From f58a6a8e34d7db14871f2cf9bfd657e44a5c8b7b Mon Sep 17 00:00:00 2001 From: qmuntal Date: Thu, 5 Feb 2026 13:16:12 +0100 Subject: [PATCH] internal/poll: make waitIO more idempontent This is a step towards deferring adding the handle to IOCP until the first IO operation. waitIO should use the overlapped event if it is provided, regardless of whether FD is pollable or not. This simplifies reasoning about the code and makes it more robust to race conditions. While here, remove the panic in waitIO that was triggered when called with a blocking handle. That shouldn't happen, but if it does, fd.pd.wait will return an error that will already be promoted to a panic. For #76391 Change-Id: I8e84592568a3ef66e71161eb2c5f515dde638117 Reviewed-on: https://go-review.googlesource.com/c/go/+/742280 Reviewed-by: Damien Neil Reviewed-by: Michael Pratt LUCI-TryBot-Result: Go LUCI --- src/internal/poll/fd_windows.go | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-) diff --git a/src/internal/poll/fd_windows.go b/src/internal/poll/fd_windows.go index 699239c57b..8340794545 100644 --- a/src/internal/poll/fd_windows.go +++ b/src/internal/poll/fd_windows.go @@ -201,10 +201,7 @@ var operationPool = sync.Pool{ // waitIO waits for the IO operation to complete, // handling cancellation if necessary. func (fd *FD) waitIO(o *operation) error { - if fd.isBlocking { - panic("can't wait on blocking operations") - } - if !fd.pollable() { + if o.o.HEvent != 0 { // The overlapped handle is not added to the runtime poller, // the only way to wait for the IO to complete is block until // the overlapped event is signaled. -- 2.52.0