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Fixes #3462 Add ProjectionStateTracker for health check improvements #3775

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Merged
jeremydmiller merged 1 commit into from
Aug 19, 2025
Merged

Fixes #3462 Add ProjectionStateTracker for health check improvements #3775

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28 changes: 20 additions & 8 deletions src/DaemonTests/HealthChecks/AsyncDaemonHealthCheckExtensionsTests.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -22,6 +22,7 @@ public class AsyncDaemonHealthCheckExtensionsTests: DaemonContext
private FakeHealthCheckBuilderStub _builder = new();
private readonly TimeProvider _timeProvider = Substitute.For<TimeProvider>();
private readonly DateTime _now = DateTime.UtcNow;
private readonly ProjectionStateTracker _stateTracker = new();

public AsyncDaemonHealthCheckExtensionsTests(ITestOutputHelper output) : base(output)
{
Expand Down Expand Up @@ -51,6 +52,17 @@ public void should_add_timeprovider_to_services()
_builder.Services.ShouldContain(x => x.ServiceType == typeof(TimeProvider));
}

[Fact]
public void should_add_projectionstatetracker_to_services()
{
_builder = new();
_builder.Services.ShouldNotContain(x => x.ServiceType == typeof(ProjectionStateTracker));

_builder.AddMartenAsyncDaemonHealthCheck(200, TimeSpan.FromSeconds(5));

_builder.Services.ShouldContain(x => x.ServiceType == typeof(ProjectionStateTracker));
}

[Fact]
public void should_add_healthcheck_to_services()
{
Expand All @@ -70,7 +82,7 @@ public async Task should_be_healthy_without_events()
{
x.Projections.Add(new FakeSingleStream1Projection(), ProjectionLifecycle.Async);
});
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(100), _timeProvider);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(100), _timeProvider, _stateTracker);

var result = await healthCheck.CheckHealthAsync(new());

Expand All @@ -89,7 +101,7 @@ public async Task should_be_healthy_with_one_projection_no_relevant_events()
session.Events.Append(Guid.NewGuid(), new FakeIrrellevantEvent());
await session.SaveChangesAsync();
await agent.Tracker.WaitForHighWaterMark(1);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(100), _timeProvider);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(100), _timeProvider, _stateTracker);

var result = await healthCheck.CheckHealthAsync(new());

Expand All @@ -112,7 +124,7 @@ public async Task should_be_unhealthy_with_no_projection_lag_allowed()
await session.SaveChangesAsync();
await agent.Tracker.WaitForHighWaterMark(eventCount);
await agent.Tracker.WaitForShardState(new ShardState("FakeStream2:All", eventCount), 15.Seconds());
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(0), _timeProvider);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(0), _timeProvider, _stateTracker);

var result = await healthCheck.CheckHealthAsync(new());

Expand Down Expand Up @@ -143,7 +155,7 @@ public async Task should_be_healthy_with_all_projections_caught_up()
await agent.Tracker.WaitForShardState(new ShardState("FakeStream3:All", eventCount), 15.Seconds());
await agent.Tracker.WaitForShardState(new ShardState("FakeStream4:All", eventCount), 15.Seconds());
await agent.Tracker.WaitForHighWaterMark(eventCount);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(1), _timeProvider);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(1), _timeProvider, _stateTracker);

var result = await healthCheck.CheckHealthAsync(new());

Expand Down Expand Up @@ -177,7 +189,7 @@ public async Task should_be_unhealthy_with_one_projection_lagging()

await theSession.ExecuteAsync(treeCommand);

var healthCheck = new AsyncDaemonHealthCheck(theStore, new(1), _timeProvider);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(1), _timeProvider, _stateTracker);

var result = await healthCheck.CheckHealthAsync(new());

Expand Down Expand Up @@ -211,7 +223,7 @@ public async Task should_be_healthy_with_one_projection_lagging_but_within_max_s

await theSession.ExecuteAsync(treeCommand);

var healthCheck = new AsyncDaemonHealthCheck(theStore, new(1, TimeSpan.FromSeconds(30)), _timeProvider);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(1, TimeSpan.FromSeconds(30)), _timeProvider, _stateTracker);

var result = await healthCheck.CheckHealthAsync(new());

Expand Down Expand Up @@ -247,7 +259,7 @@ public async Task should_be_unhealthy_with_one_projection_lagging_for_more_than_
await theSession.ExecuteAsync(treeCommand);

var maxSameLagTime = TimeSpan.FromSeconds(30);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(1, maxSameLagTime), _timeProvider);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(1, maxSameLagTime), _timeProvider, _stateTracker);
await healthCheck.CheckHealthAsync(new());

