summaryrefslogtreecommitdiff
path: root/src/lib/shm_ap_rbuff.c
blob: 63aa8813e7d2bde0c0933f12f92a5e6b7d431a8c (plain)
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
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
/*
 * Ouroboros - Copyright (C) 2016
 *
 * Ring buffer for application processes
 *
 *    Dimitri Staessens <dimitri.staessens@intec.ugent.be>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

#include <ouroboros/shm_ap_rbuff.h>
#define OUROBOROS_PREFIX "shm_ap_rbuff"

#include <ouroboros/logs.h>

#include <pthread.h>
#include <sys/mman.h>
#include <fcntl.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <unistd.h>
#include <stdbool.h>
#include <errno.h>

#define SHM_RBUFF_FILE_SIZE (SHM_RBUFF_SIZE * sizeof(struct rb_entry)          \
                             + 2 * sizeof(size_t) + sizeof(pthread_mutex_t)    \
                             + sizeof (pthread_cond_t))

#define shm_rbuff_used(rb)((*rb->ptr_head + SHM_RBUFF_SIZE - *rb->ptr_tail)    \
                          & (SHM_RBUFF_SIZE - 1))
#define shm_rbuff_free(rb)(shm_rbuff_used(rb) + 1 < SHM_RBUFF_SIZE)
#define head_el_ptr (rb->shm_base + *rb->ptr_head)
#define tail_el_ptr (rb->shm_base + *rb->ptr_tail)

struct shm_ap_rbuff {
        struct rb_entry * shm_base;    /* start of entry */
        size_t *          ptr_head;    /* start of ringbuffer head */
        size_t *          ptr_tail;    /* start of ringbuffer tail */
        pthread_mutex_t * shm_mutex;   /* lock all free space in shm */
        pthread_cond_t *  work;        /* threads will wait for a signal */
        pid_t             pid;         /* pid to which this rb belongs */
        int               fd;
};

struct shm_ap_rbuff * shm_ap_rbuff_create()
{
        struct shm_ap_rbuff * rb;
        int                   shm_fd;
        struct rb_entry *     shm_base;
        pthread_mutexattr_t   mattr;
        pthread_condattr_t    cattr;
        char                  fn[25];

        sprintf(fn, SHM_AP_RBUFF_PREFIX "%d", getpid());

        rb = malloc(sizeof(*rb));
        if (rb == NULL) {
                LOG_DBGF("Could not allocate struct.");
                return NULL;
        }

        shm_fd = shm_open(fn, O_CREAT | O_EXCL | O_RDWR, 0666);
        if (shm_fd == -1) {
                LOG_DBGF("Failed creating ring buffer.");
                free(rb);
                return NULL;
        }

        if (lseek(shm_fd, SHM_RBUFF_FILE_SIZE - 1, SEEK_SET) < 0) {
                LOG_DBGF("Failed to extend ringbuffer.");
                free(rb);
                return NULL;
        }

        if (write(shm_fd, "", 1) != 1) {
                LOG_DBGF("Failed to finalise extension of ringbuffer.");
                free(rb);
                return NULL;
        }

        shm_base = mmap(NULL,
                        SHM_RBUFF_FILE_SIZE,
                        PROT_READ | PROT_WRITE,
                        MAP_SHARED,
                        shm_fd,
                        0);

        if (shm_base == MAP_FAILED) {
                LOG_DBGF("Failed to map shared memory.");
                if (close(shm_fd) == -1)
                        LOG_DBGF("Failed to close invalid shm.");

                if (shm_unlink(fn) == -1)
                        LOG_DBGF("Failed to remove invalid shm.");

                free(rb);
                return NULL;
        }

        rb->shm_base  = shm_base;
        rb->ptr_head  = (size_t *) (rb->shm_base + SHM_RBUFF_SIZE);
        rb->ptr_tail  = rb->ptr_head + 1;
        rb->shm_mutex = (pthread_mutex_t *) (rb->ptr_tail + 1);
        rb->work      = (pthread_cond_t *) (rb->shm_mutex + 1);

        pthread_mutexattr_init(&mattr);
        pthread_mutexattr_setpshared(&mattr, PTHREAD_PROCESS_SHARED);
        pthread_mutex_init(rb->shm_mutex, &mattr);

        pthread_condattr_init(&cattr);
        pthread_condattr_setpshared(&cattr, PTHREAD_PROCESS_SHARED);
        pthread_cond_init(rb->work, &cattr);

