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[ThirdParty] Added libuv
author June Park <parkjune1995@gmail.com>
date Wed, 14 Jan 2026 19:39:52 -0800
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159:05cf9467a1c3 160:948de3f54cea
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
45 static unsigned int slow_work_thread_threshold(void) {
46 return (nthreads + 1) / 2;
47 }
48
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 */
57 static void worker(void* arg) {
58 struct uv__work* w;
59 struct uv__queue* q;
60 int is_slow_work;
61
62 uv_thread_setname("libuv-worker");
63 uv_sem_post((uv_sem_t*) arg);
64 arg = NULL;
65
66 uv_mutex_lock(&mutex);
67 for (;;) {
68 /* `mutex` should always be locked at this point. */
69
70 /* Keep waiting while either no work is present or only slow I/O
71 and we're at the threshold for that. */
72 while (uv__queue_empty(&wq) ||
73 (uv__queue_head(&wq) == &run_slow_work_message &&
74 uv__queue_next(&run_slow_work_message) == &wq &&
75 slow_io_work_running >= slow_work_thread_threshold())) {
76 idle_threads += 1;
77 uv_cond_wait(&cond, &mutex);
78 idle_threads -= 1;
79 }
80
81 q = uv__queue_head(&wq);
82 if (q == &exit_message) {
83 uv_cond_signal(&cond);
84 uv_mutex_unlock(&mutex);
85 break;
86 }
87
88 uv__queue_remove(q);
89 uv__queue_init(q); /* Signal uv_cancel() that the work req is executing. */
90
91 is_slow_work = 0;
92 if (q == &run_slow_work_message) {
93 /* If we're at the slow I/O threshold, re-schedule until after all
94 other work in the queue is done. */
95 if (slow_io_work_running >= slow_work_thread_threshold()) {
96 uv__queue_insert_tail(&wq, q);
97 continue;
98 }
99
100 /* If we encountered a request to run slow I/O work but there is none
101 to run, that means it's cancelled => Start over. */
102 if (uv__queue_empty(&slow_io_pending_wq))
103 continue;
104
105 is_slow_work = 1;
106 slow_io_work_running++;
107
108 q = uv__queue_head(&slow_io_pending_wq);
109 uv__queue_remove(q);
110 uv__queue_init(q);
111
112 /* If there is more slow I/O work, schedule it to be run as well. */
113 if (!uv__queue_empty(&slow_io_pending_wq)) {
114 uv__queue_insert_tail(&wq, &run_slow_work_message);
115 if (idle_threads > 0)
116 uv_cond_signal(&cond);
117 }
118 }
119
120 uv_mutex_unlock(&mutex);
121
122 w = uv__queue_data(q, struct uv__work, wq);
123 w->work(w);
124
125 uv_mutex_lock(&w->loop->wq_mutex);
126 w->work = NULL; /* Signal uv_cancel() that the work req is done
127 executing. */
128 uv__queue_insert_tail(&w->loop->wq, &w->wq);
129 uv_async_send(&w->loop->wq_async);
130 uv_mutex_unlock(&w->loop->wq_mutex);
131
132 /* Lock `mutex` since that is expected at the start of the next
133 * iteration. */
134 uv_mutex_lock(&mutex);
135 if (is_slow_work) {
136 /* `slow_io_work_running` is protected by `mutex`. */
137 slow_io_work_running--;
138 }
139 }
140 }
141
142
143 static void post(struct uv__queue* q, enum uv__work_kind kind) {
144 uv_mutex_lock(&mutex);
145 if (kind == UV__WORK_SLOW_IO) {
146 /* Insert into a separate queue. */
147 uv__queue_insert_tail(&slow_io_pending_wq, q);
148 if (!uv__queue_empty(&run_slow_work_message)) {
149 /* Running slow I/O tasks is already scheduled => Nothing to do here.
