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
|
/***
This file is part of PulseAudio.
Copyright 2006 Lennart Poettering
PulseAudio is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as
published by the Free Software Foundation; either version 2.1 of the
License, or (at your option) any later version.
PulseAudio is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with PulseAudio; if not, see <http://www.gnu.org/licenses/>.
***/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif
#include <unistd.h>
#include <errno.h>
#include <pulsecore/atomic.h>
#include <pulsecore/log.h>
#include <pulsecore/thread.h>
#include <pulsecore/macro.h>
#include <pulsecore/core-util.h>
#include <pulse/xmalloc.h>
#include "fdsem.h"
/* For debugging purposes we can define _Y to put and extra thread
* yield between each operation. */
/* #define PROFILE */
#ifdef PROFILE
#define _Y pa_thread_yield()
#else
#define _Y do { } while(0)
#endif
struct pa_shmasyncq {
pa_fdsem *read_fdsem, *write_fdsem;
pa_shmasyncq_data *data;
};
static int is_power_of_two(unsigned size) {
return !(size & (size - 1));
}
static int reduce(pa_shmasyncq *l, int value) {
return value & (unsigned) (l->n_elements - 1);
}
static pa_atomic_t* get_cell(pa_shmasyncq *l, unsigned i) {
pa_assert(i < l->data->n_elements);
return (pa_atomic_t*) ((uint8*t) l->data + PA_ALIGN(sizeof(pa_shmasyncq_data)) + i * (PA_ALIGN(sizeof(pa_atomic_t)) + PA_ALIGN(element_size)))
}
static void *get_cell_data(pa_atomic_t *a) {
return (uint8_t*) a + PA_ALIGN(sizeof(atomic_t));
}
pa_shmasyncq *pa_shmasyncq_new(unsigned n_elements, size_t element_size, void *data, int fd[2]) {
pa_shmasyncq *l;
pa_assert(n_elements > 0);
pa_assert(is_power_of_two(n_elements));
pa_assert(element_size > 0);
pa_assert(data);
pa_assert(fd);
l = pa_xnew(pa_shmasyncq, 1);
l->data = data;
memset(data, 0, PA_SHMASYNCQ_SIZE(n_elements, element_size));
l->data->n_elements = n_elements;
l->data->element_size = element_size;
if (!(l->read_fdsem = pa_fdsem_new_shm(&d->read_fdsem_data))) {
pa_xfree(l);
return NULL;
}
fd[0] = pa_fdsem_get(l->read_fdsem);
if (!(l->write_fdsem = pa_fdsem_new(&d->write_fdsem_data, &fd[1]))) {
pa_fdsem_free(l->read_fdsem);
pa_xfree(l);
return NULL;
}
return l;
}
void pa_shmasyncq_free(pa_shmasyncq *l, pa_free_cb_t free_cb) {
pa_assert(l);
if (free_cb) {
void *p;
while ((p = pa_shmasyncq_pop(l, 0)))
free_cb(p);
}
pa_fdsem_free(l->read_fdsem);
pa_fdsem_free(l->write_fdsem);
pa_xfree(l);
}
int pa_shmasyncq_push(pa_shmasyncq*l, void *p, int wait) {
int idx;
pa_atomic_ptr_t *cells;
pa_assert(l);
pa_assert(p);
cells = PA_SHMASYNCQ_CELLS(l);
_Y;
idx = reduce(l, l->write_idx);
if (!pa_atomic_ptr_cmpxchg(&cells[idx], NULL, p)) {
if (!wait)
return -1;
/* pa_log("sleeping on push"); */
do {
pa_fdsem_wait(l->read_fdsem);
} while (!pa_atomic_ptr_cmpxchg(&cells[idx], NULL, p));
}
_Y;
l->write_idx++;
pa_fdsem_post(l->write_fdsem);
return 0;
}
void* pa_shmasyncq_pop(pa_shmasyncq*l, int wait) {
int idx;
void *ret;
pa_atomic_ptr_t *cells;
pa_assert(l);
cells = PA_SHMASYNCQ_CELLS(l);
_Y;
idx = reduce(l, l->read_idx);
if (!(ret = pa_atomic_ptr_load(&cells[idx]))) {
if (!wait)
return NULL;
/* pa_log("sleeping on pop"); */
do {
pa_fdsem_wait(l->write_fdsem);
} while (!(ret = pa_atomic_ptr_load(&cells[idx])));
}
pa_assert(ret);
/* Guaranteed to succeed if we only have a single reader */
pa_assert_se(pa_atomic_ptr_cmpxchg(&cells[idx], ret, NULL));
_Y;
l->read_idx++;
pa_fdsem_post(l->read_fdsem);
return ret;
}
int pa_shmasyncq_get_fd(pa_shmasyncq *q) {
pa_assert(q);
return pa_fdsem_get(q->write_fdsem);
}
int pa_shmasyncq_before_poll(pa_shmasyncq *l) {
int idx;
pa_atomic_ptr_t *cells;
pa_assert(l);
cells = PA_SHMASYNCQ_CELLS(l);
_Y;
idx = reduce(l, l->read_idx);
for (;;) {
if (pa_atomic_ptr_load(&cells[idx]))
return -1;
if (pa_fdsem_before_poll(l->write_fdsem) >= 0)
return 0;
}
return 0;
}
void pa_shmasyncq_after_poll(pa_shmasyncq *l) {
pa_assert(l);
pa_fdsem_after_poll(l->write_fdsem);
}
|
