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 struct uv__queue exit_message;
41 static struct uv__queue wq;
42 static struct uv__queue run_slow_work_message;
43 static struct uv__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 struct uv__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 (uv__queue_empty(&wq) ||
72 (uv__queue_head(&wq) == &run_slow_work_message &&
73 uv__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 = uv__queue_head(&wq);
81 if (q == &exit_message) {
82 uv_cond_signal(&cond);
83 uv_mutex_unlock(&mutex);
84 break;
85 }
86
87 uv__queue_remove(q);
88 uv__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 uv__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 (uv__queue_empty(&slow_io_pending_wq))
102 continue;
103
104 is_slow_work = 1;
105 slow_io_work_running++;
106
107 q = uv__queue_head(&slow_io_pending_wq);
108 uv__queue_remove(q);
109 uv__queue_init(q);
110
111 /* If there is more slow I/O work, schedule it to be run as well. */
112 if (!uv__queue_empty(&slow_io_pending_wq)) {
113 uv__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 = uv__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 uv__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(struct uv__queue * q,enum uv__work_kind kind)142 static void post(struct uv__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 uv__queue_insert_tail(&slow_io_pending_wq, q);
147 if (!uv__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 uv__queue_insert_tail(&wq, q);
157 if (idle_threads > 0)
158 uv_cond_signal(&cond);
159 uv_mutex_unlock(&mutex);
160 }
161
162
163 #ifdef __MVS__
164 /* TODO(itodorov) - zos: revisit when Woz compiler is available. */
165 __attribute__((destructor))
166 #endif
uv__threadpool_cleanup(void)167 void uv__threadpool_cleanup(void) {
168 unsigned int i;
169
170 if (nthreads == 0)
171 return;
172
173 #ifndef __MVS__
174 /* TODO(gabylb) - zos: revisit when Woz compiler is available. */
175 post(&exit_message, UV__WORK_CPU);
176 #endif
177
178 for (i = 0; i < nthreads; i++)
179 if (uv_thread_join(threads + i))
180 abort();
181
182 if (threads != default_threads)
183 uv__free(threads);
184
185 uv_mutex_destroy(&mutex);
186 uv_cond_destroy(&cond);
187
188 threads = NULL;
189 nthreads = 0;
190 }
191
192
init_threads(void)193 static void init_threads(void) {
194 uv_thread_options_t config;
195 unsigned int i;
196 const char* val;
197 uv_sem_t sem;
198
199 nthreads = ARRAY_SIZE(default_threads);
200 val = getenv("UV_THREADPOOL_SIZE");
201 if (val != NULL)
202 nthreads = atoi(val);
203 if (nthreads == 0)
204 nthreads = 1;
205 if (nthreads > MAX_THREADPOOL_SIZE)
206 nthreads = MAX_THREADPOOL_SIZE;
207
208 threads = default_threads;
209 if (nthreads > ARRAY_SIZE(default_threads)) {
210 threads = uv__malloc(nthreads * sizeof(threads[0]));
211 if (threads == NULL) {
212 nthreads = ARRAY_SIZE(default_threads);
213 threads = default_threads;
214 }
215 }
216
217 if (uv_cond_init(&cond))
218 abort();
219
220 if (uv_mutex_init(&mutex))
221 abort();
222
223 uv__queue_init(&wq);
224 uv__queue_init(&slow_io_pending_wq);
225 uv__queue_init(&run_slow_work_message);
226
227 if (uv_sem_init(&sem, 0))
228 abort();
229
230 config.flags = UV_THREAD_HAS_STACK_SIZE;
231 config.stack_size = 8u << 20; /* 8 MB */
232
233 for (i = 0; i < nthreads; i++)
234 if (uv_thread_create_ex(threads + i, &config, worker, &sem))
235 abort();
236
237 for (i = 0; i < nthreads; i++)
238 uv_sem_wait(&sem);
239
240 uv_sem_destroy(&sem);
241 }
242
243
244 #ifndef _WIN32
reset_once(void)245 static void reset_once(void) {
246 uv_once_t child_once = UV_ONCE_INIT;
247 memcpy(&once, &child_once, sizeof(child_once));
248 }
249 #endif
250
251
init_once(void)252 static void init_once(void) {
253 #ifndef _WIN32
254 /* Re-initialize the threadpool after fork.
255 * Note that this discards the global mutex and condition as well
256 * as the work queue.
257 */
258 if (pthread_atfork(NULL, NULL, &reset_once))
259 abort();
260 #endif
261 init_threads();
262 }
263
264
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))265 void uv__work_submit(uv_loop_t* loop,
266 struct uv__work* w,
267 enum uv__work_kind kind,
268 void (*work)(struct uv__work* w),
269 void (*done)(struct uv__work* w, int status)) {
270 uv_once(&once, init_once);
271 w->loop = loop;
272 w->work = work;
273 w->done = done;
274 post(&w->wq, kind);
275 }
276
277
278 /* TODO(bnoordhuis) teach libuv how to cancel file operations
279 * that go through io_uring instead of the thread pool.
