1 files changed, 161 insertions, 0 deletions
diff --git a/src/runtime/netpoll_windows.go b/src/runtime/netpoll_windows.go
new file mode 100644
index 0000000..484a9e8
--- /dev/null
+++ b/src/runtime/netpoll_windows.go
@@ -0,0 +1,161 @@
+// Copyright 2013 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package runtime
+
+import (
+	"runtime/internal/atomic"
+	"unsafe"
+)
+
+const _DWORD_MAX = 0xffffffff
+
+const _INVALID_HANDLE_VALUE = ^uintptr(0)
+
+// net_op must be the same as beginning of internal/poll.operation.
+// Keep these in sync.
+type net_op struct {
+	// used by windows
+	o overlapped
+	// used by netpoll
+	pd    *pollDesc
+	mode  int32
+	errno int32
+	qty   uint32
+}
+
+type overlappedEntry struct {
+	key      *pollDesc
+	op       *net_op // In reality it's *overlapped, but we cast it to *net_op anyway.
+	internal uintptr
+	qty      uint32
+}
+
+var (
+	iocphandle uintptr = _INVALID_HANDLE_VALUE // completion port io handle
+
+	netpollWakeSig atomic.Uint32 // used to avoid duplicate calls of netpollBreak
+)
+
+func netpollinit() {
+	iocphandle = stdcall4(_CreateIoCompletionPort, _INVALID_HANDLE_VALUE, 0, 0, _DWORD_MAX)
+	if iocphandle == 0 {
+		println("runtime: CreateIoCompletionPort failed (errno=", getlasterror(), ")")
+		throw("runtime: netpollinit failed")
+	}
+}
+
+func netpollIsPollDescriptor(fd uintptr) bool {
+	return fd == iocphandle
+}
+
+func netpollopen(fd uintptr, pd *pollDesc) int32 {
+	// TODO(iant): Consider using taggedPointer on 64-bit systems.
+	if stdcall4(_CreateIoCompletionPort, fd, iocphandle, uintptr(unsafe.Pointer(pd)), 0) == 0 {
+		return int32(getlasterror())
+	}
+	return 0
+}
+
+func netpollclose(fd uintptr) int32 {
+	// nothing to do
+	return 0
+}
+
+func netpollarm(pd *pollDesc, mode int) {
+	throw("runtime: unused")
+}
+
+func netpollBreak() {
+	// Failing to cas indicates there is an in-flight wakeup, so we're done here.
+	if !netpollWakeSig.CompareAndSwap(0, 1) {
+		return
+	}
+
+	if stdcall4(_PostQueuedCompletionStatus, iocphandle, 0, 0, 0) == 0 {
+		println("runtime: netpoll: PostQueuedCompletionStatus failed (errno=", getlasterror(), ")")
+		throw("runtime: netpoll: PostQueuedCompletionStatus failed")
+	}
+}
+
+// netpoll checks for ready network connections.
+// Returns list of goroutines that become runnable.
+// delay < 0: blocks indefinitely
+// delay == 0: does not block, just polls
+// 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 errno int32
+	var op *net_op
+	var toRun gList
+
+	mp := getg().m
+
+	if iocphandle == _INVALID_HANDLE_VALUE {
+		return gList{}, 0
+	}
+	if delay < 0 {
+		wait = _INFINITE
+	} else if delay == 0 {
+		wait = 0
+	} else if delay < 1e6 {
+		wait = 1
+	} else if delay < 1e15 {
+		wait = uint32(delay / 1e6)
+	} else {
+		// An arbitrary cap on how long to wait for a timer.
+		// 1e9 ms == ~11.5 days.
+		wait = 1e9
+	}
+
+	n = uint32(len(entries) / int(gomaxprocs))
+	if n < 8 {
+		n = 8
+	}
+	if delay != 0 {
+		mp.blocked = true
+	}
+	if stdcall6(_GetQueuedCompletionStatusEx, iocphandle, uintptr(unsafe.Pointer(&entries[0])), uintptr(n), uintptr(unsafe.Pointer(&n)), uintptr(wait), 0) == 0 {
+		mp.blocked = false
+		errno = int32(getlasterror())
+		if errno == _WAIT_TIMEOUT {
+			return gList{}, 0
+		}
+		println("runtime: GetQueuedCompletionStatusEx failed (errno=", errno, ")")
+		throw("runtime: netpoll failed")
+	}
+	mp.blocked = false
+	delta := int32(0)
+	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())
+			}
+			delta += handlecompletion(&toRun, op, errno, qty)
+		} else {
+			netpollWakeSig.Store(0)
+			if delay == 0 {
+				// Forward the notification to the
+				// blocked poller.
+				netpollBreak()
+			}
+		}
+	}
+	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)
+}