Joseph Doherty
81 lines
3.0 KiB
C#
81 lines
3.0 KiB
C#
using ZB.MOM.WW.ScadaBridge.SiteRuntime;
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using ZB.MOM.WW.ScadaBridge.SiteRuntime.Scripts;
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namespace ZB.MOM.WW.ScadaBridge.SiteRuntime.Tests.Scripts;
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/// <summary>
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/// SiteRuntime-009: the dedicated script-execution scheduler must run script bodies on
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/// its own dedicated threads, not on the shared .NET thread pool, so blocking script
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/// I/O cannot starve the global pool.
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/// </summary>
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public class ScriptExecutionSchedulerTests
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{
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[Fact]
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public async Task Scheduler_RunsWork_OffTheThreadPool()
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{
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using var scheduler = new ScriptExecutionScheduler(2);
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bool wasThreadPoolThread = true;
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string? threadName = null;
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await Task.Factory.StartNew(() =>
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{
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wasThreadPoolThread = Thread.CurrentThread.IsThreadPoolThread;
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threadName = Thread.CurrentThread.Name;
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}, CancellationToken.None, TaskCreationOptions.DenyChildAttach, scheduler);
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Assert.False(wasThreadPoolThread,
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"Script work must not run on a shared thread-pool thread.");
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Assert.StartsWith("script-execution-", threadName);
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}
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[Fact]
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public void Scheduler_RespectsConfiguredThreadCount()
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{
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using var scheduler = new ScriptExecutionScheduler(4);
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Assert.Equal(4, scheduler.MaximumConcurrencyLevel);
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}
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[Fact]
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public void Scheduler_Shared_ReturnsSameInstanceForOptions()
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{
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var options = new SiteRuntimeOptions { ScriptExecutionThreadCount = 3 };
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var a = ScriptExecutionScheduler.Shared(options);
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var b = ScriptExecutionScheduler.Shared(options);
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Assert.Same(a, b);
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}
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// SiteRuntime-S2/UA5: the scheduler exposes observability gauges so a stuck /
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// saturated script-execution pool is visible to operators via site health.
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[Fact]
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public async Task Gauges_ReflectBusyThreadAndQueueDepth()
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{
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using var scheduler = new ScriptExecutionScheduler(1);
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using var gate = new ManualResetEventSlim(false);
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var blocking = Task.Factory.StartNew(() => gate.Wait(),
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CancellationToken.None, TaskCreationOptions.None, scheduler);
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var queued = Task.Factory.StartNew(() => { },
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CancellationToken.None, TaskCreationOptions.None, scheduler);
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await WaitUntilAsync(() => scheduler.BusyThreadCount == 1);
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Assert.Equal(1, scheduler.QueueDepth); // second task waiting
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// A busy thread reports a non-null age. Not asserting a strictly-positive
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// value: Environment.TickCount64 has ~15 ms granularity, so under load the
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// busy-timestamp and this read can fall in the same tick (age == Zero).
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Assert.NotNull(scheduler.OldestBusyAge);
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gate.Set();
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await Task.WhenAll(blocking, queued);
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await WaitUntilAsync(() => scheduler.BusyThreadCount == 0);
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Assert.Null(scheduler.OldestBusyAge);
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}
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private static async Task WaitUntilAsync(Func<bool> condition)
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{
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for (var i = 0; i < 100 && !condition(); i++)
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await Task.Delay(50);
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Assert.True(condition(), "condition not met within timeout");
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}
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}
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