# [−] [src] Struct tokio::runtime::Handle

    pub struct Handle { /* fields omitted */ }

Handle to the runtime.

The handle is internally reference-counted and can be freely cloned. A handle can be obtained using the `Runtime::handle` method.

## Implementations

### `impl Handle` [src]

#### `pub fn enter(&self) -> EnterGuard<'_>` [src]

Enter 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`.

#### `pub fn current() -> Self` [src]

Returns a `Handle` view over the currently running `Runtime`

# Panic

This will panic if called outside the context of a Tokio runtime. That means that you must call this on one of the threads being run by the runtime. Calling this from within a thread created by `std::thread::spawn` (for example) will cause a panic.

# Examples

This can be used to obtain the handle of the surrounding runtime from an async block or function running on that runtime.

    use tokio::runtime::Handle;

    // Inside an async block or function.
    let handle = Handle::current();
    handle.spawn(async {
        println!("now running in the existing Runtime");
    });

    thread::spawn(move || {
        // Notice that the handle is created outside of this thread and then moved in
        handle.spawn(async { /* ... */ })
        // This next line would cause a panic
        // let handle2 = Handle::current();
    });

#### `pub fn try_current() -> Result<Self, TryCurrentError>` [src]

Returns a Handle view over the currently running Runtime

Returns an error if no Runtime has been started

Contrary to `current`, this never panics

#### `pub fn spawn<F>(&self, future: F) -> JoinHandle<F::Output>ⓘ

### Notable traits for JoinHandle<T>

`impl<T> Future for JoinHandle<T> type Output = Result<T, JoinError>;`
where
F: Future + Send + 'static,
F::Output: Send + 'static,` [src]

Spawn 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.

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>ⓘ

### Notable traits for JoinHandle<T>

`impl<T> Future for JoinHandle<T> type Output = Result<T, JoinError>;`
where
F: FnOnce() -> R + Send + 'static,
R: Send + 'static,` [src]

Run 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");
    });

## Trait Implementations

### `impl Clone for Handle` [src]

#### `fn clone(&self) -> Handle` [src]

Returns a copy of the value. Read more

#### `fn clone_from(&mut self, source: &Self)`1.0.0 [src]

Performs copy-assignment from `source`. Read more

### `impl Debug for Handle` [src]

#### `fn fmt(&self, f: &mut Formatter<'_>) -> Result` [src]

Formats the value using the given formatter. Read more

## Auto Trait Implementations

### `impl !RefUnwindSafe for Handle`

### `impl Send for Handle`

### `impl Sync for Handle`

### `impl Unpin for Handle`

### `impl !UnwindSafe for Handle`

## Blanket Implementations

### `impl<T> Any for T where
T: 'static + ?Sized,` [src]

#### `pub fn type_id(&self) -> TypeId` [src]

Gets the `TypeId` of `self`. Read more

### `impl<T> Borrow<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow(&self) -> &Tⓘ

### Notable traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;`
` [src]

Immutably borrows from an owned value. Read more

### `impl<T> BorrowMut<T> for T where
T: ?Sized,` [src]

#### `pub fn borrow_mut(&mut self) -> &mut Tⓘ

### Notable traits for &'_ mut F

`impl<'_, F> Future for &'_ mut F where
F: Unpin + Future + ?Sized, type Output = <F as Future>::Output;`
` [src]

Mutably borrows from an owned value. Read more

### `impl<T> From<T> for T` [src]

#### `pub fn from(t: T) -> T` [src]

Performs the conversion.

### `impl<T, U> Into<U> for T where
U: From<T>,` [src]

#### `pub fn into(self) -> U` [src]

Performs the conversion.

### `impl<T> ToOwned for T where
T: Clone,` [src]

#### `type Owned = T`

The resulting type after obtaining ownership.

#### `pub fn to_owned(&self) -> T` [src]

Creates owned data from borrowed data, usually by cloning. Read more

#### `pub fn clone_into(&self, target: &mut T)` [src]

🔬 This is a nightly-only experimental API. (`toowned_clone_into`)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more

### `impl<T, U> TryFrom<U> for T where
U: Into<T>,` [src]

#### `type Error = Infallible`

The type returned in the event of a conversion error.

#### `pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>` [src]

Performs the conversion.

### `impl<T, U> TryInto<U> for T where
U: TryFrom<T>,` [src]

#### `type Error = <U as TryFrom<T>>::Error`

The type returned in the event of a conversion error.

#### `pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>` [src]

Performs the conversion.