libgo/go/runtime/netpoll_aix.go

   1 // Copyright 2017 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 package runtime
   6
   7 import "unsafe"
   8
   9 // This is based on the former libgo/runtime/netpoll_select.c implementation
  10 // except that it uses AIX pollset_poll instead of select and is written in Go.
  11
  12 type pollset_t int32
  13
  14 type pollfd struct {
  15         fd      int32
  16         events  int16
  17         revents int16
  18 }
  19
  20 const _POLLIN = 0x0001
  21 const _POLLOUT = 0x0002
  22 const _POLLHUP = 0x2000
  23 const _POLLERR = 0x4000
  24
  25 type poll_ctl struct {
  26         cmd    int16
  27         events int16
  28         fd     int32
  29 }
  30
  31 const _PS_ADD = 0x0
  32 const _PS_DELETE = 0x2
  33
  34 //extern pollset_create
  35 func pollset_create(maxfd int32) pollset_t
  36
  37 //extern pollset_ctl
  38 func pollset_ctl(ps pollset_t, pollctl_array *poll_ctl, array_length int32) int32
  39
  40 //extern pollset_poll
  41 func pollset_poll(ps pollset_t, polldata_array *pollfd, array_length int32, timeout int32) int32
  42
  43 //extern pipe
  44 func libc_pipe(fd *int32) int32
  45
  46 //extern __go_fcntl_uintptr
  47 func fcntlUintptr(fd, cmd, arg uintptr) (uintptr, uintptr)
  48
  49 func fcntl(fd, cmd int32, arg uintptr) uintptr {
  50         r, _ := fcntlUintptr(uintptr(fd), uintptr(cmd), arg)
  51         return r
  52 }
  53
  54 var (
  55         ps          pollset_t = -1
  56         mpfds       map[int32]*pollDesc
  57         pmtx        mutex
  58         rdwake      int32
  59         wrwake      int32
  60         needsUpdate bool
  61 )
  62
  63 func netpollinit() {
  64         var p [2]int32
  65
  66         if ps = pollset_create(-1); ps < 0 {
  67                 throw("runtime: netpollinit failed to create pollset")
  68         }
  69         // It is not possible to add or remove descriptors from
  70         // the pollset while pollset_poll is active.
  71         // We use a pipe to wakeup pollset_poll when the pollset
  72         // needs to be updated.
  73         if err := libc_pipe(&p[0]); err < 0 {
  74                 throw("runtime: netpollinit failed to create pipe")
  75         }
  76         rdwake = p[0]
  77         wrwake = p[1]
  78
  79         fl := fcntl(rdwake, _F_GETFL, 0)
  80         fcntl(rdwake, _F_SETFL, fl|_O_NONBLOCK)
  81         fcntl(rdwake, _F_SETFD, _FD_CLOEXEC)
  82
  83         fl = fcntl(wrwake, _F_GETFL, 0)
  84         fcntl(wrwake, _F_SETFL, fl|_O_NONBLOCK)
  85         fcntl(wrwake, _F_SETFD, _FD_CLOEXEC)
  86
  87         // Add the read side of the pipe to the pollset.
  88         var pctl poll_ctl
  89         pctl.cmd = _PS_ADD
  90         pctl.fd = rdwake
  91         pctl.events = _POLLIN
  92         if pollset_ctl(ps, &pctl, 1) != 0 {
  93                 throw("runtime: netpollinit failed to register pipe")
  94         }
  95
  96         mpfds = make(map[int32]*pollDesc)
  97 }
  98
  99 func netpolldescriptor() uintptr {
 100         // ps is not a real file descriptor.
 101         return ^uintptr(0)
 102 }
 103
 104 func netpollopen(fd uintptr, pd *pollDesc) int32 {
 105         // pollset_ctl will block if pollset_poll is active
 106         // so wakeup pollset_poll first.
 107         lock(&pmtx)
 108         needsUpdate = true
 109         unlock(&pmtx)
 110         b := [1]byte{0}
 111         write(uintptr(wrwake), unsafe.Pointer(&b[0]), 1)
 112
 113         var pctl poll_ctl
 114         pctl.cmd = _PS_ADD
 115         pctl.fd = int32(fd)
 116         pctl.events = _POLLIN | _POLLOUT
 117         if pollset_ctl(ps, &pctl, 1) != 0 {
 118                 return int32(errno())
 119         }
 120         lock(&pmtx)
 121         mpfds[int32(fd)] = pd
 122         needsUpdate = false
 123         unlock(&pmtx)
 124
 125         return 0
 126 }
 127
 128 func netpollclose(fd uintptr) int32 {
 129         // pollset_ctl will block if pollset_poll is active
 130         // so wakeup pollset_poll first.
 131         lock(&pmtx)
 132         needsUpdate = true
 133         unlock(&pmtx)
 134         b := [1]byte{0}
 135         write(uintptr(wrwake), unsafe.Pointer(&b[0]), 1)
 136
 137         var pctl poll_ctl
 138         pctl.cmd = _PS_DELETE
 139         pctl.fd = int32(fd)
 140         if pollset_ctl(ps, &pctl, 1) != 0 {
 141                 return int32(errno())
 142         }
 143         lock(&pmtx)
 144         delete(mpfds, int32(fd))
 145         needsUpdate = false
 146         unlock(&pmtx)
 147
 148         return 0
 149 }
 150
 151 func netpollarm(pd *pollDesc, mode int) {
 152         throw("runtime: unused")
 153 }
 154
 155 func netpoll(block bool) *g {
 156         if ps == -1 {
 157                 return nil
 158         }
 159         timeout := int32(-1)
 160         if !block {
 161                 timeout = 0
 162         }
 163         var pfds [128]pollfd
 164 retry:
 165         lock(&pmtx)
 166         if needsUpdate {
 167                 unlock(&pmtx)
 168                 osyield()
 169                 goto retry
 170         }
 171         unlock(&pmtx)
 172         nfound := pollset_poll(ps, &pfds[0], int32(len(pfds)), timeout)
 173         if nfound < 0 {
 174                 e := errno()
 175                 if e != _EINTR {
 176                         throw("runtime: pollset_poll failed")
 177                 }
 178                 goto retry
 179         }
 180         var gp guintptr
 181         for i := int32(0); i < nfound; i++ {
 182                 pfd := &pfds[i]
 183
 184                 var mode int32
 185                 if pfd.revents&(_POLLIN|_POLLHUP|_POLLERR) != 0 {
 186                         if pfd.fd == rdwake {
 187                                 var b [1]byte
 188                                 read(pfd.fd, unsafe.Pointer(&b[0]), 1)
 189                                 continue
 190                         }
 191                         mode += 'r'
 192                 }
 193                 if pfd.revents&(_POLLOUT|_POLLHUP|_POLLERR) != 0 {
 194                         mode += 'w'
 195                 }
 196                 if mode != 0 {
 197                         lock(&pmtx)
 198                         pd := mpfds[pfd.fd]
 199                         unlock(&pmtx)
 200                         if pd != nil {
 201                                 netpollready(&gp, pd, mode)
 202                         }
 203                 }
 204         }
 205         if block && gp == 0 {
 206                 goto retry
 207         }
 208         return gp.ptr()
 209 }