mirror of
https://github.com/mpv-player/mpv
synced 2024-12-30 19:22:11 +00:00
92b9d75d72
There is not much of a reason to have these wrappers around. Use POSIX standard functions directly, and use a separate utility function to take care of the timespec calculations. (Course POSIX for using this weird format for time values.)
273 lines
11 KiB
C
273 lines
11 KiB
C
/*
|
|
* This file is part of mpv.
|
|
*
|
|
* mpv is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License as published by
|
|
* the Free Software Foundation; either version 2 of the License, or
|
|
* (at your option) any later version.
|
|
*
|
|
* mpv is distributed in the hope that it will be useful,
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
* GNU General Public License for more details.
|
|
*
|
|
* You should have received a copy of the GNU General Public License along
|
|
* with mpv. If not, see <http://www.gnu.org/licenses/>.
|
|
*/
|
|
|
|
#include <stdbool.h>
|
|
#include <assert.h>
|
|
|
|
#include "common/common.h"
|
|
#include "osdep/threads.h"
|
|
#include "osdep/timer.h"
|
|
|
|
#include "dispatch.h"
|
|
|
|
struct mp_dispatch_queue {
|
|
struct mp_dispatch_item *head, *tail;
|
|
pthread_mutex_t lock;
|
|
pthread_cond_t cond;
|
|
int suspend_requested;
|
|
bool suspended;
|
|
void (*wakeup_fn)(void *wakeup_ctx);
|
|
void *wakeup_ctx;
|
|
// This lock grant access to the target thread's state during suspend mode.
|
|
// During suspend mode, the target thread is blocked in the function
|
|
// mp_dispatch_queue_process(), however this function may be processing
|
|
// dispatch queue items. This lock serializes the dispatch queue processing
|
|
// and external mp_dispatch_lock() calls.
|
|
// Invariant: can be held only while suspended==true, and suspend_requested
|
|
// must be >0 (unless mp_dispatch_queue_process() locks it). In particular,
|
|
// suspend mode must not be left while the lock is held.
|
|
pthread_mutex_t exclusive_lock;
|
|
};
|
|
|
|
struct mp_dispatch_item {
|
|
mp_dispatch_fn fn;
|
|
void *fn_data;
|
|
bool asynchronous;
|
|
bool completed;
|
|
struct mp_dispatch_item *next;
|
|
};
|
|
|
|
static void queue_dtor(void *p)
|
|
{
|
|
struct mp_dispatch_queue *queue = p;
|
|
assert(!queue->head);
|
|
assert(!queue->suspend_requested);
|
|
assert(!queue->suspended);
|
|
pthread_cond_destroy(&queue->cond);
|
|
pthread_mutex_destroy(&queue->lock);
|
|
pthread_mutex_destroy(&queue->exclusive_lock);
|
|
}
|
|
|
|
// A dispatch queue lets other threads runs callbacks in a target thread.
|
|
// The target thread is the thread which created the queue and which calls
|
|
// mp_dispatch_queue_process().
|
|
// Free the dispatch queue with talloc_free(). (It must be empty.)
|
|
struct mp_dispatch_queue *mp_dispatch_create(void *ta_parent)
|
|
{
|
|
struct mp_dispatch_queue *queue = talloc_ptrtype(ta_parent, queue);
|
|
*queue = (struct mp_dispatch_queue){0};
|
|
talloc_set_destructor(queue, queue_dtor);
|
|
pthread_mutex_init(&queue->exclusive_lock, NULL);
|
|
pthread_mutex_init(&queue->lock, NULL);
|
|
pthread_cond_init(&queue->cond, NULL);
|
|
return queue;
|
|
}
|
|
|
|
// Set a custom function that should be called to guarantee that the target
|
|
// thread wakes up. This is intended for use with code that needs to block
|
|
// on non-pthread primitives, such as e.g. select(). In the case of select(),
|
|
// the wakeup_fn could for example write a byte into a "wakeup" pipe in order
|
|
// to unblock the select(). The wakeup_fn is called from the dispatch queue
|
|
// when there are new dispatch items, and the target thread should then enter
|
|
// mp_dispatch_queue_process() as soon as possible. Note that wakeup_fn is
|
|
// called under no lock, so you might have to do synchronization yourself.
