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319 lines
9.1 KiB
Rust
319 lines
9.1 KiB
Rust
// Copyright (C) 2018-2020 Sebastian Dröge <sebastian@centricular.com>
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// Copyright (C) 2019-2021 François Laignel <fengalin@free.fr>
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Library General Public
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// License as published by the Free Software Foundation; either
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// version 2 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Library General Public License for more details.
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//
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// You should have received a copy of the GNU Library General Public
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// License along with this library; if not, write to the
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// Free Software Foundation, Inc., 51 Franklin Street, Suite 500,
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// Boston, MA 02110-1335, USA.
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use futures::channel::oneshot;
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use gio::glib::clone::Downgrade;
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use gst::{gst_debug, gst_trace};
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use std::cell::RefCell;
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use std::future::Future;
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use std::sync::mpsc as sync_mpsc;
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use std::sync::{Arc, Mutex, Weak};
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use std::thread;
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use std::time::Duration;
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use super::task::{SubTaskOutput, TaskFuture, TaskId, TaskQueue};
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use super::{CallOnDrop, JoinHandle};
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use crate::runtime::RUNTIME_CAT;
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thread_local! {
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static CURRENT_SCHEDULER: RefCell<Option<Weak<Scheduler>>> = RefCell::new(None);
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}
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#[derive(Debug)]
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pub(super) struct Scheduler {
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context_name: Arc<str>,
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max_throttling: Duration,
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task_queue: Mutex<TaskQueue>,
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rt_handle: Mutex<tokio::runtime::Handle>,
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shutdown: Mutex<Option<SchedulerShutdown>>,
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}
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impl Scheduler {
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pub const DUMMY_NAME: &'static str = "DUMMY";
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pub fn start(context_name: &str, max_throttling: Duration) -> Handle {
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let context_name = Arc::from(context_name);
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let (handle_sender, handle_receiver) = sync_mpsc::channel();
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let (shutdown_sender, shutdown_receiver) = oneshot::channel();
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let thread_ctx_name = Arc::clone(&context_name);
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let join = thread::spawn(move || {
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gst_debug!(
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RUNTIME_CAT,
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"Started Scheduler thread for Context '{}'",
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thread_ctx_name
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);
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let (mut rt, handle) = Scheduler::init(thread_ctx_name, max_throttling);
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handle_sender.send(handle.clone()).unwrap();
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let _ = rt.block_on(shutdown_receiver);
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});
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let handle = handle_receiver.recv().expect("Context thread init failed");
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*handle.0.shutdown.lock().unwrap() = Some(SchedulerShutdown {
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context_name,
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sender: Some(shutdown_sender),
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join: Some(join),
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});
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handle
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}
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fn init(context_name: Arc<str>, max_throttling: Duration) -> (tokio::runtime::Runtime, Handle) {
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let runtime = tokio::runtime::Builder::new()
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.basic_scheduler()
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.enable_all()
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.max_throttling(max_throttling)
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.build()
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.expect("Couldn't build the runtime");
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let scheduler = Arc::new(Scheduler {
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context_name: context_name.clone(),
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max_throttling,
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task_queue: Mutex::new(TaskQueue::new(context_name)),
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rt_handle: Mutex::new(runtime.handle().clone()),
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shutdown: Mutex::new(None),
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});
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CURRENT_SCHEDULER.with(|cur_scheduler| {
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*cur_scheduler.borrow_mut() = Some(scheduler.downgrade());
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});
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(runtime, scheduler.into())
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}
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pub fn block_on<F: Future>(future: F) -> <F as Future>::Output {
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assert!(
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!Scheduler::is_scheduler_thread(),
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"Attempt at blocking on from an existing Scheduler thread."
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);
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let (mut rt, handle) = Scheduler::init(Scheduler::DUMMY_NAME.into(), Duration::ZERO);
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let handle_clone = handle.clone();
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let task = handle.0.task_queue.lock().unwrap().add(async move {
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let res = future.await;
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let task_id = TaskId::current().unwrap();
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while handle_clone.has_sub_tasks(task_id) {
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if handle_clone.drain_sub_tasks(task_id).await.is_err() {
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break;
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}
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}
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res
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});
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let task_id = task.id();
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gst_trace!(RUNTIME_CAT, "Blocking on current thread with {:?}", task_id,);
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let _guard = CallOnDrop::new(|| {
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gst_trace!(
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RUNTIME_CAT,
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"Blocking on current thread with {:?} done",
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task_id,
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);
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handle.remove_task(task_id);
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});
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rt.block_on(task)
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}
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pub(super) fn is_scheduler_thread() -> bool {
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CURRENT_SCHEDULER.with(|cur_scheduler| cur_scheduler.borrow().is_some())
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}
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pub(super) fn current() -> Option<Handle> {
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CURRENT_SCHEDULER.with(|cur_scheduler| {
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cur_scheduler
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.borrow()
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.as_ref()
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.and_then(Weak::upgrade)
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.map(Handle::from)
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})
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}
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}
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impl Drop for Scheduler {
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fn drop(&mut self) {
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// No more strong handlers point to this
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// Scheduler, so remove its thread local key.
