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Fix race condition in ViewCountService #192

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Fix race condition in ViewCountService #192

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11 changes: 9 additions & 2 deletions OrchardCoreContrib.Modules.sln
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@

Microsoft Visual Studio Solution File, Format Version 12.00
# Visual Studio Version 17
VisualStudioVersion = 17.0.31912.275
# Visual Studio Version 18
VisualStudioVersion = 18.1.11312.151 d18.0
MinimumVisualStudioVersion = 10.0.40219.1
Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{C80A325F-F4C4-4C7B-A3CF-FB77CD8C9949}"
EndProject
Expand Down Expand Up @@ -78,6 +78,8 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OrchardCoreContrib.UserGrou
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OrchardCoreContrib.UserGroups.Tests", "test\OrchardCoreContrib.UserGroups.Tests\OrchardCoreContrib.UserGroups.Tests.csproj", "{689A006D-0992-456E-86C9-66B7A2EE06A5}"
EndProject
Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "OrchardCoreContrib.ViewCount.Tests", "test\OrchardCoreContrib.ViewCount.Tests\OrchardCoreContrib.ViewCount.Tests.csproj", "{8FFF983F-F6B5-4990-B571-77EDEC2FAA00}"
EndProject
Global
GlobalSection(SolutionConfigurationPlatforms) = preSolution
Debug|Any CPU = Debug|Any CPU
Expand Down Expand Up @@ -204,6 +206,10 @@ Global
{689A006D-0992-456E-86C9-66B7A2EE06A5}.Debug|Any CPU.Build.0 = Debug|Any CPU
{689A006D-0992-456E-86C9-66B7A2EE06A5}.Release|Any CPU.ActiveCfg = Release|Any CPU
{689A006D-0992-456E-86C9-66B7A2EE06A5}.Release|Any CPU.Build.0 = Release|Any CPU
{8FFF983F-F6B5-4990-B571-77EDEC2FAA00}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
{8FFF983F-F6B5-4990-B571-77EDEC2FAA00}.Debug|Any CPU.Build.0 = Debug|Any CPU
{8FFF983F-F6B5-4990-B571-77EDEC2FAA00}.Release|Any CPU.ActiveCfg = Release|Any CPU
{8FFF983F-F6B5-4990-B571-77EDEC2FAA00}.Release|Any CPU.Build.0 = Release|Any CPU
EndGlobalSection
GlobalSection(SolutionProperties) = preSolution
HideSolutionNode = FALSE
Expand Down Expand Up @@ -239,6 +245,7 @@ Global
{330877B1-7BE6-4B57-8714-2DADE1C53563} = {C80A325F-F4C4-4C7B-A3CF-FB77CD8C9949}
{C76B5687-3079-4E80-B7D2-B691F2B05A8A} = {C80A325F-F4C4-4C7B-A3CF-FB77CD8C9949}
{689A006D-0992-456E-86C9-66B7A2EE06A5} = {A239BFB0-9BA7-467C-AD41-405D0740633F}
{8FFF983F-F6B5-4990-B571-77EDEC2FAA00} = {A239BFB0-9BA7-467C-AD41-405D0740633F}
EndGlobalSection
GlobalSection(ExtensibilityGlobals) = postSolution
SolutionGuid = {48F73B05-7D3D-4ACF-81AE-A98B2B4EFDB2}
Expand Down
10 changes: 9 additions & 1 deletion src/OrchardCoreContrib.ViewCount/Services/ViewCountService.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -20,6 +20,8 @@ public class ViewCountService(
IEnumerable<IViewCountContentHandler> handlers,
ILogger<ViewCountService> logger) : IViewCountService
{
private static readonly SemaphoreSlim _semaphore = new(initialCount: 1, maxCount: 1);

/// <inheritdoc/>
public int GetViewsCount(ContentItem contentItem)
{
Expand All @@ -35,19 +37,25 @@ public async Task ViewAsync(ContentItem contentItem)
{
Guard.ArgumentNotNull(contentItem, nameof(contentItem));

await _semaphore.WaitAsync();
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@MikeAlhayek MikeAlhayek Jan 16, 2026 •
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Your service is registered as scoped, so it won't block others from creating raise condition. And if you make it singleton, it will cause a bottleneck on a busy site.

