Struct TokioRuntime

pub struct TokioRuntime { /* private fields */ }

A spawned tokio runtime.

Methods from Deref<Target = Handle>

pub fn enter(&self) -> EnterGuard<'_>

Enters the runtime context. This allows you to construct types that must have an executor available on creation such as Sleep or TcpStream. It will also allow you to call methods such as tokio::spawn and [Handle::current] without panicking.

Panics

When calling Handle::enter multiple times, the returned guards must be dropped in the reverse order that they were acquired. Failure to do so will result in a panic and possible memory leaks.

Examples

use tokio::runtime::Runtime;

let rt = Runtime::new().unwrap();

let _guard = rt.enter();
tokio::spawn(async {
    println!("Hello world!");
});

Do not do the following, this shows a scenario that will result in a panic and possible memory leak.

use tokio::runtime::Runtime;

let rt1 = Runtime::new().unwrap();
let rt2 = Runtime::new().unwrap();

let enter1 = rt1.enter();
let enter2 = rt2.enter();

drop(enter1);
drop(enter2);

pub fn spawn<F>(&self, future: F) -> JoinHandle<<F as Future>::Output>

where F: Future + Send + 'static, <F as Future>::Output: Send + 'static,

Spawns a future onto the Tokio runtime.

This spawns the given future onto the runtime’s executor, usually a thread pool. The thread pool is then responsible for polling the future until it completes.

The provided future will start running in the background immediately when spawn is called, even if you don’t await the returned JoinHandle.

See module level documentation for more details.

Examples

use tokio::runtime::Runtime;

// Create the runtime
let rt = Runtime::new().unwrap();
// Get a handle from this runtime
let handle = rt.handle();

// Spawn a future onto the runtime using the handle
handle.spawn(async {
    println!("now running on a worker thread");
});

pub fn spawn_blocking<F, R>(&self, func: F) -> JoinHandle<R>

where F: FnOnce() -> R + Send + 'static, R: Send + 'static,

Runs the provided function on an executor dedicated to blocking operations.

Examples

use tokio::runtime::Runtime;

// Create the runtime
let rt = Runtime::new().unwrap();
// Get a handle from this runtime
let handle = rt.handle();

// Spawn a blocking function onto the runtime using the handle
handle.spawn_blocking(|| {
    println!("now running on a worker thread");
});

pub fn block_on<F>(&self, future: F) -> <F as Future>::Output

where F: Future,

Runs a future to completion on this Handle’s associated Runtime.

This runs the given future on the current thread, blocking until it is complete, and yielding its resolved result. Any tasks or timers which the future spawns internally will be executed on the runtime.

When this is used on a current_thread runtime, only the Runtime::block_on method can drive the IO and timer drivers, but the Handle::block_on method cannot drive them. This means that, when using this method on a current_thread runtime, anything that relies on IO or timers will not work unless there is another thread currently calling Runtime::block_on on the same runtime.

If the runtime has been shut down

If the Handle’s associated Runtime has been shut down (through Runtime::shutdown_background, Runtime::shutdown_timeout, or by dropping it) and Handle::block_on is used it might return an error or panic. Specifically IO resources will return an error and timers will panic. Runtime independent futures will run as normal.

Panics

This function panics if the provided future panics, if called within an asynchronous execution context, or if a timer future is executed on a runtime that has been shut down.

Examples

use tokio::runtime::Runtime;

// Create the runtime
let rt  = Runtime::new().unwrap();

// Get a handle from this runtime
let handle = rt.handle();

// Execute the future, blocking the current thread until completion
handle.block_on(async {
    println!("hello");
});

Or using Handle::current:

use tokio::runtime::Handle;

#[tokio::main]
async fn main () {
    let handle = Handle::current();
    std::thread::spawn(move || {
        // Using Handle::block_on to run async code in the new thread.
        handle.block_on(async {
            println!("hello");
        });
    });
}

pub fn runtime_flavor(&self) -> RuntimeFlavor

Returns the flavor of the current Runtime.

Examples

use tokio::runtime::{Handle, RuntimeFlavor};

#[tokio::main(flavor = "current_thread")]
async fn main() {
  assert_eq!(RuntimeFlavor::CurrentThread, Handle::current().runtime_flavor());
}

use tokio::runtime::{Handle, RuntimeFlavor};

#[tokio::main(flavor = "multi_thread", worker_threads = 4)]
async fn main() {
  assert_eq!(RuntimeFlavor::MultiThread, Handle::current().runtime_flavor());
}

pub fn metrics(&self) -> RuntimeMetrics

Returns a view that lets you get information about how the runtime is performing.

Trait Implementations

impl AppRuntime for TokioRuntime

type Guard<'a> = EnterGuard<'a>

The guard type returned from entering the context of the app’s runtime.

fn enter(&self) -> Self::Guard<'_>

Enter the application’s rutime context.

impl Clone for TokioRuntime

fn clone(&self) -> TokioRuntime

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for TokioRuntime

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for TokioRuntime

fn default() -> Self

Returns the “default value” for a type.

impl Deref for TokioRuntime

type Target = Handle

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl From<Handle> for TokioRuntime

fn from(handle: Handle) -> Self

Converts to this type from the input type.