runtime,internal/poll: move websocket handling out of the runtime on Windows

On Windows, the netpoll is currently coupled with the websocket usage
in the internal/poll package.

This CL moves the websocket handling out of the runtime and puts it into
the internal/poll package, which already contains most of the async I/O
logic for websockets.

This is a good refactor per se, as the Go runtime shouldn't know about
websockets. In addition, it will make it easier (in a future CL) to only
load ws2_32.dll when the Go program actually uses websockets.

Change-Id: Ic820872cf9bdbbf092505ed7f7504edb6687735e
Reviewed-on: https://go-review.googlesource.com/c/go/+/556936
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>

2 files changed, 8 insertions, 32 deletions

diff --git a/src/runtime/netpoll_windows.go b/src/runtime/netpoll_windows.go
index 484a9e85b2..59377bc588 100644
--- a/src/runtime/netpoll_windows.go
+++ b/src/runtime/netpoll_windows.go
@@ -19,10 +19,8 @@ type net_op struct {
 	// used by windows
 	o overlapped
 	// used by netpoll
-	pd    *pollDesc
-	mode  int32
-	errno int32
-	qty   uint32
+	pd   *pollDesc
+	mode int32
 }
 
 type overlappedEntry struct {
@@ -86,7 +84,7 @@ func netpollBreak() {
 // delay > 0: block for up to that many nanoseconds
 func netpoll(delay int64) (gList, int32) {
 	var entries [64]overlappedEntry
-	var wait, qty, flags, n, i uint32
+	var wait, n, i uint32
 	var errno int32
 	var op *net_op
 	var toRun gList
@@ -131,12 +129,12 @@ func netpoll(delay int64) (gList, int32) {
 	for i = 0; i < n; i++ {
 		op = entries[i].op
 		if op != nil && op.pd == entries[i].key {
-			errno = 0
-			qty = 0
-			if stdcall5(_WSAGetOverlappedResult, op.pd.fd, uintptr(unsafe.Pointer(op)), uintptr(unsafe.Pointer(&qty)), 0, uintptr(unsafe.Pointer(&flags))) == 0 {
-				errno = int32(getlasterror())
+			mode := op.mode
+			if mode != 'r' && mode != 'w' {
+				println("runtime: GetQueuedCompletionStatusEx returned net_op with invalid mode=", mode)
+				throw("runtime: netpoll failed")
 			}
-			delta += handlecompletion(&toRun, op, errno, qty)
+			delta += netpollready(&toRun, op.pd, mode)
 		} else {
 			netpollWakeSig.Store(0)
 			if delay == 0 {
@@ -148,14 +146,3 @@ func netpoll(delay int64) (gList, int32) {
 	}
 	return toRun, delta
 }
-
-func handlecompletion(toRun *gList, op *net_op, errno int32, qty uint32) int32 {
-	mode := op.mode
-	if mode != 'r' && mode != 'w' {
-		println("runtime: GetQueuedCompletionStatusEx returned invalid mode=", mode)
-		throw("runtime: netpoll failed")
-	}
-	op.errno = errno
-	op.qty = qty
-	return netpollready(toRun, op.pd, mode)
-}
diff --git a/src/runtime/os_windows.go b/src/runtime/os_windows.go
index cd0a3c260e..7e9bbd04f2 100644
--- a/src/runtime/os_windows.go
+++ b/src/runtime/os_windows.go
@@ -139,7 +139,6 @@ var (
 	// These are from non-kernel32.dll, so we prefer to LoadLibraryEx them.
 	_timeBeginPeriod,
 	_timeEndPeriod,
-	_WSAGetOverlappedResult,
 	_ stdFunction
 )
 
@@ -148,7 +147,6 @@ var (
 	ntdlldll            = [...]uint16{'n', 't', 'd', 'l', 'l', '.', 'd', 'l', 'l', 0}
 	powrprofdll         = [...]uint16{'p', 'o', 'w', 'r', 'p', 'r', 'o', 'f', '.', 'd', 'l', 'l', 0}
 	winmmdll            = [...]uint16{'w', 'i', 'n', 'm', 'm', '.', 'd', 'l', 'l', 0}
-	ws2_32dll           = [...]uint16{'w', 's', '2', '_', '3', '2', '.', 'd', 'l', 'l', 0}
 )
 
 // Function to be called by windows CreateThread
@@ -256,15 +254,6 @@ func loadOptionalSyscalls() {
 	}
 	_RtlGetCurrentPeb = windowsFindfunc(n32, []byte("RtlGetCurrentPeb\000"))
 	_RtlGetNtVersionNumbers = windowsFindfunc(n32, []byte("RtlGetNtVersionNumbers\000"))
-
-	ws232 := windowsLoadSystemLib(ws2_32dll[:])
-	if ws232 == 0 {
-		throw("ws2_32.dll not found")
-	}
-	_WSAGetOverlappedResult = windowsFindfunc(ws232, []byte("WSAGetOverlappedResult\000"))
-	if _WSAGetOverlappedResult == nil {
-		throw("WSAGetOverlappedResult not found")
-	}
 }
 
 func monitorSuspendResume() {