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@hishamco hishamco Jan 16, 2026

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So how your approach fixing the issue?

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@MikeAlhayek MikeAlhayek Jan 16, 2026

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It does not write to the document directly. It writes to tables that are dedicated to tracking views. So the more the view, you increase the insert which isn't going to block or cause ease condition to updating the same content item.

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@hishamco hishamco Jan 18, 2026

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Any suggestions in this particular case after I register it as a singleton?

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@MikeAlhayek MikeAlhayek Jan 18, 2026

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#193 (comment)


var viewCountPart = contentItem.As<ViewCountPart>()
?? throw new InvalidOperationException($"The content item doesn't have a `{nameof(ViewCountPart)}`.");
var count = viewCountPart.Count;
var context = new ViewCountContentContext(contentItem, count);

await handlers.InvokeAsync((handler, context) => handler.ViewingAsync(context), context, logger);

contentItem.Content.ViewCountPart.Count = ++count;
viewCountPart.Count = ++count;

contentItem.Content.ViewCountPart.Count = count;

await contentManager.UpdateAsync(contentItem);

context = new ViewCountContentContext(contentItem, count);

await handlers.InvokeAsync((handler, context) => handler.ViewedAsync(context), context, logger);

_semaphore.Release();
}
}
23 changes: 23 additions & 0 deletions test/OrchardCoreContrib.ViewCount.Tests/OrchardCoreContrib.ViewCount.Tests.csproj
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Original file line number Diff line number Diff line change
@@ -0,0 +1,23 @@
<Project Sdk="Microsoft.NET.Sdk">

<PropertyGroup>
<IsTestProject>true</IsTestProject>
</PropertyGroup>

<ItemGroup>
<PackageReference Include="coverlet.collector" />
<PackageReference Include="Microsoft.NET.Test.Sdk" />
<PackageReference Include="Moq" />
<PackageReference Include="xunit" />
<PackageReference Include="xunit.runner.visualstudio" />
</ItemGroup>

<ItemGroup>
<ProjectReference Include="..\..\src\OrchardCoreContrib.ViewCount\OrchardCoreContrib.ViewCount.csproj" />
</ItemGroup>

<ItemGroup>
<Using Include="Xunit" />
</ItemGroup>

</Project>
39 changes: 39 additions & 0 deletions test/OrchardCoreContrib.ViewCount.Tests/Services/ViewCountServiceTests.cs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
using Microsoft.Extensions.Logging;
using Moq;
using OrchardCore.ContentManagement;
using OrchardCoreContrib.ViewCount.Models;

namespace OrchardCoreContrib.ViewCount.Services.Tests;

public class ViewCountServiceTests
{
[Fact]
public async Task ViewAsync_ConcurrentCalls_WithSemaphore_AllIncrementsAreApplied()
{
// Arrange
const int concurrentCalls = 20;
var contentItem = new ContentItem();
contentItem.Weld(new ViewCountPart { Count = 0 });

var contentManagerMock = new Mock<IContentManager>();
contentManagerMock
.Setup(m => m.UpdateAsync(It.IsAny<ContentItem>()))
.Returns(async () => await Task.Delay(10).ConfigureAwait(false));

var service = new ViewCountService(
contentManagerMock.Object,
[],
Mock.Of<ILogger<ViewCountService>>());

// Act
var tasks = Enumerable.Range(0, concurrentCalls)
.Select(_ => Task.Run(() => service.ViewAsync(contentItem)))
.ToArray();

await Task.WhenAll(tasks);

// Assert
var count = contentItem.As<ViewCountPart>().Count;
Assert.Equal(concurrentCalls, count);
}
}
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