Tokio Guide 中文翻译

use mini_redis::{client, Result};

#[tokio::main]
pub async fn main() -> Result<()> {
    // Open a connection to the mini-redis address.
    let mut client = client::connect("127.0.0.1:6379").await?;

    // Set the key "hello" with value "world"
    client.set("hello", "world".into()).await?;

    // Get key "hello"
    let result = client.get("hello").await?;

    println!("got value from the server; result={:?}", result);

    Ok(())
}

use mini_redis::Result;
use mini_redis::client::Client;
use tokio::net::ToSocketAddrs;

pub async fn connect<T: ToSocketAddrs>(addr: T) -> Result<Client> {
    // ...
}

async fn say_world() {
    println!("world");
}

#[tokio::main]
async fn main() {
    // Calling `say_world()` does not execute the body of `say_world()`.
    let op = say_world();

    // This println! comes first
    println!("hello");

    // Calling `.await` on `op` starts executing `say_world`.
    op.await;
}

#[tokio::main]
async fn main() {
    println!("hello");
}

fn main() {
    let mut rt = tokio::runtime::Runtime::new().unwrap();
    rt.block_on(async {
        println!("hello");
    })
}

tokio = { version = "0.3", features = ["full"] }

use tokio::net::{TcpListener, TcpStream};
use mini_redis::{Connection, Frame};

#[tokio::main]
async fn main() {
    // Bind the listener to the address
    let listener = TcpListener::bind("127.0.0.1:6379").await.unwrap();
    loop {
        // The second item contains the IP and port of the new connection.
        let (socket, _) = listener.accept().await.unwrap();
        process(socket).await;
    }
}

async fn process(socket: TcpStream) {
    // The `Connection` lets us read/write redis **frames** instead of
    // byte streams. The `Connection` type is defined by mini-redis.
    let mut connection = Connection::new(socket);

    if let Some(frame) = connection.read_frame().await.unwrap() {
        println!("GOT: {:?}", frame);

        // Respond with an error
        let response = Frame::Error("unimplemented".to_string());
        connection.write_frame(&response).await.unwrap();
    }
}

use tokio::net::TcpListener;

#[tokio::main]
async fn main() {
    let listener = TcpListener::bind("127.0.0.1:6379").await.unwrap();
    loop {
        let (socket, _) = listener.accept().await.unwrap();
        // A new task is spawned for each inbound socket. The socket is
        // moved to the new task and processed there.
        tokio::spawn(async move {
            process(socket).await;
        });
    }
}

#[tokio::main]
async fn main() {
    let handle = tokio::spawn(async {
        // Do some async work
        "return value"
    });
    // Do some other work
    let out = handle.await.unwrap();
    println!("GOT {}", out);
}

use tokio::task;

#[tokio::main]
async fn main() {
    let v = vec![1, 2, 3];
    task::spawn(async {
        println!("Here's a vec: {:?}", v);
    });
}

use tokio::task::yield_now;
use std::rc::Rc;

#[tokio::main]
async fn main() {
    tokio::spawn(async {
        // The scope forces `rc` to drop before `.await`.
        {
            let rc = Rc::new("hello");
            println!("{}", rc);
        }
        // `rc` is no longer used. It is **not** persisted when
        // the task yields to the scheduler
        yield_now().await;
    });
}

use tokio::task::yield_now;
use std::rc::Rc;

#[tokio::main]
async fn main() {
    tokio::spawn(async {
        let rc = Rc::new("hello");
        // `rc` is used after `.await`. It must be persisted to
        // the task's state.
        yield_now().await;
        println!("{}", rc);
    });
}

use tokio::net::TcpStream;
use mini_redis::{Connection, Frame};