|
|
void mp_dispatch_set_wakeup_fn(struct mp_dispatch_queue *queue,
|
|
void (*wakeup_fn)(void *wakeup_ctx),
|
|
void *wakeup_ctx)
|
|
{
|
|
queue->wakeup_fn = wakeup_fn;
|
|
queue->wakeup_ctx = wakeup_ctx;
|
|
}
|
|
|
|
static void mp_dispatch_append(struct mp_dispatch_queue *queue,
|
|
struct mp_dispatch_item *item)
|
|
{
|
|
pthread_mutex_lock(&queue->lock);
|
|
if (queue->tail) {
|
|
queue->tail->next = item;
|
|
} else {
|
|
queue->head = item;
|
|
}
|
|
queue->tail = item;
|
|
// Wake up the main thread; note that other threads might wait on this
|
|
// condition for reasons, so broadcast the condition.
|
|
pthread_cond_broadcast(&queue->cond);
|
|
pthread_mutex_unlock(&queue->lock);
|
|
if (queue->wakeup_fn)
|
|
queue->wakeup_fn(queue->wakeup_ctx);
|
|
}
|
|
|
|
// Enqueue a callback to run it on the target thread asynchronously. The target
|
|
// thread will run fn(fn_data) as soon as it enter mp_dispatch_queue_process.
|
|
// Note that mp_dispatch_enqueue() will usually return long before that happens.
|
|
// It's up to the user to signal completion of the callback. It's also up to
|
|
// the user to guarantee that the context fn_data has correct lifetime, i.e.
|
|
// lives until the callback is run, and is freed after that.
|
|
void mp_dispatch_enqueue(struct mp_dispatch_queue *queue,
|
|
mp_dispatch_fn fn, void *fn_data)
|
|
{
|
|
struct mp_dispatch_item *item = talloc_ptrtype(NULL, item);
|
|
*item = (struct mp_dispatch_item){
|
|
.fn = fn,
|
|
.fn_data = fn_data,
|
|
.asynchronous = true,
|
|
};
|
|
mp_dispatch_append(queue, item);
|
|
}
|
|
|
|
// Like mp_dispatch_enqueue(), but the queue code will call talloc_free(fn_data)
|
|
// after the fn callback has been run. (The callback could trivially do that
|
|
// itself, but it makes it easier to implement synchronous and asynchronous
|
|
// requests with the same callback implementation.)
|
|
void mp_dispatch_enqueue_autofree(struct mp_dispatch_queue *queue,
|
|
mp_dispatch_fn fn, void *fn_data)
|
|
{
|
|
struct mp_dispatch_item *item = talloc_ptrtype(NULL, item);
|
|
*item = (struct mp_dispatch_item){
|
|
.fn = fn,
|
|
.fn_data = talloc_steal(item, fn_data),
|
|
.asynchronous = true,
|
|
};
|
|
mp_dispatch_append(queue, item);
|
|
}
|
|
|
|
// Run fn(fn_data) on the target thread synchronously. This function enqueues
|
|
// the callback and waits until the target thread is done doing this.
|
|
// This is redundant to calling the function inside mp_dispatch_[un]lock(),
|
|
// but can be helpful with code that relies on TLS (such as OpenGL).
|
|
void mp_dispatch_run(struct mp_dispatch_queue *queue,
|
|
mp_dispatch_fn fn, void *fn_data)
|
|
{
|
|
struct mp_dispatch_item item = {
|
|
.fn = fn,
|
|
.fn_data = fn_data,
|
|
};
|
|
mp_dispatch_append(queue, &item);
|
|
|
|
pthread_mutex_lock(&queue->lock);
|
|
while (!item.completed)
|
|
pthread_cond_wait(&queue->cond, &queue->lock);
|
|
pthread_mutex_unlock(&queue->lock);
|
|
}
|
|
|
|
// Process any outstanding dispatch items in the queue. This also handles
|
|
// suspending or locking the target thread.
|
|
// The timeout specifies the minimum wait time. The actual time spent in this
|
|
// function can be much higher if the suspending/locking functions are used, or
|
|
// if executing the dispatch items takes time. On the other hand, this function
|
|
// can return much earlier than the timeout due to sporadic wakeups.
|
|
// It is also guaranteed that if at least one queue item was processed, the
|
|
// function will return as soon as possible, ignoring the timeout. This
|
|
// simplifies users, such as re-checking conditions before waiting. (It will
|
|
// still process the remaining queue items, and wait for unsuspend.)
