threadshare/udpsrc: Port udpsrc to new API

gst-plugin-threadshare/src/lib.rs

@@ -29,10 +29,10 @@ pub use tokio;
 #[macro_use]
 pub mod runtime;
 
-//pub mod socket;
+pub mod socket;
 //mod tcpclientsrc;
 //mod udpsink;
-//mod udpsrc;
+mod udpsrc;
 //
 //mod appsrc;
 //pub mod dataqueue;
@@ -49,7 +49,7 @@ use gst::prelude::*;
 use gstreamer_sys as gst_ffi;
 
 fn plugin_init(plugin: &gst::Plugin) -> Result<(), glib::BoolError> {
-    //udpsrc::register(plugin)?;
+    udpsrc::register(plugin)?;
     //udpsink::register(plugin)?;
     //tcpclientsrc::register(plugin)?;
     //queue::register(plugin)?;

gst-plugin-threadshare/src/socket.rs

@@ -16,10 +16,8 @@
 // Free Software Foundation, Inc., 51 Franklin Street, Suite 500,
 // Boston, MA 02110-1335, USA.
 
-use either::Either;
-
 use futures::future::{abortable, AbortHandle, Aborted, BoxFuture};
-use futures::lock::Mutex;
+use futures::prelude::*;
 
 use gst;
 use gst::prelude::*;
@@ -28,7 +26,7 @@ use gst::{gst_debug, gst_error, gst_error_msg};
 use lazy_static::lazy_static;
 
 use std::io;
-use std::sync::Arc;
+use std::sync::{Arc, Mutex};
 
 use gio;
 use gio::prelude::*;
@@ -49,7 +47,6 @@ lazy_static! {
     );
 }
 
-#[derive(Debug)]
 pub struct Socket<T: SocketRead + 'static>(Arc<Mutex<SocketInner<T>>>);
 
 pub trait SocketRead: Send + Unpin {
@@ -61,44 +58,51 @@ pub trait SocketRead: Send + Unpin {
     ) -> BoxFuture<'buf, io::Result<(usize, Option<std::net::SocketAddr>)>>;
 }
 
-#[derive(PartialEq, Eq, Debug)]
-enum SocketState {
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
+pub enum SocketState {
     Paused,
     Prepared,
     Started,
     Unprepared,
 }
 
-#[derive(Debug)]
 struct SocketInner<T: SocketRead + 'static> {
     state: SocketState,
     element: gst::Element,
-    reader: T,
     buffer_pool: gst::BufferPool,
     clock: Option<gst::Clock>,
     base_time: Option<gst::ClockTime>,
+    create_read_handle: Option<AbortHandle>,
+    create_reader_fut: Option<BoxFuture<'static, Result<T, SocketError>>>,
     read_handle: Option<AbortHandle>,
+    reader: Option<T>,
 }
 
 impl<T: SocketRead + 'static> Socket<T> {
-    pub fn new(element: &gst::Element, reader: T, buffer_pool: gst::BufferPool) -> Self {
-        Socket(Arc::new(Mutex::new(SocketInner::<T> {
+    pub fn new<F>(
+        element: &gst::Element,
+        buffer_pool: gst::BufferPool,
+        create_reader_fut: F,
+    ) -> Result<Self, ()>
+    where
+        F: Future<Output = Result<T, SocketError>> + Send + 'static,
+    {
+        let socket = Socket(Arc::new(Mutex::new(SocketInner::<T> {
             state: SocketState::Unprepared,
             element: element.clone(),
-            reader,
             buffer_pool,
             clock: None,
             base_time: None,
+            create_read_handle: None,
+            create_reader_fut: Some(create_reader_fut.boxed()),
             read_handle: None,
-        })))
-    }
+            reader: None,
+        })));
 
-    pub async fn prepare(&self) -> Result<SocketStream<T>, ()> {
-        // Null->Ready
-        let mut inner = self.0.lock().await;
+        let mut inner = socket.0.lock().unwrap();
         if inner.state != SocketState::Unprepared {
             gst_debug!(SOCKET_CAT, obj: &inner.element, "Socket already prepared");
-            return Ok(SocketStream::<T>::new(self));
+            return Err(());
         }
         gst_debug!(SOCKET_CAT, obj: &inner.element, "Preparing socket");
 
@@ -106,28 +110,39 @@ impl<T: SocketRead + 'static> Socket<T> {
             gst_error!(SOCKET_CAT, obj: &inner.element, "Failed to prepare socket: {}", err);
         })?;
         inner.state = SocketState::Prepared;
+        drop(inner);
 
