mirror of
https://github.com/pezkuwichain/revive-differential-tests.git
synced 2026-04-22 19:37:57 +00:00
Update the async runtime with syntactic sugar.
This commit is contained in:
Omar Abdulla
@@ -0,0 +1,203 @@
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//! The alloy crate __requires__ a tokio runtime.
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//! We contain any async rust right here.
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use std::{any::Any, panic::AssertUnwindSafe, pin::Pin, thread};
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use futures::FutureExt;
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use once_cell::sync::Lazy;
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use tokio::{
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runtime::Builder,
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sync::{mpsc::UnboundedSender, oneshot},
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};
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/// A blocking async executor.
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///
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/// This struct exposes the abstraction of a blocking async executor. It is a global and static
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/// executor which means that it doesn't require for new instances of it to be created, it's a
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/// singleton and can be accessed by any thread that wants to perform some async computation on the
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/// blocking executor thread.
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///
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/// The API of the blocking executor is created in a way so that it's very natural, simple to use,
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/// and unbounded to specific tasks or return types. The following is an example of using this
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/// executor to drive an async computation:
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///
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/// ```rust,no_run
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/// fn blocking_function() {
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/// let result = BlockingExecutor::execute(async move {
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/// tokio::time::sleep(std::time::Duration::from_secs(1)).await;
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/// 0xFFu8
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/// })
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/// .expect("Computation failed");
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///
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/// assert_eq!(result, 0xFF);
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/// }
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/// ```
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///
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/// Users get to pass in their async tasks without needing to worry about putting them in a [`Box`],
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/// [`Pin`], needing to perform down-casting, or the internal channel mechanism used by the runtime.
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/// To the user, it just looks like a function that converts some async code into sync code.
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///
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/// This struct also handled panics that occur in the passed futures and converts them into errors
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/// that can be handled by the user. This is done to allow the executor to be robust.
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///
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/// Internally, the executor communicates with the tokio runtime thread through channels which carry
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/// the [`TaskMessage`] and the results of the execution.
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pub struct BlockingExecutor;
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impl BlockingExecutor {
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pub fn execute<R>(future: impl Future<Output = R> + Send + 'static) -> Result<R, anyhow::Error>
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where
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R: Send + 'static,
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{
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// A static of the state associated with the async runtime. This is initialized on the first
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// access of the state.
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static STATE: Lazy<ExecutorState> = Lazy::new(|| {
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tracing::trace!("Initializing the BlockingExecutor state");
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// Creating a multiple-producer-single-consumer channel which allows all of the other
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// threads to communicate with this one async runtime thread.
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let (tx, mut rx) = tokio::sync::mpsc::unbounded_channel::<TaskMessage>();
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// We spawn a new thread which will house the async runtime and will always be listening
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// for new tasks coming in and executing them as they come in.
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thread::spawn(move || {
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// Creating the tokio runtime on this current thread.
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let runtime = Builder::new_current_thread()
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.enable_all()
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.build()
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.expect("Failed to create the async runtime");
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runtime.block_on(async move {
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// Keep getting new task messages from all of the other threads.
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while let Some(TaskMessage {
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future: task,
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response_tx: response_channel,
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}) = rx.recv().await
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{
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// Spawn off each job so that the receive loop is not blocked.
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tracing::trace!("Received a new future to execute");
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tokio::spawn(async move {
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let task = AssertUnwindSafe(task).catch_unwind();
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let result = task.await;
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let _ = response_channel.send(result);
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});
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}
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})
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});
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// Creating the state of the async runtime.
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ExecutorState { tx }
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});
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// Creating a one-shot channel for this task that will be used to send and receive the
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// response of the task.
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let (response_tx, response_rx) =
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oneshot::channel::<Result<Box<dyn Any + Send>, Box<dyn Any + Send>>>();
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// Converting the future from the shape that it is in into the shape that the runtime is
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// expecting it to be in.
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let future = Box::pin(async move { Box::new(future.await) as Box<dyn Any + Send> });
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// Sending the task to the runtime,
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let task = TaskMessage {
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future,
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response_tx,
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};
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if let Err(error) = STATE.tx.send(task) {
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tracing::error!(?error, "Failed to send the task to the blocking executor");
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anyhow::bail!("Failed to send the task to the blocking executor: {error:?}")
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}
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// Await for the result of the execution to come back over the channel.
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let result = match response_rx.blocking_recv() {
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Ok(result) => result,
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Err(error) => {
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tracing::error!(
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?error,
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"Failed to get the response from the blocking executor"
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);
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anyhow::bail!("Failed to get the response from the blocking executor: {error:?}")
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}
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};
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match result.map(|result| {
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*result
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.downcast::<R>()
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.expect("Type mismatch in the downcast")
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}) {
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Ok(result) => Ok(result),
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Err(error) => {
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tracing::error!(
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?error,
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"Failed to downcast the returned result into the expected type"
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);
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anyhow::bail!(
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"Failed to downcast the returned result into the expected type: {error:?}"
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)
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}
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}
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}
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}
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/// Represents the state of the async runtime. This runtime is designed to be a singleton runtime
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/// which means that in the current running program there's just a single thread that has an async
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/// runtime.
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struct ExecutorState {
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/// The sending side of the task messages channel. This is used by all of the other threads to
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/// communicate with the async runtime thread.
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tx: UnboundedSender<TaskMessage>,
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}
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/// Represents a message that contains an asynchronous task that's to be executed by the runtime
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/// as well as a way for the runtime to report back on the result of the execution.
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struct TaskMessage {
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/// The task that's being requested to run. This is a future that returns an object that does
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/// implement [`Any`] and [`Send`] to allow it to be sent between the requesting thread and the
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/// async thread.
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future: Pin<Box<dyn Future<Output = Box<dyn Any + Send>> + Send>>,
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/// A one shot sender channel where the sender of the task is expecting to hear back on the
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/// result of the task.
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response_tx: oneshot::Sender<Result<Box<dyn Any + Send>, Box<dyn Any + Send>>>,
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}
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#[cfg(test)]
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mod test {
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use super::*;
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#[test]
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fn simple_future_works() {
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// Act
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let result = BlockingExecutor::execute(async move {
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tokio::time::sleep(std::time::Duration::from_secs(1)).await;
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0xFFu8
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})
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.unwrap();
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// Assert
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assert_eq!(result, 0xFFu8);
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}
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#[test]
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#[allow(unreachable_code, clippy::unreachable)]
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fn panics_in_futures_are_caught() {
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// Act
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let result = BlockingExecutor::execute(async move {
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panic!("This is a panic!");
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0xFFu8
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});
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// Assert
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assert!(result.is_err());
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// Act
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let result = BlockingExecutor::execute(async move {
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tokio::time::sleep(std::time::Duration::from_secs(1)).await;
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0xFFu8
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})
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.unwrap();
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// Assert
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assert_eq!(result, 0xFFu8)
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}
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}
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