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
|
/*
* libiio - Library for interfacing industrial I/O (IIO) devices
*
* Copyright (C) 2016 Analog Devices, Inc.
* Author: Paul Cercueil <paul.cercueil@analog.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* 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.
*/
#include "thread-pool.h"
#include <errno.h>
#include <pthread.h>
#include <signal.h>
#include <stdint.h>
#include <stdlib.h>
#include <sys/eventfd.h>
#include <unistd.h>
/*
* This is used to make sure that all active threads have finished cleanup when
* a STOP event is received. We don't use pthread_join() since for most threads
* we are OK with them exiting asynchronously and there really is no place to
* call pthread_join() to free the thread's resources. We only need to
* synchronize the threads that are still active when the iiod is shutdown to
* give them a chance to release all resources, disable buffers etc, before
* iio_context_destroy() is called.
*/
struct thread_pool {
pthread_mutex_t thread_count_lock;
pthread_cond_t thread_count_cond;
unsigned int thread_count;
int stop_fd;
};
struct thread_body_data {
struct thread_pool *pool;
void (*f)(struct thread_pool *, void *);
void *d;
};
static void thread_pool_thread_started(struct thread_pool *pool)
{
pthread_mutex_lock(&pool->thread_count_lock);
pool->thread_count++;
pthread_mutex_unlock(&pool->thread_count_lock);
}
static void thread_pool_thread_stopped(struct thread_pool *pool)
{
pthread_mutex_lock(&pool->thread_count_lock);
pool->thread_count--;
pthread_cond_signal(&pool->thread_count_cond);
pthread_mutex_unlock(&pool->thread_count_lock);
}
static void * thread_body(void *d)
{
struct thread_body_data *pdata = d;
(*pdata->f)(pdata->pool, pdata->d);
thread_pool_thread_stopped(pdata->pool);
free(pdata);
return NULL;
}
int thread_pool_add_thread(struct thread_pool *pool,
void (*f)(struct thread_pool *, void *),
void *d, const char *name)
{
struct thread_body_data *pdata;
sigset_t sigmask, oldsigmask;
pthread_attr_t attr;
pthread_t thd;
int ret;
pdata = malloc(sizeof(*pdata));
if (!pdata)
return -ENOMEM;
pdata->f = f;
pdata->d = d;
pdata->pool = pool;
sigfillset(&sigmask);
pthread_sigmask(SIG_BLOCK, &sigmask, &oldsigmask);
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
/* In order to avoid race conditions thread_pool_thread_started() must
* be called before the thread is created and
* thread_pool_thread_stopped() must be called right before leaving
* the thread. */
thread_pool_thread_started(pool);
ret = pthread_create(&thd, &attr, thread_body, pdata);
if (ret) {
free(pdata);
thread_pool_thread_stopped(pool);
} else {
#ifdef HAS_PTHREAD_SETNAME_NP
pthread_setname_np(thd, name);
#endif
}
pthread_attr_destroy(&attr);
pthread_sigmask(SIG_SETMASK, &oldsigmask, NULL);
return ret;
}
struct thread_pool * thread_pool_new(void)
{
struct thread_pool *pool;
pool = malloc(sizeof(*pool));
if (!pool) {
errno = ENOMEM;
return NULL;
}
pool->stop_fd = eventfd(0, EFD_NONBLOCK);
if (pool->stop_fd == -1) {
int err = errno;
free(pool);
errno = err;
return NULL;
}
pthread_mutex_init(&pool->thread_count_lock, NULL);
pthread_cond_init(&pool->thread_count_cond, NULL);
pool->thread_count = 0;
return pool;
}
int thread_pool_get_poll_fd(const struct thread_pool *pool)
{
return pool->stop_fd;
}
void thread_pool_stop(struct thread_pool *pool)
{
uint64_t e = 1;
int ret;
do {
ret = write(pool->stop_fd, &e, sizeof(e));
} while (ret == -1 && errno == EINTR);
}
void thread_pool_stop_and_wait(struct thread_pool *pool)
{
uint64_t e;
int ret;
thread_pool_stop(pool);
pthread_mutex_lock(&pool->thread_count_lock);
while (pool->thread_count)
pthread_cond_wait(&pool->thread_count_cond,
&pool->thread_count_lock);
pthread_mutex_unlock(&pool->thread_count_lock);
do {
ret = read(pool->stop_fd, &e, sizeof(e));
} while (ret != -1 || errno == EINTR);
}
void thread_pool_destroy(struct thread_pool *pool)
{
pthread_mutex_destroy(&pool->thread_count_lock);
pthread_cond_destroy(&pool->thread_count_cond);
close(pool->stop_fd);
free(pool);
}
|
