github.com/tcnksm/go@v0.0.0-20141208075154-439b32936367/src/runtime/netpoll_kqueue.go (about)

     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  func kqueue() int32
    14  
    15  //go:noescape
    16  func kevent(kq int32, ch *keventt, nch int32, ev *keventt, nev int32, ts *timespec) int32
    17  func closeonexec(fd int32)
    18  
    19  var (
    20  	kq             int32 = -1
    21  	netpolllasterr int32
    22  )
    23  
    24  func netpollinit() {
    25  	kq = kqueue()
    26  	if kq < 0 {
    27  		println("netpollinit: kqueue failed with", -kq)
    28  		gothrow("netpollinit: kqueue failed")
    29  	}
    30  	closeonexec(kq)
    31  }
    32  
    33  func netpollopen(fd uintptr, pd *pollDesc) int32 {
    34  	// Arm both EVFILT_READ and EVFILT_WRITE in edge-triggered mode (EV_CLEAR)
    35  	// for the whole fd lifetime.  The notifications are automatically unregistered
    36  	// when fd is closed.
    37  	var ev [2]keventt
    38  	*(*uintptr)(unsafe.Pointer(&ev[0].ident)) = fd
    39  	ev[0].filter = _EVFILT_READ
    40  	ev[0].flags = _EV_ADD | _EV_CLEAR
    41  	ev[0].fflags = 0
    42  	ev[0].data = 0
    43  	ev[0].udata = (*byte)(unsafe.Pointer(pd))
    44  	ev[1] = ev[0]
    45  	ev[1].filter = _EVFILT_WRITE
    46  	n := kevent(kq, &ev[0], 2, nil, 0, nil)
    47  	if n < 0 {
    48  		return -n
    49  	}
    50  	return 0
    51  }
    52  
    53  func netpollclose(fd uintptr) int32 {
    54  	// Don't need to unregister because calling close()
    55  	// on fd will remove any kevents that reference the descriptor.
    56  	return 0
    57  }
    58  
    59  func netpollarm(pd *pollDesc, mode int) {
    60  	gothrow("unused")
    61  }
    62  
    63  // Polls for ready network connections.
    64  // Returns list of goroutines that become runnable.
    65  func netpoll(block bool) (gp *g) {
    66  	if kq == -1 {
    67  		return
    68  	}
    69  	var tp *timespec
    70  	var ts timespec
    71  	if !block {
    72  		tp = &ts
    73  	}
    74  	var events [64]keventt
    75  retry:
    76  	n := kevent(kq, nil, 0, &events[0], int32(len(events)), tp)
    77  	if n < 0 {
    78  		if n != -_EINTR && n != netpolllasterr {
    79  			netpolllasterr = n
    80  			println("runtime: kevent on fd", kq, "failed with", -n)
    81  		}
    82  		goto retry
    83  	}
    84  	for i := 0; i < int(n); i++ {
    85  		ev := &events[i]
    86  		var mode int32
    87  		if ev.filter == _EVFILT_READ {
    88  			mode += 'r'
    89  		}
    90  		if ev.filter == _EVFILT_WRITE {
    91  			mode += 'w'
    92  		}
    93  		if mode != 0 {
    94  			netpollready((**g)(noescape(unsafe.Pointer(&gp))), (*pollDesc)(unsafe.Pointer(ev.udata)), mode)
    95  		}
    96  	}
    97  	if block && gp == nil {
    98  		goto retry
    99  	}
   100  	return gp
   101  }