280 */
uv__work_cancel(uv_loop_t * loop,uv_req_t * req,struct uv__work * w)281 static int uv__work_cancel(uv_loop_t* loop, uv_req_t* req, struct uv__work* w) {
282 int cancelled;
283
284 uv_once(&once, init_once); /* Ensure |mutex| is initialized. */
285 uv_mutex_lock(&mutex);
286 uv_mutex_lock(&w->loop->wq_mutex);
287
288 cancelled = !uv__queue_empty(&w->wq) && w->work != NULL;
289 if (cancelled)
290 uv__queue_remove(&w->wq);
291
292 uv_mutex_unlock(&w->loop->wq_mutex);
293 uv_mutex_unlock(&mutex);
294
295 if (!cancelled)
296 return UV_EBUSY;
297
298 w->work = uv__cancelled;
299 uv_mutex_lock(&loop->wq_mutex);
300 uv__queue_insert_tail(&loop->wq, &w->wq);
301 uv_async_send(&loop->wq_async);
302 uv_mutex_unlock(&loop->wq_mutex);
303
304 return 0;
305 }
306
307
uv__work_done(uv_async_t * handle)308 void uv__work_done(uv_async_t* handle) {
309 struct uv__work* w;
310 uv_loop_t* loop;
311 struct uv__queue* q;
312 struct uv__queue wq;
313 int err;
314 int nevents;
315
316 loop = container_of(handle, uv_loop_t, wq_async);
317 uv_mutex_lock(&loop->wq_mutex);
318 uv__queue_move(&loop->wq, &wq);
319 uv_mutex_unlock(&loop->wq_mutex);
320
321 nevents = 0;
322
323 while (!uv__queue_empty(&wq)) {
324 q = uv__queue_head(&wq);
325 uv__queue_remove(q);
326
327 w = container_of(q, struct uv__work, wq);
328 err = (w->work == uv__cancelled) ? UV_ECANCELED : 0;
329 w->done(w, err);
330 nevents++;
331 }
332
333 /* This check accomplishes 2 things:
334 * 1. Even if the queue was empty, the call to uv__work_done() should count
335 * as an event. Which will have been added by the event loop when
336 * calling this callback.
337 * 2. Prevents accidental wrap around in case nevents == 0 events == 0.
338 */
339 if (nevents > 1) {
340 /* Subtract 1 to counter the call to uv__work_done(). */
341 uv__metrics_inc_events(loop, nevents - 1);
342 if (uv__get_internal_fields(loop)->current_timeout == 0)
343 uv__metrics_inc_events_waiting(loop, nevents - 1);
344 }
345 }
346
347
uv__queue_work(struct uv__work * w)348 static void uv__queue_work(struct uv__work* w) {
349 uv_work_t* req = container_of(w, uv_work_t, work_req);
350
351 req->work_cb(req);
352 }
353
354
uv__queue_done(struct uv__work * w,int err)355 static void uv__queue_done(struct uv__work* w, int err) {
356 uv_work_t* req;
357
358 req = container_of(w, uv_work_t, work_req);
359 uv__req_unregister(req->loop, req);
360
361 if (req->after_work_cb == NULL)
362 return;
363
364 req->after_work_cb(req, err);
365 }
366
367
uv_queue_work(uv_loop_t * loop,uv_work_t * req,uv_work_cb work_cb,uv_after_work_cb after_work_cb)368 int uv_queue_work(uv_loop_t* loop,
369 uv_work_t* req,
370 uv_work_cb work_cb,
371 uv_after_work_cb after_work_cb) {
372 if (work_cb == NULL)
373 return UV_EINVAL;
374
375 uv__req_init(loop, req, UV_WORK);
376 req->loop = loop;
377 req->work_cb = work_cb;
378 req->after_work_cb = after_work_cb;
379 uv__work_submit(loop,
380 &req->work_req,
381 UV__WORK_CPU,
382 uv__queue_work,
383 uv__queue_done);
384 return 0;
385 }
386
387
uv_cancel(uv_req_t * req)388 int uv_cancel(uv_req_t* req) {
389 struct uv__work* wreq;
390 uv_loop_t* loop;
391
392 switch (req->type) {
393 case UV_FS:
394 loop = ((uv_fs_t*) req)->loop;
395 wreq = &((uv_fs_t*) req)->work_req;
396 break;
397 case UV_GETADDRINFO:
398 loop = ((uv_getaddrinfo_t*) req)->loop;
399 wreq = &((uv_getaddrinfo_t*) req)->work_req;
400 break;
401 case UV_GETNAMEINFO:
402 loop = ((uv_getnameinfo_t*) req)->loop;
403 wreq = &((uv_getnameinfo_t*) req)->work_req;
404 break;
405 case UV_RANDOM:
406 loop = ((uv_random_t*) req)->loop;
407 wreq = &((uv_random_t*) req)->work_req;
408 break;
409 case UV_WORK:
410 loop = ((uv_work_t*) req)->loop;
411 wreq = &((uv_work_t*) req)->work_req;
412 break;
413 default:
414 return UV_EINVAL;
415 }
416
417 return uv__work_cancel(loop, req, wreq);
418 }
419