150 The worker that runs said other task will schedule this one as well. */
151 uv_mutex_unlock(&mutex);
152 return;
153 }
154 q = &run_slow_work_message;
155 }
156
157 uv__queue_insert_tail(&wq, q);
158 if (idle_threads > 0)
159 uv_cond_signal(&cond);
160 uv_mutex_unlock(&mutex);
161 }
162
163
164 #ifdef __MVS__
165 /* TODO(itodorov) - zos: revisit when Woz compiler is available. */
166 __attribute__((destructor))
167 #endif
168 void uv__threadpool_cleanup(void) {
169 unsigned int i;
170
171 if (nthreads == 0)
172 return;
173
174 #ifndef __MVS__
175 /* TODO(gabylb) - zos: revisit when Woz compiler is available. */
176 post(&exit_message, UV__WORK_CPU);
177 #endif
178
179 for (i = 0; i < nthreads; i++)
180 if (uv_thread_join(threads + i))
181 abort();
182
183 if (threads != default_threads)
184 uv__free(threads);
185
186 uv_mutex_destroy(&mutex);
187 uv_cond_destroy(&cond);
188
189 threads = NULL;
190 nthreads = 0;
191 }
192
193
194 static void init_threads(void) {
195 uv_thread_options_t config;
196 unsigned int i;
197 const char* val;
198 uv_sem_t sem;
199
200 nthreads = ARRAY_SIZE(default_threads);
201 val = getenv("UV_THREADPOOL_SIZE");
202 if (val != NULL)
203 nthreads = atoi(val);
204 if (nthreads == 0)
205 nthreads = 1;
206 if (nthreads > MAX_THREADPOOL_SIZE)
207 nthreads = MAX_THREADPOOL_SIZE;
208
209 threads = default_threads;
210 if (nthreads > ARRAY_SIZE(default_threads)) {
211 threads = uv__malloc(nthreads * sizeof(threads[0]));
212 if (threads == NULL) {
213 nthreads = ARRAY_SIZE(default_threads);
214 threads = default_threads;
215 }
216 }
217
218 if (uv_cond_init(&cond))
219 abort();
220
221 if (uv_mutex_init(&mutex))
222 abort();
223
224 uv__queue_init(&wq);
225 uv__queue_init(&slow_io_pending_wq);
226 uv__queue_init(&run_slow_work_message);
227
228 if (uv_sem_init(&sem, 0))
229 abort();
230
231 config.flags = UV_THREAD_HAS_STACK_SIZE;
232 config.stack_size = 8u << 20; /* 8 MB */
233
234 for (i = 0; i < nthreads; i++)
235 if (uv_thread_create_ex(threads + i, &config, worker, &sem))
236 abort();
237
238 for (i = 0; i < nthreads; i++)
239 uv_sem_wait(&sem);
240
241 uv_sem_destroy(&sem);
242 }
243
244
245 #ifndef _WIN32
246 static void reset_once(void) {
247 uv_once_t child_once = UV_ONCE_INIT;
248 memcpy(&once, &child_once, sizeof(child_once));
249 }
250 #endif
251
252
253 static void init_once(void) {
254 #ifndef _WIN32
255 /* Re-initialize the threadpool after fork.
256 * Note that this discards the global mutex and condition as well
257 * as the work queue.
258 */
259 if (pthread_atfork(NULL, NULL, &reset_once))
260 abort();
261 #endif
262 init_threads();
263 }
264
265
266 void uv__work_submit(uv_loop_t* loop,
267 struct uv__work* w,
268 enum uv__work_kind kind,
269 void (*work)(struct uv__work* w),
270 void (*done)(struct uv__work* w, int status)) {
271 uv_once(&once, init_once);
272 w->loop = loop;
273 w->work = work;
274 w->done = done;
275 post(&w->wq, kind);
276 }
277
278
279 /* TODO(bnoordhuis) teach libuv how to cancel file operations
280 * that go through io_uring instead of the thread pool.
