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Merged
harsimar merged 6 commits into from
Feb 20, 2026
Merged

Modify track calls to not modify the passed in dictionary #3119

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8b29621
initial fix to github issue
harsimar Feb 18, 2026
482eba6
remove duplicate documentaion
harsimar Feb 18, 2026
8e67232
pr feedback
harsimar Feb 19, 2026
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remove note
harsimar Feb 20, 2026
adf6eb7
changelog
harsimar Feb 20, 2026
a083821
Update CHANGELOG.md
harsimar Feb 20, 2026
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89 changes: 89 additions & 0 deletions ...osoft.ApplicationInsights.Test/Microsoft.ApplicationInsights.Tests/TelemetryClientTest.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ namespace Microsoft.ApplicationInsights
{
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.ComponentModel;
using System.Diagnostics;
using System.Diagnostics.CodeAnalysis;
Expand Down Expand Up @@ -176,6 +177,54 @@ public void TrackEventWithNullNameHandlesGracefully()
// Note: This test verifies error handling
}

[Fact]
public void TrackEventDoesNotMutateReadOnlyPropertiesDictionary()
{
var inner = new Dictionary<string, string> { { "key1", "value1" } };
var readOnly = new ReadOnlyDictionary<string, string>(inner);
var originalCount = inner.Count;

this.telemetryClient.TrackEvent("TestEvent", readOnly);
this.telemetryClient.Flush();

// The original dictionary behind the read-only wrapper must not be modified
Assert.Equal(originalCount, inner.Count);
Assert.False(inner.ContainsKey("microsoft.custom_event.name"),
"Internal attribute should not leak into caller's dictionary");
}

[Fact]
public void TrackEventAcceptsReadOnlyDictionary()
{
var inner = new Dictionary<string, string> { { "key1", "value1" } };
var readOnly = new ReadOnlyDictionary<string, string>(inner);

// Must not throw NotSupportedException
this.telemetryClient.TrackEvent("TestEvent", readOnly);
this.telemetryClient.Flush();

var logRecord = this.logItems.FirstOrDefault(l =>
l.Attributes != null && l.Attributes.Any(a =>
a.Key == "microsoft.custom_event.name" && a.Value?.ToString() == "TestEvent"));
Assert.NotNull(logRecord);

// Verify user property is still present
Assert.True(logRecord.Attributes.Any(a => a.Key == "key1" && a.Value?.ToString() == "value1"));
}

[Fact]
public void TrackEventCanBeCalledTwiceWithSameDictionary()
{
var properties = new Dictionary<string, string> { { "key1", "value1" } };

// Both calls should succeed without ArgumentException from duplicate keys
this.telemetryClient.TrackEvent("Event1", properties);
this.telemetryClient.TrackEvent("Event2", properties);
this.telemetryClient.Flush();

Assert.True(this.logItems.Count >= 2, "Both events should be recorded");
}

#endregion

#region TrackAvailability
Expand Down Expand Up @@ -524,6 +573,19 @@ public void TrackTraceWithEmptyMessageInTraceTelemetry()
Assert.NotNull(logRecord);
}

[Fact]
public void TrackTraceAcceptsReadOnlyDictionary()
{
var inner = new Dictionary<string, string> { { "key1", "value1" } };
var readOnly = new ReadOnlyDictionary<string, string>(inner);

// Must not throw NotSupportedException
this.telemetryClient.TrackTrace("Test message", readOnly);
this.telemetryClient.Flush();

Assert.True(this.logItems.Count > 0, "Log should be collected");
}

#endregion

#region TrackMetric
Expand Down Expand Up @@ -1070,6 +1132,33 @@ public void TrackExceptionWithInnerExceptionPreservesInnerException()
Assert.Equal("Inner exception message", logRecord.Exception.InnerException.Message);
}

[Fact]
public void TrackExceptionDoesNotMutatePropertiesDictionary()
{
var properties = new Dictionary<string, string> { { "key1", "value1" } };
var originalCount = properties.Count;
var exception = new InvalidOperationException("Test");

this.telemetryClient.TrackException(exception, properties);
this.telemetryClient.Flush();

Assert.Equal(originalCount, properties.Count);
}

[Fact]
public void TrackExceptionAcceptsReadOnlyDictionary()
{
var inner = new Dictionary<string, string> { { "key1", "value1" } };
var readOnly = new ReadOnlyDictionary<string, string>(inner);
var exception = new InvalidOperationException("Test");

// Must not throw NotSupportedException
this.telemetryClient.TrackException(exception, readOnly);
this.telemetryClient.Flush();

Assert.True(this.logItems.Count > 0, "Log should be collected");
}

#endregion

#region TrackRequest
Expand Down
60 changes: 37 additions & 23 deletions BASE/src/Microsoft.ApplicationInsights/TelemetryClient.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -138,13 +138,9 @@ public void TrackEvent(string eventName, IDictionary<string, string> properties
return;
}

if (properties == null)
{
properties = new Dictionary<string, string>();
}

properties.Add("microsoft.custom_event.name", eventName);
var state = new DictionaryLogState(this.Context, properties, String.Empty);
var mergedProperties = EnsureMutable(properties);
mergedProperties["microsoft.custom_event.name"] = eventName;
var state = new DictionaryLogState(this.Context, mergedProperties, String.Empty);
this.Logger.Log(LogLevel.Information, 0, state, null, (s, ex) => s.Message);
}

Expand All @@ -165,26 +161,26 @@ public void TrackEvent(EventTelemetry telemetry)
return;
}

var properties = telemetry.Properties ?? new Dictionary<string, string>();
properties.Add("microsoft.custom_event.name", telemetry.Name);
var mergedProperties = EnsureMutable(telemetry.Properties);
mergedProperties["microsoft.custom_event.name"] = telemetry.Name;

