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
|
/* This file is part of the Spring engine (GPL v2 or later), see LICENSE.html */
#include "Futex.h"
#include <cstdlib>
#include <linux/futex.h>
#include <sys/syscall.h>
#include <unistd.h>
#include <climits>
#include <algorithm>
spring_futex::spring_futex() noexcept
{
mtx = 0;
}
spring_futex::~spring_futex()
{
mtx = 0;
}
void spring_futex::lock()
{
native_type c;
if ((c = __sync_val_compare_and_swap(&mtx, 0, 1)) == 0)
return;
do {
if ((c == 2) || __sync_val_compare_and_swap(&mtx, 1, 2) != 0)
syscall(SYS_futex, &mtx, FUTEX_WAIT_PRIVATE, 2, NULL, NULL, 0);
} while((c = __sync_val_compare_and_swap(&mtx, 0, 2)) != 0);
}
bool spring_futex::try_lock() noexcept
{
return __sync_bool_compare_and_swap(&mtx, 0, 1);
}
void spring_futex::unlock()
{
if (__sync_fetch_and_sub(&mtx, 1) != 1) {
mtx = 0;
syscall(SYS_futex, &mtx, FUTEX_WAKE_PRIVATE, 4, NULL, NULL, 0);
}
}
/*
recursive_futex::recursive_futex() noexcept
{
mtx = 0;
}
recursive_futex::~recursive_futex()
{
mtx = 0;
}
void recursive_futex::lock()
{
native_type c;
if ((c = __sync_val_compare_and_swap(&mtx, 0, 1)) == 0)
return;
do {
if ((c == 2) || __sync_val_compare_and_swap(&mtx, 1, 2) != 0)
syscall(SYS_futex, &mtx, FUTEX_WAIT_PRIVATE, 2, NULL, NULL, 0);
} while((c = __sync_val_compare_and_swap(&mtx, 0, 2)) != 0);
}
bool recursive_futex::try_lock() noexcept
{
return __sync_bool_compare_and_swap(&mtx, 0, 1);
}
void recursive_futex::unlock()
{
if (__sync_fetch_and_sub(&mtx, 1) != 1) {
mtx = 0;
syscall(SYS_futex, &mtx, FUTEX_WAKE_PRIVATE, 1, NULL, NULL, 0);
}
}
*/
linux_signal::linux_signal() noexcept
: sleepers(false)
, gen(0)
, mtx(0)
{
}
linux_signal::~linux_signal()
{
gen = {0};
mtx = 0;
}
void linux_signal::wait()
{
int m; // cur gen
const int g = gen.load(); // our gen
sleepers++;
while ((g - (m = mtx)) >= 0) {
syscall(SYS_futex, &mtx, FUTEX_WAIT_PRIVATE, m, NULL, NULL, 0);
}
sleepers--;
}
void linux_signal::wait_for(spring_time t)
{
int m; // cur gen
const int g = gen.load(); // our gen
sleepers++;
struct timespec linux_t;
linux_t.tv_sec = 0;
linux_t.tv_nsec = t.toNanoSecsi();
const spring_time endTimer = spring_now() + t;
while (((g - (m = mtx)) >= 0) && (spring_now() < endTimer)) {
syscall(SYS_futex, &mtx, FUTEX_WAIT_PRIVATE, m, &linux_t, NULL, 0);
}
sleepers--;
}
void linux_signal::notify_all(const int min_sleepers)
{
if (sleepers.load() < std::max(1, min_sleepers))
return;
mtx = gen++;
syscall(SYS_futex, &mtx, FUTEX_WAKE_PRIVATE, INT_MAX, NULL, NULL, 0);
}
|
