Tracker: 0.6 release

[dhardy]

Existing and planned changes for 0.6 (excluding things already merged into the 0.5 series). @pitdicker do you have more to add?

Required items:

sequences

• Revise API for choose/choose_multiple/shuffle Sequence functionality: API revisions #483, Improve tests for some seq APIs #515
• Revise weighted sampling Implement weighted sampling API #518

distributions

• Add Dirichlet distribution Support for Dirichlet distribution #485
• Add gen_ratio Add API for getting a bool with chance of exactly 1-in-10 or 2-in-3 #491
• Make Uniform support Borrow-ed arguments Make Uniform and its helper traits use arguments of type Borrow<X> #506, Fix ambiguity issues in use of Borrow<T> #509
• Add basic SIMD support Add basic SIMD support #523
• Sampling from unit sphere and circle Implement sampling from the unit sphere and circle #567

Core

• Seeding via u64 Convenient PRNG construction: seed_from_u64 / from_hashable #522, Implement SeedableRng::seed_from_u64 #537
• Merge into master (+ bug fix) Merge 0.5 #599
• Publish rand_core 0.3 [0.5 branch] Prepare rand_core 0.3 release #614

PRNGs

• Move ISAAC generators to thei own crate Move ISAAC generators to their own crate #551
• Move XorShiftRng to its own crate Move XorShiftRng to its own crate #557
• Move ChaCha and Hc128 RNGs to their own crates Move ChaChaRng and Hc128Rng to their own crates #607
• Publish above crates
• Replace SmallRng algorithm SmallRng algorithm #603
• Add performance metrics to documentation? Use real PRNG benchmarks in documentation #450
• Reorganise PRNG documentation PRNG module documentation #622

Documentation

• See Documentation organisation #634

Optional items:

ThreadRng

• Future of thread_rng (algorithms) Future of thread_rng #463
• ThreadRng::new vs thread_rng Rename thread_rng to ThreadRng::new()? #404
• Make available without std Make thread_rng() available without std #313 ThreadRng / EntropyRng improvements #579

Seeding

• Seeding via hashable value Convenient PRNG construction: seed_from_u64 / from_hashable #522, Universal seeder #554

Optimisations and extensions

• IteratorRandom::choose could use size_hint Optimise IteratorRandom::choose for size_hint or ExactSizeIterator #511 Implement SeedableRng::seed_from_u64 #537
• Make fill work on derived array types Implement Fill for derived array types #489
• Optimise Rng::gen on arrays Optimise Rng::gen on arrays? #269

other

• New rust-random organisation Project organisation #578
• Add fork protection to ReseedingRng Add Unix fork protection #466
• Add support for WASM-bindgen Add support for wasm-bindgen #541

[pitdicker]

There are a couple of things I would like to see, but my time is getting a little more limited...

A few things I have on my personal wish list:

• SeedableRng::new_from_u64(seed: u64). Seeding PRNGs (traits and bit size) dhardy/rand#18 (comment). Depending on the PRNG it can use the seed unmodified (for CSPRNGs), use some form of seed extension, or just run the PRNG for a couple of rounds using the unmodified seed. Convenient PRNG construction: seed_from_u64 / from_hashable #522
• SeedableRng::split(&mut self, split_level: usize). Add rayon support #399 (comment). The PRNG can implement splitting using streams, jumping, or self-reseeding.
• rngs::adapter::SplittableRng Add rayon support #399 (comment). Splits the PRNG on clone(). Can have multiple uses, but intended for Rayon.
• basic SIMD support Investigate SIMD support #377. At least the ability to generate SIMD types (using fill_bytes).

New PRNGs (dhardy#60 (comment)):

• addition of PCG-XSL-RR 128/64 (MCG) and PCG-XSH-RR 64/32 (LCG).
• addition of SFC-32 and SFC-64.
• maybe addition of XoroshiroMT.
• maybe addition of Xoroshiro128+.
• deprecation of XorShiftRng.

It would be nice if we could make some progress with no_std support (#313):

• I was playing with a lock-free shared CSPRNG (to use for thread_rng with no_std).
• have a way to set another fallback in EntropyRng, like RDRAND.

[dhardy]

I opened #522, but this actually concerns rand_core and can be completely independent of Rand 0.6.

[vks]

• I agree that SeedableRng::new_from_u64 would be a great usability improvement.
• I'm a bit sceptical about streams. They don't seem as well tested as the RNGs, and some people claim their statistical quality is poor.
• I think xoshiro should be considered as well.

[dhardy]

I'm a bit sceptical about streams

To what are you referring?

