perf(adminui): coalesce /script-log and /alerts renders with a ring buffer (R04 P7)
Each received event used to Insert(0) into a List and render the full page. LiveTailBuffer queues events from the bridge thread into a bounded newest-first ring; CoalescingRenderScheduler (TimeProvider-driven, drained on dispose) flushes and renders at most once per 200 ms window. ScriptLog's filtered rows are recomputed on flush/filter change instead of three times per render. Refs #745 Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
This commit is contained in:
Joseph Doherty
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using Shouldly;
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using Xunit;
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using ZB.MOM.WW.OtOpcUa.AdminUI.LiveTail;
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namespace ZB.MOM.WW.OtOpcUa.AdminUI.Tests.LiveTail;
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/// <summary>
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/// R04 P7: the live-tail pages coalesce event bursts into one render per window and keep their rows
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/// in a bounded ring. All timing here is driven by a manual <see cref="TimeProvider"/>, so nothing
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/// depends on wall-clock scheduling.
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/// </summary>
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[Trait("Category", "Unit")]
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public sealed class LiveTailTests
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{
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[Fact]
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public void Buffer_items_are_newest_first_and_only_change_on_flush()
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{
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var buffer = new LiveTailBuffer<int>(capacity: 3);
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buffer.Add(1).ShouldBeTrue(); // first pending ⇒ caller schedules
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buffer.Add(2).ShouldBeFalse(); // already pending ⇒ no second schedule
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buffer.Items.ShouldBeEmpty(); // not visible until flush
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buffer.Flush().ShouldBeTrue();
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buffer.Items.ShouldBe([2, 1]);
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buffer.Flush().ShouldBeFalse(); // nothing queued ⇒ no render worth doing
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}
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[Fact]
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public void Buffer_evicts_the_oldest_past_capacity()
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{
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var buffer = new LiveTailBuffer<int>(capacity: 3);
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for (var i = 1; i <= 5; i++) buffer.Add(i);
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buffer.Flush();
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buffer.Items.ShouldBe([5, 4, 3]);
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buffer.Add(6);
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buffer.Flush();
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buffer.Items.ShouldBe([6, 5, 4]);
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}
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[Fact]
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public void Buffer_Clear_drops_retained_and_pending_items()
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{
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var buffer = new LiveTailBuffer<int>(capacity: 3);
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buffer.Add(1);
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buffer.Flush();
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buffer.Add(2);
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buffer.Clear();
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buffer.Items.ShouldBeEmpty();
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buffer.Flush().ShouldBeFalse();
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// Positive control: the buffer still works after a clear, and the next add re-arms scheduling.
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buffer.Add(3).ShouldBeTrue();
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buffer.Flush();
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buffer.Items.ShouldBe([3]);
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}
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[Fact]
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public async Task Scheduler_runs_one_flush_per_window_for_a_burst()
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{
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var time = new ManualTimeProvider();
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var flushes = 0;
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await using var scheduler = new CoalescingRenderScheduler(
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TimeSpan.FromMilliseconds(200), () => { flushes++; return Task.CompletedTask; }, time);
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for (var i = 0; i < 100; i++) scheduler.Schedule();
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flushes.ShouldBe(0);
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time.Advance(TimeSpan.FromMilliseconds(199));
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flushes.ShouldBe(0);
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time.Advance(TimeSpan.FromMilliseconds(1));
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flushes.ShouldBe(1);
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// The window re-arms after a fire: a later burst gets exactly one more flush.
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scheduler.Schedule();
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scheduler.Schedule();
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time.Advance(TimeSpan.FromMilliseconds(200));
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flushes.ShouldBe(2);
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}
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[Fact]
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public async Task Scheduler_does_not_flush_after_dispose()
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{
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var time = new ManualTimeProvider();
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var flushes = 0;
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var scheduler = new CoalescingRenderScheduler(
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TimeSpan.FromMilliseconds(200), () => { flushes++; return Task.CompletedTask; }, time);
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// Positive control: the scheduler does flush before dispose.
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scheduler.Schedule();
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time.Advance(TimeSpan.FromMilliseconds(200));
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flushes.ShouldBe(1);
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scheduler.Schedule();
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await scheduler.DisposeAsync();
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time.Advance(TimeSpan.FromMilliseconds(500));
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flushes.ShouldBe(1);
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Should.NotThrow(scheduler.Schedule);
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}
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[Fact]
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public async Task Scheduler_swallows_a_faulting_flush_and_keeps_working()
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{
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var time = new ManualTimeProvider();
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var calls = 0;
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await using var scheduler = new CoalescingRenderScheduler(TimeSpan.FromMilliseconds(200), () =>
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{
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calls++;
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if (calls == 1) throw new ObjectDisposedException("renderer");
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return Task.FromException(new InvalidOperationException("late"));
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}, time);
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scheduler.Schedule();
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Should.NotThrow(() => time.Advance(TimeSpan.FromMilliseconds(200)));
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scheduler.Schedule();
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Should.NotThrow(() => time.Advance(TimeSpan.FromMilliseconds(200)));
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calls.ShouldBe(2);
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}
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[Fact]
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public void Pages_use_the_coalescing_tail_instead_of_a_render_per_event()
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{
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foreach (var page in new[] { "ScriptLog.razor", "Alerts.razor" })
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{
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var src = AdminUiSource.Read("Components", "Pages", page);
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src.ShouldContain("CoalescingRenderScheduler", customMessage: page);
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src.ShouldContain("LiveTailBuffer<", customMessage: page);
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src.ShouldNotContain("_rows.Insert(0,", customMessage: page);
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}
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}
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/// <summary>A deterministic <see cref="TimeProvider"/>: timers fire only when <see cref="Advance"/> passes their due time.</summary>
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private sealed class ManualTimeProvider : TimeProvider
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{
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private readonly List<ManualTimer> _timers = new();
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private DateTimeOffset _now = new(2026, 10, 22, 0, 0, 0, TimeSpan.Zero);
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public override DateTimeOffset GetUtcNow() => _now;
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public override ITimer CreateTimer(TimerCallback callback, object? state, TimeSpan dueTime, TimeSpan period)
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{
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var timer = new ManualTimer(this, callback, state);
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timer.Change(dueTime, period);
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_timers.Add(timer);
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return timer;
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}
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public void Advance(TimeSpan by)
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{
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_now += by;
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foreach (var t in _timers.ToArray()) t.FireIfDue(_now);
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}
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private sealed class ManualTimer(ManualTimeProvider owner, TimerCallback callback, object? state) : ITimer
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{
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private DateTimeOffset? _due;
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private bool _disposed;
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public bool Change(TimeSpan dueTime, TimeSpan period)
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{
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if (_disposed) throw new ObjectDisposedException(nameof(ManualTimer));
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_due = dueTime == Timeout.InfiniteTimeSpan ? null : owner._now + dueTime;
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return true;
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}
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public void FireIfDue(DateTimeOffset now)
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{
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if (_disposed || _due is null || _due > now) return;
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_due = null;
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callback(state);
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}
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public void Dispose() => _disposed = true;
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public ValueTask DisposeAsync()
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{
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_disposed = true;
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return ValueTask.CompletedTask;
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}
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}
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}
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}
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