async fn process(socket: TcpStream) {
    use mini_redis::Command::{self, Get, Set};
    use std::collections::HashMap;
    // A hashmap is used to store data
    let mut db = HashMap::new();
    // Connection, provided by `mini-redis`, handles parsing frames from
    // the socket
    let mut connection = Connection::new(socket);
    // Use `read_frame` to receive a command from the connection.
    while let Some(frame) = connection.read_frame().await.unwrap() {
        let response = match Command::from_frame(frame).unwrap() {
            Set(cmd) => {
                // The value is stored as `Vec<u8>`
                db.insert(cmd.key().to_string(), cmd.value().to_vec());
                Frame::Simple("OK".to_string())
            }
            Get(cmd) => {
                if let Some(value) = db.get(cmd.key()) {
                    // `Frame::Bulk` expects data to be of type `Bytes`. This
                    // type will be covered later in the tutorial. For now,
                    // `&Vec<u8>` is converted to `Bytes` using `into()`.
                    Frame::Bulk(value.clone().into())
                } else {
                    Frame::Null
                }
            }
            cmd => panic!("unimplemented {:?}", cmd),
        };
        // Write the response to the client
        connection.write_frame(&response).await.unwrap();
    }
}

use bytes::Bytes;
use std::collections::HashMap;
use std::sync::{Arc, Mutex};
type Db = Arc<Mutex<HashMap<String, Bytes>>>;

use tokio::net::TcpListener;
use std::collections::HashMap;
use std::sync::{Arc, Mutex};

#[tokio::main]
async fn main() {
    let listener = TcpListener::bind("127.0.0.1:6379").await.unwrap();
    println!("Listening");
    let db = Arc::new(Mutex::new(HashMap::new()));
    loop {
        let (socket, _) = listener.accept().await.unwrap();
        // Clone the handle to the hash map.
        let db = db.clone();
        println!("Accepted");
        tokio::spawn(async move {
            process(socket, db).await;
        });
    }
}

use tokio::net::TcpStream;
use mini_redis::{Connection, Frame};

async fn process(socket: TcpStream, db: Db) {
    use mini_redis::Command::{self, Get, Set};
    // Connection, provided by `mini-redis`, handles parsing frames from
    // the socket
    let mut connection = Connection::new(socket);
    while let Some(frame) = connection.read_frame().await.unwrap() {
        let response = match Command::from_frame(frame).unwrap() {
            Set(cmd) => {
                let mut db = db.lock().unwrap();
                db.insert(cmd.key().to_string(), cmd.value().clone());
                Frame::Simple("OK".to_string())
            }           
            Get(cmd) => {
                let db = db.lock().unwrap();
                if let Some(value) = db.get(cmd.key()) {
                    Frame::Bulk(value.clone())
                } else {
                    Frame::Null
                }
            }
            cmd => panic!("unimplemented {:?}", cmd),
        };
        // Write the response to the client
        connection.write_frame(&response).await.unwrap();
    }
}

type ShardedDb = Arc<Vec<Mutex<HashMap<String, Vec<u8>>>>>;

let shard = db[hash(key) % db.len()].lock().unwrap();
shard.insert(key, value);

use std::sync::Mutex;
async fn increment_and_do_stuff(mutex: &Mutex<i32>) {
    let mut lock = mutex.lock().unwrap();
    *lock += 1;
    do_something_async().await;
} // lock goes out of scope here

// This works!
async fn increment_and_do_stuff(mutex: &Mutex<i32>) {
    {
        let mut lock = mutex.lock().unwrap();
        *lock += 1;
    } // lock goes out of scope here
    do_something_async().await;
}

use std::sync::Mutex;

// This fails too.
async fn increment_and_do_stuff(mutex: &Mutex<i32>) {
    let mut lock = mutex.lock().unwrap();
    *lock += 1;
    drop(lock);
    do_something_async().await;
}

use std::sync::Mutex;

struct CanIncrement {
    mutex: Mutex<i32>,
}
impl CanIncrement {
    // This function is not marked async.
    fn increment(&self) {
        let mut lock = self.mutex.lock().unwrap();
        *lock += 1;
    }
}
async fn increment_and_do_stuff(can_incr: &CanIncrement) {
    can_incr.increment();
    do_something_async().await;
}

use tokio::sync::Mutex; // note! This uses the Tokio mutex
// This compiles!
// (but restructuring the code would be better in this case)
async fn increment_and_do_stuff(mutex: &Mutex<i32>) {
    let mut lock = mutex.lock().await;
    *lock += 1;
    do_something_async().await;
} // lock goes out of scope here

use mini_redis::client;
#[tokio::main]
async fn main() {
    // Establish a connection to the server
    let mut client = client::connect("127.0.0.1:6379").await.unwrap();
    // Spawn two tasks, one gets a key, the other sets a key
    let t1 = tokio::spawn(async {
        let res = client.get("hello").await;
    });
    let t2 = tokio::spawn(async {
        client.set("foo", "bar".into()).await;
    });
    t1.await.unwrap();
    t2.await.unwrap();
}

use bytes::Bytes;

