src/runtime/netpoll_solaris.go - go - Git at Google

 // Copyright 2014 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"

 // Solaris runtime-integrated network poller.
 //
 // Solaris uses event ports for scalable network I/O. Event
 // ports are level-triggered, unlike epoll and kqueue which
 // can be configured in both level-triggered and edge-triggered
 // mode. Level triggering means we have to keep track of a few things
 // ourselves. After we receive an event for a file descriptor,
 // it's our responsibility to ask again to be notified for future
 // events for that descriptor. When doing this we must keep track of
 // what kind of events the goroutines are currently interested in,
 // for example a fd may be open both for reading and writing.
 //
 // A description of the high level operation of this code
 // follows. Networking code will get a file descriptor by some means
 // and will register it with the netpolling mechanism by a code path
 // that eventually calls runtime·netpollopen. runtime·netpollopen
 // calls port_associate with an empty event set. That means that we
 // will not receive any events at this point. The association needs
 // to be done at this early point because we need to process the I/O
 // readiness notification at some point in the future. If I/O becomes
 // ready when nobody is listening, when we finally care about it,
 // nobody will tell us anymore.
 //
 // Beside calling runtime·netpollopen, the networking code paths
 // will call runtime·netpollarm each time goroutines are interested
 // in doing network I/O. Because now we know what kind of I/O we
 // are interested in (reading/writing), we can call port_associate
 // passing the correct type of event set (POLLIN/POLLOUT). As we made
 // sure to have already associated the file descriptor with the port,
 // when we now call port_associate, we will unblock the main poller
 // loop (in runtime·netpoll) right away if the socket is actually
 // ready for I/O.
 //
 // The main poller loop runs in its own thread waiting for events
 // using port_getn. When an event happens, it will tell the scheduler
 // about it using runtime·netpollready. Besides doing this, it must
 // also re-associate the events that were not part of this current
 // notification with the file descriptor. Failing to do this would
 // mean each notification will prevent concurrent code using the
 // same file descriptor in parallel.
 //
 // The logic dealing with re-associations is encapsulated in
 // runtime·netpollupdate. This function takes care to associate the
 // descriptor only with the subset of events that were previously
 // part of the association, except the one that just happened. We
 // can't re-associate with that right away, because event ports
 // are level triggered so it would cause a busy loop. Instead, that
 // association is effected only by the runtime·netpollarm code path,
 // when Go code actually asks for I/O.
 //
 // The open and arming mechanisms are serialized using the lock
 // inside PollDesc. This is required because the netpoll loop runs
 // asynchronously in respect to other Go code and by the time we get
 // to call port_associate to update the association in the loop, the
 // file descriptor might have been closed and reopened already. The
 // lock allows runtime·netpollupdate to be called synchronously from
 // the loop thread while preventing other threads operating to the
 // same PollDesc, so once we unblock in the main loop, until we loop
 // again we know for sure we are always talking about the same file
 // descriptor and can safely access the data we want (the event set).

 //go:cgo_import_dynamic libc_port_create port_create "libc.so"
 //go:cgo_import_dynamic libc_port_associate port_associate "libc.so"
 //go:cgo_import_dynamic libc_port_dissociate port_dissociate "libc.so"
 //go:cgo_import_dynamic libc_port_getn port_getn "libc.so"

 //go:linkname libc_port_create libc_port_create
 //go:linkname libc_port_associate libc_port_associate
 //go:linkname libc_port_dissociate libc_port_dissociate
 //go:linkname libc_port_getn libc_port_getn

 var (
 	libc_port_create,
 	libc_port_associate,
 	libc_port_dissociate,
 	libc_port_getn libcFunc
 )

 func errno() int32 {
 	return *getg().m.perrno
 }

 func fcntl(fd, cmd int32, arg uintptr) int32 {
 	return int32(sysvicall3(&libc_fcntl, uintptr(fd), uintptr(cmd), arg))
 }

 func port_create() int32 {
 	return int32(sysvicall0(&libc_port_create))
 }

 func port_associate(port, source int32, object uintptr, events uint32, user uintptr) int32 {
 	return int32(sysvicall5(&libc_port_associate, uintptr(port), uintptr(source), object, uintptr(events), user))
 }

 func port_dissociate(port, source int32, object uintptr) int32 {
 	return int32(sysvicall3(&libc_port_dissociate, uintptr(port), uintptr(source), object))
 }

