examples: Simplify basic futures / async examples a bit

Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/-/merge_requests/1724>

examples/src/bin/futures.rs

@@ -11,30 +11,6 @@ use gst::prelude::*;
 #[path = "../examples-common.rs"]
 mod examples_common;
 
-async fn message_loop(bus: gst::Bus) {
-    let mut messages = bus.stream();
-
-    while let Some(msg) = messages.next().await {
-        use gst::MessageView;
-
-        // Determine whether we want to quit: on EOS or error message
-        // we quit, otherwise simply continue.
-        match msg.view() {
-            MessageView::Eos(..) => break,
-            MessageView::Error(err) => {
-                println!(
-                    "Error from {:?}: {} ({:?})",
-                    err.src().map(|s| s.path_string()),
-                    err.error(),
-                    err.debug()
-                );
-                break;
-            }
-            _ => (),
-        };
-    }
-}
-
 fn example_main() {
     // Read the pipeline to launch from the commandline, using the launch syntax.
     let pipeline_str = env::args().collect::<Vec<String>>()[1..].join(" ");
@@ -53,7 +29,29 @@ fn example_main() {
     let mut pool = LocalPool::new();
 
     // Run until our message loop finishes, e.g. EOS/error happens
-    pool.run_until(message_loop(bus));
+    pool.run_until(async {
+        let mut messages = bus.stream();
+
+        while let Some(msg) = messages.next().await {
+            use gst::MessageView;
+
+            // Determine whether we want to quit: on EOS or error message
+            // we quit, otherwise simply continue.
+            match msg.view() {
+                MessageView::Eos(..) => break,
+                MessageView::Error(err) => {
+                    println!(
+                        "Error from {:?}: {} ({:?})",
+                        err.src().map(|s| s.path_string()),
+                        err.error(),
+                        err.debug()
+                    );
+                    break;
+                }
+                _ => (),
+            };
+        }
+    });
 
     pipeline
         .set_state(gst::State::Null)

examples/src/bin/glib-futures.rs

@@ -6,35 +6,10 @@ use gst::prelude::*;
 #[path = "../examples-common.rs"]
 mod examples_common;
 
-async fn message_handler(loop_: glib::MainLoop, bus: gst::Bus) {
-    let mut messages = bus.stream();
-
-    while let Some(msg) = messages.next().await {
-        use gst::MessageView;
-
-        // Determine whether we want to quit: on EOS or error message
-        // we quit, otherwise simply continue.
-        match msg.view() {
-            MessageView::Eos(..) => loop_.quit(),
-            MessageView::Error(err) => {
-                println!(
-                    "Error from {:?}: {} ({:?})",
-                    err.src().map(|s| s.path_string()),
-                    err.error(),
-                    err.debug()
-                );
-                loop_.quit();
-            }
-            _ => (),
-        }
-    }
-}
-
 fn example_main() {
     // Get the default main context and make it also the thread default, then create
     // a main loop for it
     let ctx = glib::MainContext::default();
-    let loop_ = glib::MainLoop::new(Some(&ctx), false);
 
     // Read the pipeline to launch from the commandline, using the launch syntax.
     let pipeline_str = env::args().collect::<Vec<String>>()[1..].join(" ");
@@ -50,11 +25,29 @@ fn example_main() {
         .expect("Unable to set the pipeline to the `Playing` state");
 
     // Spawn our message handling stream
-    ctx.spawn_local(message_handler(loop_.clone(), bus));
+    ctx.block_on(async {
+        let mut messages = bus.stream();
 
-    // And run until something is quitting the loop, i.e. an EOS
+        while let Some(msg) = messages.next().await {
-    // or error message is received above
+            use gst::MessageView;
-    loop_.run();
+
+            // Determine whether we want to quit: on EOS or error message
+            // we quit, otherwise simply continue.
+            match msg.view() {
+                MessageView::Eos(..) => break,
+                MessageView::Error(err) => {
+                    println!(
+                        "Error from {:?}: {} ({:?})",
+                        err.src().map(|s| s.path_string()),
+                        err.error(),
+                        err.debug()
+                    );
+                    break;
+                }
+                _ => (),
+            }
+        }
+    });
 
     pipeline
         .set_state(gst::State::Null)