Implement `BufRead` for `VecDeque<u8>` #110604

a1phyr · 2023-04-20T14:05:30Z

Note: it would become insta-stable

rustbot · 2023-04-20T14:05:36Z

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rustbot · 2023-04-20T14:05:40Z

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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.

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Mark-Simulacrum · 2023-04-24T12:47:44Z

r? @joshtriplett for libs-api FCP

workingjubilee · 2023-07-31T19:59:33Z

r? libs-api

Need FCP for impl BufRead on VecDeque<u8>. It's needed for VecDeque<u8> instead of using the one for &[u8] because unlike Vec<u8>, the VecDeque can't simply deref to &[u8] (due to being internally disjoint).

dtolnay · 2023-09-07T20:40:31Z

r? dtolnay

dtolnay

This is great!

dtolnay · 2023-09-07T20:48:34Z

@rust-lang/libs-api:
@rfcbot fcp merge

Note that there is no impl BufRead for Vec<u8>. It wouldn't make sense -- .consume(n) could not be implemented efficiently. But for VecDeque<u8> it can!

For Vec<u8>, one must use a Cursor instead. That impl looks like this:

impl<T> BufRead for Cursor<T>
where
    T: AsRef<[u8]>

With or without the impl proposed by this PR, a Cursor does not work for VecDeque<u8> because it cannot be viewed as a single contiguous &[u8].

An alternative worth considering instead of this PR would be how to generalize that Cursor impl so that it works regardless of whether the &[u8] covers the whole buffer, or only a prefix of it.

pub trait PrefixBytes {
    fn prefix_bytes(&self) -> &[u8];
}

impl PrefixBytes for VecDeque<u8> {
    fn prefix_bytes(&self) -> &[u8] {
        let (front, _) = self.as_slices();
        front
    }
}

impl<T> PrefixBytes for T
where
    T: AsRef<[u8]>,
{
    fn prefix_bytes(&self) -> &[u8] {
        self.as_ref()
    }
}

impl<T> BufRead for Cursor<T>
where
    T: PrefixBytes  // instead of AsRef<[u8]>
...

rfcbot · 2023-09-07T20:48:35Z

Team member @dtolnay has proposed to merge this. The next step is review by the rest of the tagged team members:

No concerns currently listed.

Once a majority of reviewers approve (and at most 2 approvals are outstanding), this will enter its final comment period. If you spot a major issue that hasn't been raised at any point in this process, please speak up!

See this document for info about what commands tagged team members can give me.

rfcbot · 2023-10-05T17:24:26Z

🔔 This is now entering its final comment period, as per the review above. 🔔

rfcbot · 2023-10-15T17:35:17Z

The final comment period, with a disposition to merge, as per the review above, is now complete.

As the automated representative of the governance process, I would like to thank the author for their work and everyone else who contributed.

This will be merged soon.

dtolnay

Thank you!

dtolnay · 2023-10-15T17:40:22Z

@bors r+

bors · 2023-10-15T17:40:24Z

📌 Commit a9ece12 has been approved by dtolnay

It is now in the queue for this repository.

bors · 2023-10-15T19:15:04Z

⌛ Testing commit a9ece12 with merge f70779b...

bors · 2023-10-15T21:09:41Z

☀️ Test successful - checks-actions
Approved by: dtolnay
Pushing f70779b to master...

rust-timer · 2023-10-16T02:34:26Z

Finished benchmarking commit (f70779b): comparison URL.

Overall result: no relevant changes - no action needed

@rustbot label: -perf-regression

Instruction count

This benchmark run did not return any relevant results for this metric.

Max RSS (memory usage)

This benchmark run did not return any relevant results for this metric.

Cycles

This benchmark run did not return any relevant results for this metric.

Binary size

This benchmark run did not return any relevant results for this metric.

Bootstrap: 625.359s -> 625.093s (-0.04%)
Artifact size: 305.52 MiB -> 305.52 MiB (-0.00%)

Implement `BufRead` for `VecDeque<u8>` Note: it would become insta-stable

wiseaidev · 2024-01-11T18:24:26Z

Hello friends. While reviewing this feature, I realized that we can the accomplish the same using the as_slices. Here is an example using as_slices:

use std::collections::VecDeque;

fn main() {
    let mut vec_deque: VecDeque<u8> = VecDeque::new();
    vec_deque.push_back(1);
    vec_deque.push_back(2);
    vec_deque.push_back(3);

    let (buffer, _) = vec_deque.as_slices();
    println!("Buffer: {:?}", buffer);

    vec_deque.drain(..2);

    let (new_buffer, _) = vec_deque.as_slices();
    println!("New Buffer: {:?}", new_buffer);
}

This would accomplish the same as BufRead:

use std::collections::VecDeque;
use std::io::BufRead;

fn main() {
    let mut vec_deque: VecDeque<u8> = VecDeque::new();

    vec_deque.push_back(1);
    vec_deque.push_back(2);
    vec_deque.push_back(3);

    let buf_reader: &mut dyn BufRead = &mut vec_deque;

    let buffer = buf_reader.fill_buf().expect("Error reading buffer");

    println!("Buffer: {:?}", buffer);

    buf_reader.consume(2);

    let new_buffer = buf_reader.fill_buf().expect("Error reading buffer after consume");

    println!("New Buffer: {:?}", new_buffer);
}

So, I am wondering when this feature could be useful. Thanks!

