Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 87 insertions, 0 deletions

diff --git a/third_party/rust/tokio-0.1.22/examples/manual-runtime.rs b/third_party/rust/tokio-0.1.22/examples/manual-runtime.rs
new file mode 100644
index 0000000000..8e3e129965
--- /dev/null
+++ b/third_party/rust/tokio-0.1.22/examples/manual-runtime.rs
@@ -0,0 +1,87 @@
+//! An example how to manually assemble a runtime and run some tasks on it.
+//!
+//! This is closer to the single-threaded runtime than the default tokio one, as it is simpler to
+//! grasp. There are conceptually similar, but the multi-threaded one would be more code. If you
+//! just want to *use* a single-threaded runtime, use the one provided by tokio directly
+//! (`tokio::runtime::current_thread::Runtime::new()`. This is a demonstration only.
+//!
+//! Note that the error handling is a bit left out. Also, the `run` could be modified to return the
+//! result of the provided future.
+
+extern crate futures;
+extern crate tokio;
+extern crate tokio_current_thread;
+extern crate tokio_executor;
+extern crate tokio_reactor;
+extern crate tokio_timer;
+
+use std::io::Error as IoError;
+use std::time::{Duration, Instant};
+
+use futures::{future, Future};
+use tokio_current_thread::CurrentThread;
+use tokio_reactor::Reactor;
+use tokio_timer::timer::{self, Timer};
+
+/// Creates a "runtime".
+///
+/// This is similar to running `tokio::runtime::current_thread::Runtime::new()`.
+fn run<F: Future<Item = (), Error = ()>>(f: F) -> Result<(), IoError> {
+    // We need a reactor to receive events about IO objects from kernel
+    let reactor = Reactor::new()?;
+    let reactor_handle = reactor.handle();
+    // Place a timer wheel on top of the reactor. If there are no timeouts to fire, it'll let the
+    // reactor pick up some new external events.
+    let timer = Timer::new(reactor);
+    let timer_handle = timer.handle();
+    // And now put a single-threaded executor on top of the timer. When there are no futures ready
+    // to do something, it'll let the timer or the reactor generate some new stimuli for the
+    // futures to continue in their life.
+    let mut executor = CurrentThread::new_with_park(timer);
+    // Binds an executor to this thread
+    let mut enter = tokio_executor::enter().expect("Multiple executors at once");
+    // This will set the default handle and timer to use inside the closure and run the future.
+    tokio_reactor::with_default(&reactor_handle, &mut enter, |enter| {
+        timer::with_default(&timer_handle, enter, |enter| {
+            // The TaskExecutor is a fake executor that looks into the current single-threaded
+            // executor when used. This is a trick, because we need two mutable references to the
+            // executor (one to run the provided future, another to install as the default one). We
+            // use the fake one here as the default one.
+            let mut default_executor = tokio_current_thread::TaskExecutor::current();
+            tokio_executor::with_default(&mut default_executor, enter, |enter| {
+                let mut executor = executor.enter(enter);
+                // Run the provided future
+                executor.block_on(f).unwrap();
+                // Run all the other futures that are still left in the executor
+                executor.run().unwrap();
+            });
+        });
+    });
+    Ok(())
+}
+
+fn main() -> Result<(), Box<std::error::Error>> {
+    run(future::lazy(|| {
+        // Here comes the application logic. It can spawn further tasks by tokio_current_thread::spawn().
+        // It also can use the default reactor and create timeouts.
+
+        // Connect somewhere. And then do nothing with it. Yes, useless.
+        //
+        // This will use the default reactor which runs in the current thread.
+        let connect = tokio::net::TcpStream::connect(&"127.0.0.1:53".parse().unwrap())
+            .map(|_| println!("Connected"))
+            .map_err(|e| println!("Failed to connect: {}", e));
+        // We can spawn it without requiring Send. This would panic if we run it outside of the
+        // `run` (or outside of anything else)
+        tokio_current_thread::spawn(connect);
+
+        // We can also create timeouts.
+        let deadline = tokio::timer::Delay::new(Instant::now() + Duration::from_secs(5))
+            .map(|()| println!("5 seconds are over"))
+            .map_err(|e| println!("Failed to wait: {}", e));
+        // We can spawn on the default executor, which is also the local one.
+        tokio::executor::spawn(deadline);
+        Ok(())
+    }))?;
+    Ok(())
+}