[Do not merge] Changes to Rayon in fork for rustc #569
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Can you give a high level summary of what the changes are, and why they are needed? |
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I've made a commit for each feature added.
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| /// Sets the current thread-local value | ||
| pub fn set(value: usize) { |
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ok so this is some sort of "token" where:
- it starts as 0
- you can set it and get it
- when you spawn a job, it inherits the value at the time that job was spawned?
| /// The type for a closure that gets invoked with a | ||
| /// function which runs rayon tasks. | ||
| /// The closure is passed the index of the thread on which it is invoked. | ||
| /// Note that this same closure may be invoked multiple times in parallel. |
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How is this distinct from the StartHandler?
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Oh, I see, it kind of "takes over" the thread
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It allows up to run code both before and after the Rayon worker, so it is more powerful than StartHandler and ExitHandler. You can see it used here.
rayon-core/src/thread_local.rs
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| impl<T> ThreadLocal<Vec<T>> { | ||
| /// Joins the elements of all the thread locals into one Vec | ||
| pub fn join(self) -> Vec<T> { |
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Apart from this method, I believe we could just use a "regular" thread-local value, no?
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I wonder if @cuviper's "broadcast" primitive could be used to simulate this from a regular thread-local. I don't remember if it lets you return values — but it probably could. =)
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If by "regular" thread-local value, you mean something like the thread_local crate, then yes. However that is less efficient since it doesn't exploit the fact that our thread pool has a fixed number of threads.
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My take on these changes:
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I think we can close this – we are currently issuing |
This just shows to changes intended for use in rustc via a rustc_rayon and rustc_rayon_core fork of Rayon.