Avoid buffering large amounts of rustc output. #7838
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,86 @@ | ||
| use std::collections::VecDeque; | ||
| use std::sync::{Condvar, Mutex}; | ||
| use std::time::{Duration, Instant}; | ||
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| /// A simple, threadsafe, queue of items of type `T` | ||
| /// | ||
| /// This is a sort of channel where any thread can push to a queue and any | ||
| /// thread can pop from a queue. | ||
| /// | ||
| /// This supports both bounded and unbounded operations. `push` will never block, | ||
| /// and allows the queue to grow without bounds. `push_bounded` will block if the | ||
| /// queue is over capacity, and will resume once there is enough capacity. | ||
| pub struct Queue<T> { | ||
| state: Mutex<State<T>>, | ||
| popper_cv: Condvar, | ||
| bounded_cv: Condvar, | ||
| bound: usize, | ||
| } | ||
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| struct State<T> { | ||
| items: VecDeque<T>, | ||
| } | ||
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| impl<T> Queue<T> { | ||
| pub fn new(bound: usize) -> Queue<T> { | ||
| Queue { | ||
| state: Mutex::new(State { | ||
| items: VecDeque::new(), | ||
| }), | ||
| popper_cv: Condvar::new(), | ||
| bounded_cv: Condvar::new(), | ||
| bound, | ||
| } | ||
| } | ||
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| pub fn push(&self, item: T) { | ||
| self.state.lock().unwrap().items.push_back(item); | ||
| self.popper_cv.notify_one(); | ||
| } | ||
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| /// Pushes an item onto the queue, blocking if the queue is full. | ||
| pub fn push_bounded(&self, item: T) { | ||
| let mut state = self.state.lock().unwrap(); | ||
| loop { | ||
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| if state.items.len() >= self.bound { | ||
| state = self.bounded_cv.wait(state).unwrap(); | ||
| } else { | ||
| state.items.push_back(item); | ||
| self.popper_cv.notify_one(); | ||
| break; | ||
| } | ||
| } | ||
| } | ||
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| pub fn pop(&self, timeout: Duration) -> Option<T> { | ||
| let mut state = self.state.lock().unwrap(); | ||
| let now = Instant::now(); | ||
| while state.items.is_empty() { | ||
| let elapsed = now.elapsed(); | ||
| if elapsed >= timeout { | ||
| break; | ||
| } | ||
| let (lock, result) = self | ||
| .popper_cv | ||
| .wait_timeout(state, timeout - elapsed) | ||
| .unwrap(); | ||
| state = lock; | ||
| if result.timed_out() { | ||
| break; | ||
| } | ||
| } | ||
| let value = state.items.pop_front()?; | ||
| if state.items.len() < self.bound { | ||
| // Assumes threads cannot be canceled. | ||
| self.bounded_cv.notify_one(); | ||
| } | ||
| Some(value) | ||
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| } | ||
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| pub fn try_pop_all(&self) -> Vec<T> { | ||
| let mut state = self.state.lock().unwrap(); | ||
| let result = state.items.drain(..).collect(); | ||
| self.bounded_cv.notify_all(); | ||
| result | ||
| } | ||
| } | ||
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I think this change may no longer be necessary, but did you want to include it anyway here?
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It is necessary, otherwise the cached message playback would deadlock if there were more than 100 messages. The playback shouldn't happen on the main thread, otherwise there is nothing to drain messages while they are added to the queue.
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Ah right yeah, forgot about that!
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I added a test for message caching to check for deadlock.