github.com/riscv/riscv-go@v0.0.0-20200123204226-124ebd6fcc8e/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  )
    24  
    25  func netpollinit() {
    26  	epfd = epollcreate1(_EPOLL_CLOEXEC)
    27  	if epfd >= 0 {
    28  		return
    29  	}
    30  	epfd = epollcreate(1024)
    31  	if epfd >= 0 {
    32  		closeonexec(epfd)
    33  		return
    34  	}
    35  	println("netpollinit: failed to create epoll descriptor", -epfd)
    36  	throw("netpollinit: failed to create descriptor")
    37  }
    38  
    39  func netpollopen(fd uintptr, pd *pollDesc) int32 {
    40  	var ev epollevent
    41  	ev.events = _EPOLLIN | _EPOLLOUT | _EPOLLRDHUP | _EPOLLET
    42  	*(**pollDesc)(unsafe.Pointer(&ev.data)) = pd
    43  	return -epollctl(epfd, _EPOLL_CTL_ADD, int32(fd), &ev)
    44  }
    45  
    46  func netpollclose(fd uintptr) int32 {
    47  	var ev epollevent
    48  	return -epollctl(epfd, _EPOLL_CTL_DEL, int32(fd), &ev)
    49  }
    50  
    51  func netpollarm(pd *pollDesc, mode int) {
    52  	throw("unused")
    53  }
    54  
    55  // polls for ready network connections
    56  // returns list of goroutines that become runnable
    57  func netpoll(block bool) *g {
    58  	if epfd == -1 {
    59  		return nil
    60  	}
    61  	waitms := int32(-1)
    62  	if !block {
    63  		waitms = 0
    64  	}
    65  	var events [128]epollevent
    66  retry:
    67  	n := epollwait(epfd, &events[0], int32(len(events)), waitms)
    68  	if n < 0 {
    69  		if n != -_EINTR {
    70  			println("runtime: epollwait on fd", epfd, "failed with", -n)
    71  			throw("epollwait failed")
    72  		}
    73  		goto retry
    74  	}
    75  	var gp guintptr
    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  
    91  			netpollready(&gp, pd, mode)
    92  		}
    93  	}
    94  	if block && gp == 0 {
    95  		goto retry
    96  	}
    97  	return gp.ptr()
    98  }