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
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
|
// Copyright 2018 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 (
"runtime/internal/atomic"
"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.
// It's also based on Solaris implementation for the arming mechanisms
//go:cgo_import_dynamic libc_poll poll "libc.a/shr_64.o"
//go:linkname libc_poll libc_poll
var libc_poll libFunc
//go:nosplit
func poll(pfds *pollfd, npfds uintptr, timeout uintptr) (int32, int32) {
r, err := syscall3(&libc_poll, uintptr(unsafe.Pointer(pfds)), npfds, timeout)
return int32(r), int32(err)
}
// pollfd represents the poll structure for AIX operating system.
type pollfd struct {
fd int32
events int16
revents int16
}
const _POLLIN = 0x0001
const _POLLOUT = 0x0002
const _POLLHUP = 0x2000
const _POLLERR = 0x4000
var (
pfds []pollfd
pds []*pollDesc
mtxpoll mutex
mtxset mutex
rdwake int32
wrwake int32
pendingUpdates int32
netpollWakeSig uint32 // used to avoid duplicate calls of netpollBreak
)
func netpollinit() {
// Create the pipe we use to wakeup poll.
r, w, errno := nonblockingPipe()
if errno != 0 {
throw("netpollinit: failed to create pipe")
}
rdwake = r
wrwake = w
// 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
pds = make([]*pollDesc, 1, 128)
pds[0] = nil
}
func netpollIsPollDescriptor(fd uintptr) bool {
return fd == uintptr(rdwake) || fd == uintptr(wrwake)
}
// netpollwakeup writes on wrwake to wakeup poll before any changes.
func netpollwakeup() {
if pendingUpdates == 0 {
pendingUpdates = 1
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))
pfds = append(pfds, pollfd{fd: int32(fd)})
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)
}
// netpollBreak interrupts a poll.
func netpollBreak() {
if atomic.Cas(&netpollWakeSig, 0, 1) {
b := [1]byte{0}
write(uintptr(wrwake), unsafe.Pointer(&b[0]), 1)
}
}
// netpoll checks for ready network connections.
// Returns list of goroutines that become runnable.
// delay < 0: blocks indefinitely
// delay == 0: does not block, just polls
// delay > 0: block for up to that many nanoseconds
//
//go:nowritebarrierrec
func netpoll(delay int64) gList {
var timeout uintptr
if delay < 0 {
timeout = ^uintptr(0)
} else if delay == 0 {
// TODO: call poll with timeout == 0
return gList{}
} else if delay < 1e6 {
timeout = 1
} else if delay < 1e15 {
timeout = uintptr(delay / 1e6)
} else {
// An arbitrary cap on how long to wait for a timer.
// 1e9 ms == ~11.5 days.
timeout = 1e9
}
retry:
lock(&mtxpoll)
lock(&mtxset)
pendingUpdates = 0
unlock(&mtxpoll)
n, e := poll(&pfds[0], uintptr(len(pfds)), timeout)
if n < 0 {
if e != _EINTR {
println("errno=", e, " len(pfds)=", len(pfds))
throw("poll failed")
}
unlock(&mtxset)
// If a timed sleep was interrupted, just return to
// recalculate how long we should sleep now.
if timeout > 0 {
return gList{}
}
goto retry
}
// Check if some descriptors need to be changed
if n != 0 && pfds[0].revents&(_POLLIN|_POLLHUP|_POLLERR) != 0 {
if delay != 0 {
// A netpollwakeup could be picked up by a
// non-blocking poll. Only clear the wakeup
// if blocking.
var b [1]byte
for read(rdwake, unsafe.Pointer(&b[0]), 1) == 1 {
}
atomic.Store(&netpollWakeSig, 0)
}
// Still look at the other fds even if the mode may have
// changed, as netpollBreak might have been called.
n--
}
var toRun gList
for i := 1; 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 {
pds[i].setEventErr(pfd.revents == _POLLERR)
netpollready(&toRun, pds[i], mode)
n--
}
}
unlock(&mtxset)
return toRun
}
|
