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wintun: manage ring memory manually

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It's large and Go's garbage collector doesn't deal with it especially
well.
This commit is contained in:
Jason A. Donenfeld
2019-11-21 14:48:21 +01:00
parent 4cdf805b29
commit 2b242f9393
2 changed files with 27 additions and 7 deletions
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28
tun/wintun/ring_windows.go
View File

@@ -6,6 +6,7 @@
package wintun
import (
"runtime"
"unsafe"
"golang.org/x/sys/windows"
@@ -53,25 +54,44 @@ func PacketAlign(size uint32) uint32 {
return (size + (PacketAlignment - 1)) &^ (PacketAlignment - 1)
}
func (descriptor *RingDescriptor) Init() (err error) {
func NewRingDescriptor() (descriptor *RingDescriptor, err error) {
descriptor = new(RingDescriptor)
allocatedRegion, err := windows.VirtualAlloc(0, unsafe.Sizeof(Ring{})*2, windows.MEM_COMMIT|windows.MEM_RESERVE, windows.PAGE_READWRITE)
if err != nil {
return
}
defer func() {
if err != nil {
descriptor.free()
descriptor = nil
}
}()
descriptor.Send.Size = uint32(unsafe.Sizeof(Ring{}))
descriptor.Send.Ring = &Ring{}
descriptor.Send.Ring = (*Ring)(unsafe.Pointer(allocatedRegion))
descriptor.Send.TailMoved, err = windows.CreateEvent(nil, 0, 0, nil)
if err != nil {
return
}
descriptor.Receive.Size = uint32(unsafe.Sizeof(Ring{}))
descriptor.Receive.Ring = &Ring{}
descriptor.Receive.Ring = (*Ring)(unsafe.Pointer(allocatedRegion + unsafe.Sizeof(Ring{})))
descriptor.Receive.TailMoved, err = windows.CreateEvent(nil, 0, 0, nil)
if err != nil {
windows.CloseHandle(descriptor.Send.TailMoved)
return
}
runtime.SetFinalizer(descriptor, func(d *RingDescriptor) { d.free() })
return
}
func (descriptor *RingDescriptor) free() {
if descriptor.Send.Ring != nil {
windows.VirtualFree(uintptr(unsafe.Pointer(descriptor.Send.Ring)), 0, windows.MEM_RELEASE)
descriptor.Send.Ring = nil
descriptor.Receive.Ring = nil
}
}
func (descriptor *RingDescriptor) Close() {
if descriptor.Send.TailMoved != 0 {
windows.CloseHandle(descriptor.Send.TailMoved)