-        Ok(SocketStream::<T>::new(self))
+        Ok(socket)
     }
 
-    pub async fn start(&self, clock: Option<gst::Clock>, base_time: Option<gst::ClockTime>) {
+    pub fn state(&self) -> SocketState {
+        self.0.lock().unwrap().state
+    }
+
+    pub fn start(
+        &self,
+        clock: Option<gst::Clock>,
+        base_time: Option<gst::ClockTime>,
+    ) -> Result<SocketStream<T>, ()> {
         // Paused->Playing
-        let mut inner = self.0.lock().await;
+        let mut inner = self.0.lock().unwrap();
         assert_ne!(SocketState::Unprepared, inner.state);
         if inner.state == SocketState::Started {
             gst_debug!(SOCKET_CAT, obj: &inner.element, "Socket already started");
-            return;
+            return Err(());
         }
 
         gst_debug!(SOCKET_CAT, obj: &inner.element, "Starting socket");
         inner.clock = clock;
         inner.base_time = base_time;
         inner.state = SocketState::Started;
+
+        Ok(SocketStream::<T>::new(self))
     }
 
-    pub async fn pause(&self) {
+    pub fn pause(&self) {
         // Playing->Paused
-        let mut inner = self.0.lock().await;
+        let mut inner = self.0.lock().unwrap();
         assert_ne!(SocketState::Unprepared, inner.state);
         if inner.state != SocketState::Started {
             gst_debug!(SOCKET_CAT, obj: &inner.element, "Socket not started");
@@ -142,22 +157,26 @@ impl<T: SocketRead + 'static> Socket<T> {
             read_handle.abort();
         }
     }
+}
 
-    pub async fn unprepare(&self) -> Result<(), ()> {
+impl<T: SocketRead> Drop for Socket<T> {
+    fn drop(&mut self) {
         // Ready->Null
-        let mut inner = self.0.lock().await;
+        let mut inner = self.0.lock().unwrap();
         assert_ne!(SocketState::Started, inner.state);
         if inner.state == SocketState::Unprepared {
             gst_debug!(SOCKET_CAT, obj: &inner.element, "Socket already unprepared");
-            return Ok(());
+            return;
         }
 
-        inner.buffer_pool.set_active(false).map_err(|err| {
-            gst_error!(SOCKET_CAT, obj: &inner.element, "Failed to unprepare socket: {}", err);
-        })?;
-        inner.state = SocketState::Unprepared;
+        if let Some(create_read_handle_handle) = inner.create_read_handle.take() {
+            create_read_handle_handle.abort();
+        }
 
-        Ok(())
+        if let Err(err) = inner.buffer_pool.set_active(false) {
+            gst_error!(SOCKET_CAT, obj: &inner.element, "Failed to unprepare socket: {}", err);
+        }
+        inner.state = SocketState::Unprepared;
     }
 }
 
@@ -167,10 +186,14 @@ impl<T: SocketRead + Unpin + 'static> Clone for Socket<T> {
     }
 }
 
-pub type SocketStreamItem =
-    Result<(gst::Buffer, Option<std::net::SocketAddr>), Either<gst::FlowError, io::Error>>;
+pub type SocketStreamItem = Result<(gst::Buffer, Option<std::net::SocketAddr>), SocketError>;
 
 #[derive(Debug)]
+pub enum SocketError {
+    Gst(gst::FlowError),
+    Io(io::Error),
+}
+
 pub struct SocketStream<T: SocketRead + 'static> {
     socket: Socket<T>,
     mapped_buffer: Option<gst::MappedBuffer<gst::buffer::Writable>>,
@@ -184,18 +207,57 @@ impl<T: SocketRead + 'static> SocketStream<T> {
         }
     }
 
-    // Implementing `next` as an `async fn` instead of a `Stream` because of the `async` `Mutex`
-    // See https://gitlab.freedesktop.org/gstreamer/gst-plugins-rs/merge_requests/204#note_322774
     #[allow(clippy::should_implement_trait)]
     pub async fn next(&mut self) -> Option<SocketStreamItem> {
+        // First create if needed
+        let (create_reader_fut, element) = {
+            let mut inner = self.socket.0.lock().unwrap();
+
+            if let Some(create_reader_fut) = inner.create_reader_fut.take() {
+                let (create_reader_fut, abort_handle) = abortable(create_reader_fut);
+                inner.create_read_handle = Some(abort_handle);
+                (Some(create_reader_fut), inner.element.clone())
+            } else {
+                (None, inner.element.clone())
+            }
+        };
+
+        if let Some(create_reader_fut) = create_reader_fut {
+            match create_reader_fut.await {
+                Ok(Ok(read)) => {
+                    let mut inner = self.socket.0.lock().unwrap();
+                    inner.create_read_handle = None;
+                    inner.reader = Some(read);
+                }
+                Ok(Err(err)) => {
+                    gst_debug!(SOCKET_CAT, obj: &element, "Create reader error {:?}", err);
+
+                    return Some(Err(err));
+                }
+                Err(Aborted) => {
+                    gst_debug!(SOCKET_CAT, obj: &element, "Create reader Aborted");
+
+                    return None;
+                }
+            }
+        }
+
         // take the mapped_buffer before locking the socket so as to please the mighty borrow checker
-        let read_fut = {
-            let mut inner = self.socket.0.lock().await;
+        let (read_fut, clock, base_time) = {
+            let mut inner = self.socket.0.lock().unwrap();
             if inner.state != SocketState::Started {
                 gst_debug!(SOCKET_CAT, obj: &inner.element, "DataQueue is not Started");
                 return None;
             }
 