 func port_getn(port int32, evs *portevent, max uint32, nget *uint32, timeout *timespec) int32 {
 	return int32(sysvicall5(&libc_port_getn, uintptr(port), uintptr(unsafe.Pointer(evs)), uintptr(max), uintptr(unsafe.Pointer(nget)), uintptr(unsafe.Pointer(timeout))))
 }

 var portfd int32 = -1

 func netpollinit() {
 	portfd = port_create()
 	if portfd >= 0 {
 		fcntl(portfd, _F_SETFD, _FD_CLOEXEC)
 		return
 	}

 	print("netpollinit: failed to create port (", errno(), ")\n")
 	throw("netpollinit: failed to create port")
 }

 func netpollopen(fd uintptr, pd *pollDesc) int32 {
 	lock(&pd.lock)
 	// We don't register for any specific type of events yet, that's
 	// netpollarm's job. We merely ensure we call port_associate before
 	// asynchronous connect/accept completes, so when we actually want
 	// to do any I/O, the call to port_associate (from netpollarm,
 	// with the interested event set) will unblock port_getn right away
 	// because of the I/O readiness notification.
 	pd.user = 0
 	r := port_associate(portfd, _PORT_SOURCE_FD, fd, 0, uintptr(unsafe.Pointer(pd)))
 	unlock(&pd.lock)
 	return r
 }

 func netpollclose(fd uintptr) int32 {
 	return port_dissociate(portfd, _PORT_SOURCE_FD, fd)
 }

 // Updates the association with a new set of interested events. After
 // this call, port_getn will return one and only one event for that
 // particular descriptor, so this function needs to be called again.
 func netpollupdate(pd *pollDesc, set, clear uint32) {
 	if pd.closing {
 		return
 	}

 	old := pd.user
 	events := (old & ^clear) | set
 	if old == events {
 		return
 	}

 	if events != 0 && port_associate(portfd, _PORT_SOURCE_FD, pd.fd, events, uintptr(unsafe.Pointer(pd))) != 0 {
 		print("netpollupdate: failed to associate (", errno(), ")\n")
 		throw("netpollupdate: failed to associate")
 	}
 	pd.user = events
 }

 // subscribe the fd to the port such that port_getn will return one event.
 func netpollarm(pd *pollDesc, mode int) {
 	lock(&pd.lock)
 	switch mode {
 	case 'r':
 		netpollupdate(pd, _POLLIN, 0)
 	case 'w':
 		netpollupdate(pd, _POLLOUT, 0)
 	default:
 		throw("netpollarm: bad mode")
 	}
 	unlock(&pd.lock)
 }

 // polls for ready network connections
 // returns list of goroutines that become runnable
 func netpoll(block bool) *g {
 	if portfd == -1 {
 		return nil
 	}

 	var wait *timespec
 	var zero timespec
 	if !block {
 		wait = &zero
 	}

 	var events [128]portevent
 retry:
 	var n uint32 = 1
 	if port_getn(portfd, &events[0], uint32(len(events)), &n, wait) < 0 {
 		if e := errno(); e != _EINTR {
 			print("runtime: port_getn on fd ", portfd, " failed with ", e, "\n")
 			throw("port_getn failed")
 		}
 		goto retry
 	}

 	var gp guintptr
 	for i := 0; i < int(n); i++ {
 		ev := &events[i]

 		if ev.portev_events == 0 {
 			continue
 		}
 		pd := (*pollDesc)(unsafe.Pointer(ev.portev_user))

 		var mode, clear int32
 		if (ev.portev_events & (_POLLIN | _POLLHUP | _POLLERR)) != 0 {
 			mode += 'r'
 			clear |= _POLLIN
 		}
 		if (ev.portev_events & (_POLLOUT | _POLLHUP | _POLLERR)) != 0 {
 			mode += 'w'
 			clear |= _POLLOUT
 		}
 		// To effect edge-triggered events, we need to be sure to
 		// update our association with whatever events were not
 		// set with the event. For example if we are registered
 		// for POLLIN|POLLOUT, and we get POLLIN, besides waking
 		// the goroutine interested in POLLIN we have to not forget
 		// about the one interested in POLLOUT.
 		if clear != 0 {
 			lock(&pd.lock)
 			netpollupdate(pd, 0, uint32(clear))
 			unlock(&pd.lock)
 		}

 		if mode != 0 {
 			netpollready(&gp, pd, mode)
 		}
 	}

 	if block && gp == 0 {
 		goto retry
 	}
 	return gp.ptr()
 }
	// Copyright 2014 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"

