summaryrefslogtreecommitdiff
path: root/src/lib/shm_rbuff_ll.c
blob: 43eac7f672ab92ea9b25e282393b14f9124be9f1 (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
/*
 * Ouroboros - Copyright (C) 2016 - 2018
 *
 * Lockless ring buffer for incoming packets
 *
 *    Dimitri Staessens <dimitri.staessens@ugent.be>
 *    Sander Vrijders   <sander.vrijders@ugent.be>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public License
 * version 2.1 as published by the Free Software Foundation.
 *
 * This library 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 this library; if not, write to the Free Software
 * Foundation, Inc., http://www.fsf.org/about/contact/.
 */

#define RB_HEAD __sync_fetch_and_add(rb->head, 0)
#define RB_TAIL __sync_fetch_and_add(rb->tail, 0)

void shm_rbuff_destroy(struct shm_rbuff * rb)
{
        char fn[FN_MAX_CHARS];

        assert(rb);

        sprintf(fn, SHM_RBUFF_PREFIX "%d.%d", rb->pid, rb->port_id);

        shm_rbuff_close(rb);

        shm_unlink(fn);
}

int shm_rbuff_write(struct shm_rbuff * rb,
                    size_t             idx)
{
        size_t ohead;
        size_t nhead;
        bool   was_empty = false;

        assert(rb);
        assert(idx < SHM_BUFFER_SIZE);

        if (__sync_fetch_and_add(rb->acl, 0) != ACL_RDWR) {
                if (__sync_fetch_and_add(rb->acl, 0) & ACL_FLOWDOWN)
                        return -EFLOWDOWN;
                else if (__sync_fetch_and_add(rb->acl, 0) & ACL_RDONLY)
                        return -ENOTALLOC;
        }

        if (!shm_rbuff_free(rb))
                return -EAGAIN;

        if (shm_rbuff_empty(rb))
                was_empty = true;

        nhead = RB_HEAD;

        *(rb->shm_base + nhead) = (ssize_t) idx;

        do {
                ohead = nhead;
                nhead = (ohead + 1) & ((SHM_BUFFER_SIZE) - 1);
                nhead = __sync_val_compare_and_swap(rb->head, ohead, nhead);
        } while (nhead != ohead);

        if (was_empty)
                pthread_cond_broadcast(rb->add);

        return 0;
}

ssize_t shm_rbuff_read(struct shm_rbuff * rb)
{
        size_t otail;
        size_t ntail;

        assert(rb);

        if (shm_rbuff_empty(rb))
                return __sync_fetch_and_add(rb->acl, 0) & ACL_FLOWDOWN ?
                        -EFLOWDOWN : -EAGAIN;

        ntail = RB_TAIL;

        do {
                otail = ntail;
                ntail = (otail + 1) & ((SHM_BUFFER_SIZE) - 1);
                ntail = __sync_val_compare_and_swap(rb->tail, otail, ntail);
        } while (ntail != otail);

        pthread_cond_broadcast(rb->del);

        return *(rb->shm_base + ntail);
}

ssize_t shm_rbuff_read_b(struct shm_rbuff *      rb,
                         const struct timespec * abstime)
{
        ssize_t idx = -1;

        assert(rb);

        /* try a non-blocking read first */
        idx = shm_rbuff_read(rb);
        if (idx != -EAGAIN)
                return idx;

#ifndef HAVE_ROBUST_MUTEX
        pthread_mutex_lock(rb->lock);
#else
        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD)
                pthread_mutex_consistent(rb->lock);
#endif
        pthread_cleanup_push((void(*)(void *))pthread_mutex_unlock,
                             (void *) rb->lock);

        while (shm_rbuff_empty(rb) && (idx != -ETIMEDOUT)) {
                if (abstime != NULL)
                        idx = -pthread_cond_timedwait(rb->add,
                                                      rb->lock,
                                                      abstime);
                else
                        idx = -pthread_cond_wait(rb->add, rb->lock);
#ifdef HAVE_ROBUST_MUTEX
                if (idx == -EOWNERDEAD)
                        pthread_mutex_consistent(rb->lock);
#endif
        }

        if (idx != -ETIMEDOUT) {
                /* do a nonblocking read */
                idx = shm_rbuff_read(rb);

                assert(idx >= 0);
        }

        pthread_cleanup_pop(true);

        return idx;
}

void shm_rbuff_set_acl(struct shm_rbuff * rb,
                       uint32_t           flags)
{
        assert(rb);

        __sync_bool_compare_and_swap(rb->acl, *rb->acl, flags);
}

uint32_t shm_rbuff_get_acl(struct shm_rbuff * rb)
{
        assert(rb);

        return __sync_fetch_and_add(rb->acl, 0);
}

void shm_rbuff_fini(struct shm_rbuff * rb)
{
        assert(rb);

        if (shm_rbuff_empty(rb))
                return;

#ifndef HAVE_ROBUST_MUTEX
        pthread_mutex_lock(rb->lock);
#else
        if (pthread_mutex_lock(rb->lock) == EOWNERDEAD)
                pthread_mutex_consistent(rb->lock);
#endif

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

        while (!shm_rbuff_empty(rb))
#ifndef HAVE_ROBUST_MUTEX
                pthread_cond_wait(rb->del, rb->lock);
#else
                if (pthread_cond_wait(rb->del, rb->lock) == EOWNERDEAD)
                        pthread_mutex_consistent(rb->lock);
#endif
        pthread_cleanup_pop(true);
}

size_t shm_rbuff_queued(struct shm_rbuff * rb)
{
        assert(rb);

        return shm_rbuff_used(rb);
}