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CsvLayout - Faster CSV encoding with INoAllocationStringValueRenderer#6083

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snakefoot merged 3 commits intoNLog:devfrom
snakefoot:CsvLayoutStringValue
Jan 31, 2026
Merged

CsvLayout - Faster CSV encoding with INoAllocationStringValueRenderer#6083
snakefoot merged 3 commits intoNLog:devfrom
snakefoot:CsvLayoutStringValue

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@snakefoot snakefoot commented Jan 31, 2026 •
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Extending #6082 to also apply for CsvLayout

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coderabbitai bot commented Jan 31, 2026 •
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Walkthrough

Introduces a new internal interface INoAllocationStringValueRenderer that extends IStringValueRenderer with a GetFormattedStringNoAllocation method. Multiple layout renderers are updated to implement this interface, and the CSV, JSON, and typed layout systems are optimized to use the no-allocation path when available. The existing IStringValueRenderer interface is made internal.

Changes

Cohort / File(s) Summary
Interface Definitions
src/NLog/Internal/INoAllocationStringValueRenderer.cs, src/NLog/Internal/IStringValueRenderer.cs		 New internal interface INoAllocationStringValueRenderer introduced with GetFormattedStringNoAllocation method. Existing IStringValueRenderer is now internal; documentation refined from "must not" to "should not" regarding AppDomainFixedOutput attribute.
Layout Renderers - Interface Adoption
src/NLog/LayoutRenderers/LiteralLayoutRenderer.cs, src/NLog/LayoutRenderers/LoggerNameLayoutRenderer.cs, src/NLog/LayoutRenderers/MessageLayoutRenderer.cs, src/NLog/LayoutRenderers/GdcLayoutRenderer.cs, src/NLog/LayoutRenderers/EventPropertiesLayoutRenderer.cs		 Multiple renderers switch from IStringValueRenderer to INoAllocationStringValueRenderer with explicit interface implementations providing no-allocation formatting paths. Each returns formatted string when formatting is simple, or null when complex formatting is required.
Layout Renderers - Major Refactor
src/NLog/LayoutRenderers/LevelLayoutRenderer.cs		 Significant restructuring: replaces IStringValueRenderer with INoAllocationStringValueRenderer, introduces centralized GetLogLevelStringValue method, adds GenerateLevelNames and level formatting helpers, and implements internal caching for format state and level names.
Layout Renderers - Null Safety
src/NLog/LayoutRenderers/AppSettingLayoutRenderer.cs		 When Item is null or empty, GetStringValue returns Default only if non-null; otherwise returns empty string instead of potentially null Default.
CSV Layout System
src/NLog/Layouts/CSV/CsvColumn.cs, src/NLog/Layouts/CSV/CsvLayout.cs		 CsvColumn adds SimpleStringValue caching via internal ResolveStringValueMethod for simple layout renderers. CsvLayout integrates no-allocation path: RenderColumnLayout accepts optional INoAllocationStringValueRenderer parameter and routes through AppendStringValue helpers when available.
Typed Layout System
src/NLog/Layouts/Typed/ValueTypeLayoutInfo.cs		 Adds internal SimpleStringValue property with ResolveStringValueMethod helper to cache no-allocation string renderer for simple layout scenarios.
JSON Layout System
src/NLog/Layouts/JSON/JsonAttribute.cs		 Introduces RenderAppendJsonStringValue helper and short-circuit optimization in RenderAppendJsonValue to render simple string values directly when Encode is true, avoiding generic rendering path.
Serialization & Tests
src/NLog/Targets/DefaultJsonSerializer.cs, tests/NLog.UnitTests/ApiTests.cs		 DefaultJsonSerializer adds null-safeguarding with ?? string.Empty for IFormattable formatting on NETFRAMEWORK. ApiTests excludes LiteralLayoutRenderer from IStringValueRenderer AppDomainFixedOutput attribute test.

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~25 minutes

Poem

🐰 A new interface hops into view,
INoAllocationStringValueRenderer's debut!
Renderers switch paths with grace so fine,
CSV and JSON in harmony align,
No extra allocations—just clean design! 🎉

🚥 Pre-merge checks | ✅ 1 | ❌ 2
❌ Failed checks (2 warnings)
Check name Status Explanation Resolution
Docstring Coverage ⚠️ Warning Docstring coverage is 17.95% which is insufficient. The required threshold is 80.00%. Write docstrings for the functions missing them to satisfy the coverage threshold.
Description check ⚠️ Warning The pull request has no description provided by the author, making it impossible to assess whether there is any explanation of the changes. Add a descriptive pull request description explaining the changes, objectives, and rationale for the CsvLayout optimization and interface refactoring.
✅ Passed checks (1 passed)
Check name Status Explanation
Title check ✅ Passed The title accurately describes the main change: introducing faster CSV encoding for simple log event messages by leveraging no-allocation string rendering.

✏️ Tip: You can configure your own custom pre-merge checks in the settings.

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@sonarqubecloud
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sonarqubecloud bot commented Jan 31, 2026

Quality Gate Passed Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
92.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

@snakefoot snakefoot merged commit b922e0c into NLog:dev Jan 31, 2026
5 of 6 checks passed
@snakefoot snakefoot changed the title CsvLayout - Faster CSV encoding for simple logevent messages CsvLayout - Faster CSV encoding with INoAllocationStringValueRenderer Jan 31, 2026
@snakefoot snakefoot added this to the 6.1.0 milestone Jan 31, 2026
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