1/*
2 * Copyright © 2013 Keith Packard
3 *
4 * Permission to use, copy, modify, distribute, and sell this software and its
5 * documentation for any purpose is hereby granted without fee, provided that
6 * the above copyright notice appear in all copies and that both that copyright
7 * notice and this permission notice appear in supporting documentation, and
8 * that the name of the copyright holders not be used in advertising or
9 * publicity pertaining to distribution of the software without specific,
10 * written prior permission.  The copyright holders make no representations
11 * about the suitability of this software for any purpose.  It is provided "as
12 * is" without express or implied warranty.
13 *
14 * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
15 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
16 * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
17 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
18 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
19 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
20 * OF THIS SOFTWARE.
21 */
22
23#if HAVE_CONFIG_H
24#include "config.h"
25#endif
26
27#include "xshmfenceint.h"
28
29/**
30 * xshmfence_trigger:
31 * @f: An X fence
32 *
33 * Set @f to triggered, waking all waiters.
34 *
35 * Return value: 0 on success and -1 on error (in which case, errno
36 * will be set as appropriate).
37 **/
38int
39xshmfence_trigger(struct xshmfence *f) {
40    pthread_mutex_lock(&f->lock);
41    if (f->value == 0) {
42        f->value = 1;
43        if (f->waiting) {
44            f->waiting = 0;
45            pthread_cond_broadcast(&f->wakeup);
46        }
47    }
48    pthread_mutex_unlock(&f->lock);
49    return 0;
50}
51
52/**
53 * xshmfence_await:
54 * @f: An X fence
55 *
56 * Wait for @f to be triggered. If @f is already triggered, this
57 * function returns immediately.
58 *
59 * Return value: 0 on success and -1 on error (in which case, errno
60 * will be set as appropriate).
61 **/
62int
63xshmfence_await(struct xshmfence *f) {
64    pthread_mutex_lock(&f->lock);
65    while (f->value == 0) {
66        f->waiting = 1;
67        pthread_cond_wait(&f->wakeup, &f->lock);
68    }
69    pthread_mutex_unlock(&f->lock);
70    return 0;
71}
72
73/**
74 * xshmfence_query:
75 * @f: An X fence
76 *
77 * Return value: 1 if @f is triggered, else returns 0.
78 **/
79int
80xshmfence_query(struct xshmfence *f) {
81    int value;
82
83    pthread_mutex_lock(&f->lock);
84    value = f->value;
85    pthread_mutex_unlock(&f->lock);
86    return value;
87}
88
89/**
90 * xshmfence_reset:
91 * @f: An X fence
92 *
93 * Reset @f to untriggered. If @f is already untriggered,
94 * this function has no effect.
95 **/
96void
97xshmfence_reset(struct xshmfence *f) {
98
99    pthread_mutex_lock(&f->lock);
100    f->value = 0;
101    pthread_mutex_unlock(&f->lock);
102}
103
104/**
105 * xshmfence_init:
106 * @fd: An fd for an X fence
107 *
108 * Initialize the fence when first allocated
109 **/
110
111void
112xshmfence_init(int fd)
113{
114    struct xshmfence *f = xshmfence_map_shm(fd);
115    pthread_mutexattr_t mutex_attr;
116    pthread_condattr_t cond_attr;
117
118    if (!f)
119        return;
120
121    pthread_mutexattr_init(&mutex_attr);
122    pthread_mutexattr_setpshared(&mutex_attr, PTHREAD_PROCESS_SHARED);
123    pthread_mutex_init(&f->lock, &mutex_attr);
124
125    pthread_condattr_init(&cond_attr);
126    pthread_condattr_setpshared(&cond_attr, PTHREAD_PROCESS_SHARED);
127    pthread_cond_init(&f->wakeup, &cond_attr);
128    f->value = 0;
129    f->waiting = 0;
130    xshmfence_unmap_shm(f);
131}
132