libgo/go/runtime/netpoll_solaris.go - gofrontend - 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).

 //extern port_create
 func port_create() int32

 //extern port_associate
 func port_associate(port, source int32, object uintptr, events uint32, user uintptr) int32

 //extern port_dissociate
 func port_dissociate(port, source int32, object uintptr) int32

 //go:noescape
 //extern port_getn
 func port_getn(port int32, evs *portevent, max uint32, nget *uint32, timeout *timespec) int32

 //extern port_alert
 func port_alert(port int32, flags, events uint32, user uintptr) int32

 var portfd int32 = -1

 func netpollinit() {
 	portfd = port_create()
 	if portfd >= 0 {
 		closeonexec(portfd)
 		return
 	}

 	print("runtime: port_create failed (errno=", errno(), ")\n")
 	throw("runtime: netpollinit failed")
 }

 func netpollIsPollDescriptor(fd uintptr) bool {
 	return fd == uintptr(portfd)
 }

 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)
 	if r < 0 {
 		return int32(errno())
 	}
 	return 0
 }

 func netpollclose(fd uintptr) int32 {
 	if port_dissociate(portfd, _PORT_SOURCE_FD, fd) < 0 {
 		return int32(errno())
 	}
 	return 0
 }

 // 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("runtime: port_associate failed (errno=", errno(), ")\n")
 		throw("runtime: netpollupdate failed")
 	}
 	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("runtime: bad mode")
 	}
 	unlock(&pd.lock)
 }

 // netpollBreak interrupts a port_getn wait.
 func netpollBreak() {
 	// Use port_alert to put portfd into alert mode.
 	// This will wake up all threads sleeping in port_getn on portfd,
 	// and cause their calls to port_getn to return immediately.
 	// Further, until portfd is taken out of alert mode,
 	// all calls to port_getn will return immediately.
 	if port_alert(portfd, _PORT_ALERT_UPDATE, _POLLHUP, uintptr(unsafe.Pointer(&portfd))) < 0 {
 		if e := errno(); e != _EBUSY {
 			println("runtime: port_alert failed with", e)
 			throw("runtime: netpoll: port_alert failed")
 		}
 	}
 }

 // 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
 func netpoll(delay int64) gList {
 	if portfd == -1 {
 		return gList{}
 	}

 	var wait *timespec
 	var ts timespec
 	if delay < 0 {
 		wait = nil
 	} else if delay == 0 {
 		wait = &ts
 	} else {
 		ts.setNsec(delay)
 		if ts.tv_sec > 1e6 {
 			// An arbitrary cap on how long to wait for a timer.
 			// 1e6 s == ~11.5 days.
 			ts.tv_sec = 1e6
 		}
 		wait = &ts
 	}

 	var events [128]portevent
 retry:
 	var n uint32 = 1
 	r := port_getn(portfd, &events[0], uint32(len(events)), &n, wait)
 	e := errno()
 	if r < 0 && e == _ETIME && n > 0 {
 		// As per port_getn(3C), an ETIME failure does not preclude the
 		// delivery of some number of events.  Treat a timeout failure
 		// with delivered events as a success.
 		r = 0
 	}
 	if r < 0 {
 		if e != _EINTR && e != _ETIME {
 			print("runtime: port_getn on fd ", portfd, " failed (errno=", e, ")\n")
 			throw("runtime: netpoll failed")
 		}
 		// If a timed sleep was interrupted and there are no events,
 		// just return to recalculate how long we should sleep now.
 		if delay > 0 {
 			return gList{}
 		}
 		goto retry
 	}

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

 		if ev.portev_source == _PORT_SOURCE_ALERT {
 			if ev.portev_events != _POLLHUP || unsafe.Pointer(ev.portev_user) != unsafe.Pointer(&portfd) {
 				throw("runtime: netpoll: bad port_alert wakeup")
 			}
 			if delay != 0 {
 				// Now that a blocking call to netpoll
 				// has seen the alert, take portfd
 				// back out of alert mode.
 				// See the comment in netpollBreak.
 				if port_alert(portfd, 0, 0, 0) < 0 {
 					e := errno()
 					println("runtime: port_alert failed with", e)
 					throw("runtime: netpoll: port_alert failed")
 				}
 			}
 			continue
 		}

 		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 {
 			// TODO(mikio): Consider implementing event
 			// scanning error reporting once we are sure
 			// about the event port on SmartOS.
 			//
 			// See golang.org/x/issue/30840.
 			netpollready(&toRun, pd, mode)
 		}
 	}

 	return toRun
 }
	// 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).

