Fixed continuously triggering tasks in timezones ahead of UTC. (#152)

Author: JuusoSuominen

MFiles.VAF.Extensions.Tests/Configuration/ScheduledExecution/DailyTriggerTests.cs

@@ -154,6 +154,27 @@ public static IEnumerable<object[]> GetNextExecutionData()
 				new DateTimeOffset(2024, 04, 17, 10, 00, 00, TimeSpan.Zero), // Wednesday @ 10am
 				TimeZoneInfo.Utc,
 			};
+
+			// Regression: Positive UTC offset (UTC+8) where trigger time just passed.
+			// When the server is at UTC+8, 02:01 local = 18:01 UTC (previous day).
+			// The next execution should be the NEXT day, not immediate re-trigger.
+			var sgTimezone = TimeZoneInfo.FindSystemTimeZoneById("Singapore Standard Time");
+			yield return new object[]
+			{
+				new []{ new TimeSpan(2, 0, 0) }, // Trigger at 02:00 local
+				new DateTimeOffset(2024, 04, 17, 2, 01, 00, TimeSpan.FromHours(8)), // 02:01 SGT (= 16 Apr 18:01 UTC)
+				new DateTimeOffset(2024, 04, 18, 2, 00, 00, TimeSpan.FromHours(8)), // Next day 02:00 SGT
+				sgTimezone,
+			};
+
+			// Regression: Positive UTC offset (UTC+8) where trigger time is still ahead today.
+			yield return new object[]
+			{
+				new []{ new TimeSpan(10, 0, 0) }, // Trigger at 10:00 local
+				new DateTimeOffset(2024, 04, 17, 2, 00, 00, TimeSpan.FromHours(8)), // 02:00 SGT (= 16 Apr 18:00 UTC)
+				new DateTimeOffset(2024, 04, 17, 10, 00, 00, TimeSpan.FromHours(8)), // Same day 10:00 SGT
+				sgTimezone,
+			};
 		}
 	}
 }

MFiles.VAF.Extensions.Tests/Configuration/ScheduledExecution/ScheduleTests.cs

@@ -383,6 +383,69 @@ public static IEnumerable<object[]> GetNextExecutionData_AusEastern()
 			};
 		}
 
+		[TestMethod]
+		[DynamicData(nameof(GetNextExecutionData_Singapore), DynamicDataSourceType.Method)]
+		public void GetNextExecution_Singapore
+		(
+			IEnumerable<TriggerBase> triggers,
+			DateTime? after,
+			DateTime? expected
+		)
+		{
+			var execution = new Schedule()
+			{
+				Enabled = true,
+				Triggers = triggers
+						.Select(t => new Trigger(t))
+						.Where(t => t != null)
+						.ToList(),
+				TriggerTimeType = TriggerTimeType.Custom,
+				TriggerTimeCustomTimeZone = "Singapore Standard Time"
+			}.GetNextExecution(after);
+			Assert.AreEqual(expected?.ToUniversalTime(), execution?.ToUniversalTime());
+		}
+
+		/// <summary>
+		/// Returns data for a high positive UTC offset (UTC+8) where the UTC day differs from local day.
+		/// Regression test: ensures trigger time just passed does not cause immediate re-trigger.
+		/// </summary>
+		public static IEnumerable<object[]> GetNextExecutionData_Singapore()
+		{
+			// Trigger at 02:00 SGT, current time is 02:01 SGT (= 18:01 UTC previous day).
+			// Next execution should be tomorrow at 02:00 SGT, NOT immediate.
+			yield return new object[]
+			{
+				new TriggerBase[]
+				{
+					new DailyTrigger(){
+						TriggerTimes = new List<TimeSpan>()
+						{
+							new TimeSpan(2, 0, 0)
+						}.ToList()
+					}
+				},
+				new DateTime(2024, 04, 16, 18, 01, 00, DateTimeKind.Utc), // 02:01 SGT on 17th = 18:01 UTC on 16th
+				new DateTime(2024, 04, 17, 18, 00, 00, DateTimeKind.Utc), // 02:00 SGT on 18th = 18:00 UTC on 17th
+			};
+
+			// Trigger at 10:00 SGT, current time is 02:00 SGT (= 18:00 UTC previous day).
+			// Next execution should be today at 10:00 SGT.
+			yield return new object[]
+			{
+				new TriggerBase[]
+				{
+					new DailyTrigger(){
+						TriggerTimes = new List<TimeSpan>()
+						{
+							new TimeSpan(10, 0, 0)
+						}.ToList()
+					}
+				},
+				new DateTime(2024, 04, 16, 18, 00, 00, DateTimeKind.Utc), // 02:00 SGT on 17th = 18:00 UTC on 16th
+				new DateTime(2024, 04, 17, 02, 00, 00, DateTimeKind.Utc), // 10:00 SGT on 17th = 02:00 UTC on 17th
+			};
+		}
+
 		/// <summary>
 		/// Returns data for a high UTC offset where the trigger times are the next day in UTC.
 		/// </summary>

MFiles.VAF.Extensions/Configuration/ScheduledExecution/DailyTrigger.cs

@@ -59,8 +59,7 @@ public DailyTrigger()
 			timeZoneInfo = timeZoneInfo ?? TimeZoneInfo.Local;
 
 			// When should we start looking?
-			var before = (after ?? DateTime.UtcNow);
-			after = before.ToUniversalTime();
+			after = (after ?? DateTime.UtcNow).ToUniversalTime();
 
 			// Convert the time into the timezone we're after.
 			after = TimeZoneInfo.ConvertTime(after.Value, timeZoneInfo);
@@ -74,12 +73,7 @@ public DailyTrigger()
 						// What is the potential time that this will run?
 						DateTimeOffset potential;
 						{
-							// If the timezone conversion changed the date then go back to the start of the date.
-							var date = after.Value.Date;
-							if (after.Value.Date != before.Date)
-								date = new DateTime(before.Date.Ticks);
-
-							var dateTime = date.Add(t);
+							var dateTime = after.Value.Date.Add(t);
 							potential = new DateTimeOffset(dateTime, timeZoneInfo.GetUtcOffset(dateTime));
 						}
 

MFiles.VAF.Extensions/Configuration/ScheduledExecution/DayOfMonthTrigger.cs

@@ -89,6 +89,7 @@ public DayOfMonthTrigger()
 				(
 					d => GetNextDayOfMonth(after.Value, d, this.UnrepresentableDateHandling)
 				)
+				.Select(d => new DateTimeOffset(d.DateTime, timeZoneInfo.GetUtcOffset(d.DateTime)))
 				.Select
 				(
 					d => new DailyTrigger() { Type = ScheduleTriggerType.Daily, TriggerTimes = this.TriggerTimes }

MFiles.VAF.Extensions/Configuration/ScheduledExecution/WeeklyTrigger.cs

@@ -65,6 +65,7 @@ public WeeklyTrigger()
 			// Get the next execution time (this will not find run times today).
 			var potentialMatches = this.TriggerDays
 				.SelectMany(d => GetNextDayOfWeek(after.Value, d))
+				.Select(d => new DateTimeOffset(d.DateTime, timeZoneInfo.GetUtcOffset(d.DateTime)))
 				.Select
 				(
 					d => new DailyTrigger() { Type = ScheduleTriggerType.Daily, TriggerTimes = this.TriggerTimes }