blob: 3d3fa4b76d3a9915ae1cbc10747def0996765038 [file] [log] [blame]
// Copyright 2019 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 "unsafe"
// FIXME: Improve network poller for hurd.
// This is based on the former libgo/runtime/netpoll_select.c implementation
// except that it uses poll instead of select and is written in Go.
// It's also based on Solaris implementation for the arming mechanisms
// Inspiration was also taken from netpoll_aix.go and netpoll_solaris.go
//From /usr/include/x86_64-linux-gnu/sys/poll.h
//go:noescape
//extern poll
func libc_poll(pfds *pollfd, nfds int32, timeout int32) int32
//go:noescape
//extern pipe2
func libc_pipe2(fd *int32, flags int32) int32
//pollfd represents the poll structure for GNU/Hurd operating system.
type pollfd struct {
fd int32 // File descriptor to poll.
events int16 // Types of events poller cares about.
revents int16 // Types of events that actually occurred.
}
//From /usr/include/i386-gnu/bits/poll.h
const _POLLIN = 01 // There is data to read.
const _POLLPRI = 02 // There is urgent data to read.
const _POLLOUT = 04 // Writing now will not block.
const _POLLERR = 010 // Error condition.
const _POLLHUP = 020 // Hung up.
const _POLLNVAL = 040 // Invalid polling request.
var (
pfds []pollfd
pds []*pollDesc
mtxpoll mutex
mtxset mutex
rdwake int32
wrwake int32
pendingUpdates int32
)
const pollVerbose = false
func netpollinit() {
var p [2]int32
// Create the pipe we use to wakeup poll.
if err := libc_pipe2(&p[0], _O_CLOEXEC|_O_NONBLOCK); err < 0 {
throw("runtime:netpollinit(): failed to create pipe2")
}
rdwake = p[0]
wrwake = p[1]
// Pre-allocate array of pollfd structures for poll.
if pollVerbose {
println("*** allocating")
}
pfds = make([]pollfd, 1, 128)
if pollVerbose {
println("*** allocating done", &pfds[0])
}
// Poll the read side of the pipe.
pfds[0].fd = int32(rdwake)
pfds[0].events = int16(_POLLIN)
pfds[0].revents = int16(0)
pds = make([]*pollDesc, 1, 128)
// Checks for pd != nil are made in netpoll.
pds[0] = nil
}
func netpolldescriptor() uintptr {
// Both fds must be returned.
if rdwake > 0xFFFF || wrwake > 0xFFFF {
throw("netpolldescriptor: invalid fd number")
}
return uintptr(rdwake<<16 | wrwake)
}
func netpollIsPollDescriptor(fd uintptr) bool {
return fd == uintptr(rdwake) || fd == uintptr(wrwake)
}
// netpollwakeup writes on wrwake to wakeup poll before any changes.
func netpollwakeup() {
if pendingUpdates == 0 {
pendingUpdates = 1
if pollVerbose {
println("*** writing 1 byte")
}
b := [1]byte{0}
write(uintptr(wrwake), unsafe.Pointer(&b[0]), 1)
}
}
func netpollopen(fd uintptr, pd *pollDesc) int32 {
if pollVerbose {
println("*** netpollopen", fd)
}
lock(&mtxpoll)
netpollwakeup()
lock(&mtxset)
unlock(&mtxpoll)
pd.user = uint32(len(pfds))
pfds = append(pfds, pollfd{fd: int32(fd)})
pds = append(pds, pd)
unlock(&mtxset)
return 0
}
func netpollclose(fd uintptr) int32 {
if pollVerbose {
println("*** netpollclose", fd)
}
lock(&mtxpoll)
netpollwakeup()
lock(&mtxset)
unlock(&mtxpoll)
for i := 0; i < len(pfds); i++ {
if pfds[i].fd == int32(fd) {
pfds[i] = pfds[len(pfds)-1]
pfds = pfds[:len(pfds)-1]
pds[i] = pds[len(pds)-1]
pds[i].user = uint32(i)
pds = pds[:len(pds)-1]
break
}
}
unlock(&mtxset)
return 0
}
func netpollarm(pd *pollDesc, mode int) {
if pollVerbose {
println("*** netpollarm", pd.fd, mode)
}
lock(&mtxpoll)
netpollwakeup()
lock(&mtxset)
unlock(&mtxpoll)
switch mode {
case 'r':
pfds[pd.user].events |= _POLLIN
case 'w':
pfds[pd.user].events |= _POLLOUT
}
unlock(&mtxset)
}
// netpollBreak interrupts an epollwait.
func netpollBreak() {
netpollwakeup()
}
// 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
//go:nowritebarrierrec
func netpoll(delay int64) gList {
timeout := int32(0)
if delay < 0 {
timeout = 0
} else if delay == 0 {
// TODO: call poll with timeout == 0
return gList{}
} else if delay < 1e6 {
timeout = 1
} else if delay < 1e15 {
timeout = int32(delay / 1e6)
} else {
// An arbitrary cap on how long to wait for a timer.
// 1e9 ms == ~11.5 days.
timeout = 1e9
}
retry:
lock(&mtxpoll)
lock(&mtxset)
pendingUpdates = 0
unlock(&mtxpoll)
n := libc_poll(&pfds[0], int32(len(pfds)), timeout)
if n < 0 {
e := errno()
if e != _EINTR {
println("errno=", e, " len(pfds)=", len(pfds))
throw("poll failed")
}
unlock(&mtxset)
// If a timed sleep was interrupted, just return to
// recalculate how long we should sleep now.
if timeout > 0 {
return gList{}
}
goto retry
}
// Check if some descriptors need to be changed
if n != 0 && pfds[0].revents&(_POLLIN|_POLLHUP|_POLLERR) != 0 {
if delay != 0 {
// A netpollwakeup could be picked up by a
// non-blocking poll. Only clear the wakeup
// if blocking.
var b [1]byte
for read(rdwake, unsafe.Pointer(&b[0]), 1) == 1 {
}
}
// Still look at the other fds even if the mode may have
// changed, as netpollBreak might have been called.
n--
}
var toRun gList
for i := 1; i < len(pfds) && n > 0; i++ {
pfd := &pfds[i]
var mode int32
if pfd.revents&(_POLLIN|_POLLHUP|_POLLERR) != 0 {
mode += 'r'
pfd.events &= ^_POLLIN
}
if pfd.revents&(_POLLOUT|_POLLHUP|_POLLERR) != 0 {
mode += 'w'
pfd.events &= ^_POLLOUT
}
if mode != 0 {
pds[i].everr = false
if pfd.revents == _POLLERR {
pds[i].everr = true
}
netpollready(&toRun, pds[i], mode)
n--
}
}
unlock(&mtxset)
return toRun
}