+            let reader = match inner.reader {
+                None => {
+                    gst_debug!(SOCKET_CAT, obj: &inner.element, "Have no reader");
+                    return None;
+                }
+                Some(ref reader) => reader,
+            };
+
             gst_debug!(SOCKET_CAT, obj: &inner.element, "Trying to read data");
             if self.mapped_buffer.is_none() {
                 match inner.buffer_pool.acquire_buffer(None) {
@@ -204,32 +266,34 @@ impl<T: SocketRead + 'static> SocketStream<T> {
                     }
                     Err(err) => {
                         gst_debug!(SOCKET_CAT, obj: &inner.element, "Failed to acquire buffer {:?}", err);
-                        return Some(Err(Either::Left(err)));
+                        return Some(Err(SocketError::Gst(err)));
                     }
                 }
             }
 
-            let (read_fut, abort_handle) = abortable(
-                inner
-                    .reader
-                    .read(self.mapped_buffer.as_mut().unwrap().as_mut_slice()),
-            );
+            let (read_fut, abort_handle) =
+                abortable(reader.read(self.mapped_buffer.as_mut().unwrap().as_mut_slice()));
             inner.read_handle = Some(abort_handle);
 
-            read_fut
+            (read_fut, inner.clock.clone(), inner.base_time)
         };
 
         match read_fut.await {
             Ok(Ok((len, saddr))) => {
-                let inner = self.socket.0.lock().await;
-
                 let dts = if T::DO_TIMESTAMP {
-                    let time = inner.clock.as_ref().unwrap().get_time();
-                    let running_time = time - inner.base_time.unwrap();
-                    gst_debug!(SOCKET_CAT, obj: &inner.element, "Read {} bytes at {} (clock {})", len, running_time, time);
+                    let time = clock.as_ref().unwrap().get_time();
+                    let running_time = time - base_time.unwrap();
+                    gst_debug!(
+                        SOCKET_CAT,
+                        obj: &element,
+                        "Read {} bytes at {} (clock {})",
+                        len,
+                        running_time,
+                        time
+                    );
                     running_time
                 } else {
-                    gst_debug!(SOCKET_CAT, obj: &inner.element, "Read {} bytes", len);
+                    gst_debug!(SOCKET_CAT, obj: &element, "Read {} bytes", len);
                     gst::CLOCK_TIME_NONE
                 };
 
@@ -245,12 +309,12 @@ impl<T: SocketRead + 'static> SocketStream<T> {
                 Some(Ok((buffer, saddr)))
             }
             Ok(Err(err)) => {
-                gst_debug!(SOCKET_CAT, obj: &self.socket.0.lock().await.element, "Read error {:?}", err);
+                gst_debug!(SOCKET_CAT, obj: &element, "Read error {:?}", err);
 
-                Some(Err(Either::Right(err)))
+                Some(Err(SocketError::Io(err)))
             }
             Err(Aborted) => {
-                gst_debug!(SOCKET_CAT, obj: &self.socket.0.lock().await.element, "Read Aborted");
+                gst_debug!(SOCKET_CAT, obj: &element, "Read Aborted");
 
                 None
             }

gst-plugin-threadshare/src/udpsrc.rs

@@ -15,10 +15,8 @@
 // Free Software Foundation, Inc., 51 Franklin Street, Suite 500,
 // Boston, MA 02110-1335, USA.
 
