Adding upstream version 1.20.14.upstream/1.20.14upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 318 insertions, 0 deletions

diff --git a/src/runtime/netpoll_solaris.go b/src/runtime/netpoll_solaris.go
new file mode 100644
index 0000000..fad7f78
--- /dev/null
+++ b/src/runtime/netpoll_solaris.go
@@ -0,0 +1,318 @@
+// 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 (
+	"runtime/internal/atomic"
+	"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:cgo_import_dynamic libc_port_alert port_alert "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
+//go:linkname libc_port_alert libc_port_alert
+
+var (
+	libc_port_create,
+	libc_port_associate,
+	libc_port_dissociate,
+	libc_port_getn,
+	libc_port_alert libcFunc
+	netpollWakeSig atomic.Uint32 // used to avoid duplicate calls of netpollBreak
+)
+
+func errno() int32 {
+	return *getg().m.perrno
+}
+
+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))))
+}
+
+func port_alert(port int32, flags, events uint32, user uintptr) int32 {
+	return int32(sysvicall4(&libc_port_alert, uintptr(port), uintptr(flags), uintptr(events), user))
+}
+
+var portfd int32 = -1
+
+func netpollinit() {
+	portfd = port_create()
+	if portfd >= 0 {
+		fcntl(portfd, _F_SETFD, _FD_CLOEXEC)
+		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)
+	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.info().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() {
+	// Failing to cas indicates there is an in-flight wakeup, so we're done here.
+	if !netpollWakeSig.CompareAndSwap(0, 1) {
+		return
+	}
+
+	// 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")
+				}
+				netpollWakeSig.Store(0)
+			}
+			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
+}