1 /* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
2 *
3 * Permission is hereby granted, free of charge, to any person obtaining a copy
4 * of this software and associated documentation files (the "Software"), to
5 * deal in the Software without restriction, including without limitation the
6 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
7 * sell copies of the Software, and to permit persons to whom the Software is
8 * furnished to do so, subject to the following conditions:
9 *
10 * The above copyright notice and this permission notice shall be included in
11 * all copies or substantial portions of the Software.
12 *
13 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
16 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
17 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
18 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
19 * IN THE SOFTWARE.
20 */
21
22 #include "uv-common.h"
23
24 #if !defined(_WIN32)
25 # include "unix/internal.h"
26 #endif
27
28 #include <stdlib.h>
29
30 #define MAX_THREADPOOL_SIZE 1024
31
32 static uv_once_t once = UV_ONCE_INIT;
33 static uv_cond_t cond;
34 static uv_mutex_t mutex;
35 static unsigned int idle_threads;
36 static unsigned int slow_io_work_running;
37 static unsigned int nthreads;
38 static uv_thread_t* threads;
39 static uv_thread_t default_threads[4];
40 static QUEUE exit_message;
41 static QUEUE wq;
42 static QUEUE run_slow_work_message;
43 static QUEUE slow_io_pending_wq;
44
slow_work_thread_threshold(void)45 static unsigned int slow_work_thread_threshold(void) {
46 return (nthreads + 1) / 2;
47 }
48
uv__cancelled(struct uv__work * w)49 static void uv__cancelled(struct uv__work* w) {
50 abort();
51 }
52
53
54 /* To avoid deadlock with uv_cancel() it's crucial that the worker
55 * never holds the global mutex and the loop-local mutex at the same time.
56 */
worker(void * arg)57 static void worker(void* arg) {
58 struct uv__work* w;
59 QUEUE* q;
60 int is_slow_work;
61
62 uv_sem_post((uv_sem_t*) arg);
63 arg = NULL;
64
65 uv_mutex_lock(&mutex);
66 for (;;) {
67 /* `mutex` should always be locked at this point. */
68
69 /* Keep waiting while either no work is present or only slow I/O
70 and we're at the threshold for that. */
71 while (QUEUE_EMPTY(&wq) ||
72 (QUEUE_HEAD(&wq) == &run_slow_work_message &&
73 QUEUE_NEXT(&run_slow_work_message) == &wq &&
74 slow_io_work_running >= slow_work_thread_threshold())) {
75 idle_threads += 1;
76 uv_cond_wait(&cond, &mutex);
77 idle_threads -= 1;
78 }
79
80 q = QUEUE_HEAD(&wq);
81 if (q == &exit_message) {
82 uv_cond_signal(&cond);
83 uv_mutex_unlock(&mutex);
84 break;
85 }
86
87 QUEUE_REMOVE(q);
88 QUEUE_INIT(q); /* Signal uv_cancel() that the work req is executing. */
89
90 is_slow_work = 0;
91 if (q == &run_slow_work_message) {
92 /* If we're at the slow I/O threshold, re-schedule until after all
93 other work in the queue is done. */
94 if (slow_io_work_running >= slow_work_thread_threshold()) {
95 QUEUE_INSERT_TAIL(&wq, q);
96 continue;
97 }
98
99 /* If we encountered a request to run slow I/O work but there is none
100 to run, that means it's cancelled => Start over. */
101 if (QUEUE_EMPTY(&slow_io_pending_wq))
102 continue;
103
104 is_slow_work = 1;
105 slow_io_work_running++;
106
107 q = QUEUE_HEAD(&slow_io_pending_wq);
108 QUEUE_REMOVE(q);
109 QUEUE_INIT(q);
110
111 /* If there is more slow I/O work, schedule it to be run as well. */
112 if (!QUEUE_EMPTY(&slow_io_pending_wq)) {
113 QUEUE_INSERT_TAIL(&wq, &run_slow_work_message);
114 if (idle_threads > 0)
115 uv_cond_signal(&cond);
116 }
117 }
118
119 uv_mutex_unlock(&mutex);
120
121 w = QUEUE_DATA(q, struct uv__work, wq);
122 w->work(w);
123
124 uv_mutex_lock(&w->loop->wq_mutex);
125 w->work = NULL; /* Signal uv_cancel() that the work req is done
126 executing. */
127 QUEUE_INSERT_TAIL(&w->loop->wq, &w->wq);
128 uv_async_send(&w->loop->wq_async);
129 uv_mutex_unlock(&w->loop->wq_mutex);
130
131 /* Lock `mutex` since that is expected at the start of the next
132 * iteration. */
133 uv_mutex_lock(&mutex);
134 if (is_slow_work) {
135 /* `slow_io_work_running` is protected by `mutex`. */
136 slow_io_work_running--;
137 }
138 }
139 }
140
141
post(QUEUE * q,enum uv__work_kind kind)142 static void post(QUEUE* q, enum uv__work_kind kind) {
143 uv_mutex_lock(&mutex);
144 if (kind == UV__WORK_SLOW_IO) {
145 /* Insert into a separate queue. */
146 QUEUE_INSERT_TAIL(&slow_io_pending_wq, q);
147 if (!QUEUE_EMPTY(&run_slow_work_message)) {
148 /* Running slow I/O tasks is already scheduled => Nothing to do here.