-use either::Either;
-
 use futures::future::BoxFuture;
-use futures::lock::Mutex;
+use futures::lock::Mutex as FutMutex;
 use futures::prelude::*;
 
 use gio;
@@ -41,13 +39,16 @@ use rand;
 
 use std::io;
 use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
+use std::sync::Mutex as StdMutex;
 use std::sync::{self, Arc};
 use std::u16;
 
 use crate::runtime::prelude::*;
-use crate::runtime::{self, Context, JoinHandle, PadSrc, PadSrcRef};
+use crate::runtime::{Context, PadSrc, PadSrcRef};
 
-use super::socket::{wrap_socket, GioSocketWrapper, Socket, SocketRead, SocketStream};
+use super::socket::{
+    wrap_socket, GioSocketWrapper, Socket, SocketError, SocketRead, SocketState, SocketStream,
+};
 
 const DEFAULT_ADDRESS: Option<&str> = Some("127.0.0.1");
 const DEFAULT_PORT: u32 = 5000;
@@ -196,11 +197,11 @@ struct UdpReaderInner {
 }
 
 #[derive(Debug)]
-pub struct UdpReader(Arc<Mutex<UdpReaderInner>>);
+pub struct UdpReader(Arc<FutMutex<UdpReaderInner>>);
 
 impl UdpReader {
     fn new(socket: tokio::net::UdpSocket) -> Self {
-        UdpReader(Arc::new(Mutex::new(UdpReaderInner { socket })))
+        UdpReader(Arc::new(FutMutex::new(UdpReaderInner { socket })))
     }
 }
 
@@ -247,41 +248,39 @@ impl Default for UdpSrcPadHandlerState {
 #[derive(Debug, Default)]
 struct UdpSrcPadHandlerInner {
     state: sync::RwLock<UdpSrcPadHandlerState>,
-    socket_stream: Mutex<Option<SocketStream<UdpReader>>>,
-    flush_join_handle: sync::Mutex<Option<JoinHandle<Result<(), ()>>>>,
 }
 
 #[derive(Clone, Debug, Default)]
 struct UdpSrcPadHandler(Arc<UdpSrcPadHandlerInner>);
 
 impl UdpSrcPadHandler {
-    async fn start_task(&self, pad: PadSrcRef<'_>, element: &gst::Element) {
+    fn start_task(
+        &self,
+        pad: PadSrcRef<'_>,
+        element: &gst::Element,
+        socket_stream: SocketStream<UdpReader>,
+    ) {
         let this = self.clone();
         let pad_weak = pad.downgrade();
         let element = element.clone();
+        let socket_stream = Arc::new(FutMutex::new(socket_stream));
+
         pad.start_task(move || {
             let this = this.clone();
             let pad_weak = pad_weak.clone();
             let element = element.clone();
+            let socket_stream = socket_stream.clone();
+
             async move {
-                let item = this
-                    .0
-                    .socket_stream
-                    .lock()
-                    .await
-                    .as_mut()
-                    .expect("Missing SocketStream")
-                    .next()
-                    .await;
+                let item = socket_stream.lock().await.next().await;
 
                 let pad = pad_weak.upgrade().expect("PadSrc no longer exists");
                 let (mut buffer, saddr) = match item {
                     Some(Ok((buffer, saddr))) => (buffer, saddr),
                     Some(Err(err)) => {
-                        gst_error!(CAT, obj: &element, "Got error {}", err);
+                        gst_error!(CAT, obj: &element, "Got error {:?}", err);
                         match err {
-                            Either::Left(gst::FlowError::CustomError) => (),
-                            Either::Left(err) => {
+                            SocketError::Gst(err) => {
                                 gst_element_error!(
                                     element,
                                     gst::StreamError::Failed,
@@ -289,7 +288,7 @@ impl UdpSrcPadHandler {
                                     ["streaming stopped, reason {}", err]
                                 );
                             }
-                            Either::Right(err) => {
+                            SocketError::Io(err) => {
                                 gst_element_error!(
                                     element,
                                     gst::StreamError::Failed,
@@ -298,12 +297,11 @@ impl UdpSrcPadHandler {
                                 );
                             }
                         }
-                        return;
+                        return glib::Continue(false);
                     }
                     None => {
                         gst_log!(CAT, obj: pad.gst_pad(), "SocketStream Stopped");
-                        pad.pause_task().await;
-                        return;
+                        return glib::Continue(false);
                     }
                 };
 
@@ -323,74 +321,83 @@ impl UdpSrcPadHandler {
                     }
                 }
 
-                this.push_buffer(pad, &element, buffer).await;
-            }
-        })
-        .await;
-    }
+                let res = this.push_buffer(&pad, &element, buffer).await;
 
