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#[cfg(feature = "rt-core")]
use crate::runtime::basic_scheduler;
#[cfg(feature = "rt-full")]
use crate::runtime::thread_pool;
use crate::runtime::{blocking, io, time};
#[cfg(feature = "rt-core")]
use crate::task::JoinHandle;
#[cfg(feature = "rt-core")]
use std::future::Future;
/// Handle to the runtime
#[derive(Debug, Clone)]
pub struct Handle {
pub(super) kind: Kind,
/// Handles to the I/O drivers
pub(super) io_handles: Vec<io::Handle>,
/// Handles to the time drivers
pub(super) time_handles: Vec<time::Handle>,
pub(super) clock: time::Clock,
/// Blocking pool spawner
pub(super) blocking_spawner: blocking::Spawner,
}
#[derive(Debug, Clone)]
pub(super) enum Kind {
Shell,
#[cfg(feature = "rt-core")]
Basic(basic_scheduler::Spawner),
#[cfg(feature = "rt-full")]
ThreadPool(thread_pool::Spawner),
}
impl Handle {
/// 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][mod] documentation for more details.
///
/// [mod]: index.html
///
/// # Examples
///
/// ```
/// use tokio::runtime::Runtime;
///
/// # fn dox() {
/// // Create the runtime
/// let rt = Runtime::new().unwrap();
/// let handle = rt.handle();
///
/// // Spawn a future onto the runtime
/// handle.spawn(async {
/// println!("now running on a worker thread");
/// });
/// # }
/// ```
///
/// # Panics
///
/// This function panics if the spawn fails. Failure occurs if the executor
/// is currently at capacity and is unable to spawn a new future.
#[cfg(feature = "rt-core")]
pub fn spawn<F>(&self, future: F) -> JoinHandle<F::Output>
where
F: Future + Send + 'static,
F::Output: Send + 'static,
{
match &self.kind {
Kind::Shell => panic!("spawning not enabled for runtime"),
#[cfg(feature = "rt-core")]
Kind::Basic(spawner) => spawner.spawn(future),
#[cfg(feature = "rt-full")]
Kind::ThreadPool(spawner) => spawner.spawn(future),
}
}
/// Enter the runtime context
pub fn enter<F, R>(&self, f: F) -> R
where
F: FnOnce() -> R,
{
self.blocking_spawner.enter(|| {
let _io = io::set_default(&self.io_handles[0]);
time::with_default(&self.time_handles[0], &self.clock, f)
})
}
}
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