1/*
2 * This file is part of the MicroPython project, http://micropython.org/
3 *
4 * The MIT License (MIT)
5 *
6 * Copyright (c) 2016 Damien P. George on behalf of Pycom Ltd
7 *
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is
13 * furnished to do so, subject to the following conditions:
14 *
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
19 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
20 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
21 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
22 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
23 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
24 * THE SOFTWARE.
25 */
26
27#include <stdio.h>
28#include <stdlib.h>
29#include <errno.h>
30
31#include "py/runtime.h"
32#include "py/mpthread.h"
33#include "py/gc.h"
34
35#if MICROPY_PY_THREAD
36
37#include <fcntl.h>
38#include <signal.h>
39#include <sched.h>
40#include <semaphore.h>
41
42#include "lib/utils/gchelper.h"
43
44// Some platforms don't have SIGRTMIN but if we do have it, use it to avoid
45// potential conflict with other uses of the more commonly used SIGUSR1.
46#ifdef SIGRTMIN
47#define MP_THREAD_GC_SIGNAL (SIGRTMIN + 5)
48#else
49#define MP_THREAD_GC_SIGNAL (SIGUSR1)
50#endif
51
52// This value seems to be about right for both 32-bit and 64-bit builds.
53#define THREAD_STACK_OVERFLOW_MARGIN (8192)
54
55// this structure forms a linked list, one node per active thread
56typedef struct _thread_t {
57 pthread_t id; // system id of thread
58 int ready; // whether the thread is ready and running
59 void *arg; // thread Python args, a GC root pointer
60 struct _thread_t *next;
61} thread_t;
62
63STATIC pthread_key_t tls_key;
64
65// The mutex is used for any code in this port that needs to be thread safe.
66// Specifically for thread management, access to the linked list is one example.
67// But also, e.g. scheduler state.
68STATIC pthread_mutex_t thread_mutex;
69STATIC thread_t *thread;
70
71// this is used to synchronise the signal handler of the thread
72// it's needed because we can't use any pthread calls in a signal handler
73#if defined(__APPLE__)
74STATIC char thread_signal_done_name[25];
75STATIC sem_t *thread_signal_done_p;
76#else
77STATIC sem_t thread_signal_done;
78#endif
79
80void mp_thread_unix_begin_atomic_section(void) {
81 pthread_mutex_lock(&thread_mutex);
82}
83
84void mp_thread_unix_end_atomic_section(void) {
85 pthread_mutex_unlock(&thread_mutex);
86}
87
88// this signal handler is used to scan the regs and stack of a thread
89STATIC void mp_thread_gc(int signo, siginfo_t *info, void *context) {
90 (void)info; // unused
91 (void)context; // unused
92 if (signo == MP_THREAD_GC_SIGNAL) {
93 gc_helper_collect_regs_and_stack();
94 // We have access to the context (regs, stack) of the thread but it seems
95 // that we don't need the extra information, enough is captured by the
96 // gc_collect_regs_and_stack function above
97 // gc_collect_root((void**)context, sizeof(ucontext_t) / sizeof(uintptr_t));
98 #if MICROPY_ENABLE_PYSTACK
99 void **ptrs = (void **)(void *)MP_STATE_THREAD(pystack_start);
100 gc_collect_root(ptrs, (MP_STATE_THREAD(pystack_cur) - MP_STATE_THREAD(pystack_start)) / sizeof(void *));
101 #endif
102 #if defined(__APPLE__)
103 sem_post(thread_signal_done_p);
104 #else
105 sem_post(&thread_signal_done);
106 #endif
107 }
108}
109
110void mp_thread_init(void) {
111 pthread_key_create(&tls_key, NULL);
112 pthread_setspecific(tls_key, &mp_state_ctx.thread);
113
114 // Needs to be a recursive mutex to emulate the behavior of
115 // BEGIN_ATOMIC_SECTION on bare metal.
116 pthread_mutexattr_t thread_mutex_attr;
117 pthread_mutexattr_init(&thread_mutex_attr);
118 pthread_mutexattr_settype(&thread_mutex_attr, PTHREAD_MUTEX_RECURSIVE);
119 pthread_mutex_init(&thread_mutex, &thread_mutex_attr);
120
121 // create first entry in linked list of all threads
122 thread = malloc(sizeof(thread_t));
123 thread->id = pthread_self();
124 thread->ready = 1;
125 thread->arg = NULL;
126 thread->next = NULL;
127
128 #if defined(__APPLE__)
129 snprintf(thread_signal_done_name, sizeof(thread_signal_done_name), "micropython_sem_%d", (int)thread->id);
130 thread_signal_done_p = sem_open(thread_signal_done_name, O_CREAT | O_EXCL, 0666, 0);
131 #else
132 sem_init(&thread_signal_done, 0, 0);
133 #endif
134
135 // enable signal handler for garbage collection
136 struct sigaction sa;
137 sa.sa_flags = SA_SIGINFO;
138 sa.sa_sigaction = mp_thread_gc;
139 sigemptyset(&sa.sa_mask);
140 sigaction(MP_THREAD_GC_SIGNAL, &sa, NULL);
141}
142
143void mp_thread_deinit(void) {
144 mp_thread_unix_begin_atomic_section();
145 while (thread->next != NULL) {
146 thread_t *th = thread;
147 thread = thread->next;
148 pthread_cancel(th->id);
149 free(th);
150 }
151 mp_thread_unix_end_atomic_section();
152 #if defined(__APPLE__)
153 sem_close(thread_signal_done_p);
154 sem_unlink(thread_signal_done_name);
155 #endif
156 assert(thread->id == pthread_self());
157 free(thread);
158}
159
160// This function scans all pointers that are external to the current thread.