-    async fn push_buffer(&self, pad: PadSrcRef<'_>, element: &gst::Element, buffer: gst::Buffer) {
-        {
-            let mut events = Vec::new();
-            {
-                // Only `read` the state in the hot path
-                if self.0.state.read().unwrap().need_initial_events {
-                    // We will need to `write` and we also want to prevent
-                    // any changes on the state while we are handling initial events
-                    let mut state = self.0.state.write().unwrap();
-                    assert!(state.need_initial_events);
-
-                    gst_debug!(CAT, obj: pad.gst_pad(), "Pushing initial events");
-
-                    let stream_id =
-                        format!("{:08x}{:08x}", rand::random::<u32>(), rand::random::<u32>());
-                    events.push(
-                        gst::Event::new_stream_start(&stream_id)
-                            .group_id(gst::GroupId::next())
-                            .build(),
-                    );
-
-                    if let Some(ref caps) = state.caps {
-                        events.push(gst::Event::new_caps(&caps).build());
-                        state.configured_caps = Some(caps.clone());
+                match res {
+                    Ok(_) => {
+                        gst_log!(CAT, obj: pad.gst_pad(), "Successfully pushed buffer");
+                        glib::Continue(true)
+                    }
+                    Err(gst::FlowError::Flushing) => {
+                        gst_debug!(CAT, obj: pad.gst_pad(), "Flushing");
+                        glib::Continue(false)
+                    }
+                    Err(gst::FlowError::Eos) => {
+                        gst_debug!(CAT, obj: pad.gst_pad(), "EOS");
+                        let eos = gst::Event::new_eos().build();
+                        pad.push_event(eos).await;
+                        glib::Continue(false)
+                    }
+                    Err(err) => {
+                        gst_error!(CAT, obj: pad.gst_pad(), "Got error {}", err);
+                        gst_element_error!(
+                            element,
+                            gst::StreamError::Failed,
+                            ("Internal data stream error"),
+                            ["streaming stopped, reason {}", err]
+                        );
+                        glib::Continue(false)
                     }
-                    events.push(
-                        gst::Event::new_segment(&gst::FormattedSegment::<gst::format::Time>::new())
-                            .build(),
-                    );
-
-                    state.need_initial_events = false;
                 }
             }
+        });
+    }
 
-            for event in events {
-                pad.push_event(event).await;
+    async fn push_prelude(&self, pad: &PadSrcRef<'_>, _element: &gst::Element) {
+        let mut events = Vec::new();
+
+        // Only `read` the state in the hot path
+        if self.0.state.read().unwrap().need_initial_events {
+            // We will need to `write` and we also want to prevent
+            // any changes on the state while we are handling initial events
+            let mut state = self.0.state.write().unwrap();
+            assert!(state.need_initial_events);
+
+            gst_debug!(CAT, obj: pad.gst_pad(), "Pushing initial events");
+
+            let stream_id = format!("{:08x}{:08x}", rand::random::<u32>(), rand::random::<u32>());
+            events.push(
+                gst::Event::new_stream_start(&stream_id)
+                    .group_id(gst::GroupId::next())
+                    .build(),
+            );
+
+            if let Some(ref caps) = state.caps {
+                events.push(gst::Event::new_caps(&caps).build());
+                state.configured_caps = Some(caps.clone());
             }
+            events.push(
+                gst::Event::new_segment(&gst::FormattedSegment::<gst::format::Time>::new()).build(),
+            );
+
+            state.need_initial_events = false;
         }
 
-        match pad.push(buffer).await {
-            Ok(_) => {
-                gst_log!(CAT, obj: pad.gst_pad(), "Successfully pushed buffer");
-            }
-            Err(gst::FlowError::Flushing) => {
-                gst_debug!(CAT, obj: pad.gst_pad(), "Flushing");
-                pad.pause_task().await;
-            }
-            Err(gst::FlowError::Eos) => {
-                gst_debug!(CAT, obj: pad.gst_pad(), "EOS");
-                pad.pause_task().await;
-            }
-            Err(err) => {
-                gst_error!(CAT, obj: pad.gst_pad(), "Got error {}", err);
-                gst_element_error!(
-                    element,
-                    gst::StreamError::Failed,
-                    ("Internal data stream error"),
-                    ["streaming stopped, reason {}", err]
-                );
-            }
+        for event in events {
+            pad.push_event(event).await;
         }
     }
+
+    async fn push_buffer(
+        &self,
+        pad: &PadSrcRef<'_>,
+        element: &gst::Element,
+        buffer: gst::Buffer,
+    ) -> Result<gst::FlowSuccess, gst::FlowError> {
+        self.push_prelude(pad, element).await;
+
+        pad.push(buffer).await
+    }
 }
 
 impl PadSrcHandler for UdpSrcPadHandler {
@@ -399,68 +406,24 @@ impl PadSrcHandler for UdpSrcPadHandler {
     fn src_event(
         &self,
         pad: &PadSrcRef,
-        _udpsrc: &UdpSrc,
+        udpsrc: &UdpSrc,
         element: &gst::Element,
         event: gst::Event,
-    ) -> Either<bool, BoxFuture<'static, bool>> {
+    ) -> bool {
         use gst::EventView;
 