// Map context properties to semantic conventions
if (!string.IsNullOrEmpty(telemetry.Context?.Location?.Ip))
{
properties["microsoft.client.ip"] = telemetry.Context.Location.Ip;
mergedProperties["microsoft.client.ip"] = telemetry.Context.Location.Ip;
}

if (!string.IsNullOrEmpty(telemetry.Context?.User?.Id))
{
properties[SemanticConventions.AttributeEnduserPseudoId] = telemetry.Context.User.Id;
mergedProperties[SemanticConventions.AttributeEnduserPseudoId] = telemetry.Context.User.Id;
}

if (!string.IsNullOrEmpty(telemetry.Context?.User?.AuthenticatedUserId))
{
properties[SemanticConventions.AttributeEnduserId] = telemetry.Context.User.AuthenticatedUserId;
mergedProperties[SemanticConventions.AttributeEnduserId] = telemetry.Context.User.AuthenticatedUserId;
}

var state = new DictionaryLogState(telemetry.Context, properties, String.Empty);
var state = new DictionaryLogState(telemetry.Context, mergedProperties, String.Empty);
this.Logger.Log(LogLevel.Information, 0, state, null, (s, ex) => s.Message);
}

Expand Down Expand Up @@ -364,25 +360,25 @@ public void TrackTrace(TraceTelemetry telemetry)
}

// Map context properties to semantic conventions that exporter understands
var properties = telemetry.Properties ?? new Dictionary<string, string>();
var mergedProperties = EnsureMutable(telemetry.Properties);

if (!string.IsNullOrEmpty(telemetry.Context?.Location?.Ip))
{
properties["microsoft.client.ip"] = telemetry.Context.Location.Ip;
mergedProperties["microsoft.client.ip"] = telemetry.Context.Location.Ip;
}

if (!string.IsNullOrEmpty(telemetry.Context?.User?.Id))
{
properties[SemanticConventions.AttributeEnduserPseudoId] = telemetry.Context.User.Id;
mergedProperties[SemanticConventions.AttributeEnduserPseudoId] = telemetry.Context.User.Id;
}

if (!string.IsNullOrEmpty(telemetry.Context?.User?.AuthenticatedUserId))
{
properties[SemanticConventions.AttributeEnduserId] = telemetry.Context.User.AuthenticatedUserId;
mergedProperties[SemanticConventions.AttributeEnduserId] = telemetry.Context.User.AuthenticatedUserId;
}

LogLevel logLevel = GetLogLevel(telemetry.SeverityLevel.Value);
var state = new DictionaryLogState(telemetry.Context, properties, telemetry.Message);
var state = new DictionaryLogState(telemetry.Context, mergedProperties, telemetry.Message);
this.Logger.Log(logLevel, 0, state, null, (s, ex) => s.Message);
}

Expand Down Expand Up @@ -500,24 +496,24 @@ public void TrackException(ExceptionTelemetry telemetry)
var reconstructedException = ConvertToException(telemetry);

// Map context properties to semantic conventions
var properties = telemetry.Properties ?? new Dictionary<string, string>();
var mergedProperties = EnsureMutable(telemetry.Properties);

if (!string.IsNullOrEmpty(telemetry.Context?.Location?.Ip))
{
properties["microsoft.client.ip"] = telemetry.Context.Location.Ip;
mergedProperties["microsoft.client.ip"] = telemetry.Context.Location.Ip;
}

if (!string.IsNullOrEmpty(telemetry.Context?.User?.Id))
{
properties[SemanticConventions.AttributeEnduserPseudoId] = telemetry.Context.User.Id;
mergedProperties[SemanticConventions.AttributeEnduserPseudoId] = telemetry.Context.User.Id;
}

if (!string.IsNullOrEmpty(telemetry.Context?.User?.AuthenticatedUserId))
{
properties[SemanticConventions.AttributeEnduserId] = telemetry.Context.User.AuthenticatedUserId;
mergedProperties[SemanticConventions.AttributeEnduserId] = telemetry.Context.User.AuthenticatedUserId;
}

var state = new DictionaryLogState(telemetry.Context, properties, reconstructedException.Message);
var state = new DictionaryLogState(telemetry.Context, mergedProperties, reconstructedException.Message);
var logLevel = GetLogLevel(telemetry.SeverityLevel ?? SeverityLevel.Error);
this.Logger.Log(logLevel, 0, state, reconstructedException, (s, ex) => s.Message);
}
Expand Down Expand Up @@ -1374,6 +1370,24 @@ private static void EnrichExceptionWithMetadata(Exception exception, ExceptionTe
}
}

/// <summary>
/// Returns the dictionary as-is if it is mutable, or creates a mutable copy if it is read-only or null.
/// </summary>
private static IDictionary<string, string> EnsureMutable(IDictionary<string, string> properties)
{
if (properties == null)
{
return new Dictionary<string, string>();
}

if (properties.IsReadOnly)
{
return new Dictionary<string, string>(properties);
}

return properties;
}

/// <summary>
/// Applies CloudContext (RoleName/RoleInstance) and ComponentContext (Version) to the OpenTelemetry Resource if set.
/// </summary>
Expand Down
3 changes: 3 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
@@ -1,5 +1,8 @@
# Changelog

## Unreleased
- [Fix Track API calls to not mutate the passed in dictionary if it is readonly](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3119)

## Version 3.0.0
- [Replaced `netstandard2.0` with `net8.0` target framework in `Microsoft.ApplicationInsights.NLogTarget` package.](https://github.com/microsoft/ApplicationInsights-dotnet/pull/3102)

Expand Down
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