Pipeline: Minor refactor

Use the proper Stream API to return a future to run on the
executor. Previously I was using a workaround to convert the
Stream into a future and run it to completion in the Executor,
since I was not aware of a better API.

podcasts-data/src/pipeline.rs

@@ -1,7 +1,7 @@
 // FIXME:
 //! Docs.
 
-use futures::{future::ok, lazy, prelude::*, stream::iter_ok};
+use futures::{lazy, prelude::*, stream::iter_ok};
 use tokio_core::reactor::Core;
 use tokio_threadpool::{self, ThreadPool};
 
@@ -26,26 +26,23 @@ pub fn pipeline<'a, S>(
     sources: S,
     client: HttpsClient,
     pool: tokio_threadpool::Sender,
-) -> impl Future<Item = Vec<()>, Error = DataError> + 'a
+) -> impl Future<Item = (), Error = ()> + 'a
 where
     S: Stream<Item = Source, Error = DataError> + 'a,
 {
     sources
         .and_then(move |s| s.into_feed(client.clone()))
-        .and_then(move |feed| {
-            let fut = lazy(|| feed.index().map_err(|err| error!("Error: {}", err)));
-            pool.spawn(fut).map_err(From::from)
-        })
-        // the stream will stop at the first error so
-        // we ensure that everything will succeded regardless.
         .map_err(|err| {
             match err {
                 // Avoid spamming the stderr when its not an eactual error
                 DataError::FeedNotModified(_) => (),
                 _ => error!("Error: {}", err),
             }
-        }).then(|_| ok::<(), DataError>(()))
-        .collect()
+        })
+        .for_each(move |feed| {
+            let fut = lazy(|| feed.index().map_err(|err| error!("Error: {}", err)));
+            pool.spawn(fut).map_err(|_| ())
+        })
 }
 
 /// Creates a tokio `reactor::Core`, and a `hyper::Client` and
@@ -62,7 +59,7 @@ where
 
     let stream = iter_ok::<_, DataError>(sources);
     let p = pipeline(stream, client, sender);
-    core.run(p)?;
+    let _ = core.run(p);
 
     pool.shutdown_on_idle().wait().unwrap();
     Ok(())