         gst_log!(CAT, obj: pad.gst_pad(), "Handling {:?}", event);
 
         let ret = match event.view() {
             EventView::FlushStart(..) => {
-                let mut flush_join_handle = self.0.flush_join_handle.lock().unwrap();
-                if flush_join_handle.is_none() {
-                    let element = element.clone();
-                    let pad_weak = pad.downgrade();
-
-                    *flush_join_handle = Some(pad.spawn(async move {
-                        let res = UdpSrc::from_instance(&element).pause(&element).await;
-                        let pad = pad_weak.upgrade().unwrap();
-                        if res.is_ok() {
-                            gst_debug!(CAT, obj: pad.gst_pad(), "FlushStart complete");
-                        } else {
-                            gst_debug!(CAT, obj: pad.gst_pad(), "FlushStart failed");
-                        }
-
-                        res
-                    }));
-                } else {
-                    gst_debug!(CAT, obj: pad.gst_pad(), "FlushStart ignored: previous Flush in progress");
-                }
+                udpsrc.pause(element).unwrap();
 
                 true
             }
             EventView::FlushStop(..) => {
-                let element = element.clone();
-                let inner_weak = Arc::downgrade(&self.0);
-                let pad_weak = pad.downgrade();
+                udpsrc.flush_stop(element);
 
-                let fut = async move {
-                    let mut ret = false;
-
-                    let pad = pad_weak.upgrade().unwrap();
-                    let inner_weak = inner_weak.upgrade().unwrap();
-                    let flush_join_handle = inner_weak.flush_join_handle.lock().unwrap().take();
-                    if let Some(flush_join_handle) = flush_join_handle {
-                        if let Ok(Ok(())) = flush_join_handle.await {
-                            ret = UdpSrc::from_instance(&element)
-                                .start(&element)
-                                .await
-                                .is_ok();
-                            gst_debug!(CAT, obj: pad.gst_pad(), "FlushStop complete");
-                        } else {
-                            gst_debug!(CAT, obj: pad.gst_pad(), "FlushStop aborted: FlushStart failed");
-                        }
-                    } else {
-                        gst_debug!(CAT, obj: pad.gst_pad(), "FlushStop ignored: no Flush in progress");
-                    }
-
-                    ret
-                }
-                .boxed();
-
-                return Either::Right(fut);
+                true
             }
             EventView::Reconfigure(..) => true,
             EventView::Latency(..) => true,
@@ -473,7 +436,7 @@ impl PadSrcHandler for UdpSrcPadHandler {
             gst_log!(CAT, obj: pad.gst_pad(), "Didn't handle {:?}", event);
         }
 
-        Either::Left(ret)
+        ret
     }
 
     fn src_query(
@@ -526,23 +489,11 @@ impl PadSrcHandler for UdpSrcPadHandler {
     }
 }
 
-#[derive(Debug)]
-struct State {
-    socket: Option<Socket<UdpReader>>,
-}
-
-impl Default for State {
-    fn default() -> State {
-        State { socket: None }
-    }
-}
-
-#[derive(Debug)]
 struct UdpSrc {
     src_pad: PadSrc,
     src_pad_handler: UdpSrcPadHandler,
-    state: Mutex<State>,
-    settings: Mutex<Settings>,
+    socket: StdMutex<Option<Socket<UdpReader>>>,
+    settings: StdMutex<Settings>,
 }
 
 lazy_static! {
@@ -554,9 +505,9 @@ lazy_static! {
 }
 
 impl UdpSrc {
-    async fn prepare(&self, element: &gst::Element) -> Result<(), gst::ErrorMessage> {
-        let mut state = self.state.lock().await;
-        let mut settings = self.settings.lock().await.clone();
+    fn prepare(&self, element: &gst::Element) -> Result<(), gst::ErrorMessage> {
+        let mut socket_storage = self.socket.lock().unwrap();
+        let mut settings = self.settings.lock().unwrap().clone();
 
         gst_debug!(CAT, obj: element, "Preparing");
 
@@ -725,8 +676,10 @@ impl UdpSrc {
             )
         })?;
 
-        let socket = Socket::new(element.upcast_ref(), UdpReader::new(socket), buffer_pool);
-        let socket_stream = socket.prepare().await.map_err(|err| {
+        let socket = Socket::new(element.upcast_ref(), buffer_pool, async move {
+            Ok(UdpReader::new(socket))
+        })
+        .map_err(|err| {
             gst_error_msg!(
                 gst::ResourceError::OpenRead,
                 ["Failed to prepare socket {:?}", err]
@@ -736,20 +689,16 @@ impl UdpSrc {
         {
             let mut src_pad_handler_state = self.src_pad_handler.0.state.write().unwrap();
             src_pad_handler_state.retrieve_sender_address = settings.retrieve_sender_address;
-            src_pad_handler_state.caps = settings.caps.clone();
+            src_pad_handler_state.caps = settings.caps;
         }
 