	// Solaris runtime-integrated network poller.
	//
	// Solaris uses event ports for scalable network I/O. Event
	// ports are level-triggered, unlike epoll and kqueue which
	// can be configured in both level-triggered and edge-triggered
	// mode. Level triggering means we have to keep track of a few things
	// ourselves. After we receive an event for a file descriptor,
	// it's our responsibility to ask again to be notified for future
	// events for that descriptor. When doing this we must keep track of
	// what kind of events the goroutines are currently interested in,
	// for example a fd may be open both for reading and writing.
	//
	// A description of the high level operation of this code
	// follows. Networking code will get a file descriptor by some means
	// and will register it with the netpolling mechanism by a code path
	// that eventually calls runtime·netpollopen. runtime·netpollopen
	// calls port_associate with an empty event set. That means that we
	// will not receive any events at this point. The association needs
	// to be done at this early point because we need to process the I/O
	// readiness notification at some point in the future. If I/O becomes
	// ready when nobody is listening, when we finally care about it,
	// nobody will tell us anymore.
	//
	// Beside calling runtime·netpollopen, the networking code paths
	// will call runtime·netpollarm each time goroutines are interested
	// in doing network I/O. Because now we know what kind of I/O we
	// are interested in (reading/writing), we can call port_associate
	// passing the correct type of event set (POLLIN/POLLOUT). As we made
	// sure to have already associated the file descriptor with the port,
	// when we now call port_associate, we will unblock the main poller
	// loop (in runtime·netpoll) right away if the socket is actually
	// ready for I/O.
	//
	// The main poller loop runs in its own thread waiting for events
	// using port_getn. When an event happens, it will tell the scheduler
	// about it using runtime·netpollready. Besides doing this, it must
	// also re-associate the events that were not part of this current
	// notification with the file descriptor. Failing to do this would
	// mean each notification will prevent concurrent code using the
	// same file descriptor in parallel.
	//
	// The logic dealing with re-associations is encapsulated in
	// runtime·netpollupdate. This function takes care to associate the
	// descriptor only with the subset of events that were previously
	// part of the association, except the one that just happened. We
	// can't re-associate with that right away, because event ports
	// are level triggered so it would cause a busy loop. Instead, that
	// association is effected only by the runtime·netpollarm code path,
	// when Go code actually asks for I/O.
	//
	// The open and arming mechanisms are serialized using the lock
	// inside PollDesc. This is required because the netpoll loop runs
	// asynchronously in respect to other Go code and by the time we get
	// to call port_associate to update the association in the loop, the
	// file descriptor might have been closed and reopened already. The
	// lock allows runtime·netpollupdate to be called synchronously from
	// the loop thread while preventing other threads operating to the
	// same PollDesc, so once we unblock in the main loop, until we loop
	// again we know for sure we are always talking about the same file
	// descriptor and can safely access the data we want (the event set).

	//go:cgo_import_dynamic libc_port_create port_create "libc.so"
	//go:cgo_import_dynamic libc_port_associate port_associate "libc.so"
	//go:cgo_import_dynamic libc_port_dissociate port_dissociate "libc.so"
	//go:cgo_import_dynamic libc_port_getn port_getn "libc.so"

	//go:linkname libc_port_create libc_port_create
	//go:linkname libc_port_associate libc_port_associate
	//go:linkname libc_port_dissociate libc_port_dissociate
	//go:linkname libc_port_getn libc_port_getn

	var (
	libc_port_create,
	libc_port_associate,
	libc_port_dissociate,
	libc_port_getn libcFunc
	)

	func errno() int32 {
	return *getg().m.perrno
	}

	func fcntl(fd, cmd int32, arg uintptr) int32 {
	return int32(sysvicall3(&libc_fcntl, uintptr(fd), uintptr(cmd), arg))
	}

	func port_create() int32 {
	return int32(sysvicall0(&libc_port_create))
	}

	func port_associate(port, source int32, object uintptr, events uint32, user uintptr) int32 {
	return int32(sysvicall5(&libc_port_associate, uintptr(port), uintptr(source), object, uintptr(events), user))
	}

	func port_dissociate(port, source int32, object uintptr) int32 {
	return int32(sysvicall3(&libc_port_dissociate, uintptr(port), uintptr(source), object))
	}

