libgo/go/runtime/netpoll_kqueue.go

   1 // Copyright 2013 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // +build darwin dragonfly freebsd netbsd openbsd
   6
   7 package runtime
   8
   9 // Integrated network poller (kqueue-based implementation).
  10
  11 import "unsafe"
  12
  13 //extern kqueue
  14 func kqueue() int32
  15
  16 //go:noescape
  17 //extern kevent
  18 func kevent(kq int32, ch *keventt, nch uintptr, ev *keventt, nev uintptr, ts *timespec) int32
  19
  20 //extern __go_fcntl_uintptr
  21 func fcntlUintptr(fd, cmd, arg uintptr) (uintptr, uintptr)
  22
  23 func closeonexec(fd int32) {
  24         fcntlUintptr(uintptr(fd), _F_SETFD, _FD_CLOEXEC)
  25 }
  26
  27 var (
  28         kq int32 = -1
  29 )
  30
  31 func netpollinit() {
  32         kq = kqueue()
  33         if kq < 0 {
  34                 println("netpollinit: kqueue failed with", errno())
  35                 throw("netpollinit: kqueue failed")
  36         }
  37         closeonexec(kq)
  38 }
  39
  40 func netpollopen(fd uintptr, pd *pollDesc) int32 {
  41         // Arm both EVFILT_READ and EVFILT_WRITE in edge-triggered mode (EV_CLEAR)
  42         // for the whole fd lifetime. The notifications are automatically unregistered
  43         // when fd is closed.
  44         var ev [2]keventt
  45         *(*uintptr)(unsafe.Pointer(&ev[0].ident)) = fd
  46         ev[0].filter = _EVFILT_READ
  47         ev[0].flags = _EV_ADD | _EV_CLEAR
  48         ev[0].fflags = 0
  49         ev[0].data = 0
  50         ev[0].udata = (*byte)(unsafe.Pointer(pd))
  51         ev[1] = ev[0]
  52         ev[1].filter = _EVFILT_WRITE
  53         n := kevent(kq, &ev[0], 2, nil, 0, nil)
  54         if n < 0 {
  55                 return int32(errno())
  56         }
  57         return 0
  58 }
  59
  60 func netpollclose(fd uintptr) int32 {
  61         // Don't need to unregister because calling close()
  62         // on fd will remove any kevents that reference the descriptor.
  63         return 0
  64 }
  65
  66 func netpollarm(pd *pollDesc, mode int) {
  67         throw("unused")
  68 }
  69
  70 // Polls for ready network connections.
  71 // Returns list of goroutines that become runnable.
  72 func netpoll(block bool) *g {
  73         if kq == -1 {
  74                 return nil
  75         }
  76         var tp *timespec
  77         var ts timespec
  78         if !block {
  79                 tp = &ts
  80         }
  81         var events [64]keventt
  82 retry:
  83         n := kevent(kq, nil, 0, &events[0], uintptr(len(events)), tp)
  84         if n < 0 {
  85                 e := errno()
  86                 if e != _EINTR {
  87                         println("runtime: kevent on fd", kq, "failed with", e)
  88                         throw("kevent failed")
  89                 }
  90                 goto retry
  91         }
  92         var gp guintptr
  93         for i := 0; i < int(n); i++ {
  94                 ev := &events[i]
  95                 var mode int32
  96                 if ev.filter == _EVFILT_READ {
  97                         mode += 'r'
  98                 }
  99                 if ev.filter == _EVFILT_WRITE {
 100                         mode += 'w'
 101                 }
 102                 if mode != 0 {
 103                         netpollready(&gp, (*pollDesc)(unsafe.Pointer(ev.udata)), mode)
 104                 }
 105         }
 106         if block && gp == 0 {
 107                 goto retry
 108         }
 109         return gp.ptr()
 110 }