From 81318b00ea460d7bda809f7d4bad8ff82ae06ad2 Mon Sep 17 00:00:00 2001
From: Ryan <ryan.wang@clickview.com.au>
Date: Wed, 10 Apr 2024 15:21:48 +1000
Subject: [PATCH] just use Task.Delay() in conjunction with cron

---
 src/Hosting/Hosting/src/Workers/CronWorker.cs | 65 +++++++------------
 .../CronWorkerTests.cs                        |  4 --
 2 files changed, 24 insertions(+), 45 deletions(-)

diff --git a/src/Hosting/Hosting/src/Workers/CronWorker.cs b/src/Hosting/Hosting/src/Workers/CronWorker.cs
index b010843..e6e0fc4 100644
--- a/src/Hosting/Hosting/src/Workers/CronWorker.cs
+++ b/src/Hosting/Hosting/src/Workers/CronWorker.cs
@@ -6,13 +6,11 @@
 using Cronos;
 using Microsoft.Extensions.Logging;
 
-public abstract class CronWorker : Worker, IDisposable
+public abstract class CronWorker : Worker
 {
     private readonly ILogger _logger;
     private readonly Random _delayGenerator = new();
     private readonly CronWorkerOption? _option;
-    private Timer? _timer;
-    private CancellationTokenSource? _cancellationTokenSource;
 
     // Cron format: https://www.nuget.org/packages/Cronos/
     protected abstract string CronSchedule { get; }
@@ -28,42 +26,36 @@ protected CronWorker(CronWorkerOption option, ILogger logger) : base(logger)
         _logger = logger;
     }
 
-    protected override Task ExecuteAsync(CancellationToken cancellationToken)
+    protected override async Task ExecuteAsync(CancellationToken cancellationToken)
     {
-        var dueTime = GetNextScheduleDelay();
-        if (!dueTime.HasValue)
-            throw new Exception("Failed to get next schedule");
-
-        _cancellationTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken);
-        _timer = new Timer(_ => TimerCallbackAsync(_cancellationTokenSource.Token), null, dueTime.Value, Timeout.InfiniteTimeSpan);
+        while (!cancellationToken.IsCancellationRequested)
+        {
+            var dueTime = GetNextScheduleDelay();
+            if (!dueTime.HasValue)
+            {
+                _logger.LogWarning("Failed to get next schedule");
 
-        return Task.CompletedTask;
-    }
+                // Wait for a while before retrying
+                await Task.Delay(TimeSpan.FromSeconds(10), cancellationToken);
+                continue;
+            }
 
-    private async void TimerCallbackAsync(CancellationToken cancellationToken)
-    {
-        if (cancellationToken.IsCancellationRequested)
-            return;
+            try
+            {
+                await Task.Delay(dueTime.Value, cancellationToken);
+            }
+            catch (OperationCanceledException)
+            {
+                return;
+            }
 
-        try
-        {
-            await RunAsync(cancellationToken);
-        }
-        catch (Exception ex)
-        {
-            _logger.LogError(ex, "Unhandled exception caught in SchedulerWorker ({WorkerName})", Name);
-        }
-        finally
-        {
-            var dueTime = GetNextScheduleDelay();
-            if (dueTime.HasValue)
+            try
             {
-                // Reschedule the timer
-                _timer?.Change(dueTime.Value, Timeout.InfiniteTimeSpan);
+                await RunAsync(cancellationToken);
             }
-            else
+            catch (Exception ex)
             {
-                _logger.LogError("Unable to get the next schedule in SchedulerWorker ({WorkerName})", Name);
+                _logger.LogError(ex, "Unhandled exception caught in CronWorker ({WorkerName})", Name);
             }
         }
     }
@@ -87,14 +79,5 @@ private async void TimerCallbackAsync(CancellationToken cancellationToken)
         return delay.Add(extraDelay);
     }
 
-    public void Dispose()
-    {
-        _cancellationTokenSource?.Cancel();
-
-        // Stop the timer
-        _timer?.Change(Timeout.Infinite, 0);
-        _timer?.Dispose();
-    }
-
     protected abstract Task RunAsync(CancellationToken cancellationToken);
 }
diff --git a/src/Hosting/Hosting/test/ClickView.Extensions.Hosting.Tests/CronWorkerTests.cs b/src/Hosting/Hosting/test/ClickView.Extensions.Hosting.Tests/CronWorkerTests.cs
index c339ee7..f11f9f9 100644
--- a/src/Hosting/Hosting/test/ClickView.Extensions.Hosting.Tests/CronWorkerTests.cs
+++ b/src/Hosting/Hosting/test/ClickView.Extensions.Hosting.Tests/CronWorkerTests.cs
@@ -22,8 +22,6 @@ public async Task RunAsync_RunEveryTwoSeconds()
         await scheduler.StopAsync(CancellationToken.None);
 
         Assert.True(scheduler.Counter >= 2);
-
-        scheduler.Dispose();
     }
 
     [Fact]
@@ -52,8 +50,6 @@ public async Task RunAsync_RunEveryTwoSeconds_return()
 
         Assert.NotNull(scheduler.FirstExecutionTime);
         Assert.True(scheduler.FirstExecutionTime.Value - currentTime > TimeSpan.FromSeconds(2));
-
-        scheduler.Dispose();
     }
 
     public class TestScheduler : CronWorker