`std::thread` support for the Nintendo 3DS #98514

AzureMarker · 2022-06-26T00:26:41Z

Rustc supports compiling for the Nintendo 3DS using the armv6k-nintendo-3ds target (Tier 3). Just recently we merged std support in #95897. A notable exclusion was std::thread support, which was moved into this PR as a follow-up since it required more complicated changes.

See #95897 for background on how rustc is able to support std for the 3DS.

A notable change in this PR is the addition of a "native options" parameter to the internal implementation of the thread builder on each platform. This is due to the 3DS requiring the "processor ID" where the thread should be spawned (certain cores are either cooperative or preemptive) and the thread priority up-front. There is an unstable thread builder extension trait added which allows users to set these values.

There are 2 non-portable pthread APIs which we depend on. Where possible, we tried to reuse existing standard APIs, but there are some features of the 3DS thread system which required us to add non-portable functions.

pthread_attr_setprocessorid_np: Used to set the new thread's processor ID.
pthread_getprocessorid_np: Used to retrieve the current thread's processor ID.

These are both implemented by https://github.com/Meziu/pthread-3ds, which is already noted as in the platform support doc as a requirement for the target's std support (note: it provides the backend for other pthread-based types such as Mutex). These functions have already been added to libc and are in the currently used version (rust-lang/libc#2715).

~~Edit: libs team ACP has been opened for the changes to the thread builder: rust-lang/libs-team#71~~

~~Blocked on #101222~~ and ACP ~~rust-lang/libs-team#71~~ rust-lang/libs-team#195

Priority and affinity are passed through special pthread attr functions which will be added to our libc fork. The current thread's priority also needs to be fetched since it is the default priority value. This is done using another new pthread function, though this value/mechanism isn't exposed as part of std's API.

…zon::thread Also renamed "affinity" to "processor_id".

rust-highfive · 2022-06-26T00:26:43Z

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

Examples of T-libs-api changes:

Stabilizing library features
Introducing insta-stable changes such as new implementations of existing stable traits on existing stable types
Introducing new or changing existing unstable library APIs (excluding permanently unstable features / features without a tracking issue)
Changing public documentation in ways that create new stability guarantees
Changing observable runtime behavior of library APIs

rust-highfive · 2022-06-26T00:26:45Z

r? @kennytm

(rust-highfive has picked a reviewer for you, use r? to override)

AzureMarker · 2022-06-26T00:28:42Z

library/std/src/os/horizon/thread.rs

+//!
+//! [`std::thread`]: crate::thread
+
+#![unstable(feature = "horizon_thread_ext", issue = "none")]


I looked at creating a tracking issue for this, but held off for now due to this note in the template:

If the new feature is small, it may be fine to skip the RFC process. In that
case, you can use use issue = "none" in your initial implementation PR. The
reviewer will ask you to open a tracking issue if they agree your feature can be
added without an RFC.

So once someone comments that this is an acceptable feature to skip an RFC for, I can create the tracking issue.

AzureMarker · 2022-06-26T00:30:18Z

@rustbot label +T-libs-api

Since this adds an unstable library feature.

AzureMarker · 2022-06-26T00:33:22Z

r? @nagisa

You reviewed the std PR and were very helpful, so hopefully you can help review this PR as well :).

library/std/src/sys/unix/thread.rs

nagisa · 2022-07-03T22:43:09Z

r? @rust-lang/libs

This seems reasonable enough to me, but I’m not in a position to vet changes to a stable and widely used type like the thread builder.

library/std/src/os/horizon/thread.rs

Mark-Simulacrum · 2022-07-11T13:25:33Z

Per the latest guidance from T-libs-api, I believe you'll want to file an MCP on their repo (see the opening comment from rust-highfive):

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

rustbot · 2022-07-12T03:37:05Z

Hey! It looks like you've submitted a new PR for the library teams!

