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
7package runtime
8
9import "unsafe"
10
11func epollcreate(size int32) int32
12func epollcreate1(flags int32) int32
13
14//go:noescape
15func epollctl(epfd, op, fd int32, ev *epollevent) int32
16
17//go:noescape
18func epollwait(epfd int32, ev *epollevent, nev, timeout int32) int32
19func closeonexec(fd int32)
20
21var (
22	epfd int32 = -1 // epoll descriptor
23)
24
25func 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
39func netpolldescriptor() uintptr {
40	return uintptr(epfd)
41}
42
43func 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
50func netpollclose(fd uintptr) int32 {
51	var ev epollevent
52	return -epollctl(epfd, _EPOLL_CTL_DEL, int32(fd), &ev)
53}
54
55func 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
61func 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
70retry:
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