Make the Entry API of HashMap<K, V> Sync and Send #58369

nox · 2019-02-11T10:52:14Z

Mark-Simulacrum · 2019-02-11T11:42:44Z

alexcrichton · 2019-02-11T13:21:54Z

Would it be possible to place these impls at the root cause of why they're not send/sync today? Placing them so high up looks pretty tricky and error prone

nox · 2019-02-11T13:25:27Z

Not really, see my comment in the issue:

If we make table::RawBucket Send and Sync itself, then table::Iter will have an auto implementation of Send where K: Send, V: Send, which is incorrect. I would rather have additional impls on the leafs (here OccupiedEntry and VacantEntry) than implementation at the root which can then cause error-prone auto implementations on other leaves.

nox · 2019-02-11T13:26:54Z

BTreeMap avoids this issue through a marker on NodeRef, but hash tables lack such a concept.

rust/src/liballoc/collections/btree/node.rs

Lines 348 to 351 in 57d7cfc

    
           unsafe impl<'a, K: Sync + 'a, V: Sync + 'a, Type> Send 
        
              for NodeRef<marker::Immut<'a>, K, V, Type> { } 
        
           unsafe impl<'a, K: Send + 'a, V: Send + 'a, Type> Send 
        
              for NodeRef<marker::Mut<'a>, K, V, Type> { }

alexcrichton · 2019-02-12T15:29:45Z

@Amanieu having likely looked at the internals here more recently than I, would you be willing to review this?

Amanieu · 2019-02-12T16:50:47Z

Entry is already Send+Sync in hashbrown, so this change looks fine to me.

Do we want to gate this behind a feature or should we just make it immediately stable? I don't think this change is very controversial.

alexcrichton · 2019-02-13T19:07:40Z

We don't have a way to gate impls like these currently, so it'll be insta-stable. In that case though I'll...

r? @Amanieu

Amanieu · 2019-02-13T19:12:34Z

@nox Can you remove the unstable feature and just mark the Send/Sync impls as stable?

Amanieu · 2019-02-25T20:34:33Z

ping @nox

nox · 2019-02-26T10:25:43Z

What version number should I put in the attribute?

Amanieu · 2019-02-26T10:44:20Z

Since this really should have been done since 1.0, just use the same as the Entry API itself:

#[stable(feature = "rust1", since = "1.0.0")]

)

nox · 2019-03-04T09:21:37Z

Fixed!

Amanieu · 2019-03-04T12:18:06Z

@bors r+ rollup

bors · 2019-03-04T12:18:07Z

📌 Commit 1fec8c2 has been approved by Amanieu

Make the Entry API of HashMap<K, V> Sync and Send Fixes rust-lang#45219

@ghost

Rollup of 24 pull requests Successful merges: - #58080 (Add FreeBSD armv6 and armv7 targets) - #58204 (On return type `impl Trait` for block with no expr point at last semi) - #58269 (Add librustc and libsyntax to rust-src distribution.) - #58369 (Make the Entry API of HashMap<K, V> Sync and Send) - #58861 (Expand where negative supertrait specific error is shown) - #58877 (Suggest removal of `&` when borrowing macro and appropriate) - #58883 (Suggest appropriate code for unused field when destructuring pattern) - #58891 (Remove stray ` in the docs for the FromIterator implementation for Option) - #58893 (race condition in thread local storage example) - #58906 (Monomorphize generator field types for debuginfo) - #58911 (Regression test for #58435.) - #58912 (Regression test for #58813) - #58916 (Fix release note problems noticed after merging.) - #58918 (Regression test added for an async ICE.) - #58921 (Add an explicit test for issue #50582) - #58926 (Make the lifetime parameters of tcx consistent.) - #58931 (Elide invalid method receiver error when it contains TyErr) - #58940 (Remove JSBackend from config.toml) - #58950 (Add self to mailmap) - #58961 (On incorrect cfg literal/identifier, point at the right span) - #58963 (libstd: implement Error::source for io::Error) - #58970 (delay_span_bug in wfcheck's ty.lift_to_tcx unwrap) - #58984 (Teach `-Z treat-err-as-bug` to take a number of errors to emit) - #59007 (Add a test for invalid const arguments) Failed merges: - #58959 (Add release notes for PR #56243) r? @ghost

Elarnon · 2019-05-01T09:24:35Z

Won't using since = "1.0.0" be confusing for people trying to figure out why sharing entries doesn't work with old versions of Rust when the official docs says it should? I know I would be confused had I not stumbled on this issue by accident.