#[derive(Debug)]
enum Command {
    Get {
        key: String,
    },
    Set {
        key: String,
        val: Bytes,
    }
}

use tokio::sync::mpsc;

#[tokio::main]
async fn main() {
    // Create a new channel with a capacity of at most 32.
    let (mut tx, mut rx) = mpsc::channel(32);
    // ... Rest comes here
}

use tokio::sync::mpsc;

#[tokio::main]
async fn main() {
    let (mut tx, mut rx) = mpsc::channel(32);
    let mut tx2 = tx.clone();

    tokio::spawn(async move {
        tx.send("sending from first handle").await;
    });

    tokio::spawn(async move {
        tx2.send("sending from second handle").await;
    });

    while let Some(message) = rx.recv().await {
        println!("GOT = {}", message);
    }
}

use mini_redis::client;
// The `move` keyword is used to **move** ownership of `rx` into the task.
let manager = tokio::spawn(async move {
    // Establish a connection to the server
    let mut client = client::connect("127.0.0.1:6379").await.unwrap();

    // Start receiving messages
    while let Some(cmd) = rx.recv().await {
        use Command::*;

        match cmd {
            Get { key } => {
                client.get(&key).await;
            }
            Set { key, val } => {
                client.set(&key, val).await;
            }
        }
    }
});

// The `Sender` handles are moved into the tasks. As there are two
// tasks, we need a second `Sender`.
let mut tx2 = tx.clone();

// Spawn two tasks, one gets a key, the other sets a key
let t1 = tokio::spawn(async move {
    let cmd = Command::Get {
        key: "hello".to_string(),
    };

    tx.send(cmd).await.unwrap();
});

let t2 = tokio::spawn(async move {
    let cmd = Command::Set {
        key: "foo".to_string(),
        val: "bar".into(),
    };

    tx2.send(cmd).await.unwrap();
});

t1.await.unwrap();
t2.await.unwrap();
manager.await.unwrap();

use tokio::sync::oneshot;
let (tx, rx) = oneshot::channel();

use tokio::sync::oneshot;
use bytes::Bytes;

/// Multiple different commands are multiplexed over a single channel.
#[derive(Debug)]
enum Command {
    Get {
        key: String,
        resp: Responder<Option<Bytes>>,
    },
    Set {
        key: String,
        val: Vec<u8>,
        resp: Responder<()>,
    },
}
/// Provided by the requester and used by the manager task to send
/// the command response back to the requester.
type Responder<T> = oneshot::Sender<mini_redis::Result<T>>;

let t1 = tokio::spawn(async move {
    let (resp_tx, resp_rx) = oneshot::channel();
    let cmd = Command::Get {
        key: "hello".to_string(),
        resp: resp_tx,
    };
    // Send the GET request
    tx.send(cmd).await.unwrap();
    // Await the response
    let res = resp_rx.await;
    println!("GOT = {:?}", res);
});

let t2 = tokio::spawn(async move {
    let (resp_tx, resp_rx) = oneshot::channel();
    let cmd = Command::Set {
        key: "foo".to_string(),
        val: b"bar".to_vec(),
        resp: resp_tx,
    };
    // Send the SET request
    tx2.send(cmd).await.unwrap();
    // Await the response
    let res = resp_rx.await;
    println!("GOT = {:?}", res);
});

while let Some(cmd) = rx.recv().await {
    match cmd {
        Command::Get { key, resp } => {
            let res = client.get(&key).await;
            // Ignore errors
            let _ = resp.send(res);
        }
        Command::Set { key, val, resp } => {
            let res = client.set(&key, val.into()).await;
            // Ignore errors
            let _ = resp.send(res);
        }
    }
}

loop {
    async_op();
}

use tokio::fs::File;
use tokio::io::{self, AsyncReadExt};

#[tokio::main]
async fn main() -> io::Result<()> {
    let mut f = File::open("foo.txt").await?;
    let mut buffer = [0; 10];

