broker_tokio/task/
blocking.rs

1use crate::task::JoinHandle;
2
3cfg_rt_threaded! {
4    /// Run the provided blocking function without blocking the executor.
5    ///
6    /// In general, issuing a blocking call or performing a lot of compute in a
7    /// future without yielding is not okay, as it may prevent the executor from
8    /// driving other futures forward. If you run a closure through this method,
9    /// the current executor thread will relegate all its executor duties to another
10    /// (possibly new) thread, and only then poll the task. Note that this requires
11    /// additional synchronization.
12    ///
13    /// # Note
14    ///
15    /// This function can only be called from a spawned task when working with
16    /// the [threaded scheduler](https://docs.rs/tokio/0.2.10/tokio/runtime/index.html#threaded-scheduler).
17    /// Consider using [tokio::task::spawn_blocking](https://docs.rs/tokio/0.2.10/tokio/task/fn.spawn_blocking.html).
18    ///
19    /// # Examples
20    ///
21    /// ```
22    /// use tokio::task;
23    ///
24    /// # async fn docs() {
25    /// task::block_in_place(move || {
26    ///     // do some compute-heavy work or call synchronous code
27    /// });
28    /// # }
29    /// ```
30    #[cfg_attr(docsrs, doc(cfg(feature = "blocking")))]
31    pub fn block_in_place<F, R>(f: F) -> R
32    where
33        F: FnOnce() -> R,
34    {
35        use crate::runtime::{enter, thread_pool};
36
37        enter::exit(|| thread_pool::block_in_place(f))
38    }
39}
40
41cfg_blocking! {
42    /// Run the provided closure on a thread where blocking is acceptable.
43    ///
44    /// In general, issuing a blocking call or performing a lot of compute in a future without
45    /// yielding is not okay, as it may prevent the executor from driving other futures forward.
46    /// A closure that is run through this method will instead be run on a dedicated thread pool for
47    /// such blocking tasks without holding up the main futures executor.
48    ///
49    /// # Examples
50    ///
51    /// ```
52    /// use tokio::task;
53    ///
54    /// # async fn docs() -> Result<(), Box<dyn std::error::Error>>{
55    /// let res = task::spawn_blocking(move || {
56    ///     // do some compute-heavy work or call synchronous code
57    ///     "done computing"
58    /// }).await?;
59    ///
60    /// assert_eq!(res, "done computing");
61    /// # Ok(())
62    /// # }
63    /// ```
64    pub fn spawn_blocking<F, R>(f: F) -> JoinHandle<R>
65    where
66        F: FnOnce() -> R + Send + 'static,
67        R: Send + 'static,
68    {
69        crate::runtime::spawn_blocking(f)
70    }
71}
broker_tokio/task/blocking.rs

broker_tokio/task/
blocking.rs