[pitdicker]

I think it is about a comment by Vigna about PCG streams. I can see why he thought it would have problems, because Xorshift and Xoroshiro are sensitive to the choice of constants, and he put a lot of effort into finding good ones.

A post on the PCG blog proved streams implemented using different increment constants are all of similar quality, but with different multiplier constants are questionable.

[dhardy]

Ah, so that comment was about splitting RNGs. I'm not convinced on this issue either (more with regards to utility & applicability to threading). It would be good to create a new issue on that topic for further discussion.

I think xoshiro should be considered as well.

Again, the PRNGs we pick is not a topic to discuss in the tracking issue. We already have a couple of threads on this: dhardy#52, dhardy#60 (and related: dhardy#58, #431). If need be create yet another issue.

[vks]

This is the criticism of PCG streams: Vigna, Blackman, O'Neil

This does not make me comfortable using them, especially since they are not really tested as rigorously as the RNG itself.

[sicking]

I'd like to see a more thoughtful look at what the Rng trait looks like. #483 did some big revisions there and proposed we go down a path where Rng mainly has functions for directly generating values. I'd like to see what it'd look like to follow through on that more consistently.

I won't propose any changes here in order to keep this discussion on track. But I'll file a separate issue on this topic. Implementation work for this is trivial if we can get agreement (big "if", obviously), so might be doable relatively quickly.

Relatedly, we have a number of issues filed on the future and name of thread_rng(). This is similarly API-breaking so would be good to get done sooner rather than later. But I don't have any full proposals here, so might be too optimistic to get done for 0.6.

[dhardy]

@sicking we already worked on Rng a lot last year, leading up to the current Rng: RngCore design. We've already removed all core trait functions and all remaining methods do appear to be simple wrappers, as mentioned in #483. Yes, open another issue if you like.

Good point on thread_rng.

[sicking]

I opened #552 for one of the two backwards-breaking changes that I'd like to consider for Rng.

[sicking]

And #553 for the other one.

[sicking]

FWIW, I'd also love to rename gen_range to just range. But it feels like the transition process would be very painful.

[dhardy]

At least at the moment gen_range, gen_bool and gen_ratio are somewhat consistent.

[dhardy]

According to the new milestone we're half way to 0.6, though one or two items (specifically thread-rng) may slip to later; probably we're well past half way in terms of work.

[dhardy]

Progress note: we have now completed the most important stuff for 0.6 (in my opinion), except for limited progress on introducing new PRNG crates, and SmallRng.

[coltfred]

@dhardy Do you have any idea when 0.6 would be available? We're currently working off master, but would like to stabilize on a release version soon if we can. Our main driver is WASM support.

[dhardy]

@coltfred it would be nice to have 0.6 ready soon but I can't promise anything. Possibly around the end of the month, but that still requires some effort from those involved.

[coltfred]

@dhardy It seems unclear to me which of the things listed here are going to be in 0.6. I'd also be happy to help in any way I can to drive this to the finish line.

[dhardy]

@coltfred thanks for the offer of help. I've updated the above list to clarify the required changes for 0.6. If you like, review open PRs or have a look at #603.

[coltfred]

@dhardy I can give it a look this Friday if others haven't gotten to it. Thanks so much for this library!

[dhardy]

rand_xorshift and rand_pcg have now been published.

I started updating SmallRng and removing rand_xorshift from this repo, but hit a weird compile error.

I just created #622 regarding PRNG documentation; this isn't critical for the 0.6 release but it would be very nice to have some help with this.

[dhardy]

I think we're getting close to being able to make a release! Help with the following please:

• review Update SmallRng and remove rand_xorshift crate #623
• any suggestions regarding documentation?
• compile a list of changes for the changelog
• write the next chapter in the update guide

[dhardy]

I published:

• Rand 0.6.0-pre.0
• rand_isaac 0.1.0
• rand_hc128 0.1.0
• rand_chacha 0.1.0

The last three have had no recent changes and should be ready.

Rand itself hopefully has code in sufficiently good shape for 0.6, but I'll wait two weeks before marking it final. In the mean-time, some documentation work is needed (see previous post).

[dhardy]

I added an item to the tracker: #634. Please help out!

[hcpl]

Can i128_support feature be removed now that compile-time detection has been merged?

[dhardy]

That flag doesn't do anything any more; it's only there to avoid breakage. Probably we'll remove it for 0.7.

[dhardy]

That flag doesn't do anything any more; it's only there to avoid breakage. Probably we'll remove it for 0.7.

Other news: I've scheduled the 0.6 release for Wednesday. The following two PRs will be merged first:

• Doc changes for 0.6 and the new book #639
• Update the book book#4