer = new Timer(state => OnTriggered(), null, dueTime, TimeSpan.FromMilliseconds(-1));
+        }
+
+        /// <summary>
+        /// Stops waiting for the trigger action
+        /// </summary>
+        public void Stop()
+        {
+            DisposeTimer();
+        }
+
+        /// <summary>
+        /// Disposes the timer.
+        /// </summary>
+        private void DisposeTimer()
+        {
+            if (Timer != null)
+            {
+                Timer.Dispose();
+            }
+        }
+
+        /// <summary>
+        /// Occurs when [triggered].
+        /// </summary>
+        public event EventHandler<GenericEventArgs<TaskExecutionOptions>> Triggered;
+
+        /// <summary>
+        /// Called when [triggered].
+        /// </summary>
+        private void OnTriggered()
+        {
+            DisposeTimer();
+
+            if (Triggered != null)
+            {
+                _lastStartDate = DateTime.UtcNow;
+                Triggered(this, new GenericEventArgs<TaskExecutionOptions>(TaskOptions));
+            }
+        }
+    }
+}