gstreamer-rs/gstreamer/src/task_pool.rs

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// Take a look at the license at the top of the repository in the LICENSE file.
use std::ptr;
use glib::{ffi::gpointer, prelude::*, translate::*};
use crate::TaskPool;
unsafe extern "C" fn task_pool_trampoline<P: FnOnce() + Send + 'static>(data: gpointer) {
let func = Box::from_raw(data as *mut P);
func()
}
pub trait TaskPoolExtManual: 'static {
#[doc(alias = "gst_task_pool_push")]
fn push<P: FnOnce() + Send + 'static>(
&self,
func: P,
) -> Result<Option<TaskPoolTaskHandle>, glib::Error>;
}
impl<O: IsA<TaskPool>> TaskPoolExtManual for O {
fn push<P: FnOnce() + Send + 'static>(
&self,
func: P,
) -> Result<Option<TaskPoolTaskHandle>, glib::Error> {
unsafe {
let mut error = ptr::null_mut();
let func: Box<P> = Box::new(func);
let func = Box::into_raw(func);
let handle = ffi::gst_task_pool_push(
self.as_ref().to_glib_none().0,
Some(task_pool_trampoline::<P>),
func as gpointer,
&mut error,
);
if !error.is_null() {
assert!(handle.is_null());
// Assume that task_pool_trampoline was
// not called and will not be called
drop(Box::from_raw(func));
return Err(from_glib_full(error));
}
let handle = ptr::NonNull::new(handle).map(|handle| TaskPoolTaskHandle {
handle,
task_pool: Some(self.as_ref().clone()),
});
Ok(handle)
}
}
}
impl TaskPool {
unsafe fn join(&self, id: ptr::NonNull<libc::c_void>) {
ffi::gst_task_pool_join(self.to_glib_none().0, id.as_ptr())
}
#[cfg(any(feature = "v1_20", feature = "dox"))]
#[cfg_attr(feature = "dox", doc(cfg(feature = "v1_20")))]
unsafe fn dispose_handle(&self, id: ptr::NonNull<libc::c_void>) {
ffi::gst_task_pool_dispose_handle(self.to_glib_none().0, id.as_ptr())
}
}
// rustdoc-stripper-ignore-next
/// A handle for a task which was pushed to a task pool.
pub trait TaskHandle {
// rustdoc-stripper-ignore-next
/// Wait for the task to complete.
fn join(self);
}
impl TaskHandle for () {
fn join(self) {}
}
impl TaskHandle for std::convert::Infallible {
fn join(self) {}
}
// rustdoc-stripper-ignore-next
/// An opaque handle for a task associated with a particular task pool.
///
/// Keeps a reference to the pool alive.
///
/// If the `v1_20` feature is enabled, requests the task pool to dispose of the handle when it is
/// dropped. Otherwise, needs to be `join`ed to avoid a leak.
#[cfg_attr(not(any(feature = "v1_20", feature = "dox")), must_use)]
#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct TaskPoolTaskHandle {
handle: ptr::NonNull<libc::c_void>,
task_pool: Option<TaskPool>,
}
impl TaskHandle for TaskPoolTaskHandle {
#[doc(alias = "gst_task_pool_join")]
fn join(mut self) {
let task_pool = self.task_pool.take().unwrap();
unsafe { task_pool.join(self.handle) }
}
}
impl Drop for TaskPoolTaskHandle {
#[doc(alias = "gst_task_pool_dispose_handle")]
#[inline]
fn drop(&mut self) {
if let Some(task_pool) = self.task_pool.take() {
cfg_if::cfg_if! {
if #[cfg(any(feature = "v1_20", feature = "dox"))] {
unsafe { task_pool.dispose_handle(self.handle) }
} else {
crate::warning!(crate::CAT_RUST, obj: &task_pool, "Leaked task handle");
}
}
}
}
}
#[cfg(test)]
mod tests {
use std::sync::mpsc::{channel, RecvError};
use super::*;
use crate::prelude::*;
#[test]
fn test_simple() {
crate::init().unwrap();
let pool = TaskPool::new();
pool.prepare().unwrap();
let (sender, receiver) = channel();
let handle = pool
.push(move || {
sender.send(()).unwrap();
})
.unwrap();
assert_eq!(receiver.recv(), Ok(()));
if let Some(handle) = handle {
handle.join();
}
// Can't test try_recv here as the default task pool produces no
// handles and thus no way to wait for channel destruction
assert_eq!(receiver.recv(), Err(RecvError));
pool.cleanup();
}
}