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
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
|
// +build linux, darwin, freebsd, openbsd
package sync
import "core:sys/unix"
import "core:time"
// A recursive lock that can only be held by one thread at once
Mutex :: struct {
handle: unix.pthread_mutex_t,
}
mutex_init :: proc(m: ^Mutex) {
// NOTE(tetra, 2019-11-01): POSIX OOM if we cannot init the attrs or the mutex.
attrs: unix.pthread_mutexattr_t
assert(unix.pthread_mutexattr_init(&attrs) == 0)
defer unix.pthread_mutexattr_destroy(&attrs) // ignores destruction error
unix.pthread_mutexattr_settype(&attrs, unix.PTHREAD_MUTEX_RECURSIVE)
assert(unix.pthread_mutex_init(&m.handle, &attrs) == 0)
}
mutex_destroy :: proc(m: ^Mutex) {
assert(unix.pthread_mutex_destroy(&m.handle) == 0)
m.handle = {}
}
mutex_lock :: proc(m: ^Mutex) {
assert(unix.pthread_mutex_lock(&m.handle) == 0)
}
// Returns false if someone else holds the lock.
mutex_try_lock :: proc(m: ^Mutex) -> bool {
return unix.pthread_mutex_trylock(&m.handle) == 0
}
mutex_unlock :: proc(m: ^Mutex) {
assert(unix.pthread_mutex_unlock(&m.handle) == 0)
}
Blocking_Mutex :: struct {
handle: unix.pthread_mutex_t,
}
blocking_mutex_init :: proc(m: ^Blocking_Mutex) {
// NOTE(tetra, 2019-11-01): POSIX OOM if we cannot init the attrs or the mutex.
attrs: unix.pthread_mutexattr_t
assert(unix.pthread_mutexattr_init(&attrs) == 0)
defer unix.pthread_mutexattr_destroy(&attrs) // ignores destruction error
assert(unix.pthread_mutex_init(&m.handle, &attrs) == 0)
}
blocking_mutex_destroy :: proc(m: ^Blocking_Mutex) {
assert(unix.pthread_mutex_destroy(&m.handle) == 0)
m.handle = {}
}
blocking_mutex_lock :: proc(m: ^Blocking_Mutex) {
assert(unix.pthread_mutex_lock(&m.handle) == 0)
}
// Returns false if someone else holds the lock.
blocking_mutex_try_lock :: proc(m: ^Blocking_Mutex) -> bool {
return unix.pthread_mutex_trylock(&m.handle) == 0
}
blocking_mutex_unlock :: proc(m: ^Blocking_Mutex) {
assert(unix.pthread_mutex_unlock(&m.handle) == 0)
}
// Blocks until signalled, and then lets past exactly
// one thread.
Condition :: struct {
handle: unix.pthread_cond_t,
mutex: Condition_Mutex_Ptr,
// NOTE(tetra, 2019-11-11): Used to mimic the more sane behavior of Windows' AutoResetEvent.
// This means that you may signal the condition before anyone is waiting to cause the
// next thread that tries to wait to just pass by uninterrupted, without sleeping.
// Without this, signalling a condition will only wake up a thread which is already waiting,
// but not one that is about to wait, which can cause your program to become out of sync in
// ways that are hard to debug or fix.
flag: bool, // atomically mutated
}
condition_init :: proc(c: ^Condition, mutex: Condition_Mutex_Ptr) -> bool {
// NOTE(tetra, 2019-11-01): POSIX OOM if we cannot init the attrs or the condition.
attrs: unix.pthread_condattr_t
if unix.pthread_condattr_init(&attrs) != 0 {
return false
}
defer unix.pthread_condattr_destroy(&attrs) // ignores destruction error
c.flag = false
c.mutex = mutex
return unix.pthread_cond_init(&c.handle, &attrs) == 0
}
condition_destroy :: proc(c: ^Condition) {
assert(unix.pthread_cond_destroy(&c.handle) == 0)
c.handle = {}
}
// Awaken exactly one thread who is waiting on the condition
condition_signal :: proc(c: ^Condition) -> bool {
switch m in c.mutex {
case ^Mutex:
mutex_lock(m)
defer mutex_unlock(m)
atomic_swap(&c.flag, true, .Sequentially_Consistent)
return unix.pthread_cond_signal(&c.handle) == 0
case ^Blocking_Mutex:
blocking_mutex_lock(m)
defer blocking_mutex_unlock(m)
atomic_swap(&c.flag, true, .Sequentially_Consistent)
return unix.pthread_cond_signal(&c.handle) == 0
}
return false
}
// Awaken all threads who are waiting on the condition
condition_broadcast :: proc(c: ^Condition) -> bool {
return unix.pthread_cond_broadcast(&c.handle) == 0
}
// Wait for the condition to be signalled.
