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Source file src/runtime/netpoll_epoll.go

Documentation: runtime

     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("runtime: epollcreate failed with", -epfd)
    36  	throw("runtime: netpollinit failed")
    37  }
    38  
    39  func netpolldescriptor() uintptr {
    40  	return uintptr(epfd)
    41  }
    42  
    43  func netpollopen(fd uintptr, pd *pollDesc) int32 {
    44  	var ev epollevent
    45  	ev.events = _EPOLLIN | _EPOLLOUT | _EPOLLRDHUP | _EPOLLET
    46  	*(**pollDesc)(unsafe.Pointer(&ev.data)) = pd
    47  	return -epollctl(epfd, _EPOLL_CTL_ADD, int32(fd), &ev)
    48  }
    49  
    50  func netpollclose(fd uintptr) int32 {
    51  	var ev epollevent
    52  	return -epollctl(epfd, _EPOLL_CTL_DEL, int32(fd), &ev)
    53  }
    54  
    55  func netpollarm(pd *pollDesc, mode int) {
    56  	throw("runtime: unused")
    57  }
    58  
    59  // polls for ready network connections
    60  // returns list of goroutines that become runnable
    61  func netpoll(block bool) *g {
    62  	if epfd == -1 {
    63  		return nil
    64  	}
    65  	waitms := int32(-1)
    66  	if !block {
    67  		waitms = 0
    68  	}
    69  	var events [128]epollevent
    70  retry:
    71  	n := epollwait(epfd, &events[0], int32(len(events)), waitms)
    72  	if n < 0 {
    73  		if n != -_EINTR {
    74  			println("runtime: epollwait on fd", epfd, "failed with", -n)
    75  			throw("runtime: netpoll failed")
    76  		}
    77  		goto retry
    78  	}
    79  	var gp guintptr
    80  	for i := int32(0); i < n; i++ {
    81  		ev := &events[i]
    82  		if ev.events == 0 {
    83  			continue
    84  		}
    85  		var mode int32
    86  		if ev.events&(_EPOLLIN|_EPOLLRDHUP|_EPOLLHUP|_EPOLLERR) != 0 {
    87  			mode += 'r'
    88  		}
    89  		if ev.events&(_EPOLLOUT|_EPOLLHUP|_EPOLLERR) != 0 {
    90  			mode += 'w'
    91  		}
    92  		if mode != 0 {
    93  			pd := *(**pollDesc)(unsafe.Pointer(&ev.data))
    94  
    95  			netpollready(&gp, pd, mode)
    96  		}
    97  	}
    98  	if block && gp == 0 {
    99  		goto retry
   100  	}
   101  	return gp.ptr()
   102  }
   103  

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