1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92
// Copyright 2018 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. #![unstable(feature = "futures_api", reason = "futures in libcore are unstable", issue = "50547")] use fmt; use super::{Executor, Waker, LocalWaker}; /// Information about the currently-running task. /// /// Contexts are always tied to the stack, since they are set up specifically /// when performing a single `poll` step on a task. pub struct Context<'a> { local_waker: &'a LocalWaker, executor: &'a mut dyn Executor, } impl<'a> fmt::Debug for Context<'a> { fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { f.debug_struct("Context") .finish() } } impl<'a> Context<'a> { /// Create a new task `Context` with the provided `local_waker`, `waker`, and `executor`. #[inline] pub fn new(local_waker: &'a LocalWaker, executor: &'a mut dyn Executor) -> Context<'a> { Context { local_waker, executor, } } /// Get the `LocalWaker` associated with the current task. #[inline] pub fn local_waker(&self) -> &'a LocalWaker { self.local_waker } /// Get the `Waker` associated with the current task. #[inline] pub fn waker(&self) -> &'a Waker { unsafe { &*(self.local_waker as *const LocalWaker as *const Waker) } } /// Get the default executor associated with this task. /// /// This method is useful primarily if you want to explicitly handle /// spawn failures. #[inline] pub fn executor(&mut self) -> &mut dyn Executor { self.executor } /// Produce a context like the current one, but using the given waker instead. /// /// This advanced method is primarily used when building "internal /// schedulers" within a task, where you want to provide some customized /// wakeup logic. #[inline] pub fn with_waker<'b>(&'b mut self, local_waker: &'b LocalWaker) -> Context<'b> { Context { local_waker, executor: self.executor, } } /// Produce a context like the current one, but using the given executor /// instead. /// /// This advanced method is primarily used when building "internal /// schedulers" within a task. #[inline] pub fn with_executor<'b, E>(&'b mut self, executor: &'b mut E) -> Context<'b> where E: Executor { Context { local_waker: self.local_waker, executor: executor, } } }