	//extern port_create
	func port_create() int32

	//extern port_associate
	func port_associate(port, source int32, object uintptr, events uint32, user uintptr) int32

	//extern port_dissociate
	func port_dissociate(port, source int32, object uintptr) int32

	//go:noescape
	//extern port_getn
	func port_getn(port int32, evs portevent, max uint32, nget uint32, timeout *timespec) int32

	//extern port_alert
	func port_alert(port int32, flags, events uint32, user uintptr) int32

	var portfd int32 = -1

	func netpollinit() {
	portfd = port_create()
	if portfd >= 0 {
	closeonexec(portfd)
	return
	}

	print("runtime: port_create failed (errno=", errno(), ")\n")
	throw("runtime: netpollinit failed")
	}

	func netpollIsPollDescriptor(fd uintptr) bool {
	return fd == uintptr(portfd)
	}

	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)
	if r < 0 {
	return int32(errno())
	}
	return 0
	}

	func netpollclose(fd uintptr) int32 {
	if port_dissociate(portfd, _PORT_SOURCE_FD, fd) < 0 {
	return int32(errno())
	}
	return 0
	}

	// 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("runtime: port_associate failed (errno=", errno(), ")\n")
	throw("runtime: netpollupdate failed")
	}
	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("runtime: bad mode")
	}
	unlock(&pd.lock)
	}

	// netpollBreak interrupts a port_getn wait.
	func netpollBreak() {
	// Use port_alert to put portfd into alert mode.
	// This will wake up all threads sleeping in port_getn on portfd,
	// and cause their calls to port_getn to return immediately.
	// Further, until portfd is taken out of alert mode,
	// all calls to port_getn will return immediately.
	if port_alert(portfd, _PORT_ALERT_UPDATE, _POLLHUP, uintptr(unsafe.Pointer(&portfd))) < 0 {
	if e := errno(); e != _EBUSY {
	println("runtime: port_alert failed with", e)
	throw("runtime: netpoll: port_alert failed")
	}
	}
	}

	// 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
	func netpoll(delay int64) gList {
	if portfd == -1 {
	return gList{}
	}

	var wait *timespec
	var ts timespec
	if delay < 0 {
	wait = nil
	} else if delay == 0 {
	wait = &ts
	} else {
	ts.setNsec(delay)
	if ts.tv_sec > 1e6 {
	// An arbitrary cap on how long to wait for a timer.
	// 1e6 s == ~11.5 days.
	ts.tv_sec = 1e6
	}
	wait = &ts
	}

	var events [128]portevent
	retry:
	var n uint32 = 1
	r := port_getn(portfd, &events[0], uint32(len(events)), &n, wait)
	e := errno()
	if r < 0 && e == _ETIME && n > 0 {
	// As per port_getn(3C), an ETIME failure does not preclude the
	// delivery of some number of events. Treat a timeout failure
	// with delivered events as a success.
	r = 0
	}
	if r < 0 {
	if e != _EINTR && e != _ETIME {
	print("runtime: port_getn on fd ", portfd, " failed (errno=", e, ")\n")
	throw("runtime: netpoll failed")
	}
	// If a timed sleep was interrupted and there are no events,
	// just return to recalculate how long we should sleep now.
	if delay > 0 {
	return gList{}
	}
	goto retry
	}

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

	if ev.portev_source == _PORT_SOURCE_ALERT {
	if ev.portev_events != _POLLHUP \|\| unsafe.Pointer(ev.portev_user) != unsafe.Pointer(&portfd) {
	throw("runtime: netpoll: bad port_alert wakeup")
	}
	if delay != 0 {
	// Now that a blocking call to netpoll
	// has seen the alert, take portfd
	// back out of alert mode.
	// See the comment in netpollBreak.
	if port_alert(portfd, 0, 0, 0) < 0 {
	e := errno()
	println("runtime: port_alert failed with", e)
	throw("runtime: netpoll: port_alert failed")
	}
	}
	continue
	}

	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 {
	// TODO(mikio): Consider implementing event
	// scanning error reporting once we are sure
	// about the event port on SmartOS.
	//
	// See golang.org/x/issue/30840.
	netpollready(&toRun, pd, mode)
	}
	}

	return toRun
	}