Prevent duplicate pooled buffer returns

[xuzhg]

Remove duplicate stream ownership in ODataJsonValueSerializer. EndStreamValueScope and EndStreamValueScopeAsync are now solely responsible for disposing writer-owned streams, preventing the serializer and writer from returning the same pooled byte array twice.

Make binary stream and text writer disposal idempotent across synchronous, asynchronous, repeated, and mixed disposal paths. Interlocked disposal gates and atomic ownership detachment guarantee that each rented byte or character array is returned at most once and that repeated scope completion cannot reuse an already-disposed writer.

This prevents duplicate references from entering a shared ArrayPool, where simultaneous later rentals could otherwise alias the same array and cause cross-operation data corruption or disclosure.

Use nested try/finally cleanup so writer scopes are completed when copying fails and source streams still honor ODataBinaryStreamValue.LeaveOpen. Preserve ConfigureAwait(false) for asynchronous library cleanup.

Add internal injectable array pools for deterministic ownership tests while production constructors continue using the shared pools. Cover exact rent/return accounting, repeated and mixed disposal, serializer ownership, and Base64 boundary payload sizes 1, 2, 3, 2048, and 2049.

Issues

This pull request fixes #xxx.

Description

Briefly describe the changes of this pull request.

Checklist (Uncheck if it is not completed)

• Test cases added
• Build and test with one-click build and test script passed

Additional work necessary

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[xuzhg]

/AzurePipelines run

[Copilot]

Pull request overview

This PR hardens JSON streaming/text-writing paths against duplicate buffer returns by making writer-owned stream/text-writer disposal idempotent and by moving stream lifetime responsibility fully into EndStreamValueScope{Async}. It also adds targeted unit tests to validate that pooled buffers and writer-owned streams are disposed/returned exactly once across repeated and mixed sync/async disposal paths.

Changes:

• Make ODataUtf8JsonWriteStream and ODataUtf8JsonTextWriter disposal idempotent (sync/async) using an interlocked disposal gate and atomic buffer detachment, and allow injecting ArrayPool<T> for deterministic tests.
• Ensure ODataUtf8JsonWriter scope-ending methods detach writer-owned streams/text-writers before disposing them, preventing repeated scope completion from double-disposing.
• Update ODataJsonValueSerializer sync/async stream writing to always call EndStreamValueScope{Async} via try/finally, while still honoring ODataBinaryStreamValue.LeaveOpen, and add tests verifying “dispose once” semantics.

Reviewed changes

Copilot reviewed 8 out of 8 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
test/UnitTests/Microsoft.OData.Core.Tests/Json/ODataUtf8JsonWriterStreamTests.cs	Adds buffer rent/return accounting tests for repeated and mixed disposal of ODataUtf8JsonWriteStream, plus a tracking ArrayPool<T>.
test/UnitTests/Microsoft.OData.Core.Tests/Json/ODataUtf8JsonTextWriterTests.cs	Adds mixed sync/async disposal test for ODataUtf8JsonTextWriter buffer return idempotency.
test/UnitTests/Microsoft.OData.Core.Tests/Json/ODataJsonValueSerializerTests.cs	Adds a regression test verifying writer-owned stream is disposed exactly once during WriteStreamValue.
test/UnitTests/Microsoft.OData.Core.Tests/Json/ODataJsonValueSerializerAsyncTests.cs	Adds an async regression test verifying writer-owned stream is disposed exactly once during WriteStreamValueAsync.
test/UnitTests/Microsoft.OData.Core.Tests/Json/MockJsonWriter.cs	Extends the mock to support stream scope start/end (sync/async) so disposal behavior can be asserted.
src/Microsoft.OData.Core/Json/ODataUtf8JsonWriter.TextWriter.cs	Makes writer-owned text-writer scope completion idempotent; adds injectable char pool and interlocked disposal gate to prevent double returns.
src/Microsoft.OData.Core/Json/ODataUtf8JsonWriter.Stream.cs	Makes writer-owned stream scope completion idempotent; adds injectable byte pool and interlocked disposal gate to prevent double returns.
src/Microsoft.OData.Core/Json/ODataJsonValueSerializer.cs	Removes duplicate ownership/disposal of writer-owned streams and ensures scope end is always invoked (sync/async) via try/finally.

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