If this PR contains changes to any rust-lang/rust public library APIs then please comment with @rustbot label +T-libs-api -T-libs to tag it appropriately. If this PR contains changes to any unstable APIs please edit the PR description to add a link to the relevant API Change Proposal or create one if you haven't already. If you're unsure where your change falls no worries, just leave it as is and the reviewer will take a look and make a decision to forward on if necessary.

Examples of T-libs-api changes:

Stabilizing library features
Introducing insta-stable changes such as new implementations of existing stable traits on existing stable types
Introducing new or changing existing unstable library APIs (excluding permanently unstable features / features without a tracking issue)
Changing public documentation in ways that create new stability guarantees
Changing observable runtime behavior of library APIs

AzureMarker · 2022-07-16T22:54:25Z

Per the latest guidance from T-libs-api, I believe you'll want to file an MCP on their repo

I've opened the ACP: rust-lang/libs-team#71

joshtriplett · 2022-07-27T18:42:39Z

Registering as a quick comment that I'd prefer to see this not go in in its current form, and instead be changed in one of two ways. Will comment further on the ACP.

bors · 2022-10-25T12:54:14Z

☔ The latest upstream changes (presumably #103513) made this pull request unmergeable. Please resolve the merge conflicts.

hkBst · 2025-02-14T16:15:41Z

It seems this is blocked on #195

AzureMarker added 3 commits June 25, 2022 16:22

Add "native options" concept to thread builder and make std::os::hori…

fe1cdcf

…zon::thread Also renamed "affinity" to "processor_id".

Add std::os::horizon::thread::current_processor

1fb2f72

rustbot added the T-libs Relevant to the library team, which will review and decide on the PR/issue. label Jun 26, 2022

rust-highfive assigned kennytm Jun 26, 2022

rust-highfive added the S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. label Jun 26, 2022

AzureMarker commented Jun 26, 2022

View reviewed changes

rustbot added the T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. label Jun 26, 2022

rust-highfive assigned nagisa and unassigned kennytm Jun 26, 2022

Add Default impl derive for thread BuilderOptions on other platforms

6b97b2c

AzureMarker mentioned this pull request Jun 26, 2022

Rapier Physics example blocks runtime init rust3ds/ctru-rs#60

Closed

nagisa reviewed Jul 3, 2022

View reviewed changes

library/std/src/sys/unix/thread.rs Show resolved Hide resolved

rust-highfive assigned Mark-Simulacrum and unassigned nagisa Jul 3, 2022

Mark-Simulacrum reviewed Jul 11, 2022

View reviewed changes

library/std/src/os/horizon/thread.rs Outdated Show resolved Hide resolved

Mark-Simulacrum added S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. and removed S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. labels Jul 11, 2022

Seal the BuilderExt trait

bfd108d

AzureMarker mentioned this pull request Jul 16, 2022

Add Special Thread Builder Functions for the Nintendo 3DS rust-lang/libs-team#71

Closed

ian-h-chamberlain mentioned this pull request Aug 31, 2022

Partially implement thread scheduling attributes API proposal #101222

Closed

Dylan-DPC added S-blocked Status: Blocked on something else such as an RFC or other implementation work. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Jan 21, 2023

ian-h-chamberlain mentioned this pull request Mar 17, 2023

Thread priority + affinity rust3ds/pthread-3ds#24

Open

5 tasks

ian-h-chamberlain mentioned this pull request Mar 24, 2023

OS-level thread::Builder priority and affinity extensions rust-lang/libs-team#195

Open

Dylan-DPC added S-waiting-on-ACP Status: PR has an ACP and is waiting for the ACP to complete. and removed S-blocked Status: Blocked on something else such as an RFC or other implementation work. labels May 14, 2023

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`std::thread` support for the Nintendo 3DS #98514

`std::thread` support for the Nintendo 3DS #98514

AzureMarker commented Jun 26, 2022 •

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`std::thread` support for the Nintendo 3DS #98514

`std::thread` support for the Nintendo 3DS #98514

AzureMarker commented Jun 26, 2022 •

edited by Dylan-DPC

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