	func port_getn(port int32, evs portevent, max uint32, nget uint32, timeout *timespec) int32 {
	return int32(sysvicall5(&libc_port_getn, uintptr(port), uintptr(unsafe.Pointer(evs)), uintptr(max), uintptr(unsafe.Pointer(nget)), uintptr(unsafe.Pointer(timeout))))
	}

	var portfd int32 = -1

	func netpollinit() {
	portfd = port_create()
	if portfd >= 0 {
	fcntl(portfd, _F_SETFD, _FD_CLOEXEC)
	return
	}

	print("netpollinit: failed to create port (", errno(), ")\n")
	throw("netpollinit: failed to create port")
	}

	func netpollopen(fd uintptr, pd *pollDesc) int32 {
	lock(&pd.lock)
	// We don't register for any specific type of events yet, that's
	// netpollarm's job. We merely ensure we call port_associate before
	// asynchronous connect/accept completes, so when we actually want
	// to do any I/O, the call to port_associate (from netpollarm,
	// with the interested event set) will unblock port_getn right away
	// because of the I/O readiness notification.
	pd.user = 0
	r := port_associate(portfd, _PORT_SOURCE_FD, fd, 0, uintptr(unsafe.Pointer(pd)))
	unlock(&pd.lock)
	return r
	}

	func netpollclose(fd uintptr) int32 {
	return port_dissociate(portfd, _PORT_SOURCE_FD, fd)
	}

	// Updates the association with a new set of interested events. After
	// this call, port_getn will return one and only one event for that
	// particular descriptor, so this function needs to be called again.
	func netpollupdate(pd *pollDesc, set, clear uint32) {
	if pd.closing {
	return
	}

	old := pd.user
	events := (old & ^clear) \| set
	if old == events {
	return
	}

	if events != 0 && port_associate(portfd, _PORT_SOURCE_FD, pd.fd, events, uintptr(unsafe.Pointer(pd))) != 0 {
	print("netpollupdate: failed to associate (", errno(), ")\n")
	throw("netpollupdate: failed to associate")
	}
	pd.user = events
	}

	// subscribe the fd to the port such that port_getn will return one event.
	func netpollarm(pd *pollDesc, mode int) {
	lock(&pd.lock)
	switch mode {
	case 'r':
	netpollupdate(pd, _POLLIN, 0)
	case 'w':
	netpollupdate(pd, _POLLOUT, 0)
	default:
	throw("netpollarm: bad mode")
	}
	unlock(&pd.lock)
	}

	// polls for ready network connections
	// returns list of goroutines that become runnable
	func netpoll(block bool) *g {
	if portfd == -1 {
	return nil
	}

	var wait *timespec
	var zero timespec
	if !block {
	wait = &zero
	}

	var events [128]portevent
	retry:
	var n uint32 = 1
	if port_getn(portfd, &events[0], uint32(len(events)), &n, wait) < 0 {
	if e := errno(); e != _EINTR {
	print("runtime: port_getn on fd ", portfd, " failed with ", e, "\n")
	throw("port_getn failed")
	}
	goto retry
	}

	var gp guintptr
	for i := 0; i < int(n); i++ {
	ev := &events[i]

	if ev.portev_events == 0 {
	continue
	}
	pd := (*pollDesc)(unsafe.Pointer(ev.portev_user))

	var mode, clear int32
	if (ev.portev_events & (_POLLIN \| _POLLHUP \| _POLLERR)) != 0 {
	mode += 'r'
	clear \|= _POLLIN
	}
	if (ev.portev_events & (_POLLOUT \| _POLLHUP \| _POLLERR)) != 0 {
	mode += 'w'
	clear \|= _POLLOUT
	}
	// To effect edge-triggered events, we need to be sure to
	// update our association with whatever events were not
	// set with the event. For example if we are registered
	// for POLLIN\|POLLOUT, and we get POLLIN, besides waking
	// the goroutine interested in POLLIN we have to not forget
	// about the one interested in POLLOUT.
	if clear != 0 {
	lock(&pd.lock)
	netpollupdate(pd, 0, uint32(clear))
	unlock(&pd.lock)
	}

	if mode != 0 {
	netpollready(&gp, pd, mode)
	}
	}

	if block && gp == 0 {
	goto retry
	}
	return gp.ptr()
	}