281 */
282 static int uv__work_cancel(uv_loop_t* loop, uv_req_t* req, struct uv__work* w) {
283 int cancelled;
284
285 uv_once(&once, init_once); /* Ensure |mutex| is initialized. */
286 uv_mutex_lock(&mutex);
287 uv_mutex_lock(&w->loop->wq_mutex);
288
289 cancelled = !uv__queue_empty(&w->wq) && w->work != NULL;
290 if (cancelled)
291 uv__queue_remove(&w->wq);
292
293 uv_mutex_unlock(&w->loop->wq_mutex);
294 uv_mutex_unlock(&mutex);
295
296 if (!cancelled)
297 return UV_EBUSY;
298
299 w->work = uv__cancelled;
300 uv_mutex_lock(&loop->wq_mutex);
301 uv__queue_insert_tail(&loop->wq, &w->wq);
302 uv_async_send(&loop->wq_async);
303 uv_mutex_unlock(&loop->wq_mutex);
304
305 return 0;
306 }
307
308
309 void uv__work_done(uv_async_t* handle) {
310 struct uv__work* w;
311 uv_loop_t* loop;
312 struct uv__queue* q;
313 struct uv__queue wq;
314 int err;
315 int nevents;
316
317 loop = container_of(handle, uv_loop_t, wq_async);
318 uv_mutex_lock(&loop->wq_mutex);
319 uv__queue_move(&loop->wq, &wq);
320 uv_mutex_unlock(&loop->wq_mutex);
321
322 nevents = 0;
323
324 while (!uv__queue_empty(&wq)) {
325 q = uv__queue_head(&wq);
326 uv__queue_remove(q);
327
328 w = container_of(q, struct uv__work, wq);
329 err = (w->work == uv__cancelled) ? UV_ECANCELED : 0;
330 w->done(w, err);
331 nevents++;
332 }
333
334 /* This check accomplishes 2 things:
335 * 1. Even if the queue was empty, the call to uv__work_done() should count
336 * as an event. Which will have been added by the event loop when
337 * calling this callback.
338 * 2. Prevents accidental wrap around in case nevents == 0 events == 0.
339 */
340 if (nevents > 1) {
341 /* Subtract 1 to counter the call to uv__work_done(). */
342 uv__metrics_inc_events(loop, nevents - 1);
343 if (uv__get_internal_fields(loop)->current_timeout == 0)
344 uv__metrics_inc_events_waiting(loop, nevents - 1);
345 }
346 }
347
348
349 static void uv__queue_work(struct uv__work* w) {
350 uv_work_t* req = container_of(w, uv_work_t, work_req);
351
352 req->work_cb(req);
353 }
354
355
356 static void uv__queue_done(struct uv__work* w, int err) {
357 uv_work_t* req;
358
359 req = container_of(w, uv_work_t, work_req);
360 uv__req_unregister(req->loop);
361
362 if (req->after_work_cb == NULL)
363 return;
364
365 req->after_work_cb(req, err);
366 }
367
368
369 int uv_queue_work(uv_loop_t* loop,
370 uv_work_t* req,
371 uv_work_cb work_cb,
372 uv_after_work_cb after_work_cb) {
373 if (work_cb == NULL)
374 return UV_EINVAL;
375
376 uv__req_init(loop, req, UV_WORK);
377 req->loop = loop;
378 req->work_cb = work_cb;
379 req->after_work_cb = after_work_cb;
380 uv__work_submit(loop,
381 &req->work_req,
382 UV__WORK_CPU,
383 uv__queue_work,
384 uv__queue_done);
385 return 0;
386 }
387
388
389 int uv_cancel(uv_req_t* req) {
390 struct uv__work* wreq;
391 uv_loop_t* loop;
392
393 switch (req->type) {
394 case UV_FS:
395 loop = ((uv_fs_t*) req)->loop;
396 wreq = &((uv_fs_t*) req)->work_req;
397 break;
398 case UV_GETADDRINFO:
399 loop = ((uv_getaddrinfo_t*) req)->loop;
400 wreq = &((uv_getaddrinfo_t*) req)->work_req;
401 break;
402 case UV_GETNAMEINFO:
403 loop = ((uv_getnameinfo_t*) req)->loop;
404 wreq = &((uv_getnameinfo_t*) req)->work_req;
405 break;
406 case UV_RANDOM:
407 loop = ((uv_random_t*) req)->loop;
408 wreq = &((uv_random_t*) req)->work_req;
409 break;
410 case UV_WORK:
411 loop = ((uv_work_t*) req)->loop;
412 wreq = &((uv_work_t*) req)->work_req;
413 break;
414 default:
415 return UV_EINVAL;
416 }
417
418 return uv__work_cancel(loop, req, wreq);
419 }