Version 1.35.0 (2019-05-23) ========================== Language -------- - [`FnOnce`, `FnMut`, and the `Fn` traits are now implemented for `Box<FnOnce>`, `Box<FnMut>`, and `Box<Fn>` respectively.][59500] - [You can now coerce closures into unsafe function pointers.][59580] e.g. ```rust unsafe fn call_unsafe(func: unsafe fn()) { func() } pub fn main() { unsafe { call_unsafe(|| {}); } } ``` Compiler -------- - [Added the `armv6-unknown-freebsd-gnueabihf` and `armv7-unknown-freebsd-gnueabihf` targets.][58080] - [Added the `wasm32-unknown-wasi` target.][59464] Libraries --------- - [`Thread` will now show its ID in `Debug` output.][59460] - [`StdinLock`, `StdoutLock`, and `StderrLock` now implement `AsRawFd`.][59512] - [`alloc::System` now implements `Default`.][59451] - [Expanded `Debug` output (`{:#?}`) for structs now has a trailing comma on the last field.][59076] - [`char::{ToLowercase, ToUppercase}` now implement `ExactSizeIterator`.][58778] - [All `NonZero` numeric types now implement `FromStr`.][58717] - [Removed the `Read` trait bounds on the `BufReader::{get_ref, get_mut, into_inner}` methods.][58423] - [You can now call the `dbg!` macro without any parameters to print the file and line where it is called.][57847] - [In place ASCII case conversions are now up to 4× faster.][59283] e.g. `str::make_ascii_lowercase` - [`hash_map::{OccupiedEntry, VacantEntry}` now implement `Sync` and `Send`.][58369] Stabilized APIs --------------- - [`f32::copysign`] - [`f64::copysign`] - [`RefCell::replace_with`] - [`RefCell::map_split`] - [`ptr::hash`] - [`Range::contains`] - [`RangeFrom::contains`] - [`RangeTo::contains`] - [`RangeInclusive::contains`] - [`RangeToInclusive::contains`] - [`Option::copied`] Cargo ----- - [You can now set `cargo:rustc-cdylib-link-arg` at build time to pass custom linker arguments when building a `cdylib`.][cargo/6298] Its usage is highly platform specific. Misc ---- - [The Rust toolchain is now available natively for musl based distros.][58575] [59460]: rust-lang/rust#59460 [59464]: rust-lang/rust#59464 [59500]: rust-lang/rust#59500 [59512]: rust-lang/rust#59512 [59580]: rust-lang/rust#59580 [59283]: rust-lang/rust#59283 [59451]: rust-lang/rust#59451 [59076]: rust-lang/rust#59076 [58778]: rust-lang/rust#58778 [58717]: rust-lang/rust#58717 [58369]: rust-lang/rust#58369 [58423]: rust-lang/rust#58423 [58080]: rust-lang/rust#58080 [57847]: rust-lang/rust#57847 [58575]: rust-lang/rust#58575 [cargo/6298]: rust-lang/cargo#6298 [`f32::copysign`]: https://doc.rust-lang.org/stable/std/primitive.f32.html#method.copysign [`f64::copysign`]: https://doc.rust-lang.org/stable/std/primitive.f64.html#method.copysign [`RefCell::replace_with`]: https://doc.rust-lang.org/stable/std/cell/struct.RefCell.html#method.replace_with [`RefCell::map_split`]: https://doc.rust-lang.org/stable/std/cell/struct.RefCell.html#method.map_split [`ptr::hash`]: https://doc.rust-lang.org/stable/std/ptr/fn.hash.html [`Range::contains`]: https://doc.rust-lang.org/std/ops/struct.Range.html#method.contains [`RangeFrom::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeFrom.html#method.contains [`RangeTo::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeTo.html#method.contains [`RangeInclusive::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeInclusive.html#method.contains [`RangeToInclusive::contains`]: https://doc.rust-lang.org/std/ops/struct.RangeToInclusive.html#method.contains [`Option::copied`]: https://doc.rust-lang.org/std/option/enum.Option.html#method.copied

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nox force-pushed the sync-hash-map-entry branch from 5b84f65 to fafe8ce Compare February 11, 2019 11:03

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nox force-pushed the sync-hash-map-entry branch from fafe8ce to 1bcb6b3 Compare February 11, 2019 11:21

rust-highfive assigned alexcrichton and unassigned Mark-Simulacrum Feb 11, 2019

Mark-Simulacrum changed the title ~~Make the Entry API of HashMap<K, V> Sync and Send (fixes #45219)~~ Make the Entry API of HashMap<K, V> Sync and Send Feb 27, 2019

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 Feb 27, 2019

Make the Entry API of HashMap<K, V> Sync and Send (fixes rust-lang#45219

1fec8c2

)

nox force-pushed the sync-hash-map-entry branch from 1bcb6b3 to 1fec8c2 Compare March 4, 2019 09:21

bors added S-waiting-on-bors Status: Waiting on bors to run and complete tests. Bors will change the label on completion. and removed S-waiting-on-author Status: This is awaiting some action (such as code changes or more information) from the author. labels Mar 4, 2019

pietroalbini added a commit to pietroalbini/rust that referenced this pull request Mar 8, 2019

Rollup merge of rust-lang#58369 - nox:sync-hash-map-entry, r=Amanieu

55dc386

Make the Entry API of HashMap<K, V> Sync and Send Fixes rust-lang#45219

pietroalbini mentioned this pull request Mar 8, 2019

Rollup of 24 pull requests #59012

Merged

bors merged commit 1fec8c2 into rust-lang:master Mar 9, 2019

Centril added this to the 1.35 milestone Apr 27, 2019

Centril added the relnotes Marks issues that should be documented in the release notes of the next release. label Apr 27, 2019

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Make the Entry API of HashMap<K, V> Sync and Send #58369

Make the Entry API of HashMap<K, V> Sync and Send #58369

nox commented Feb 11, 2019 •

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Make the Entry API of HashMap<K, V> Sync and Send #58369

Make the Entry API of HashMap<K, V> Sync and Send #58369

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