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b878f05a JG |
1 | /* |
2 | * Copyright (C) 2018 - Jérémie Galarneau <jeremie.galarneau@efficios.com> | |
3 | * | |
4 | * This program is free software; you can redistribute it and/or modify it | |
5 | * under the terms of the GNU General Public License, version 2 only, as | |
6 | * published by the Free Software Foundation. | |
7 | * | |
8 | * This program is distributed in the hope that it will be useful, but WITHOUT | |
9 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
10 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for | |
11 | * more details. | |
12 | * | |
13 | * You should have received a copy of the GNU General Public License along with | |
14 | * this program; if not, write to the Free Software Foundation, Inc., 51 | |
15 | * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. | |
16 | */ | |
17 | ||
18 | #include "thread.h" | |
19 | #include <urcu/list.h> | |
20 | #include <urcu/ref.h> | |
21 | #include <pthread.h> | |
22 | #include <common/macros.h> | |
23 | #include <common/error.h> | |
24 | #include <common/defaults.h> | |
25 | ||
26 | static struct thread_list { | |
27 | struct cds_list_head head; | |
28 | pthread_mutex_t lock; | |
29 | } thread_list = { | |
30 | .head = CDS_LIST_HEAD_INIT(thread_list.head), | |
31 | .lock = PTHREAD_MUTEX_INITIALIZER, | |
32 | }; | |
33 | ||
34 | struct lttng_thread { | |
35 | struct urcu_ref ref; | |
36 | struct cds_list_head node; | |
37 | pthread_t thread; | |
38 | const char *name; | |
39 | /* Main thread function */ | |
40 | lttng_thread_entry_point entry; | |
41 | /* | |
42 | * Thread-specific shutdown method. Allows threads to implement their | |
43 | * own shutdown mechanism as some of them use a structured message | |
44 | * passed through a command queue and some rely on a dedicated "quit" | |
45 | * pipe. | |
46 | */ | |
47 | lttng_thread_shutdown_cb shutdown; | |
48 | lttng_thread_cleanup_cb cleanup; | |
49 | /* Thread implementation-specific data. */ | |
50 | void *data; | |
51 | }; | |
52 | ||
53 | static | |
54 | void lttng_thread_destroy(struct lttng_thread *thread) | |
55 | { | |
56 | if (thread->cleanup) { | |
57 | thread->cleanup(thread->data); | |
58 | } | |
59 | free(thread); | |
60 | } | |
61 | ||
62 | static | |
63 | void lttng_thread_release(struct urcu_ref *ref) | |
64 | { | |
65 | lttng_thread_destroy(container_of(ref, struct lttng_thread, ref)); | |
66 | } | |
67 | ||
68 | static | |
69 | void *launch_thread(void *data) | |
70 | { | |
71 | void *ret; | |
72 | struct lttng_thread *thread = (struct lttng_thread *) data; | |
73 | ||
74 | DBG("Launching \"%s\" thread", thread->name); | |
75 | ret = thread->entry(thread->data); | |
76 | DBG("Thread \"%s\" has returned", thread->name); | |
77 | return ret; | |
78 | } | |
79 | ||
80 | struct lttng_thread *lttng_thread_create(const char *name, | |
81 | lttng_thread_entry_point entry, | |
82 | lttng_thread_shutdown_cb shutdown, | |
83 | lttng_thread_cleanup_cb cleanup, | |
84 | void *thread_data) | |
85 | { | |
86 | int ret; | |
87 | struct lttng_thread *thread; | |
88 | ||
89 | thread = zmalloc(sizeof(*thread)); | |
90 | if (!thread) { | |
21fa020e | 91 | goto error_alloc; |
b878f05a JG |
92 | } |
93 | ||
94 | urcu_ref_init(&thread->ref); | |
95 | CDS_INIT_LIST_HEAD(&thread->node); | |
96 | /* | |
97 | * Thread names are assumed to be statically allocated strings. | |
98 | * It is unnecessary to copy this attribute. | |
99 | */ | |
100 | thread->name = name; | |
101 | thread->entry = entry; | |
102 | thread->shutdown = shutdown; | |
