vxworks pthread porting code

最新推荐文章于 2021-04-25 23:37:15 发布

转载最新推荐文章于 2021-04-25 23:37:15 发布 · 221 阅读

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CC 4.0 BY-SA版权

原文链接：http://www.cnblogs.com/ambulance/archive/2009/06/24/1509954.html

本文详细介绍了Pthreads中条件变量的初始化、销毁、等待及信号发送等操作的具体实现过程，并提供了源代码级别的解释。

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  1 /* pthreads implementation, by Craig Vanderborgh, craigv@voxware.com) */
  2
  3 /*---------------------------------------------------------------------------*
  4  * DESCRIPTION
  5  * Initialize a condition variable
  6  *---------------------------------------------------------------------------*/
  7 {
  8   if (!cond)
  9     return PTHR_FAILURE;
10
11   cond->defunct = TRUE;
12   if ((cond->waitersMsgQ = msgQCreate(PTHR_MAX_WAITERS, sizeof(Int),
13                                      MSG_Q_FIFO)) == NULL)
14     return PTHR_FAILURE;
15   cond->defunct = FALSE;
16   return PTHR_SUCCESS;
17 }
18
19 Int
20 pthread_cond_destroy(pthread_cond_t * cond)
21 /*---------------------------------------------------------------------------*
22  * DESCRIPTION
23  * Destroy a condition variable
24  *---------------------------------------------------------------------------*/
25 {
26   Int tid;
27
28   if (!cond)
29     return PTHR_FAILURE;
30
31   cond->defunct = TRUE;
32   while (msgQNumMsgs(cond->waitersMsgQ) > 0) {
33     if (msgQReceive(cond->waitersMsgQ, (char *)&tid, sizeof(Int),
34                     WAIT_FOREVER) == ERROR) {
35       VBX_print("ERROR: pthread_cond_signal can't read waiter tid\n");
36       return PTHR_FAILURE;
37     }
38     if (taskResume(tid) == ERROR) {
39       VBX_print("ERROR: pthread_cond_signal can't restart task %d\n", tid);
40       return PTHR_FAILURE;
41     }
42   }
43
44   if (msgQDelete(cond->waitersMsgQ) == ERROR) {
45     VBX_print("ERROR: pthread_cond_destroy can't delete msgQ!\n");
46     return PTHR_FAILURE;
47   }
48
49   return PTHR_SUCCESS;
50 }
51
52 Int
53 pthread_cond_wait(pthread_cond_t * cond , pthread_mutex_t * mutex)
54 /*---------------------------------------------------------------------------*
55  * DESCRIPTION
56  * Wait on a condition variable
57  *---------------------------------------------------------------------------*/
58 {
59   Int tid, status;
60
61   if (!cond || !mutex || cond->defunct)
62     return PTHR_FAILURE;
63
64   tid = taskIdSelf();
65
66   if (msgQSend(cond->waitersMsgQ, (char *) &tid, sizeof(Int),
67                WAIT_FOREVER, MSG_PRI_NORMAL) == ERROR) {
68     VBX_print("ERROR: pthread_cond_wait can't place taskId on waiters msgQ\n");
69     return PTHR_FAILURE;
70   }
71
72   if (pthread_mutex_unlock(mutex) != PTHR_SUCCESS) {
73     VBX_print("ERROR: pthread_cond_wait can't unlock mutex %x\n", mutex);
74     return PTHR_FAILURE;
75   }
76
77   if ((status = taskSuspend(tid)) != OK) {
78     VBX_print("ERROR: pthread_cond_wait can't suspend task 5d\n", tid);
79     return PTHR_FAILURE;
80   }
81
82   if (pthread_mutex_lock(mutex) != PTHR_SUCCESS) {
83     VBX_print("ERROR: pthread_cond_wait can't reacquire mutex %x\n", mutex);
84     return PTHR_FAILURE;
85   }
86
87   return PTHR_SUCCESS;
88 }
89
90 Int
91 pthread_cond_timedwait(pthread_cond_t * cond , pthread_mutex_t * mutex,
92                        const struct timespec * abstime)
93 /*---------------------------------------------------------------------------*
94  * DESCRIPTION
95  * Cop-out version of a timed condition variable wait
96  *---------------------------------------------------------------------------*/
97 {
98   Int tid, status;
99
100   if (!cond || !mutex || !abstime)
101     return PTHR_FAILURE;
102
103   if (pthread_mutex_unlock(mutex) != PTHR_SUCCESS) {
104     VBX_print("ERROR: pthread_cond_wait can't unlock mutex %x\n", mutex);
105     return PTHR_FAILURE;
106   }
107
108   pthread_delay_np(abstime);
109
110   if (pthread_mutex_lock(mutex) != PTHR_SUCCESS) {
111     VBX_print("ERROR: pthread_cond_wait can't reacquire mutex %x\n", mutex);
112     return PTHR_FAILURE;
113   }
114
115   return PTHR_SUCCESS;
116 }
117
118 Int
119 pthread_cond_signal(pthread_cond_t * cond)
120 /*---------------------------------------------------------------------------*
121  * DESCRIPTION
122  * Signal a condition variable
123  *---------------------------------------------------------------------------*/
124 {
125   Int tid, status;
126
127   if (!cond || cond->defunct)
128     return PTHR_FAILURE;
129
130   if (msgQNumMsgs(cond->waitersMsgQ) > 0) {
131     if (msgQReceive(cond->waitersMsgQ, (char *)&tid, sizeof(Int),
132                     WAIT_FOREVER) == ERROR) {
133       VBX_print("ERROR: pthread_cond_signal can't read waiter tid\n");
134       return PTHR_FAILURE;
135     }
136     if (taskResume(tid) == ERROR) {
137       VBX_print("ERROR: pthread_cond_signal can't restart task %d\n", tid);
138       return PTHR_FAILURE;
139     }
140   }
141
142   return PTHR_SUCCESS;
143 }
144
145

转载于:https://www.cnblogs.com/ambulance/archive/2009/06/24/1509954.html