[ReubenBond]

Problem

JsonCodec.ReadValue stages every JSON payload in a PooledBuffer before deserializing it, even when the reader already exposes the complete payload as a contiguous span. That adds a payload-sized copy and pooled-buffer operations on each non-reference read.

Solution

Use Reader.TryReadBytes to initialize Utf8JsonReader directly over contiguous input. Continue using the existing pooled sequence path for payloads spanning segments and for stream input. Both paths share JSON reader/serializer options, native JsonNode handling, and reference bookkeeping.

The change follows the existing direct-read pattern in StringCodec. Its benefit scales with payload size while keeping the wire format and public API stable. Focused coverage checks all input shapes, options, reference identity, native JSON nodes, and that contiguous JSON tokens overlap the original input buffer. No throughput claim is made without workload measurements.

Microsoft Reviewers: Open in CodeFlow

[Copilot]

Copilot review overview

🟢 Approval recommended

No unresolved review comments remain, and focused coverage supports the changes.

Review tier: Lite
Findings: None

What changed in this PR

Optimizes JSON deserialization by reading contiguous payloads directly while preserving segmented and stream fallbacks.

Changes:

• Added direct contiguous-span parsing.
• Expanded coverage for input shapes, options, references, JSON nodes, and buffer overlap.

File	Summary
test/​Orleans.Serialization.UnitTests/​JsonCodecTests.cs	Verifies supported input formats and options.
src/​Orleans.Serialization.SystemTextJson/​JsonCodec.cs	Parses contiguous JSON payloads directly.

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[Copilot]

Copilot review overview

🟢 Approval recommended

No unresolved blocking issues were identified.

Review tier: Lite
Findings: None

[github-actions]

Code coverage

Metric	Pull request
Lines	82.05% (111,957 / 136,449)
Branches	71.19% (32,162 / 45,180)

Report-only conclusion: current-main baseline stale.

The newest successful coverage run tested 3604a08, not current main 9222be9.

Coverage combines every CI test matrix job, including providers, CodeGen, .NET 8/10, Linux, Windows, and macOS, using canonical physical source and branch identities.

The comparison remains report-only while normal line and branch variance is calibrated.

Coverage details

• Pull request commit: e51aa5bccd
• View the pull request test run and coverage artifacts
• View the trusted coverage reporting run