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418 lines (336 loc) · 10.8 KB
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/* Copyright Joyent, Inc. and other Node contributors. All rights reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to
* deal in the Software without restriction, including without limitation the
* rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
* sell copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
* IN THE SOFTWARE.
*/
#include "uv-common.h"
#if !defined(_WIN32)
# include "unix/internal.h"
#endif
#include <stdlib.h>
#define MAX_THREADPOOL_SIZE 1024
static uv_once_t once = UV_ONCE_INIT;
static uv_cond_t cond;
static uv_mutex_t mutex;
static unsigned int idle_threads;
static unsigned int slow_io_work_running;
static unsigned int nthreads;
static uv_thread_t* threads;
static uv_thread_t default_threads[4];
static struct uv__queue exit_message;
static struct uv__queue wq;
static struct uv__queue run_slow_work_message;
static struct uv__queue slow_io_pending_wq;
static unsigned int slow_work_thread_threshold(void) {
return (nthreads + 1) / 2;
}
static void uv__cancelled(struct uv__work* w) {
abort();
}
/* To avoid deadlock with uv_cancel() it's crucial that the worker
* never holds the global mutex and the loop-local mutex at the same time.
*/
static void worker(void* arg) {
struct uv__work* w;
struct uv__queue* q;
int is_slow_work;
uv_sem_post((uv_sem_t*) arg);
arg = NULL;
uv_mutex_lock(&mutex);
for (;;) {
/* `mutex` should always be locked at this point. */
/* Keep waiting while either no work is present or only slow I/O
and we're at the threshold for that. */
while (uv__queue_empty(&wq) ||
(uv__queue_head(&wq) == &run_slow_work_message &&
uv__queue_next(&run_slow_work_message) == &wq &&
slow_io_work_running >= slow_work_thread_threshold())) {
idle_threads += 1;
uv_cond_wait(&cond, &mutex);
idle_threads -= 1;
}
q = uv__queue_head(&wq);
if (q == &exit_message) {
uv_cond_signal(&cond);
uv_mutex_unlock(&mutex);
break;
}
uv__queue_remove(q);
uv__queue_init(q); /* Signal uv_cancel() that the work req is executing. */
is_slow_work = 0;
if (q == &run_slow_work_message) {
/* If we're at the slow I/O threshold, re-schedule until after all
other work in the queue is done. */
if (slow_io_work_running >= slow_work_thread_threshold()) {
uv__queue_insert_tail(&wq, q);
continue;
}
/* If we encountered a request to run slow I/O work but there is none
to run, that means it's cancelled => Start over. */
if (uv__queue_empty(&slow_io_pending_wq))
continue;
is_slow_work = 1;
slow_io_work_running++;
q = uv__queue_head(&slow_io_pending_wq);
uv__queue_remove(q);
uv__queue_init(q);
/* If there is more slow I/O work, schedule it to be run as well. */
if (!uv__queue_empty(&slow_io_pending_wq)) {
uv__queue_insert_tail(&wq, &run_slow_work_message);
if (idle_threads > 0)
uv_cond_signal(&cond);
}
}
uv_mutex_unlock(&mutex);
w = uv__queue_data(q, struct uv__work, wq);
w->work(w);
uv_mutex_lock(&w->loop->wq_mutex);
w->work = NULL; /* Signal uv_cancel() that the work req is done
executing. */
uv__queue_insert_tail(&w->loop->wq, &w->wq);
uv_async_send(&w->loop->wq_async);
uv_mutex_unlock(&w->loop->wq_mutex);
/* Lock `mutex` since that is expected at the start of the next
* iteration. */
uv_mutex_lock(&mutex);
if (is_slow_work) {
/* `slow_io_work_running` is protected by `mutex`. */
slow_io_work_running--;
}
}
}
static void post(struct uv__queue* q, enum uv__work_kind kind) {
uv_mutex_lock(&mutex);
if (kind == UV__WORK_SLOW_IO) {
/* Insert into a separate queue. */
uv__queue_insert_tail(&slow_io_pending_wq, q);
if (!uv__queue_empty(&run_slow_work_message)) {
/* Running slow I/O tasks is already scheduled => Nothing to do here.
The worker that runs said other task will schedule this one as well. */
uv_mutex_unlock(&mutex);
return;
}
q = &run_slow_work_message;
}
uv__queue_insert_tail(&wq, q);
if (idle_threads > 0)
uv_cond_signal(&cond);
uv_mutex_unlock(&mutex);
}
#ifdef __MVS__
/* TODO(itodorov) - zos: revisit when Woz compiler is available. */
__attribute__((destructor))
#endif
void uv__threadpool_cleanup(void) {
unsigned int i;
if (nthreads == 0)
return;
#ifndef __MVS__
/* TODO(gabylb) - zos: revisit when Woz compiler is available. */
post(&exit_message, UV__WORK_CPU);
#endif
for (i = 0; i < nthreads; i++)
if (uv_thread_join(threads + i))
abort();
if (threads != default_threads)
uv__free(threads);
uv_mutex_destroy(&mutex);
uv_cond_destroy(&cond);
threads = NULL;
nthreads = 0;
}
static void init_threads(void) {
uv_thread_options_t config;
unsigned int i;
const char* val;
uv_sem_t sem;
nthreads = ARRAY_SIZE(default_threads);
val = getenv("UV_THREADPOOL_SIZE");
if (val != NULL)
nthreads = atoi(val);
if (nthreads == 0)
nthreads = 1;
if (nthreads > MAX_THREADPOOL_SIZE)
nthreads = MAX_THREADPOOL_SIZE;
threads = default_threads;
if (nthreads > ARRAY_SIZE(default_threads)) {
threads = uv__malloc(nthreads * sizeof(threads[0]));
if (threads == NULL) {
nthreads = ARRAY_SIZE(default_threads);
threads = default_threads;
}
}
if (uv_cond_init(&cond))
abort();
if (uv_mutex_init(&mutex))
abort();
uv__queue_init(&wq);
uv__queue_init(&slow_io_pending_wq);
uv__queue_init(&run_slow_work_message);
if (uv_sem_init(&sem, 0))
abort();
config.flags = UV_THREAD_HAS_STACK_SIZE;
config.stack_size = 8u << 20; /* 8 MB */
for (i = 0; i < nthreads; i++)
if (uv_thread_create_ex(threads + i, &config, worker, &sem))
abort();
for (i = 0; i < nthreads; i++)
uv_sem_wait(&sem);
uv_sem_destroy(&sem);
}
#ifndef _WIN32
static void reset_once(void) {
uv_once_t child_once = UV_ONCE_INIT;
memcpy(&once, &child_once, sizeof(child_once));
}
#endif
static void init_once(void) {
#ifndef _WIN32
/* Re-initialize the threadpool after fork.
