Source file src/runtime/netpoll_kqueue.go

     1	// Copyright 2013 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	// +build darwin dragonfly freebsd netbsd openbsd
     6	
     7	package runtime
     8	
     9	// Integrated network poller (kqueue-based implementation).
    10	
    11	import "unsafe"
    12	
    13	var (
    14		kq int32 = -1
    15	)
    16	
    17	func netpollinit() {
    18		kq = kqueue()
    19		if kq < 0 {
    20			println("runtime: kqueue failed with", -kq)
    21			throw("runtime: netpollinit failed")
    22		}
    23		closeonexec(kq)
    24	}
    25	
    26	func netpolldescriptor() uintptr {
    27		return uintptr(kq)
    28	}
    29	
    30	func netpollopen(fd uintptr, pd *pollDesc) int32 {
    31		// Arm both EVFILT_READ and EVFILT_WRITE in edge-triggered mode (EV_CLEAR)
    32		// for the whole fd lifetime. The notifications are automatically unregistered
    33		// when fd is closed.
    34		var ev [2]keventt
    35		*(*uintptr)(unsafe.Pointer(&ev[0].ident)) = fd
    36		ev[0].filter = _EVFILT_READ
    37		ev[0].flags = _EV_ADD | _EV_CLEAR
    38		ev[0].fflags = 0
    39		ev[0].data = 0
    40		ev[0].udata = (*byte)(unsafe.Pointer(pd))
    41		ev[1] = ev[0]
    42		ev[1].filter = _EVFILT_WRITE
    43		n := kevent(kq, &ev[0], 2, nil, 0, nil)
    44		if n < 0 {
    45			return -n
    46		}
    47		return 0
    48	}
    49	
    50	func netpollclose(fd uintptr) int32 {
    51		// Don't need to unregister because calling close()
    52		// on fd will remove any kevents that reference the descriptor.
    53		return 0
    54	}
    55	
    56	func netpollarm(pd *pollDesc, mode int) {
    57		throw("runtime: unused")
    58	}
    59	
    60	// Polls for ready network connections.
    61	// Returns list of goroutines that become runnable.
    62	func netpoll(block bool) gList {
    63		if kq == -1 {
    64			return gList{}
    65		}
    66		var tp *timespec
    67		var ts timespec
    68		if !block {
    69			tp = &ts
    70		}
    71		var events [64]keventt
    72	retry:
    73		n := kevent(kq, nil, 0, &events[0], int32(len(events)), tp)
    74		if n < 0 {
    75			if n != -_EINTR {
    76				println("runtime: kevent on fd", kq, "failed with", -n)
    77				throw("runtime: netpoll failed")
    78			}
    79			goto retry
    80		}
    81		var toRun gList
    82		for i := 0; i < int(n); i++ {
    83			ev := &events[i]
    84			var mode int32
    85			switch ev.filter {
    86			case _EVFILT_READ:
    87				mode += 'r'
    88	
    89				// On some systems when the read end of a pipe
    90				// is closed the write end will not get a
    91				// _EVFILT_WRITE event, but will get a
    92				// _EVFILT_READ event with EV_EOF set.
    93				// Note that setting 'w' here just means that we
    94				// will wake up a goroutine waiting to write;
    95				// that goroutine will try the write again,
    96				// and the appropriate thing will happen based
    97				// on what that write returns (success, EPIPE, EAGAIN).
    98				if ev.flags&_EV_EOF != 0 {
    99					mode += 'w'
   100				}
   101			case _EVFILT_WRITE:
   102				mode += 'w'
   103			}
   104			if mode != 0 {
   105				pd := (*pollDesc)(unsafe.Pointer(ev.udata))
   106				pd.everr = false
   107				if ev.flags == _EV_ERROR {
   108					pd.everr = true
   109				}
   110				netpollready(&toRun, pd, mode)
   111			}
   112		}
   113		if block && toRun.empty() {
   114			goto retry
   115		}
   116		return toRun
   117	}
   118	

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