    // read up to 10 bytes
    let n = f.read(&mut buffer[..]).await?;

    println!("The bytes: {:?}", &buffer[..n]);
    Ok(())
}

use tokio::io::{self, AsyncReadExt};
use tokio::fs::File;

#[tokio::main]
async fn main() -> io::Result<()> {
    let mut f = File::open("foo.txt").await?;
    let mut buffer = Vec::new();

    // read the whole file
    f.read_to_end(&mut buffer).await?;
    Ok(())
}

use tokio::io::{self, AsyncWriteExt};
use tokio::fs::File;

#[tokio::main]
async fn main() -> io::Result<()> {
    let mut file = File::create("foo.txt").await?;

    // Writes some prefix of the byte string, but not necessarily all of it.
    let n = file.write(b"some bytes").await?;

    println!("Wrote the first {} bytes of 'some bytes'.", n);
    Ok(())
}

use tokio::io::{self, AsyncWriteExt};
use tokio::fs::File;

#[tokio::main]
async fn main() -> io::Result<()> {
    let mut buffer = File::create("foo.txt").await?;

    buffer.write_all(b"some bytes").await?;
    Ok(())
}

use tokio::fs::File;
use tokio::io;

#[tokio::main]
async fn main() -> io::Result<()> {
    let mut reader: &[u8] = b"hello";
    let mut file = File::create("foo.txt").await?;

    io::copy(&mut reader, &mut file).await?;
    Ok(())
}

use tokio::io;
use tokio::net::TcpListener;

#[tokio::main]
async fn main() -> io::Result<()> {
    let mut listener = TcpListener::bind("127.0.0.1:6142").await.unwrap();

    loop {
        let (mut socket, _) = listener.accept().await?;

        tokio::spawn(async move {
            // Copy data here
        });
    }
}

// This fails to compile
io::copy(&mut socket, &mut socket).await

use tokio::io::{self, AsyncReadExt, AsyncWriteExt};
use tokio::net::TcpStream;
#[tokio::main]
async fn main() -> io::Result<()> {
    let socket = TcpStream::connect("127.0.0.1:6142").await?;
    let (mut rd, mut wr) = io::split(socket);
    // Write data in the background
    let write_task = tokio::spawn(async move {
        wr.write_all(b"hello\r\n").await?;
        wr.write_all(b"world\r\n").await?;
        // Sometimes, the rust type inferencer needs
        // a little help
        Ok::<_, io::Error>(())
    });
    let mut buf = vec![0; 128];
    loop {
        let n = rd.read(&mut buf).await?;
        if n == 0 {
            break;
        }
        println!("GOT {:?}", &buf[..n]);
    }
    Ok(())
}

tokio::spawn(async move {
    let (mut rd, mut wr) = socket.split();
    if io::copy(&mut rd, &mut wr).await.is_err() {
        eprintln!("failed to copy");
    }
});

use tokio::io::{self, AsyncReadExt, AsyncWriteExt};
use tokio::net::TcpListener;

#[tokio::main]
async fn main() -> io::Result<()> {
    let mut listener = TcpListener::bind("127.0.0.1:6142").await.unwrap();
    loop {
        let (mut socket, _) = listener.accept().await?;
        tokio::spawn(async move {
            let mut buf = vec![0; 1024];
            loop {
                match socket.read(&mut buf).await {
                    // Return value of `Ok(0)` signifies that the remote has
                    // closed
                    Ok(0) => return,
                    Ok(n) => {
                        // Copy the data back to socket
                        if socket.write_all(&buf[..n]).await.is_err() {
                            // Unexpected socket error. There isn't much we can
                            // do here so just stop processing.
                            return;
                        }
                    }
                    Err(_) => {
                        // Unexpected socket error. There isn't much we can do
                        // here so just stop processing.
                        return;
                    }
                }
            }
        });
    }
}

struct Task {
    // internal task fields here
    task: enum {
        AwaitingRead {
            socket: TcpStream,
            buf: [BufferType],
        },
        AwaitingWriteAll {
            socket: TcpStream,
            buf: [BufferType],
        }