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let _ = CURRENT_SCHEDULER.try_with(|cur_scheduler| {
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*cur_scheduler.borrow_mut() = None;
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});
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gst_debug!(
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RUNTIME_CAT,
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"Terminated: Scheduler for Context '{}'",
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self.context_name
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);
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}
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}
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#[derive(Debug)]
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pub(super) struct SchedulerShutdown {
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context_name: Arc<str>,
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sender: Option<oneshot::Sender<()>>,
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join: Option<thread::JoinHandle<()>>,
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}
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impl Drop for SchedulerShutdown {
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fn drop(&mut self) {
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gst_debug!(
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RUNTIME_CAT,
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"Shutting down Scheduler thread for Context '{}'",
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self.context_name
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);
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self.sender.take().unwrap();
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gst_trace!(
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RUNTIME_CAT,
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"Waiting for Scheduler to shutdown for Context '{}'",
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self.context_name
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);
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let _ = self.join.take().unwrap().join();
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}
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}
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#[derive(Clone, Debug)]
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pub(super) struct HandleWeak(Weak<Scheduler>);
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impl HandleWeak {
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pub(super) fn upgrade(&self) -> Option<Handle> {
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self.0.upgrade().map(Handle)
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}
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}
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#[derive(Clone, Debug)]
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pub(super) struct Handle(Arc<Scheduler>);
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impl Handle {
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pub fn context_name(&self) -> &str {
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&self.0.context_name
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}
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pub fn max_throttling(&self) -> Duration {
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self.0.max_throttling
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}
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pub fn enter<F, R>(&self, f: F) -> R
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where
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F: FnOnce() -> R,
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{
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self.0.rt_handle.lock().unwrap().enter(f)
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}
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pub fn add_task<F: Future>(&self, future: F) -> TaskFuture<F> {
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let task = self.0.task_queue.lock().unwrap().add(future);
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task
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}
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pub fn remove_task(&self, task_id: TaskId) {
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self.0.task_queue.lock().unwrap().remove(task_id);
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}
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pub fn spawn<F>(&self, future: F, must_awake: bool) -> JoinHandle<F::Output>
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where
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F: Future + Send + 'static,
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F::Output: Send + 'static,
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{
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let task = self.add_task(future);
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let task_id = task.id();
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let (sender, receiver) = oneshot::channel();
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gst_trace!(
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RUNTIME_CAT,
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"Spawning new task_id {:?} on context {}",
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task.id(),
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self.0.context_name
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);
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let this = self.clone();
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let spawn_fut = async move {
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gst_trace!(
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RUNTIME_CAT,
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"Running task_id {:?} on context {}",
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task_id,
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this.context_name()
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);
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let _guard = CallOnDrop::new(|| {
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gst_trace!(
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RUNTIME_CAT,
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"Task {:?} on context {} done",
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task_id,
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this.context_name()
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);
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this.0.task_queue.lock().unwrap().remove(task_id);
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});
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let _ = sender.send(task.await);
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};
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if must_awake {
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let _ = self.0.rt_handle.lock().unwrap().awake_and_spawn(spawn_fut);
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} else {
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let _ = self.0.rt_handle.lock().unwrap().spawn(spawn_fut);
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}
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JoinHandle::new(receiver, self, task_id)
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}
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pub fn has_sub_tasks(&self, task_id: TaskId) -> bool {
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let ret = self.0.task_queue.lock().unwrap().has_sub_tasks(task_id);
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ret
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}
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pub fn add_sub_task<T>(&self, task_id: TaskId, sub_task: T) -> Result<(), T>
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where
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T: Future<Output = SubTaskOutput> + Send + 'static,
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{
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let res = self
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.0
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.task_queue
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.lock()
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.unwrap()
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.add_sub_task(task_id, sub_task);
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res
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}
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pub fn downgrade(&self) -> HandleWeak {
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HandleWeak(self.0.downgrade())
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}
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pub async fn drain_sub_tasks(&self, task_id: TaskId) -> SubTaskOutput {
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let sub_tasks_fut = self.0.task_queue.lock().unwrap().drain_sub_tasks(task_id);
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sub_tasks_fut.await
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}
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}
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impl From<Arc<Scheduler>> for Handle {
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fn from(arc: Arc<Scheduler>) -> Self {
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Handle(arc)
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}
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}
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impl PartialEq for Handle {
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fn eq(&self, other: &Self) -> bool {
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Arc::ptr_eq(&self.0, &other.0)
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}
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}
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