|
|
void mp_dispatch_queue_process(struct mp_dispatch_queue *queue, double timeout)
|
|
{
|
|
int64_t wait = timeout > 0 ? mp_add_timeout(mp_time_us(), timeout) : 0;
|
|
pthread_mutex_lock(&queue->lock);
|
|
queue->suspended = true;
|
|
// Wake up thread which called mp_dispatch_suspend().
|
|
pthread_cond_broadcast(&queue->cond);
|
|
while (queue->head || queue->suspend_requested || wait > 0) {
|
|
if (queue->head) {
|
|
struct mp_dispatch_item *item = queue->head;
|
|
queue->head = item->next;
|
|
if (!queue->head)
|
|
queue->tail = NULL;
|
|
item->next = NULL;
|
|
// Unlock, because we want to allow other threads to queue items
|
|
// while the dispatch item is processed.
|
|
// At the same time, exclusive_lock must be held to protect the
|
|
// thread's user state.
|
|
pthread_mutex_unlock(&queue->lock);
|
|
pthread_mutex_lock(&queue->exclusive_lock);
|
|
item->fn(item->fn_data);
|
|
pthread_mutex_unlock(&queue->exclusive_lock);
|
|
pthread_mutex_lock(&queue->lock);
|
|
if (item->asynchronous) {
|
|
talloc_free(item);
|
|
} else {
|
|
item->completed = true;
|
|
// Wakeup mp_dispatch_run()
|
|
pthread_cond_broadcast(&queue->cond);
|
|
}
|
|
} else {
|
|
if (wait > 0) {
|
|
struct timespec ts = mp_time_us_to_timespec(wait);
|
|
pthread_cond_timedwait(&queue->cond, &queue->lock, &ts);
|
|
} else {
|
|
pthread_cond_wait(&queue->cond, &queue->lock);
|
|
}
|
|
}
|
|
wait = 0;
|
|
}
|
|
queue->suspended = false;
|
|
pthread_mutex_unlock(&queue->lock);
|
|
}
|
|
|
|
// Set the target thread into suspend mode: in this mode, the thread will enter
|
|
// mp_dispatch_queue_process(), process any outstanding dispatch items, and
|
|
// wait for new items when done (instead of exiting the process function).
|
|
// Multiple threads can enter suspend mode at the same time. Suspend mode is
|
|
// not a synchronization mechanism; it merely makes sure the target thread does
|
|
// not leave mp_dispatch_queue_process(), even if it's done. mp_dispatch_lock()
|
|
// can be used for exclusive access.
|
|
void mp_dispatch_suspend(struct mp_dispatch_queue *queue)
|
|
{
|
|
pthread_mutex_lock(&queue->lock);
|
|
queue->suspend_requested++;
|
|
while (!queue->suspended) {
|
|
pthread_mutex_unlock(&queue->lock);
|
|
if (queue->wakeup_fn)
|
|
queue->wakeup_fn(queue->wakeup_ctx);
|
|
pthread_mutex_lock(&queue->lock);
|
|
if (queue->suspended)
|
|
break;
|
|
pthread_cond_wait(&queue->cond, &queue->lock);
|
|
}
|
|
pthread_mutex_unlock(&queue->lock);
|
|
}
|
|
|
|
// Undo mp_dispatch_suspend().
|
|
void mp_dispatch_resume(struct mp_dispatch_queue *queue)
|
|
{
|
|
pthread_mutex_lock(&queue->lock);
|
|
assert(queue->suspended);
|
|
assert(queue->suspend_requested > 0);
|
|
queue->suspend_requested--;
|
|
if (queue->suspend_requested == 0)
|
|
pthread_cond_broadcast(&queue->cond);
|
|
pthread_mutex_unlock(&queue->lock);
|
|
}
|
|
|
|
// Grant exclusive access to the target thread's state. While this is active,
|
|
// no other thread can return from mp_dispatch_lock() (i.e. it behaves like
|
|
// a pthread mutex), and no other thread can get dispatch items completed.
|
|
// Other threads can still queue asynchronous dispatch items without waiting,
|
|
// and the mutex behavior applies to this function only.
|
|
void mp_dispatch_lock(struct mp_dispatch_queue *queue)
|
|
{
|
|
mp_dispatch_suspend(queue);
|
|
pthread_mutex_lock(&queue->exclusive_lock);
|
|
}
|
|
|
|
// Undo mp_dispatch_lock().
|
|
void mp_dispatch_unlock(struct mp_dispatch_queue *queue)
|
|
{
|
|
pthread_mutex_unlock(&queue->exclusive_lock);
|
|
mp_dispatch_resume(queue);
|
|
}
|