github.com/reiver/go@v0.0.0-20150109200633-1d0c7792f172/src/runtime/netpoll_epoll.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 linux
     6  
     7  package runtime
     8  
     9  import "unsafe"
    10  
    11  func epollcreate(size int32) int32
    12  func epollcreate1(flags int32) int32
    13  
    14  //go:noescape
    15  func epollctl(epfd, op, fd int32, ev *epollevent) int32
    16  
    17  //go:noescape
    18  func epollwait(epfd int32, ev *epollevent, nev, timeout int32) int32
    19  func closeonexec(fd int32)
    20  
    21  var (
    22  	epfd           int32 = -1 // epoll descriptor
    23  	netpolllasterr int32
    24  )
    25  
    26  func netpollinit() {
    27  	epfd = epollcreate1(_EPOLL_CLOEXEC)
    28  	if epfd >= 0 {
    29  		return
    30  	}
    31  	epfd = epollcreate(1024)
    32  	if epfd >= 0 {
    33  		closeonexec(epfd)
    34  		return
    35  	}
    36  	println("netpollinit: failed to create epoll descriptor", -epfd)
    37  	throw("netpollinit: failed to create descriptor")
    38  }
    39  
    40  func netpollopen(fd uintptr, pd *pollDesc) int32 {
    41  	var ev epollevent
    42  	ev.events = _EPOLLIN | _EPOLLOUT | _EPOLLRDHUP | _EPOLLET
    43  	*(**pollDesc)(unsafe.Pointer(&ev.data)) = pd
    44  	return -epollctl(epfd, _EPOLL_CTL_ADD, int32(fd), &ev)
    45  }
    46  
    47  func netpollclose(fd uintptr) int32 {
    48  	var ev epollevent
    49  	return -epollctl(epfd, _EPOLL_CTL_DEL, int32(fd), &ev)
    50  }
    51  
    52  func netpollarm(pd *pollDesc, mode int) {
    53  	throw("unused")
    54  }
    55  
    56  // polls for ready network connections
    57  // returns list of goroutines that become runnable
    58  func netpoll(block bool) (gp *g) {
    59  	if epfd == -1 {
    60  		return
    61  	}
    62  	waitms := int32(-1)
    63  	if !block {
    64  		waitms = 0
    65  	}
    66  	var events [128]epollevent
    67  retry:
    68  	n := epollwait(epfd, &events[0], int32(len(events)), waitms)
    69  	if n < 0 {
    70  		if n != -_EINTR && n != netpolllasterr {
    71  			netpolllasterr = n
    72  			println("runtime: epollwait on fd", epfd, "failed with", -n)
    73  		}
    74  		goto retry
    75  	}
    76  	for i := int32(0); i < n; i++ {
    77  		ev := &events[i]
    78  		if ev.events == 0 {
    79  			continue
    80  		}
    81  		var mode int32
    82  		if ev.events&(_EPOLLIN|_EPOLLRDHUP|_EPOLLHUP|_EPOLLERR) != 0 {
    83  			mode += 'r'
    84  		}
    85  		if ev.events&(_EPOLLOUT|_EPOLLHUP|_EPOLLERR) != 0 {
    86  			mode += 'w'
    87  		}
    88  		if mode != 0 {
    89  			pd := *(**pollDesc)(unsafe.Pointer(&ev.data))
    90  			netpollready((**g)(noescape(unsafe.Pointer(&gp))), pd, mode)
    91  		}
    92  	}
    93  	if block && gp == nil {
    94  		goto retry
    95  	}
    96  	return gp
    97  }