        *rb->ptr_head = 0;
        *rb->ptr_tail = 0;

        rb->fd  = shm_fd;
        rb->pid = getpid();

        return rb;
}

struct shm_ap_rbuff * shm_ap_rbuff_open(pid_t pid)
{
        struct shm_ap_rbuff * rb;
        int                   shm_fd;
        struct rb_entry *     shm_base;
        char                  fn[25];

        sprintf(fn, SHM_AP_RBUFF_PREFIX "%d", pid);

        rb = malloc(sizeof(*rb));
        if (rb == NULL) {
                LOG_DBGF("Could not allocate struct.");
                return NULL;
        }

        shm_fd = shm_open(fn, O_RDWR, 0666);
        if (shm_fd == -1) {
                LOG_DBGF("Failed opening shared memory %s.", fn);
                return NULL;
        }

        shm_base = mmap(NULL,
                        SHM_RBUFF_FILE_SIZE,
                        PROT_READ | PROT_WRITE,
                        MAP_SHARED,
                        shm_fd,
                        0);

        if (shm_base == MAP_FAILED) {
                LOG_DBGF("Failed to map shared memory.");
                if (close(shm_fd) == -1)
                        LOG_DBGF("Failed to close invalid shm.");

                if (shm_unlink(fn) == -1)
                        LOG_DBGF("Failed to remove invalid shm.");

                free(rb);
                return NULL;
        }

        rb->shm_base  = shm_base;
        rb->ptr_head  = (size_t *) (rb->shm_base + SHM_RBUFF_SIZE);
        rb->ptr_tail  = rb->ptr_head + 1;
        rb->shm_mutex = (pthread_mutex_t *) (rb->ptr_tail + 1);
        rb->work      = (pthread_cond_t *) (rb->shm_mutex + 1);

        rb->fd = shm_fd;
        rb->pid = pid;

        return rb;
}
void shm_ap_rbuff_close(struct shm_ap_rbuff * rb)
{
        if (rb == NULL) {
                LOG_DBGF("Bogus input. Bugging out.");
                return;
        }

        if (close(rb->fd) < 0)
                LOG_DBGF("Couldn't close shared memory.");

        if (munmap(rb->shm_base, SHM_RBUFF_FILE_SIZE) == -1)
                LOG_DBGF("Couldn't unmap shared memory.");

        free(rb);
}

void shm_ap_rbuff_destroy(struct shm_ap_rbuff * rb)
{
        char fn[25];

        if (rb == NULL) {
                LOG_DBGF("Bogus input. Bugging out.");
                return;
        }

        if (rb->pid != getpid()) {
                LOG_ERR("Tried to destroy other AP's rbuff.");
                return;
        }

        if (close(rb->fd) < 0)
                LOG_DBGF("Couldn't close shared memory.");

        sprintf(fn, SHM_AP_RBUFF_PREFIX "%d", rb->pid);

        if (munmap(rb->shm_base, SHM_RBUFF_FILE_SIZE) == -1)
                LOG_DBGF("Couldn't unmap shared memory.");

        if (shm_unlink(fn) == -1)
                LOG_DBGF("Failed to unlink shm.");

        free(rb);
}

int shm_ap_rbuff_write(struct shm_ap_rbuff * rb, struct rb_entry * e)
{
        if (rb == NULL || e == NULL)
                return -1;

        pthread_mutex_lock(rb->shm_mutex);

        if (!shm_rbuff_free(rb)) {
                pthread_mutex_unlock(rb->shm_mutex);
                return -1;
        }

        if (shm_rbuff_used(rb) == 0)
                pthread_cond_broadcast(rb->work);

        *head_el_ptr = *e;
        *rb->ptr_head = (*rb->ptr_head + 1) & (SHM_RBUFF_SIZE -1);

        pthread_mutex_unlock(rb->shm_mutex);

        return 0;
}

struct rb_entry * shm_ap_rbuff_read(struct shm_ap_rbuff * rb)
{
        struct rb_entry * e = NULL;

        if (rb == NULL)
                return NULL;

        pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
                             (void*) rb->shm_mutex);

        pthread_mutex_lock(rb->shm_mutex);
        while(shm_rbuff_used(rb) == 0)
                pthread_cond_wait(rb->work, rb->shm_mutex);

        pthread_cleanup_pop(0);

        e = malloc(sizeof(*e));
        if (e == NULL) {
                pthread_mutex_unlock(rb->shm_mutex);
                return NULL;
        }

        *e = *(rb->shm_base + *rb->ptr_tail);

        *rb->ptr_tail = (*rb->ptr_tail + 1) & (SHM_RBUFF_SIZE -1);

        pthread_mutex_unlock(rb->shm_mutex);

        return e;
}

ssize_t shm_ap_rbuff_read_port(struct shm_ap_rbuff * rb, int port_id)
{
        ssize_t idx = -1;

        pthread_mutex_lock(rb->shm_mutex);

        if (shm_rbuff_used(rb) == 0) {
                pthread_mutex_unlock(rb->shm_mutex);
                return -1;
        }

        if (tail_el_ptr->port_id != port_id) {
                pthread_mutex_unlock(rb->shm_mutex);
                return -1;
        }

        idx = tail_el_ptr->index;

        *rb->ptr_tail = (*rb->ptr_tail + 1) & (SHM_RBUFF_SIZE -1);

        pthread_mutex_unlock(rb->shm_mutex);

        return idx;
}