// Does not block if the condition has been signalled and no one
// has waited on it yet.
condition_wait_for :: proc(c: ^Condition) -> bool {
switch m in c.mutex {
case ^Mutex:
mutex_lock(m)
defer mutex_unlock(m)
// NOTE(tetra): If a thread comes by and steals the flag immediately after the signal occurs,
// the thread that gets signalled and wakes up, discovers that the flag was taken and goes
// back to sleep.
// Though this overall behavior is the most sane, there may be a better way to do this that means that
// the first thread to wait, gets the flag first.
if atomic_swap(&c.flag, false, .Sequentially_Consistent) {
return true
}
for {
if unix.pthread_cond_wait(&c.handle, &m.handle) != 0 {
return false
}
if atomic_swap(&c.flag, false, .Sequentially_Consistent) {
return true
}
}
return false
case ^Blocking_Mutex:
blocking_mutex_lock(m)
defer blocking_mutex_unlock(m)
// NOTE(tetra): If a thread comes by and steals the flag immediately after the signal occurs,
// the thread that gets signalled and wakes up, discovers that the flag was taken and goes
// back to sleep.
// Though this overall behavior is the most sane, there may be a better way to do this that means that
// the first thread to wait, gets the flag first.
if atomic_swap(&c.flag, false, .Sequentially_Consistent) {
return true
}
for {
if unix.pthread_cond_wait(&c.handle, &m.handle) != 0 {
return false
}
if atomic_swap(&c.flag, false, .Sequentially_Consistent) {
return true
}
}
return false
}
return false
}
// Wait for the condition to be signalled.
// Does not block if the condition has been signalled and no one
// has waited on it yet.
condition_wait_for_timeout :: proc(c: ^Condition, duration: time.Duration) -> bool {
switch m in c.mutex {
case ^Mutex:
mutex_lock(m)
defer mutex_unlock(m)
// NOTE(tetra): If a thread comes by and steals the flag immediately after the signal occurs,
// the thread that gets signalled and wakes up, discovers that the flag was taken and goes
// back to sleep.
// Though this overall behavior is the most sane, there may be a better way to do this that means that
// the first thread to wait, gets the flag first.
if atomic_swap(&c.flag, false, .Sequentially_Consistent) {
return true
}
ns := time.duration_nanoseconds(duration)
timeout: time.TimeSpec
timeout.tv_sec = ns / 1e9
timeout.tv_nsec = ns % 1e9
for {
if unix.pthread_cond_timedwait(&c.handle, &m.handle, &timeout) != 0 {
return false
}
if atomic_swap(&c.flag, false, .Sequentially_Consistent) {
return true
}
}
return false
case ^Blocking_Mutex:
blocking_mutex_lock(m)
defer blocking_mutex_unlock(m)
// NOTE(tetra): If a thread comes by and steals the flag immediately after the signal occurs,
// the thread that gets signalled and wakes up, discovers that the flag was taken and goes
// back to sleep.
// Though this overall behavior is the most sane, there may be a better way to do this that means that
// the first thread to wait, gets the flag first.
if atomic_swap(&c.flag, false, .Sequentially_Consistent) {
return true
}
ns := time.duration_nanoseconds(duration)
timeout: time.TimeSpec
timeout.tv_sec = ns / 1e9
timeout.tv_nsec = ns % 1e9
for {
if unix.pthread_cond_timedwait(&c.handle, &m.handle, &timeout) != 0 {
return false
}
if atomic_swap(&c.flag, false, .Sequentially_Consistent) {
return true
}
}
return false
}
return false
}
thread_yield :: proc() {
unix.sched_yield()
}
|
