github.com/4ad/go@v0.0.0-20161219182952-69a12818b605/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  )
    22  
    23  func netpollinit() {
    24  	kq = kqueue()
    25  	if kq < 0 {
    26  		println("netpollinit: kqueue failed with", -kq)
    27  		throw("netpollinit: kqueue failed")
    28  	}
    29  	closeonexec(kq)
    30  }
    31  
    32  func netpollopen(fd uintptr, pd *pollDesc) int32 {
    33  	// Arm both EVFILT_READ and EVFILT_WRITE in edge-triggered mode (EV_CLEAR)
    34  	// for the whole fd lifetime. The notifications are automatically unregistered
    35  	// when fd is closed.
    36  	var ev [2]keventt
    37  	*(*uintptr)(unsafe.Pointer(&ev[0].ident)) = fd
    38  	ev[0].filter = _EVFILT_READ
    39  	ev[0].flags = _EV_ADD | _EV_CLEAR
    40  	ev[0].fflags = 0
    41  	ev[0].data = 0
    42  	ev[0].udata = (*byte)(unsafe.Pointer(pd))
    43  	ev[1] = ev[0]
    44  	ev[1].filter = _EVFILT_WRITE
    45  	n := kevent(kq, &ev[0], 2, nil, 0, nil)
    46  	if n < 0 {
    47  		return -n
    48  	}
    49  	return 0
    50  }
    51  
    52  func netpollclose(fd uintptr) int32 {
    53  	// Don't need to unregister because calling close()
    54  	// on fd will remove any kevents that reference the descriptor.
    55  	return 0
    56  }
    57  
    58  func netpollarm(pd *pollDesc, mode int) {
    59  	throw("unused")
    60  }
    61  
    62  // Polls for ready network connections.
    63  // Returns list of goroutines that become runnable.
    64  func netpoll(block bool) *g {
    65  	if kq == -1 {
    66  		return nil
    67  	}
    68  	var tp *timespec
    69  	var ts timespec
    70  	if !block {
    71  		tp = &ts
    72  	}
    73  	var events [64]keventt
    74  retry:
    75  	n := kevent(kq, nil, 0, &events[0], int32(len(events)), tp)
    76  	if n < 0 {
    77  		if n != -_EINTR {
    78  			println("runtime: kevent on fd", kq, "failed with", -n)
    79  			throw("kevent failed")
    80  		}
    81  		goto retry
    82  	}
    83  	var gp guintptr
    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(&gp, (*pollDesc)(unsafe.Pointer(ev.udata)), mode)
    95  		}
    96  	}
    97  	if block && gp == 0 {
    98  		goto retry
    99  	}
   100  	return gp.ptr()
   101  }