103 | thread->cleanup = cleanup; | |
104 | thread->data = thread_data; | |
105 | ||
106 | pthread_mutex_lock(&thread_list.lock); | |
107 | /* | |
108 | * Add the thread at the head of the list to shutdown threads in the | |
109 | * opposite order of their creation. A reference is taken for the | |
110 | * thread list which will be released on shutdown of the thread. | |
111 | */ | |
112 | cds_list_add(&thread->node, &thread_list.head); | |
113 | (void) lttng_thread_get(thread); | |
114 | ||
115 | ret = pthread_create(&thread->thread, default_pthread_attr(), | |
116 | launch_thread, thread); | |
117 | if (ret) { | |
118 | PERROR("Failed to create \"%s\" thread", thread->name); | |
119 | goto error_pthread_create; | |
120 | } | |
121 | ||
122 | pthread_mutex_unlock(&thread_list.lock); | |
123 | return thread; | |
124 | ||
125 | error_pthread_create: | |
126 | cds_list_del(&thread->node); | |
127 | /* Release list reference. */ | |
128 | lttng_thread_put(thread); | |
129 | pthread_mutex_unlock(&thread_list.lock); | |
b878f05a JG |
130 | /* Release initial reference. */ |
131 | lttng_thread_put(thread); | |
21fa020e | 132 | error_alloc: |
b878f05a JG |
133 | return NULL; |
134 | } | |
135 | ||
136 | bool lttng_thread_get(struct lttng_thread *thread) | |
137 | { | |
138 | return urcu_ref_get_unless_zero(&thread->ref); | |
139 | } | |
140 | ||
141 | void lttng_thread_put(struct lttng_thread *thread) | |
142 | { | |
143 | assert(thread->ref.refcount); | |
144 | urcu_ref_put(&thread->ref, lttng_thread_release); | |
145 | } | |
146 | ||
147 | const char *lttng_thread_get_name(const struct lttng_thread *thread) | |
148 | { | |
149 | return thread->name; | |
150 | } | |
151 | ||
152 | static | |
153 | bool _lttng_thread_shutdown(struct lttng_thread *thread) | |
154 | { | |
155 | int ret; | |
156 | void *status; | |
157 | bool result = true; | |
158 | ||
159 | DBG("Shutting down \"%s\" thread", thread->name); | |
160 | if (thread->shutdown) { | |
161 | result = thread->shutdown(thread->data); | |
162 | if (!result) { | |
163 | result = false; | |
164 | goto end; | |
165 | } | |
166 | } | |
167 | ||
168 | ret = pthread_join(thread->thread, &status); | |
169 | if (ret) { | |
170 | PERROR("Failed to join \"%s\" thread", thread->name); | |
171 | result = false; | |
19d3c73e | 172 | goto end; |
b878f05a JG |
173 | } |
174 | /* Release the list's reference to the thread. */ | |
175 | cds_list_del(&thread->node); | |
176 | lttng_thread_put(thread); | |
177 | end: | |
178 | return result; | |
179 | } | |
180 | ||
181 | bool lttng_thread_shutdown(struct lttng_thread *thread) | |
182 | { | |
183 | bool result; | |
184 | ||
185 | pthread_mutex_lock(&thread_list.lock); | |
186 | result = _lttng_thread_shutdown(thread); | |
187 | pthread_mutex_unlock(&thread_list.lock); | |
188 | return result; | |
189 | } | |
190 | ||
191 | void lttng_thread_list_shutdown_orphans(void) | |
192 | { | |
193 | struct lttng_thread *thread, *tmp; | |
194 | ||
195 | pthread_mutex_lock(&thread_list.lock); | |
196 | cds_list_for_each_entry_safe(thread, tmp, &thread_list.head, node) { | |
197 | bool result; | |
198 | const long ref = uatomic_read(&thread->ref.refcount); | |
199 | ||
200 | if (ref != 1) { | |
201 | /* | |
202 | * Other external references to the thread exist, skip. | |
203 | */ | |
204 | continue; | |
205 | } | |
206 | ||
207 | result = _lttng_thread_shutdown(thread); | |
208 | if (!result) { | |
209 | ERR("Failed to shutdown thread \"%s\"", thread->name); | |
210 | } | |
211 | } | |
212 | pthread_mutex_unlock(&thread_list.lock); | |
213 | } |