* Note that this discards the global mutex and condition as well
* as the work queue.
*/
if (pthread_atfork(NULL, NULL, &reset_once))
abort();
#endif
init_threads();
}
void 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)) {
uv_once(&once, init_once);
w->loop = loop;
w->work = work;
w->done = done;
post(&w->wq, kind);
}
/* TODO(bnoordhuis) teach libuv how to cancel file operations
* that go through io_uring instead of the thread pool.
*/
static int uv__work_cancel(uv_loop_t* loop, uv_req_t* req, struct uv__work* w) {
int cancelled;
uv_once(&once, init_once); /* Ensure |mutex| is initialized. */
uv_mutex_lock(&mutex);
uv_mutex_lock(&w->loop->wq_mutex);
cancelled = !uv__queue_empty(&w->wq) && w->work != NULL;
if (cancelled)
uv__queue_remove(&w->wq);
uv_mutex_unlock(&w->loop->wq_mutex);
uv_mutex_unlock(&mutex);
if (!cancelled)
return UV_EBUSY;
w->work = uv__cancelled;
uv_mutex_lock(&loop->wq_mutex);
uv__queue_insert_tail(&loop->wq, &w->wq);
uv_async_send(&loop->wq_async);
uv_mutex_unlock(&loop->wq_mutex);
return 0;
}
void uv__work_done(uv_async_t* handle) {
struct uv__work* w;
uv_loop_t* loop;
struct uv__queue* q;
struct uv__queue wq;
int err;
int nevents;
loop = container_of(handle, uv_loop_t, wq_async);
uv_mutex_lock(&loop->wq_mutex);
uv__queue_move(&loop->wq, &wq);
uv_mutex_unlock(&loop->wq_mutex);
nevents = 0;
while (!uv__queue_empty(&wq)) {
q = uv__queue_head(&wq);
uv__queue_remove(q);
w = container_of(q, struct uv__work, wq);
err = (w->work == uv__cancelled) ? UV_ECANCELED : 0;
w->done(w, err);
nevents++;
}
/* This check accomplishes 2 things:
* 1. Even if the queue was empty, the call to uv__work_done() should count
* as an event. Which will have been added by the event loop when
* calling this callback.
* 2. Prevents accidental wrap around in case nevents == 0 events == 0.
*/
if (nevents > 1) {
/* Subtract 1 to counter the call to uv__work_done(). */
uv__metrics_inc_events(loop, nevents - 1);
if (uv__get_internal_fields(loop)->current_timeout == 0)
uv__metrics_inc_events_waiting(loop, nevents - 1);
}
}
static void uv__queue_work(struct uv__work* w) {
uv_work_t* req = container_of(w, uv_work_t, work_req);
req->work_cb(req);
}
static void uv__queue_done(struct uv__work* w, int err) {
uv_work_t* req;
req = container_of(w, uv_work_t, work_req);
uv__req_unregister(req->loop, req);
if (req->after_work_cb == NULL)
return;
req->after_work_cb(req, err);
}
int uv_queue_work(uv_loop_t* loop,
uv_work_t* req,
uv_work_cb work_cb,
uv_after_work_cb after_work_cb) {
if (work_cb == NULL)
return UV_EINVAL;
uv__req_init(loop, req, UV_WORK);
req->loop = loop;
req->work_cb = work_cb;
req->after_work_cb = after_work_cb;
uv__work_submit(loop,
&req->work_req,
UV__WORK_CPU,
uv__queue_work,
uv__queue_done);
return 0;
}
int uv_cancel(uv_req_t* req) {
struct uv__work* wreq;
uv_loop_t* loop;
switch (req->type) {
case UV_FS:
loop = ((uv_fs_t*) req)->loop;
wreq = &((uv_fs_t*) req)->work_req;
break;
case UV_GETADDRINFO:
loop = ((uv_getaddrinfo_t*) req)->loop;
wreq = &((uv_getaddrinfo_t*) req)->work_req;
break;
case UV_GETNAMEINFO:
loop = ((uv_getnameinfo_t*) req)->loop;
wreq = &((uv_getnameinfo_t*) req)->work_req;
break;
case UV_RANDOM:
loop = ((uv_random_t*) req)->loop;
wreq = &((uv_random_t*) req)->work_req;
break;
case UV_WORK:
loop = ((uv_work_t*) req)->loop;
wreq = &((uv_work_t*) req)->work_req;
break;
default:
return UV_EINVAL;
}
return uv__work_cancel(loop, req, wreq);
}