wslc: Switch port relay AcceptThread from WaitForMultipleObjects to IO completion ports

[benhillis]

Replace the WaitForMultipleObjects-based wait loop in relay::MultiHandleWait with an IO completion port (IOCP), removing the MAXIMUM_WAIT_OBJECTS (64) handle limit for all callers (IORelay, container IO, socket accept, etc.).

Switch the port relay AcceptThread from WaitForMultipleObjects to a direct IOCP, removing the 63-port mapping limit.

relay::MultiHandleWait changes (relay.hpp/cpp)

• Add unique_registered_wait RAII type for RegisterWaitForSingleObject handles
• Add Register() pure virtual to OverlappedIOHandle, implemented by all subclasses
• Handles that support IOCP (pipes, sockets) register directly; handles that don't (console handles, events) use a RegisterWaitForSingleObject bridge
• Convert Run() to use GetQueuedCompletionStatus instead of WaitForMultipleObjects
• Cancel() posts a key=0 completion to wake Run(); key=0 sets m_cancel on dequeue
• Fix member order: m_iocp declared before m_handles for correct destruction

Port relay changes (localhost.cpp)

• Associate listen sockets directly with an IOCP via CreateIoCompletionPort
• AcceptEx completions go straight to the IOCP — no events or thread pool waits
• Stop signal via PostQueuedCompletionStatus key=0
• Remove AcceptEvent from PortRelay (no longer needed)
• Remove the MAXIMUM_WAIT_OBJECTS port limit check

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 5 comments.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 5 comments.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 90 out of 90 changed files in this pull request and generated 4 comments.

Comments suppressed due to low confidence (1)

NOTICE.txt:645

• NOTICE.txt no longer contains any entries for Microsoft.NETCore.App.Runtime.win-* (and related license text), but packages.config still references these runtimes (now updated to 10.0.4). If NOTICE is the authoritative third-party notices file for shipped dependencies, it likely needs to be regenerated/updated to reflect the current set and versions of redistributed components rather than removing these sections entirely.

MIT License

Copyright (c) <year> <copyright holders>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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Microsoft.Xaml.Behaviors.WinUI.Managed 3.0.0 - MIT

[Copilot]

MultiHandleWait::AddHandle calls handle->Register(...) and EnsureIocp() uses m_iocp, but OverlappedIOHandle / MultiHandleWait declarations in relay.hpp currently do not declare a Register() method or any m_iocp member. As-is this TU should fail to compile. Please update relay.hpp to match the new IOCP-based design (add the virtual Register(...) API, required members, and update derived handle class declarations accordingly).

[Copilot]

MultiHandleWait::Cancel() no longer sets m_cancel (it only posts a key=0 completion if m_iocp exists). If Cancel() is invoked before Run() has dequeued the posted packet (or before m_iocp is created), the wait loop may continue scheduling work instead of stopping promptly. Consider setting m_cancel = true in Cancel() in addition to posting to the IOCP.

[Copilot]

The initramfs custom command unconditionally invokes powershell.exe, which will break configuring/building this target on non-Windows hosts. Also, the marker path uses CmakeFiles (nonstandard casing vs CMakeFiles). Consider guarding this block with if (WIN32) (or using pwsh discovery) and fix the output path casing to avoid brittle build behavior.

[Copilot]

The PR description/title focuses on IOCP changes for relay::MultiHandleWait and port relay accept handling, but this PR also includes substantial unrelated updates (e.g., initrd generation/packaging changes, VirtioProxy IPv6 changes/tests, distro metadata updates, .NET runtime/TestDistro/DeviceHost package bumps, NOTICE/cgmanifest updates). If these are intended, please reflect them in the PR description (or consider splitting) so reviewers and release notes capture the full scope.

[benhillis]

Hey @benhillis 👋 — Following up on this PR. The \wsl-github-pr\ check shows action_required status. There are also 2 unresolved review threads remaining (out of 32 total):

• \AddHandle\/\Register\ ordering concern
• \Cancel()\ no longer setting the \m_cancel\ flag

This is a large PR (3170+/1359−, 90 files) — great progress resolving 30 of 32 threads! Just those last 2 items and the CI status to sort out.