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
|
/************************************************************
* pthread_completejoin.c
*
* Copyright (C) 2007 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name Gregory Nutt nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
************************************************************/
/************************************************************
* Included Files
************************************************************/
#include <sys/types.h>
#include <pthread.h>
#include <errno.h>
#include <debug.h>
#include "os_internal.h"
#include "pthread_internal.h"
/************************************************************
* Definitions
************************************************************/
/************************************************************
* Private Type Declarations
************************************************************/
/************************************************************
* Global Variables
************************************************************/
/************************************************************
* Private Variables
************************************************************/
/************************************************************
* Private Functions
************************************************************/
/************************************************************
* Function: pthread_notifywaiters
*
* Description:
* Notify all other threads waiting in phread join for this
* thread's exit data. This must be done by the child
* at child thread destruction time.
*
************************************************************/
static boolean pthread_notifywaiters(FAR join_t *pjoin)
{
int ntasks_waiting;
int status;
dbg("pjoin=0x%p\n", pjoin);
/* Are any tasks waiting for our exit value? */
status = sem_getvalue(&pjoin->exit_sem, &ntasks_waiting);
if (status == OK && ntasks_waiting < 0)
{
/* Set the data semaphore so that this thread will be
* awakened when all waiting tasks receive the data
*/
(void)sem_init(&pjoin->data_sem, 0, (ntasks_waiting+1));
/* Post the semaphore to restart each thread that is waiting
* on the semaphore
*/
do
{
status = pthread_givesemaphore(&pjoin->exit_sem);
if (status == OK)
{
status = sem_getvalue(&pjoin->exit_sem, &ntasks_waiting);
}
}
while (ntasks_waiting < 0 && status == OK);
/* Now wait for all these restarted tasks to obtain the return
* value.
*/
(void)pthread_takesemaphore(&pjoin->data_sem);
return TRUE;
}
return FALSE;
}
/************************************************************
* Public Functions
************************************************************/
/************************************************************
* Function: pthread_completejoin
*
* Description:
* A thread has been terminated -- either by returning,
* calling pthread_exit(), or through pthread_cancel().
* In any event, we must complete any pending join events.
*
* Parameters:
* exit_value
*
* Returned Value:
* OK unless there is no join information associated with
* the pid. This could happen, for example, if a task
* started with task_create() calls pthread_exit().
*
* Assumptions:
*
************************************************************/
int pthread_completejoin(pid_t pid, FAR void *exit_value)
{
FAR join_t *pjoin;
dbg("process_id=%d exit_value=%p\n", pid, exit_value);
/* First, find thread's structure in the private data set. */
(void)pthread_takesemaphore(&g_join_semaphore);
pjoin = pthread_findjoininfo(pid);
if (!pjoin)
{
(void)pthread_givesemaphore(&g_join_semaphore);
return ERROR;
}
else
{
boolean waiters;
/* Save the return exit value in the thread structure. */
pjoin->terminated = TRUE;
pjoin->exit_value = exit_value;
/* Notify waiters of the availability of the exit value */
waiters = pthread_notifywaiters(pjoin);
/* If there are no waiters and if the thread is marked as detached.
* then discard the join information now. Otherwise, the pthread
* join logic will call pthread_destroyjoin() when all of the threads
* have sampled the exit value.
*/
if (!waiters && pjoin->detached)
{
pthread_destroyjoin(pjoin);
}
/* Giving the following semaphore will allow the waiters
* to call pthread_destroyjoin.
*/
(void)pthread_givesemaphore(&g_join_semaphore);
}
return OK;
}
/************************************************************
* Function: pthread_destroyjoin
*
* Description:
* This is called from pthread_completejoin if the join
* info was detached or from pthread_join when the last
* waiting thread has received the thread exit info.
*
* Or it may never be called if the join info was never
* detached or if no thread ever calls pthread_join. In
* case, there is a memory leak!
*
* Assumptions:
* The caller holds g_join_semaphore
*
************************************************************/
void pthread_destroyjoin(FAR join_t *pjoin)
{
dbg("pjoin=0x%p\n", pjoin);
/* Remove the join info from the set of joins */
(void)pthread_removejoininfo((pid_t)pjoin->thread);
/* Destroy its semaphores */
(void)sem_destroy(&pjoin->data_sem);
(void)sem_destroy(&pjoin->exit_sem);
/* And deallocate the pjoin structure */
sched_free(pjoin);
}
|