149 The worker that runs said other task will schedule this one as well. */
150 uv_mutex_unlock(&mutex);
151 return;
152 }
153 q = &run_slow_work_message;
154 }
155
156 QUEUE_INSERT_TAIL(&wq, q);
157 if (idle_threads > 0)
158 uv_cond_signal(&cond);
159 uv_mutex_unlock(&mutex);
160 }
161
162
uv__threadpool_cleanup(void)163 void uv__threadpool_cleanup(void) {
164 unsigned int i;
165
166 if (nthreads == 0)
167 return;
168
169 post(&exit_message, UV__WORK_CPU);
170
171 for (i = 0; i < nthreads; i++)
172 if (uv_thread_join(threads + i))
173 abort();
174
175 if (threads != default_threads)
176 uv__free(threads);
177
178 uv_mutex_destroy(&mutex);
179 uv_cond_destroy(&cond);
180
181 threads = NULL;
182 nthreads = 0;
183 }
184
185
init_threads(void)186 static void init_threads(void) {
187 unsigned int i;
188 const char* val;
189 uv_sem_t sem;
190
191 nthreads = ARRAY_SIZE(default_threads);
192 val = getenv("UV_THREADPOOL_SIZE");
193 if (val != NULL)
194 nthreads = atoi(val);
195 if (nthreads == 0)
196 nthreads = 1;
197 if (nthreads > MAX_THREADPOOL_SIZE)
198 nthreads = MAX_THREADPOOL_SIZE;
199
200 threads = default_threads;
201 if (nthreads > ARRAY_SIZE(default_threads)) {
202 threads = uv__malloc(nthreads * sizeof(threads[0]));
203 if (threads == NULL) {
204 nthreads = ARRAY_SIZE(default_threads);
205 threads = default_threads;
206 }
207 }
208
209 if (uv_cond_init(&cond))
210 abort();
211
212 if (uv_mutex_init(&mutex))
213 abort();
214
215 QUEUE_INIT(&wq);
216 QUEUE_INIT(&slow_io_pending_wq);
217 QUEUE_INIT(&run_slow_work_message);
218
219 if (uv_sem_init(&sem, 0))
220 abort();
221
222 for (i = 0; i < nthreads; i++)
223 if (uv_thread_create(threads + i, worker, &sem))
224 abort();
225
226 for (i = 0; i < nthreads; i++)
227 uv_sem_wait(&sem);
228
229 uv_sem_destroy(&sem);
230 }
231
232
233 #ifndef _WIN32
reset_once(void)234 static void reset_once(void) {
235 uv_once_t child_once = UV_ONCE_INIT;
236 memcpy(&once, &child_once, sizeof(child_once));
237 }
238 #endif
239
240
init_once(void)241 static void init_once(void) {
242 #ifndef _WIN32
243 /* Re-initialize the threadpool after fork.
244 * Note that this discards the global mutex and condition as well
245 * as the work queue.