    }
}

use bytes::Bytes;

enum Frame {
    Simple(String),
    Error(String),
    Integer(u64),
    Bulk(Bytes),
    Null,
    Array(Vec<Frame>),
}

enum HttpFrame {
    RequestHead {
        method: Method,
        uri: Uri,
        version: Version,
        headers: HeaderMap,
    },
    ResponseHead {
        status: StatusCode,
        version: Version,
        headers: HeaderMap,
    },
    BodyChunk {
        chunk: Bytes,
    },
}

use tokio::net::TcpStream;
use mini_redis::{Frame, Result};

struct Connection {
    stream: TcpStream,
    // ... other fields here
}

impl Connection {
    /// Read a frame from the connection.
    /// 
    /// Returns `None` if EOF is reached
    pub async fn read_frame(&mut self)
        -> Result<Option<Frame>>
    {
        // implementation here
    }

    /// Write a frame to the connection.
    pub async fn write_frame(&mut self, frame: &Frame)
        -> Result<()>
    {
        // implementation here
    }
}

use bytes::BytesMut;
use tokio::net::TcpStream;

pub struct Connection {
    stream: TcpStream,
    buffer: BytesMut,
}

impl Connection {
    pub fn new(stream: TcpStream) -> Connection {
        Connection {
            stream,
            // Allocate the buffer with 4kb of capacity.
            buffer: BytesMut::with_capacity(4096),
        }
    }
}

use tokio::io::AsyncReadExt;
use bytes::Buf;
use mini_redis::Result;

pub async fn read_frame(&mut self)
    -> Result<Option<Frame>>
{
    loop {
        // Attempt to parse a frame from the buffered data. If
        // enough data has been buffered, the frame is
        // returned.
        if let Some(frame) = self.parse_frame()? {
            return Ok(Some(frame));
        }

        // There is not enough buffered data to read a frame.
        // Attempt to read more data from the socket.
        //
        // On success, the number of bytes is returned. `0`
        // indicates "end of stream".
        if 0 == self.stream.read_buf(&mut self.buffer).await? {
            // The remote closed the connection. For this to be
            // a clean shutdown, there should be no data in the
            // read buffer. If there is, this means that the
            // peer closed the socket while sending a frame.
            if self.buffer.is_empty() {
                return Ok(None);
            } else {
                return Err("connection reset by peer".into());
            }
        }
    }
}

use tokio::net::TcpStream;

pub struct Connection {
    stream: TcpStream,
    buffer: Vec<u8>,
    cursor: usize,
}

impl Connection {
    pub fn new(stream: TcpStream) -> Connection {
        Connection {
            stream,
            // Allocate the buffer with 4kb of capacity.
            buffer: vec![0; 4096],
            cursor: 0,
        }
    }
}

use mini_redis::{Frame, Result};

pub async fn read_frame(&mut self)
    -> Result<Option<Frame>>
{
    loop {
        if let Some(frame) = self.parse_frame()? {
            return Ok(Some(frame));
        }
        // Ensure the buffer has capacity
        if self.buffer.len() == self.cursor {
            // Grow the buffer
            self.buffer.resize(self.cursor * 2, 0);
        }
        // Read into the buffer, tracking the number
        // of bytes read
        let n = self.stream.read(
            &mut self.buffer[self.cursor..]).await?;
        if 0 == n {
            if self.cursor == 0 {
                return Ok(None);
            } else {
                return Err("connection reset by peer".into());
            }
        } else {
            // Update our cursor
            self.cursor += n;
        }
    }
}

use mini_redis::{Frame, Result};
use mini_redis::frame::Error::Incomplete;
use bytes::Buf;
use std::io::Cursor;

fn parse_frame(&mut self)
    -> Result<Option<Frame>>
{
    // Create the `T: Buf` type.
    let mut buf = Cursor::new(&self.buffer[..]);
    // Check whether a full frame is available
    match Frame::check(&mut buf) {
        Ok(_) => {
            // Get the byte length of the frame
            let len = buf.position() as usize;
            // Reset the internal cursor for the
            // call to `parse`.
            buf.set_position(0);
            // Parse the frame
            let frame = Frame::parse(&mut buf)?;
            // Discard the frame from the buffer
            self.buffer.advance(len);
            // Return the frame to the caller.
            Ok(Some(frame))
        }
        // Not enough data has been buffered
        Err(Incomplete) => Ok(None),
        // An error was encountered
        Err(e) => Err(e.into()),
    }
}