161// It does this by signalling all other threads and getting them to scan their
162// own registers and stack. Note that there may still be some edge cases left
163// with race conditions and root-pointer scanning: a given thread may manipulate
164// the global root pointers (in mp_state_ctx) while another thread is doing a
165// garbage collection and tracing these pointers.
166void mp_thread_gc_others(void) {
167 mp_thread_unix_begin_atomic_section();
168 for (thread_t *th = thread; th != NULL; th = th->next) {
169 gc_collect_root(&th->arg, 1);
170 if (th->id == pthread_self()) {
171 continue;
172 }
173 if (!th->ready) {
174 continue;
175 }
176 pthread_kill(th->id, MP_THREAD_GC_SIGNAL);
177 #if defined(__APPLE__)
178 sem_wait(thread_signal_done_p);
179 #else
180 sem_wait(&thread_signal_done);
181 #endif
182 }
183 mp_thread_unix_end_atomic_section();
184}
185
186mp_state_thread_t *mp_thread_get_state(void) {
187 return (mp_state_thread_t *)pthread_getspecific(tls_key);
188}
189
190void mp_thread_set_state(mp_state_thread_t *state) {
191 pthread_setspecific(tls_key, state);
192}
193
194void mp_thread_start(void) {
195 pthread_setcanceltype(PTHREAD_CANCEL_ASYNCHRONOUS, NULL);
196 mp_thread_unix_begin_atomic_section();
197 for (thread_t *th = thread; th != NULL; th = th->next) {
198 if (th->id == pthread_self()) {
199 th->ready = 1;
200 break;
201 }
202 }
203 mp_thread_unix_end_atomic_section();
204}
205
206void mp_thread_create(void *(*entry)(void *), void *arg, size_t *stack_size) {
207 // default stack size is 8k machine-words
208 if (*stack_size == 0) {
209 *stack_size = 8192 * sizeof(void *);
210 }
211
212 // minimum stack size is set by pthreads
213 if (*stack_size < PTHREAD_STACK_MIN) {
214 *stack_size = PTHREAD_STACK_MIN;
215 }
216
217 // ensure there is enough stack to include a stack-overflow margin
218 if (*stack_size < 2 * THREAD_STACK_OVERFLOW_MARGIN) {
219 *stack_size = 2 * THREAD_STACK_OVERFLOW_MARGIN;
220 }
221
222 // set thread attributes
223 pthread_attr_t attr;
224 int ret = pthread_attr_init(&attr);
225 if (ret != 0) {
226 goto er;
227 }
228 ret = pthread_attr_setstacksize(&attr, *stack_size);
229 if (ret != 0) {
230 goto er;
231 }
232
233 ret = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
234 if (ret != 0) {
235 goto er;
236 }
237
238 mp_thread_unix_begin_atomic_section();
239
240 // create thread
241 pthread_t id;
242 ret = pthread_create(&id, &attr, entry, arg);
243 if (ret != 0) {
244 mp_thread_unix_end_atomic_section();
245 goto er;
246 }
247
248 // adjust stack_size to provide room to recover from hitting the limit
249 *stack_size -= THREAD_STACK_OVERFLOW_MARGIN;
250
251 // add thread to linked list of all threads
252 thread_t *th = malloc(sizeof(thread_t));
253 th->id = id;
254 th->ready = 0;
255 th->arg = arg;
256 th->next = thread;
257 thread = th;
258
259 mp_thread_unix_end_atomic_section();
260
261 return;
262
263er:
264 mp_raise_OSError(ret);
265}
266
267void mp_thread_finish(void) {
268 mp_thread_unix_begin_atomic_section();
269 thread_t *prev = NULL;
270 for (thread_t *th = thread; th != NULL; th = th->next) {
271 if (th->id == pthread_self()) {
272 if (prev == NULL) {
273 thread = th->next;
274 } else {
275 prev->next = th->next;
276 }
277 free(th);
278 break;
279 }
280 prev = th;
281 }
282 mp_thread_unix_end_atomic_section();
283}
284
285void mp_thread_mutex_init(mp_thread_mutex_t *mutex) {
286 pthread_mutex_init(mutex, NULL);
287}
288
289int mp_thread_mutex_lock(mp_thread_mutex_t *mutex, int wait) {
290 int ret;
291 if (wait) {
292 ret = pthread_mutex_lock(mutex);
293 if (ret == 0) {
294 return 1;
295 }
296 } else {
297 ret = pthread_mutex_trylock(mutex);
298 if (ret == 0) {
299 return 1;
300 } else if (ret == EBUSY) {
301 return 0;
302 }
303 }
304 return -ret;
305}
306
307void mp_thread_mutex_unlock(mp_thread_mutex_t *mutex) {
308 pthread_mutex_unlock(mutex);
309 // TODO check return value
310}
311
312#endif // MICROPY_PY_THREAD
313