// When
Expand Down Expand Up @@ -287,7 +299,7 @@ public async Task should_be_healthy_with_one_projection_lagging_for_more_than_ma
await theSession.ExecuteAsync(treeCommandSeqId0);

var maxSameLagTime = TimeSpan.FromSeconds(30);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(1, maxSameLagTime), _timeProvider);
var healthCheck = new AsyncDaemonHealthCheck(theStore, new(1, maxSameLagTime), _timeProvider, _stateTracker);
await healthCheck.CheckHealthAsync(new());

// When
Expand Down
25 changes: 18 additions & 7 deletions src/Marten.AspNetCore/Daemon/AsyncDaemonHealthCheckExtensions.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -6,7 +6,6 @@
using System.Threading.Tasks;
using JasperFx.Core;
using JasperFx.Events.Projections;
using Marten.Events.Projections;
using Marten.Storage;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.DependencyInjection.Extensions;
Expand Down Expand Up @@ -51,6 +50,7 @@ public static IHealthChecksBuilder AddMartenAsyncDaemonHealthCheck(
{
builder.Services.AddSingleton(new AsyncDaemonHealthCheckSettings(maxEventLag, maxSameLagTime));
builder.Services.TryAddSingleton(TimeProvider.System);
builder.Services.TryAddSingleton<ProjectionStateTracker>();
return builder.AddCheck<AsyncDaemonHealthCheck>(
nameof(AsyncDaemonHealthCheck),
tags: new[] { "Marten", "AsyncDaemon" }
Expand All @@ -64,14 +64,19 @@ public static IHealthChecksBuilder AddMartenAsyncDaemonHealthCheck(
/// <returns></returns>
internal record AsyncDaemonHealthCheckSettings(int MaxEventLag, TimeSpan? MaxSameLagTime = null);

/// <summary>
/// Tracks projection state across multiple health check invocations
/// </summary>
internal class ProjectionStateTracker
{
public ConcurrentDictionary<string, (DateTime CheckedAt, long Sequence)> LastProjectionsChecks { get; } = new();
}

/// <summary>
/// Health check implementation
/// </summary>
internal class AsyncDaemonHealthCheck: IHealthCheck
{
private readonly ConcurrentDictionary<string, (DateTime CheckedAt, long Sequence)>
_lastProjectionsChecks = new();

/// <summary>
/// The allowed event projection processing lag compared to the HighWaterMark.
/// </summary>
Expand All @@ -92,13 +97,19 @@ internal class AsyncDaemonHealthCheck: IHealthCheck

private readonly TimeProvider _timeProvider;

/// <summary>
/// Projection state tracker that persists between health check invocations
/// </summary>
private readonly ProjectionStateTracker _stateTracker;

public AsyncDaemonHealthCheck(IDocumentStore store, AsyncDaemonHealthCheckSettings settings,
TimeProvider timeProvider)
TimeProvider timeProvider, ProjectionStateTracker stateTracker)
{
_store = store;
_timeProvider = timeProvider;
_maxEventLag = settings.MaxEventLag;
_maxSameLagTime = settings.MaxSameLagTime;
_stateTracker = stateTracker;
}

public async Task<HealthCheckResult> CheckHealthAsync(
Expand Down Expand Up @@ -181,7 +192,7 @@ public async Task<HealthCheckResult> CheckProjectionHealthAsync(IMartenDatabase
x =>
{
var (laggingSince, lastKnownPosition) =
_lastProjectionsChecks.GetValueOrDefault(x.ShardName, (now, x.Sequence));
_stateTracker.LastProjectionsChecks.GetValueOrDefault(x.ShardName, (now, x.Sequence));

var isLaggingWithSamePositionForGivenTime =
now.Subtract(laggingSince) >= _maxSameLagTime &&
Expand All @@ -194,7 +205,7 @@ public async Task<HealthCheckResult> CheckProjectionHealthAsync(IMartenDatabase

foreach (var laggingProjection in laggingProjections)
{
_lastProjectionsChecks.AddOrUpdate(
_stateTracker.LastProjectionsChecks.AddOrUpdate(
laggingProjection.ShardName,
_ => (now, laggingProjection.Sequence),
(_, _) => (now, laggingProjection.Sequence)
Expand Down
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