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brson opened this issue Apr 22, 2013 · 3 comments
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Task-local data should not require managed boxes #6004

brson opened this issue Apr 22, 2013 · 3 comments
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A-runtime Area: std's runtime and "pre-main" init for handling backtraces, unwinds, stack overflows

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@brson
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brson commented Apr 22, 2013

As written, using task local data at all, even to store owned data, involves allocating on the local heap, turning on the GC. Because of this, many tasks that otherwise would not use GC are forced to.

Rewrite the TLS implementation and interface to not require the local heap.
@brson
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brson commented Apr 22, 2013

Nominating this for a 1.0 milestone.

@nikomatsakis
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Also we should not be using fns as keys, perhaps type descriptors

@alexcrichton alexcrichton mentioned this issue May 6, 2013
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@alexcrichton
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Although not the same issue, #3273 has some interesting information which may be related to this (especially if there ends up being a complete rewrite of task-local data)

@alexcrichton alexcrichton mentioned this issue Jul 10, 2013
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bors added a commit that referenced this issue Jul 12, 2013
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auto merge of #7677 : alexcrichton/rust/tls-gc, r=pcwalton
07183ea 
cc #6004 and #3273

This is a rewrite of TLS to get towards not requiring `@` when using task local storage. Most of the rewrite is straightforward, although there are two caveats:

1. Changing `local_set` to not require `@` is blocked on #7673
2. The code in `local_pop` is some of the most unsafe code I've written. A second set of eyes should definitely scrutinize it...

The public-facing interface currently hasn't changed, although it will have to change because `local_data::get` cannot return `Option<T>`, nor can it return `Option<&T>` (the lifetime isn't known). This will have to be changed to be given a closure which yield `&T` (or as an Option). I didn't do this part of the api rewrite in this pull request as I figured that it could wait until when `@` is fully removed.

This also doesn't deal with the issue of using something other than functions as keys, but I'm looking into using static slices (as mentioned in the issues).
flip1995 pushed a commit to flip1995/rust that referenced this issue Sep 10, 2020
@bors
Auto merge of rust-lang#6004 - mikerite:default-trait-access-20200904…
b9e35df 
…, r=ebroto

Simplify `clippy::default_trait_access`

Remove repeated matching on the same QPath.

changelog: none
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@alexcrichton @brson @nikomatsakis