use crate::PromiseResult;
use crate::Structure;
use crate::StructureRef;
use glib::translate::*;
use std::ptr;
use std::task::{Context, Poll};
use std::{ops::Deref, pin::Pin};
glib::wrapper! {
#[derive(Debug, PartialEq, Eq, PartialOrd, Ord, Hash)]
#[doc(alias = "GstPromise")]
pub struct Promise(Shared<ffi::GstPromise>);
match fn {
ref => |ptr| ffi::gst_mini_object_ref(ptr as *mut _),
unref => |ptr| ffi::gst_mini_object_unref(ptr as *mut _),
type_ => || ffi::gst_promise_get_type(),
}
}
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub enum PromiseError {
Interrupted,
Expired,
Other(PromiseResult),
}
impl Promise {
#[doc(alias = "gst_promise_new")]
pub fn new() -> Promise {
assert_initialized_main_thread!();
unsafe { from_glib_full(ffi::gst_promise_new()) }
}
#[doc(alias = "gst_promise_new_with_change_func")]
pub fn with_change_func<F>(func: F) -> Promise
where
F: FnOnce(Result<Option<&StructureRef>, PromiseError>) + Send + 'static,
{
assert_initialized_main_thread!();
let user_data: Box<Option<F>> = Box::new(Some(func));
unsafe extern "C" fn trampoline<
F: FnOnce(Result<Option<&StructureRef>, PromiseError>) + Send + 'static,
>(
promise: *mut ffi::GstPromise,
user_data: glib::ffi::gpointer,
) {
let user_data: &mut Option<F> = &mut *(user_data as *mut _);
let callback = user_data.take().unwrap();
let promise: Borrowed<Promise> = from_glib_borrow(promise);
let res = match promise.wait() {
PromiseResult::Replied => Ok(promise.get_reply()),
PromiseResult::Interrupted => Err(PromiseError::Interrupted),
PromiseResult::Expired => Err(PromiseError::Expired),
PromiseResult::Pending => {
panic!("Promise resolved but returned Pending");
}
err => Err(PromiseError::Other(err)),
};
callback(res);
}
unsafe extern "C" fn free_user_data<
F: FnOnce(Result<Option<&StructureRef>, PromiseError>) + Send + 'static,
>(
user_data: glib::ffi::gpointer,
) {
let _: Box<Option<F>> = Box::from_raw(user_data as *mut _);
}
unsafe {
from_glib_full(ffi::gst_promise_new_with_change_func(
Some(trampoline::<F>),
Box::into_raw(user_data) as *mut _,
Some(free_user_data::<F>),
))
}
}
pub fn new_future() -> (Self, PromiseFuture) {
use futures_channel::oneshot;
let (sender, receiver) = oneshot::channel();
let promise = Self::with_change_func(move |_res| {
let _ = sender.send(());
});
(promise.clone(), PromiseFuture(promise, receiver))
}
#[doc(alias = "gst_promise_expire")]
pub fn expire(&self) {
unsafe {
ffi::gst_promise_expire(self.to_glib_none().0);
}
}
#[doc(alias = "gst_promise_get_reply")]
pub fn get_reply(&self) -> Option<&StructureRef> {
unsafe {
let s = ffi::gst_promise_get_reply(self.to_glib_none().0);
if s.is_null() {
None
} else {
Some(StructureRef::from_glib_borrow(s))
}
}
}
#[doc(alias = "gst_promise_interrupt")]
pub fn interrupt(&self) {
unsafe {
ffi::gst_promise_interrupt(self.to_glib_none().0);
}
}
#[doc(alias = "gst_promise_reply")]
pub fn reply(&self, s: Option<Structure>) {
unsafe {
ffi::gst_promise_reply(
self.to_glib_none().0,
s.map(|s| s.into_glib_ptr()).unwrap_or(ptr::null_mut()),
);
}
}
#[doc(alias = "gst_promise_wait")]
pub fn wait(&self) -> PromiseResult {
unsafe { from_glib(ffi::gst_promise_wait(self.to_glib_none().0)) }
}
}
impl Default for Promise {
fn default() -> Self {
Self::new()
}
}
unsafe impl Send for Promise {}
unsafe impl Sync for Promise {}
#[derive(Debug)]
pub struct PromiseFuture(Promise, futures_channel::oneshot::Receiver<()>);
pub struct PromiseReply(Promise);
impl std::future::Future for PromiseFuture {
type Output = Result<Option<PromiseReply>, PromiseError>;
fn poll(mut self: Pin<&mut Self>, context: &mut Context) -> Poll<Self::Output> {
match Pin::new(&mut self.1).poll(context) {
Poll::Ready(Err(_)) => panic!("Sender dropped before callback was called"),
Poll::Ready(Ok(())) => {
let res = match self.0.wait() {
PromiseResult::Replied => {
if self.0.get_reply().is_none() {
Ok(None)
} else {
Ok(Some(PromiseReply(self.0.clone())))
}
}
PromiseResult::Interrupted => Err(PromiseError::Interrupted),
PromiseResult::Expired => Err(PromiseError::Expired),
PromiseResult::Pending => {
panic!("Promise resolved but returned Pending");
}
err => Err(PromiseError::Other(err)),
};
Poll::Ready(res)
}
Poll::Pending => Poll::Pending,
}
}
}
impl futures_core::future::FusedFuture for PromiseFuture {
fn is_terminated(&self) -> bool {
self.1.is_terminated()
}
}
impl Deref for PromiseReply {
type Target = StructureRef;
fn deref(&self) -> &StructureRef {
self.0.get_reply().expect("Promise without reply")
}
}
impl std::fmt::Debug for PromiseReply {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
let mut debug = f.debug_tuple("PromiseReply");
match self.0.get_reply() {
Some(reply) => debug.field(reply),
None => debug.field(&"<no reply>"),
}
.finish()
}
}
#[cfg(test)]
mod tests {
use super::*;
use std::sync::mpsc::channel;
use std::thread;
#[test]
fn test_change_func() {
crate::init().unwrap();
let (sender, receiver) = channel();
let promise = Promise::with_change_func(move |res| {
sender.send(res.map(|s| s.map(ToOwned::to_owned))).unwrap();
});
thread::spawn(move || {
promise.reply(Some(crate::Structure::new_empty("foo/bar")));
});
let res = receiver.recv().unwrap();
let res = res.expect("promise failed").expect("promise returned None");
assert_eq!(res.name(), "foo/bar");
}
}