fix(index): keep PTable construction predictable

[yordis]

• Index rebuild throughput and file-handle safety should stay consistent across supported platforms without carrying a separate native stream path.
• High-volume PTable construction should avoid per-stream allocation overhead that makes recovery and rebuild latency less predictable.

[cursor]

PR Summary

Medium Risk
Changes core index file open/disposal and memtable hot paths used during recovery and rebuild; behavior should be equivalent but platform I/O is simplified and worth validating on Windows and Linux.

Overview
Removes the EventStore.Native project and the cross-platform unbuffered transaction-log I/O stack (UnbufferedFileStream, Windows/Unix native file helpers, and their test suite). PTable now opens index files only through the existing work-item pool and standard FileStream readers on all platforms, dropping the Windows-only unbuffered path and Mono.Posix.NETStandard from central packages and license notices.

HashListMemTable and ReverseComparer are tuned for rebuild/iteration: stream keys are read via GetKeyAtIndex instead of Keys[i], descending hash sort reuses a static comparer, and reverse comparison uses Comparer<T>.Default.Compare(y, x) to avoid per-comparison boxing/allocation.

New tests cover corrupt PTable open releasing file handles, single-reader PTable lookup after init, and GC allocation bounds for ordered memtable iteration and ReverseComparer comparisons.

^{Reviewed by Cursor Bugbot for commit bd47526. Bugbot is set up for automated code reviews on this repo. Configure here.}

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: cdaadd33-0be9-4271-b917-e517c1472f97

📥 Commits

Reviewing files that changed from the base of the PR and between 1f38699 and bd47526.

📒 Files selected for processing (20)

• NOTICE.html
• qodana.yaml
• src/Directory.Packages.props
• src/EventStore.Core.Tests/Index/IndexV1/when_a_ptable_is_corrupt_on_disk.cs
• src/EventStore.Core.Tests/Index/IndexV1/when_opening_a_ptable_with_one_reader.cs
• src/EventStore.Core.Tests/Index/MemTableTests.cs
• src/EventStore.Core.Tests/Index/ReverseComparerTests.cs
• src/EventStore.Core.Tests/TransactionLog/Unbuffered/UnbufferedTests.cs
• src/EventStore.Core/EventStore.Core.csproj
• src/EventStore.Core/Index/HashListMemTable.cs
• src/EventStore.Core/Index/PTable.cs
• src/EventStore.Core/TransactionLog/Unbuffered/UnbufferedFileStream.cs
• src/EventStore.Native/EventStore.Native.csproj
• src/EventStore.Native/TransactionLog/Unbuffered/ExtendedFileOptions.cs
• src/EventStore.Native/TransactionLog/Unbuffered/INativeFile.cs
• src/EventStore.Native/TransactionLog/Unbuffered/MacCaching.cs
• src/EventStore.Native/TransactionLog/Unbuffered/NativeFileUnix.cs
• src/EventStore.Native/TransactionLog/Unbuffered/NativeFileWindows.cs
• src/EventStore.Native/TransactionLog/Unbuffered/WinNative.cs
• src/EventStore.sln

💤 Files with no reviewable changes (14)

• qodana.yaml
• src/EventStore.sln
• src/EventStore.Native/EventStore.Native.csproj
• src/EventStore.Native/TransactionLog/Unbuffered/MacCaching.cs
• NOTICE.html
• src/EventStore.Core/EventStore.Core.csproj
• src/Directory.Packages.props
• src/EventStore.Native/TransactionLog/Unbuffered/NativeFileUnix.cs
• src/EventStore.Native/TransactionLog/Unbuffered/WinNative.cs
• src/EventStore.Core/TransactionLog/Unbuffered/UnbufferedFileStream.cs
• src/EventStore.Native/TransactionLog/Unbuffered/NativeFileWindows.cs
• src/EventStore.Native/TransactionLog/Unbuffered/INativeFile.cs
• src/EventStore.Core.Tests/TransactionLog/Unbuffered/UnbufferedTests.cs
• src/EventStore.Native/TransactionLog/Unbuffered/ExtendedFileOptions.cs

---

Walkthrough

The change removes the native unbuffered file implementation and its package references. PTable now uses pooled work items directly. HashListMemTable and ReverseComparer reduce allocation overhead. New tests cover file-handle release, reader reuse, and allocation limits.

Changes

Native I/O removal

Layer / File(s)	Summary
Remove native project dependencies NOTICE.html, qodana.yaml, src/Directory.Packages.props, src/EventStore.Core/EventStore.Core.csproj, src/EventStore.Native/EventStore.Native.csproj, src/EventStore.sln	The native project, its package, license entries, project reference, and solution mappings are removed.
Delete unbuffered file I/O src/EventStore.Native/TransactionLog/Unbuffered/*, src/EventStore.Core/TransactionLog/Unbuffered/UnbufferedFileStream.cs, src/EventStore.Core.Tests/TransactionLog/Unbuffered/UnbufferedTests.cs	The native file implementations, unbuffered stream, and related tests are deleted.

Index access and allocation updates

Layer / File(s)	Summary
Use pooled PTable work items src/EventStore.Core/Index/PTable.cs	PTable always acquires and returns a pooled work item instead of using platform-specific stream handling.
Update indexed memtable access src/EventStore.Core/Index/HashListMemTable.cs	Indexed lookups use GetKeyAtIndex. Ordered iteration uses a shared descending ulong comparer. ReverseComparer<T> reverses operands without negating comparison results.
Add regression coverage src/EventStore.Core.Tests/Index/*	Tests cover failed-open file-handle release, reader reuse, ordered-iteration allocations, and comparer allocations.

Estimated code review effort: 4 (Complex) | ~45 minutes

Possibly related PRs

• TrogonStack/TrogonEventStore#22: Removes the centrally managed Mono.Posix.NETStandard package entry.

Poem

A rabbit checks the indexes bright,
No native stream remains in sight.
Pooled work items safely flow,
Fewer little allocations grow.
Tests guard each file and reader tight.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: making PTable construction more predictable through platform and allocation improvements.
Description check	✅ Passed	The description directly explains the platform consistency, file-handle safety, and allocation goals of the changeset.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

📝 Generate docstrings 💡

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch yordis/chore-reduce-platform-index-risk

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