-        drop(settings);
-
-        *self.src_pad_handler.0.socket_stream.lock().await = Some(socket_stream);
-
-        state.socket = Some(socket);
+        *socket_storage = Some(socket);
+        drop(socket_storage);
 
         element.notify("used-socket");
 
         self.src_pad
             .prepare(context, &self.src_pad_handler)
-            .await
             .map_err(|err| {
                 gst_error_msg!(
                     gst::ResourceError::OpenRead,
@@ -762,65 +711,102 @@ impl UdpSrc {
         Ok(())
     }
 
-    async fn unprepare(&self, element: &gst::Element) -> Result<(), ()> {
-        let mut state = self.state.lock().await;
+    fn unprepare(&self, element: &gst::Element) -> Result<(), ()> {
         gst_debug!(CAT, obj: element, "Unpreparing");
 
-        self.settings.lock().await.used_socket = None;
+        self.settings.lock().unwrap().used_socket = None;
+        element.notify("used-socket");
 
-        self.src_pad.stop_task().await;
-
-        *self.src_pad_handler.0.socket_stream.lock().await = None;
-
-        {
-            let socket = state.socket.take().unwrap();
-            socket.unprepare().await.unwrap();
+        if let Some(socket) = self.socket.lock().unwrap().take() {
+            drop(socket);
         }
 
-        let _ = self.src_pad.unprepare().await;
+        let _ = self.src_pad.unprepare();
+
+        *self.src_pad_handler.0.state.write().unwrap() = Default::default();
+
+        gst_debug!(CAT, obj: element, "Unprepared");
+
+        Ok(())
+    }
+
+    fn stop(&self, element: &gst::Element) -> Result<(), ()> {
+        gst_debug!(CAT, obj: element, "Stopping");
+
+        // Now stop the task if it was still running, blocking
+        // until this has actually happened
+        self.src_pad.stop_task();
+
         self.src_pad_handler
             .0
             .state
             .write()
             .unwrap()
-            .configured_caps = None;
+            .need_initial_events = true;
+
+        gst_debug!(CAT, obj: element, "Stopped");
 
-        gst_debug!(CAT, obj: element, "Unprepared");
         Ok(())
     }
 
-    async fn start(&self, element: &gst::Element) -> Result<(), ()> {
-        let state = self.state.lock().await;
-        gst_debug!(CAT, obj: element, "Starting");
+    fn start(&self, element: &gst::Element) -> Result<(), ()> {
+        let socket = self.socket.lock().unwrap();
+        if let Some(socket) = socket.as_ref() {
+            if socket.state() == SocketState::Started {
+                gst_debug!(CAT, obj: element, "Already started");
+                return Err(());
+            }
 
-        if let Some(ref socket) = state.socket {
-            socket
-                .start(element.get_clock(), Some(element.get_base_time()))
-                .await;
+            gst_debug!(CAT, obj: element, "Starting");
+
+            self.start_unchecked(element, socket);
+
+            gst_debug!(CAT, obj: element, "Started");
+
+            Ok(())
+        } else {
+            Err(())
+        }
+    }
+
+    fn flush_stop(&self, element: &gst::Element) {
+        // Keep the lock on the `socket` until `flush_stop` is complete
+        // so as to prevent race conditions due to concurrent state transitions.
+        // Note that this won't deadlock as it doesn't lock the `SocketStream`
+        // in use within the `src_pad`'s `Task`.
+        let socket = self.socket.lock().unwrap();
+        let socket = socket.as_ref().unwrap();
+        if socket.state() == SocketState::Started {
+            gst_debug!(CAT, obj: element, "Already started");
+            return;
         }
 
-        self.src_pad_handler
-            .start_task(self.src_pad.as_ref(), element)
-            .await;
+        gst_debug!(CAT, obj: element, "Stopping Flush");
 
-        gst_debug!(CAT, obj: element, "Started");
+        self.src_pad.stop_task();
+        self.start_unchecked(element, socket);
 
-        Ok(())
+        gst_debug!(CAT, obj: element, "Stopped Flush");
     }
 
-    async fn pause(&self, element: &gst::Element) -> Result<(), ()> {
-        let pause_completion = {
-            let state = self.state.lock().await;
-            gst_debug!(CAT, obj: element, "Pausing");
+    fn start_unchecked(&self, element: &gst::Element, socket: &Socket<UdpReader>) {
+        let socket_stream = socket
+            .start(element.get_clock(), Some(element.get_base_time()))
+            .unwrap();
 
