Adding upstream version 110.0.1.upstream/110.0.1upstream

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

1 files changed, 115 insertions, 0 deletions

diff --git a/third_party/rust/tokio-0.1.22/examples/echo.rs b/third_party/rust/tokio-0.1.22/examples/echo.rs
new file mode 100644
index 0000000000..45f808f89d
--- /dev/null
+++ b/third_party/rust/tokio-0.1.22/examples/echo.rs
@@ -0,0 +1,115 @@
+//! A "hello world" echo server with Tokio
+//!
+//! This server will create a TCP listener, accept connections in a loop, and
+//! write back everything that's read off of each TCP connection.
+//!
+//! Because the Tokio runtime uses a thread pool, each TCP connection is
+//! processed concurrently with all other TCP connections across multiple
+//! threads.
+//!
+//! To see this server in action, you can run this in one terminal:
+//!
+//!     cargo run --example echo
+//!
+//! and in another terminal you can run:
+//!
+//!     cargo run --example connect 127.0.0.1:8080
+//!
+//! Each line you type in to the `connect` terminal should be echo'd back to
+//! you! If you open up multiple terminals running the `connect` example you
+//! should be able to see them all make progress simultaneously.
+
+#![deny(warnings)]
+
+extern crate tokio;
+
+use tokio::io;
+use tokio::net::TcpListener;
+use tokio::prelude::*;
+
+use std::env;
+use std::net::SocketAddr;
+
+fn main() -> Result<(), Box<std::error::Error>> {
+    // Allow passing an address to listen on as the first argument of this
+    // program, but otherwise we'll just set up our TCP listener on
+    // 127.0.0.1:8080 for connections.
+    let addr = env::args().nth(1).unwrap_or("127.0.0.1:8080".to_string());
+    let addr = addr.parse::<SocketAddr>()?;
+
+    // Next up we create a TCP listener which will listen for incoming
+    // connections. This TCP listener is bound to the address we determined
+    // above and must be associated with an event loop, so we pass in a handle
+    // to our event loop. After the socket's created we inform that we're ready
+    // to go and start accepting connections.
+    let socket = TcpListener::bind(&addr)?;
+    println!("Listening on: {}", addr);
+
+    // Here we convert the `TcpListener` to a stream of incoming connections
+    // with the `incoming` method. We then define how to process each element in
+    // the stream with the `for_each` method.
+    //
+    // This combinator, defined on the `Stream` trait, will allow us to define a
+    // computation to happen for all items on the stream (in this case TCP
+    // connections made to the server).  The return value of the `for_each`
+    // method is itself a future representing processing the entire stream of
+    // connections, and ends up being our server.
+    let done = socket
+        .incoming()
+        .map_err(|e| println!("failed to accept socket; error = {:?}", e))
+        .for_each(move |socket| {
+            // Once we're inside this closure this represents an accepted client
+            // from our server. The `socket` is the client connection (similar to
+            // how the standard library operates).
+            //
+            // We just want to copy all data read from the socket back onto the
+            // socket itself (e.g. "echo"). We can use the standard `io::copy`
+            // combinator in the `tokio-core` crate to do precisely this!
+            //
+            // The `copy` function takes two arguments, where to read from and where
+            // to write to. We only have one argument, though, with `socket`.
+            // Luckily there's a method, `Io::split`, which will split an Read/Write
+            // stream into its two halves. This operation allows us to work with
+            // each stream independently, such as pass them as two arguments to the
+            // `copy` function.
+            //
+            // The `copy` function then returns a future, and this future will be
+            // resolved when the copying operation is complete, resolving to the
+            // amount of data that was copied.
+            let (reader, writer) = socket.split();
+            let amt = io::copy(reader, writer);
+
+            // After our copy operation is complete we just print out some helpful
+            // information.
+            let msg = amt.then(move |result| {
+                match result {
+                    Ok((amt, _, _)) => println!("wrote {} bytes", amt),
+                    Err(e) => println!("error: {}", e),
+                }
+
+                Ok(())
+            });
+
+            // And this is where much of the magic of this server happens. We
+            // crucially want all clients to make progress concurrently, rather than
+            // blocking one on completion of another. To achieve this we use the
+            // `tokio::spawn` function to execute the work in the background.
+            //
+            // This function will transfer ownership of the future (`msg` in this
+            // case) to the Tokio runtime thread pool that. The thread pool will
+            // drive the future to completion.
+            //
+            // Essentially here we're executing a new task to run concurrently,
+            // which will allow all of our clients to be processed concurrently.
+            tokio::spawn(msg)
+        });
+
+    // And finally now that we've define what our server is, we run it!
+    //
+    // This starts the Tokio runtime, spawns the server task, and blocks the
+    // current thread until all tasks complete execution. Since the `done` task
+    // never completes (it just keeps accepting sockets), `tokio::run` blocks
+    // forever (until ctrl-c is pressed).
+    tokio::run(done);
+    Ok(())
+}