246 */
247 if (pthread_atfork(NULL, NULL, &reset_once))
248 abort();
249 #endif
250 init_threads();
251 }
252
253
uv__work_submit(uv_loop_t * loop,struct uv__work * w,enum uv__work_kind kind,void (* work)(struct uv__work * w),void (* done)(struct uv__work * w,int status))254 void uv__work_submit(uv_loop_t* loop,
255 struct uv__work* w,
256 enum uv__work_kind kind,
257 void (*work)(struct uv__work* w),
258 void (*done)(struct uv__work* w, int status)) {
259 uv_once(&once, init_once);
260 w->loop = loop;
261 w->work = work;
262 w->done = done;
263 post(&w->wq, kind);
264 }
265
266
uv__work_cancel(uv_loop_t * loop,uv_req_t * req,struct uv__work * w)267 static int uv__work_cancel(uv_loop_t* loop, uv_req_t* req, struct uv__work* w) {
268 int cancelled;
269
270 uv_mutex_lock(&mutex);
271 uv_mutex_lock(&w->loop->wq_mutex);
272
273 cancelled = !QUEUE_EMPTY(&w->wq) && w->work != NULL;
274 if (cancelled)
275 QUEUE_REMOVE(&w->wq);
276
277 uv_mutex_unlock(&w->loop->wq_mutex);
278 uv_mutex_unlock(&mutex);
279
280 if (!cancelled)
281 return UV_EBUSY;
282
283 w->work = uv__cancelled;
284 uv_mutex_lock(&loop->wq_mutex);
285 QUEUE_INSERT_TAIL(&loop->wq, &w->wq);
286 uv_async_send(&loop->wq_async);
287 uv_mutex_unlock(&loop->wq_mutex);
288
289 return 0;
290 }
291
292
uv__work_done(uv_async_t * handle)293 void uv__work_done(uv_async_t* handle) {
294 struct uv__work* w;
295 uv_loop_t* loop;
296 QUEUE* q;
297 QUEUE wq;
298 int err;
299
300 loop = container_of(handle, uv_loop_t, wq_async);
301 uv_mutex_lock(&loop->wq_mutex);
302 QUEUE_MOVE(&loop->wq, &wq);
303 uv_mutex_unlock(&loop->wq_mutex);
304
305 while (!QUEUE_EMPTY(&wq)) {
306 q = QUEUE_HEAD(&wq);
307 QUEUE_REMOVE(q);
308
309 w = container_of(q, struct uv__work, wq);
310 err = (w->work == uv__cancelled) ? UV_ECANCELED : 0;
311 w->done(w, err);
312 }
313 }
314
315
uv__queue_work(struct uv__work * w)316 static void uv__queue_work(struct uv__work* w) {
317 uv_work_t* req = container_of(w, uv_work_t, work_req);
318
319 req->work_cb(req);
320 }
321
322
uv__queue_done(struct uv__work * w,int err)323 static void uv__queue_done(struct uv__work* w, int err) {
324 uv_work_t* req;
325
326 req = container_of(w, uv_work_t, work_req);
327 uv__req_unregister(req->loop, req);
328
329 if (req->after_work_cb == NULL)
330 return;
331
332 req->after_work_cb(req, err);
333 }
334
335
uv_queue_work(uv_loop_t * loop,uv_work_t * req,uv_work_cb work_cb,uv_after_work_cb after_work_cb)336 int uv_queue_work(uv_loop_t* loop,
337 uv_work_t* req,
338 uv_work_cb work_cb,
339 uv_after_work_cb after_work_cb) {
340 if (work_cb == NULL)
341 return UV_EINVAL;
342
343 uv__req_init(loop, req, UV_WORK);
344 req->loop = loop;
345 req->work_cb = work_cb;
346 req->after_work_cb = after_work_cb;
347 uv__work_submit(loop,
348 &req->work_req,
349 UV__WORK_CPU,
350 uv__queue_work,
351 uv__queue_done);
352 return 0;
353 }
354
355
uv_cancel(uv_req_t * req)356 int uv_cancel(uv_req_t* req) {
357 struct uv__work* wreq;
358 uv_loop_t* loop;
359
360 switch (req->type) {
361 case UV_FS:
362 loop = ((uv_fs_t*) req)->loop;
363 wreq = &((uv_fs_t*) req)->work_req;
364 break;
365 case UV_GETADDRINFO:
366 loop = ((uv_getaddrinfo_t*) req)->loop;
367 wreq = &((uv_getaddrinfo_t*) req)->work_req;
368 break;
369 case UV_GETNAMEINFO:
370 loop = ((uv_getnameinfo_t*) req)->loop;
371 wreq = &((uv_getnameinfo_t*) req)->work_req;
372 break;
373 case UV_RANDOM:
374 loop = ((uv_random_t*) req)->loop;
375 wreq = &((uv_random_t*) req)->work_req;
376 break;
377 case UV_WORK:
378 loop = ((uv_work_t*) req)->loop;
379 wreq = &((uv_work_t*) req)->work_req;
380 break;
381 default:
382 return UV_EINVAL;
383 }
384
385 return uv__work_cancel(loop, req, wreq);
386 }
387