-            let pause_completion = self.src_pad.pause_task().await;
-            state.socket.as_ref().unwrap().pause().await;
+        self.src_pad_handler
+            .start_task(self.src_pad.as_ref(), element, socket_stream);
+    }
 
-            pause_completion
-        };
+    fn pause(&self, element: &gst::Element) -> Result<(), ()> {
+        let socket = self.socket.lock().unwrap();
+        gst_debug!(CAT, obj: element, "Pausing");
 
-        gst_debug!(CAT, obj: element, "Waiting for Task Pause to complete");
-        pause_completion.await;
+        if let Some(socket) = socket.as_ref() {
+            socket.pause();
+        }
+
+        self.src_pad.cancel_task();
 
         gst_debug!(CAT, obj: element, "Paused");
 
@@ -880,8 +866,8 @@ impl ObjectSubclass for UdpSrc {
         Self {
             src_pad,
             src_pad_handler: UdpSrcPadHandler::default(),
-            state: Mutex::new(State::default()),
-            settings: Mutex::new(Settings::default()),
+            socket: StdMutex::new(None),
+            settings: StdMutex::new(Settings::default()),
         }
     }
 }
@@ -892,7 +878,7 @@ impl ObjectImpl for UdpSrc {
     fn set_property(&self, _obj: &glib::Object, id: usize, value: &glib::Value) {
         let prop = &PROPERTIES[id];
 
-        let mut settings = runtime::executor::block_on(self.settings.lock());
+        let mut settings = self.settings.lock().unwrap();
         match *prop {
             subclass::Property("address", ..) => {
                 settings.address = value.get().expect("type checked upstream");
@@ -937,7 +923,7 @@ impl ObjectImpl for UdpSrc {
     fn get_property(&self, _obj: &glib::Object, id: usize) -> Result<glib::Value, ()> {
         let prop = &PROPERTIES[id];
 
-        let settings = runtime::executor::block_on(self.settings.lock());
+        let settings = self.settings.lock().unwrap();
         match *prop {
             subclass::Property("address", ..) => Ok(settings.address.to_value()),
             subclass::Property("port", ..) => Ok(settings.port.to_value()),
@@ -982,18 +968,16 @@ impl ElementImpl for UdpSrc {
 
         match transition {
             gst::StateChange::NullToReady => {
-                runtime::executor::block_on(self.prepare(element)).map_err(|err| {
+                self.prepare(element).map_err(|err| {
                     element.post_error_message(&err);
                     gst::StateChangeError
                 })?;
             }
             gst::StateChange::PlayingToPaused => {
-                runtime::executor::block_on(self.pause(element))
-                    .map_err(|_| gst::StateChangeError)?;
+                self.pause(element).map_err(|_| gst::StateChangeError)?;
             }
             gst::StateChange::ReadyToNull => {
-                runtime::executor::block_on(self.unprepare(element))
-                    .map_err(|_| gst::StateChangeError)?;
+                self.unprepare(element).map_err(|_| gst::StateChangeError)?;
             }
             _ => (),
         }
@@ -1005,19 +989,13 @@ impl ElementImpl for UdpSrc {
                 success = gst::StateChangeSuccess::NoPreroll;
             }
             gst::StateChange::PausedToPlaying => {
-                runtime::executor::block_on(self.start(element))
-                    .map_err(|_| gst::StateChangeError)?;
+                self.start(element).map_err(|_| gst::StateChangeError)?;
             }
             gst::StateChange::PlayingToPaused => {
                 success = gst::StateChangeSuccess::NoPreroll;
             }
             gst::StateChange::PausedToReady => {
-                self.src_pad_handler
-                    .0
-                    .state
-                    .write()
-                    .unwrap()
-                    .need_initial_events = true;
+                self.stop(element).map_err(|_| gst::StateChangeError)?;
             }
             _ => (),
         }

gst-plugin-threadshare/tests/udpsrc.rs

@@ -82,18 +82,17 @@ fn test_push() {
         use gst::EventView;
 
         let event = h.pull_event().unwrap();
-        // The StickyEvent for the TaskContext is pushed first
         match event.view() {
             EventView::StreamStart(..) => {
-                assert_eq!(n_events, 1);
+                assert_eq!(n_events, 0);
             }
             EventView::Caps(ev) => {
-                assert_eq!(n_events, 2);
+                assert_eq!(n_events, 1);
                 let event_caps = ev.get_caps();
                 assert_eq!(caps.as_ref(), event_caps);
             }
             EventView::Segment(..) => {
-                assert_eq!(n_events, 3);
+                assert_eq!(n_events, 2);
                 break;
             }
             _ => (),