1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
|
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package runtime
import "unsafe"
// This is based on the former libgo/runtime/netpoll_select.c implementation
// except that it uses poll instead of select and is written in Go.
type pollfd struct {
fd int32
events int16
revents int16
}
const _POLLIN = 0x0001
const _POLLOUT = 0x0002
const _POLLHUP = 0x2000
const _POLLERR = 0x4000
//go:noescape
//extern poll
func libc_poll(pfds *pollfd, npfds uintptr, timeout uintptr) int32
//go:noescape
//extern pipe
func libc_pipe(fd *int32) int32
//extern __go_fcntl_uintptr
func fcntlUintptr(fd, cmd, arg uintptr) (uintptr, uintptr)
func fcntl(fd, cmd int32, arg uintptr) uintptr {
r, _ := fcntlUintptr(uintptr(fd), uintptr(cmd), arg)
return r
}
var (
pfds []pollfd
pds []*pollDesc
mtxpoll mutex
mtxset mutex
rdwake int32
wrwake int32
needsUpdate bool
)
func netpollinit() {
var p [2]int32
// Create the pipe we use to wakeup poll.
if err := libc_pipe(&p[0]); err < 0 {
throw("runtime: netpollinit failed to create pipe")
}
rdwake = p[0]
wrwake = p[1]
fl := fcntl(rdwake, _F_GETFL, 0)
fcntl(rdwake, _F_SETFL, fl|_O_NONBLOCK)
fcntl(rdwake, _F_SETFD, _FD_CLOEXEC)
fl = fcntl(wrwake, _F_GETFL, 0)
fcntl(wrwake, _F_SETFD, _FD_CLOEXEC)
// Pre-allocate array of pollfd structures for poll.
pfds = make([]pollfd, 1, 128)
// Poll the read side of the pipe.
pfds[0].fd = rdwake
pfds[0].events = _POLLIN
// Allocate index to pd array
pds = make([]*pollDesc, 1, 128)
pds[0] = nil
}
func netpolldescriptor() uintptr {
return ^uintptr(0)
}
func netpollwakeup() {
if !needsUpdate {
needsUpdate = true
b := [1]byte{0}
write(uintptr(wrwake), unsafe.Pointer(&b[0]), 1)
}
}
func netpollopen(fd uintptr, pd *pollDesc) int32 {
lock(&mtxpoll)
netpollwakeup()
lock(&mtxset)
unlock(&mtxpoll)
pd.user = uint32(len(pfds))
var pfd pollfd
pfd.fd = int32(fd)
pfds = append(pfds, pfd)
pds = append(pds, pd)
unlock(&mtxset)
return 0
}
func netpollclose(fd uintptr) int32 {
lock(&mtxpoll)
netpollwakeup()
lock(&mtxset)
unlock(&mtxpoll)
for i := 0; i < len(pfds); i++ {
if pfds[i].fd == int32(fd) {
pfds[i] = pfds[len(pfds)-1]
pfds = pfds[:len(pfds)-1]
pds[i] = pds[len(pds)-1]
pds[i].user = uint32(i)
pds = pds[:len(pds)-1]
break
}
}
unlock(&mtxset)
return 0
}
func netpollarm(pd *pollDesc, mode int) {
lock(&mtxpoll)
netpollwakeup()
lock(&mtxset)
unlock(&mtxpoll)
switch mode {
case 'r':
pfds[pd.user].events |= _POLLIN
case 'w':
pfds[pd.user].events |= _POLLOUT
}
unlock(&mtxset)
}
//go:nowritebarrierrec
func netpoll(block bool) *g {
timeout := ^uintptr(0)
if !block {
timeout = 0
return nil
}
retry:
lock(&mtxpoll)
lock(&mtxset)
needsUpdate = false
unlock(&mtxpoll)
n := libc_poll(&pfds[0], uintptr(len(pfds)), timeout)
if n < 0 {
e := errno()
if e != _EINTR {
throw("runtime: poll failed")
}
unlock(&mtxset)
goto retry
}
// Check if some descriptors need to be changed
if n != 0 && pfds[0].revents&(_POLLIN|_POLLHUP|_POLLERR) != 0 {
var b [1]byte
for read(rdwake, unsafe.Pointer(&b[0]), 1) == 1 {
}
// Do not look at the other fds in this case as the mode may have changed
// XXX only additions of flags are made, so maybe it is ok
unlock(&mtxset)
goto retry
}
var gp guintptr
for i := 0; i < len(pfds) && n > 0; i++ {
pfd := &pfds[i]
var mode int32
if pfd.revents&(_POLLIN|_POLLHUP|_POLLERR) != 0 {
mode += 'r'
pfd.events &= ^_POLLIN
}
if pfd.revents&(_POLLOUT|_POLLHUP|_POLLERR) != 0 {
mode += 'w'
pfd.events &= ^_POLLOUT
}
if mode != 0 {
netpollready(&gp, pds[i], mode)
n--
}
}
unlock(&mtxset)
if block && gp == 0 {
goto retry
}
return gp.ptr()
}
|
