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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-17 12:02:58 +0000 |
commit | 698f8c2f01ea549d77d7dc3338a12e04c11057b9 (patch) | |
tree | 173a775858bd501c378080a10dca74132f05bc50 /vendor/tokio/src/runtime/handle.rs | |
parent | Initial commit. (diff) | |
download | rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.tar.xz rustc-698f8c2f01ea549d77d7dc3338a12e04c11057b9.zip |
Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'vendor/tokio/src/runtime/handle.rs')
-rw-r--r-- | vendor/tokio/src/runtime/handle.rs | 324 |
1 files changed, 324 insertions, 0 deletions
diff --git a/vendor/tokio/src/runtime/handle.rs b/vendor/tokio/src/runtime/handle.rs new file mode 100644 index 000000000..7dff91448 --- /dev/null +++ b/vendor/tokio/src/runtime/handle.rs @@ -0,0 +1,324 @@ +use crate::runtime::blocking::task::BlockingTask; +use crate::runtime::task::{self, JoinHandle}; +use crate::runtime::{blocking, context, driver, Spawner}; +use crate::util::error::CONTEXT_MISSING_ERROR; + +use std::future::Future; +use std::{error, fmt}; + +/// 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. +/// +/// [`Runtime::handle`]: crate::runtime::Runtime::handle() +#[derive(Debug, Clone)] +pub struct Handle { + pub(super) spawner: Spawner, + + /// Handles to the I/O drivers + pub(super) io_handle: driver::IoHandle, + + /// Handles to the signal drivers + pub(super) signal_handle: driver::SignalHandle, + + /// Handles to the time drivers + pub(super) time_handle: driver::TimeHandle, + + /// Source of `Instant::now()` + pub(super) clock: driver::Clock, + + /// Blocking pool spawner + pub(super) blocking_spawner: blocking::Spawner, +} + +/// Runtime context guard. +/// +/// Returned by [`Runtime::enter`] and [`Handle::enter`], the context guard exits +/// the runtime context on drop. +/// +/// [`Runtime::enter`]: fn@crate::runtime::Runtime::enter +#[derive(Debug)] +#[must_use = "Creating and dropping a guard does nothing"] +pub struct EnterGuard<'a> { + handle: &'a Handle, + guard: context::EnterGuard, +} + +impl Handle { + /// 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`]. + /// + /// [`Sleep`]: struct@crate::time::Sleep + /// [`TcpStream`]: struct@crate::net::TcpStream + /// [`tokio::spawn`]: fn@crate::spawn + pub fn enter(&self) -> EnterGuard<'_> { + EnterGuard { + handle: self, + guard: context::enter(self.clone()), + } + } + + /// 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 std::thread; + /// # use tokio::runtime::Runtime; + /// # fn dox() { + /// # let rt = Runtime::new().unwrap(); + /// # rt.spawn(async { + /// use tokio::runtime::Handle; + /// + /// // Inside an async block or function. + /// let handle = Handle::current(); + /// handle.spawn(async { + /// println!("now running in the existing Runtime"); + /// }); + /// + /// # let handle = + /// 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(); + /// }); + /// # handle.join().unwrap(); + /// # }); + /// # } + /// ``` + pub fn current() -> Self { + context::current().expect(CONTEXT_MISSING_ERROR) + } + + /// 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 try_current() -> Result<Self, TryCurrentError> { + context::current().ok_or(TryCurrentError(())) + } + + /// 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(); + /// // 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"); + /// }); + /// # } + /// ``` + #[cfg_attr(tokio_track_caller, track_caller)] + pub fn spawn<F>(&self, future: F) -> JoinHandle<F::Output> + where + F: Future + Send + 'static, + F::Output: Send + 'static, + { + #[cfg(all(tokio_unstable, feature = "tracing"))] + let future = crate::util::trace::task(future, "task", None); + self.spawner.spawn(future) + } + + /// Run the provided function on an executor dedicated to blocking + /// operations. + /// + /// # Examples + /// + /// ``` + /// use tokio::runtime::Runtime; + /// + /// # fn dox() { + /// // 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"); + /// }); + /// # } + #[cfg_attr(tokio_track_caller, track_caller)] + pub fn spawn_blocking<F, R>(&self, func: F) -> JoinHandle<R> + where + F: FnOnce() -> R + Send + 'static, + R: Send + 'static, + { + self.spawn_blocking_inner(func, None) + } + + #[cfg_attr(tokio_track_caller, track_caller)] + pub(crate) fn spawn_blocking_inner<F, R>(&self, func: F, name: Option<&str>) -> JoinHandle<R> + where + F: FnOnce() -> R + Send + 'static, + R: Send + 'static, + { + let fut = BlockingTask::new(func); + + #[cfg(all(tokio_unstable, feature = "tracing"))] + let fut = { + use tracing::Instrument; + #[cfg(tokio_track_caller)] + let location = std::panic::Location::caller(); + #[cfg(tokio_track_caller)] + let span = tracing::trace_span!( + target: "tokio::task", + "task", + kind = %"blocking", + function = %std::any::type_name::<F>(), + task.name = %name.unwrap_or_default(), + spawn.location = %format_args!("{}:{}:{}", location.file(), location.line(), location.column()), + ); + #[cfg(not(tokio_track_caller))] + let span = tracing::trace_span!( + target: "tokio::task", + "task", + kind = %"blocking", + task.name = %name.unwrap_or_default(), + function = %std::any::type_name::<F>(), + ); + fut.instrument(span) + }; + + #[cfg(not(all(tokio_unstable, feature = "tracing")))] + let _ = name; + + let (task, handle) = task::joinable(fut); + let _ = self.blocking_spawner.spawn(task, &self); + handle + } + + /// Run 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"); + /// }); + /// }); + /// } + /// ``` + /// + /// [`JoinError`]: struct@crate::task::JoinError + /// [`JoinHandle`]: struct@crate::task::JoinHandle + /// [`Runtime::block_on`]: fn@crate::runtime::Runtime::block_on + /// [`Runtime::shutdown_background`]: fn@crate::runtime::Runtime::shutdown_background + /// [`Runtime::shutdown_timeout`]: fn@crate::runtime::Runtime::shutdown_timeout + /// [`spawn_blocking`]: crate::task::spawn_blocking + /// [`tokio::fs`]: crate::fs + /// [`tokio::net`]: crate::net + /// [`tokio::time`]: crate::time + pub fn block_on<F: Future>(&self, future: F) -> F::Output { + // Enter the **runtime** context. This configures spawning, the current I/O driver, ... + let _rt_enter = self.enter(); + + // Enter a **blocking** context. This prevents blocking from a runtime. + let mut blocking_enter = crate::runtime::enter(true); + + // Block on the future + blocking_enter + .block_on(future) + .expect("failed to park thread") + } + + pub(crate) fn shutdown(mut self) { + self.spawner.shutdown(); + } +} + +/// Error returned by `try_current` when no Runtime has been started +pub struct TryCurrentError(()); + +impl fmt::Debug for TryCurrentError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.debug_struct("TryCurrentError").finish() + } +} + +impl fmt::Display for TryCurrentError { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + f.write_str(CONTEXT_MISSING_ERROR) + } +} + +impl error::Error for TryCurrentError {} |