github.com/xushiwei/go@v0.0.0-20130601165731-2b9d83f45bc9/src/pkg/runtime/netpoll_kqueue.c (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
     6  
     7  #include "runtime.h"
     8  #include "defs_GOOS_GOARCH.h"
     9  
    10  // Integrated network poller (kqueue-based implementation).
    11  
    12  int32	runtime·kqueue(void);
    13  int32	runtime·kevent(int32, Kevent*, int32, Kevent*, int32, Timespec*);
    14  void	runtime·closeonexec(int32);
    15  
    16  static int32 kq = -1;
    17  
    18  void
    19  runtime·netpollinit(void)
    20  {
    21  	kq = runtime·kqueue();
    22  	if(kq < 0) {
    23  		runtime·printf("netpollinit: kqueue failed with %d\n", -kq);
    24  		runtime·throw("netpollinit: kqueue failed");
    25  	}
    26  	runtime·closeonexec(kq);
    27  }
    28  
    29  int32
    30  runtime·netpollopen(int32 fd, PollDesc *pd)
    31  {
    32  	Kevent ev[2];
    33  	int32 n;
    34  
    35  	// Arm both EVFILT_READ and EVFILT_WRITE in edge-triggered mode (EV_CLEAR)
    36  	// for the whole fd lifetime.  The notifications are automatically unregistered
    37  	// when fd is closed.
    38  	ev[0].ident = fd;
    39  	ev[0].filter = EVFILT_READ;
    40  	ev[0].flags = EV_ADD|EV_RECEIPT|EV_CLEAR;
    41  	ev[0].fflags = 0;
    42  	ev[0].data = 0;
    43  	ev[0].udata = (byte*)pd;
    44  	ev[1] = ev[0];
    45  	ev[1].filter = EVFILT_WRITE;
    46  	n = runtime·kevent(kq, ev, 2, ev, 2, nil);
    47  	if(n < 0)
    48  		return -n;
    49  	if(n != 2 ||
    50  		(ev[0].flags&EV_ERROR) == 0 || ev[0].ident != fd || ev[0].filter != EVFILT_READ ||
    51  		(ev[1].flags&EV_ERROR) == 0 || ev[1].ident != fd || ev[1].filter != EVFILT_WRITE)
    52  		return EFAULT;  // just to mark out from other errors
    53  	if(ev[0].data != 0)
    54  		return ev[0].data;
    55  	if(ev[1].data != 0)
    56  		return ev[1].data;
    57  	return 0;
    58  }
    59  
    60  int32
    61  runtime·netpollclose(int32 fd)
    62  {
    63  	// Don't need to unregister because calling close()
    64  	// on fd will remove any kevents that reference the descriptor.
    65  	USED(fd);
    66  	return 0;
    67  }
    68  
    69  // Polls for ready network connections.
    70  // Returns list of goroutines that become runnable.
    71  G*
    72  runtime·netpoll(bool block)
    73  {
    74  	static int32 lasterr;
    75  	Kevent events[64], *ev;
    76  	Timespec ts, *tp;
    77  	int32 n, i;
    78  	G *gp;
    79  
    80  	if(kq == -1)
    81  		return nil;
    82  	tp = nil;
    83  	if(!block) {
    84  		ts.tv_sec = 0;
    85  		ts.tv_nsec = 0;
    86  		tp = &ts;
    87  	}
    88  	gp = nil;
    89  retry:
    90  	n = runtime·kevent(kq, nil, 0, events, nelem(events), tp);
    91  	if(n < 0) {
    92  		if(n != -EINTR && n != lasterr) {
    93  			lasterr = n;
    94  			runtime·printf("runtime: kevent on fd %d failed with %d\n", kq, -n);
    95  		}
    96  		goto retry;
    97  	}
    98  	for(i = 0; i < n; i++) {
    99  		ev = &events[i];
   100  		if(ev->filter == EVFILT_READ)
   101  			runtime·netpollready(&gp, (PollDesc*)ev->udata, 'r');
   102  		if(ev->filter == EVFILT_WRITE)
   103  			runtime·netpollready(&gp, (PollDesc*)ev->udata, 'w');
   104  	}
   105  	if(block && gp == nil)
   106  		goto retry;
   107  	return gp;
   108  }