Edit: I just read the documentation:

    /// Returns the contents of the "front" slice as returned by
    /// [`as_slices`][`VecDeque::as_slices`]. If the contained byte slices of the `VecDeque` are
    /// discontiguous, multiple calls to `fill_buf` will be needed to read the entire content.

Now I see what's the difference. Thanks

Pkgsrc changes: * Adjust patches and cargo checksums to new versions. * For an external LLVM, set dependency of llvm >= 16, in accordance with the upstream changes. * Mark that on NetBSD we now need >= 9.0, so 8.x is no longer supported. * On NetBSD/sparc64 10.x, we now need GCC 12 to build the embedded LLVM, which is version 17; apparently GCC 10.4 or 10.5 mis-compiles it, resulting in an illegal instruction fault during the build. Ref. rust-lang/rust#117231 Upstream changes: Version 1.75.0 (2023-12-28) ========================== - [Stabilize `async fn` and return-position `impl Trait` in traits.] (rust-lang/rust#115822) - [Allow function pointer signatures containing `&mut T` in `const` contexts.] (rust-lang/rust#116015) - [Match `usize`/`isize` exhaustively with half-open ranges.] (rust-lang/rust#116692) - [Guarantee that `char` has the same size and alignment as `u32`.] (rust-lang/rust#116894) - [Document that the null pointer has the 0 address.] (rust-lang/rust#116988) - [Allow partially moved values in `match`.] (rust-lang/rust#103208) - [Add notes about non-compliant FP behavior on 32bit x86 targets.] (rust-lang/rust#113053) - [Stabilize ratified RISC-V target features.] (rust-lang/rust#116485) Compiler -------- - [Rework negative coherence to properly consider impls that only partly overlap.] (rust-lang/rust#112875) - [Bump `COINDUCTIVE_OVERLAP_IN_COHERENCE` to deny, and warn in dependencies.] (rust-lang/rust#116493) - [Consider alias bounds when computing liveness in NLL.] (rust-lang/rust#116733) - [Add the V (vector) extension to the `riscv64-linux-android` target spec.] (rust-lang/rust#116618) - [Automatically enable cross-crate inlining for small functions] (rust-lang/rust#116505) - Add several new tier 3 targets: - [`csky-unknown-linux-gnuabiv2hf`] (rust-lang/rust#117049) - [`i586-unknown-netbsd`] (rust-lang/rust#117170) - [`mipsel-unknown-netbsd`] (rust-lang/rust#117356) Refer to Rust's [platform support page][platform-support-doc] for more information on Rust's tiered platform support. Libraries --------- - [Override `Waker::clone_from` to avoid cloning `Waker`s unnecessarily.] (rust-lang/rust#96979) - [Implement `BufRead` for `VecDeque<u8>`.] (rust-lang/rust#110604) - [Implement `FusedIterator` for `DecodeUtf16` when the inner iterator does.] (rust-lang/rust#110729) - [Implement `Not, Bit{And,Or}{,Assign}` for IP addresses.] (rust-lang/rust#113747) - [Implement `Default` for `ExitCode`.] (rust-lang/rust#114589) - [Guarantee representation of None in NPO] (rust-lang/rust#115333) - [Document when atomic loads are guaranteed read-only.] (rust-lang/rust#115577) - [Broaden the consequences of recursive TLS initialization.] (rust-lang/rust#116172) - [Windows: Support sub-millisecond sleep.] (rust-lang/rust#116461) - [Fix generic bound of `str::SplitInclusive`'s `DoubleEndedIterator` impl] (rust-lang/rust#100806) - [Fix exit status / wait status on non-Unix `cfg(unix)` platforms.] (rust-lang/rust#115108) Stabilized APIs --------------- - [`Atomic*::from_ptr`] (https://doc.rust-lang.org/stable/core/sync/atomic/struct.AtomicUsize.html#method.from_ptr) - [`FileTimes`] (https://doc.rust-lang.org/stable/std/fs/struct.FileTimes.html) - [`FileTimesExt`] (https://doc.rust-lang.org/stable/std/os/windows/fs/trait.FileTimesExt.html) - [`File::set_modified`] (https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.set_modified) - [`File::set_times`] (https://doc.rust-lang.org/stable/std/fs/struct.File.html#method.set_times) - [`IpAddr::to_canonical`] (https://doc.rust-lang.org/stable/core/net/enum.IpAddr.html#method.to_canonical) - [`Ipv6Addr::to_canonical`] (https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.to_canonical) - [`Option::as_slice`] (https://doc.rust-lang.org/stable/core/option/enum.Option.html#method.as_slice) - [`Option::as_mut_slice`] (https://doc.rust-lang.org/stable/core/option/enum.Option.html#method.as_mut_slice) - [`pointer::byte_add`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_add) - [`pointer::byte_offset`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_offset) - [`pointer::byte_offset_from`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_offset_from) - [`pointer::byte_sub`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.byte_sub) - [`pointer::wrapping_byte_add`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_add) - [`pointer::wrapping_byte_offset`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_offset) - [`pointer::wrapping_byte_sub`] (https://doc.rust-lang.org/stable/core/primitive.pointer.html#method.wrapping_byte_sub) These APIs are now stable in const contexts: - [`Ipv6Addr::to_ipv4_mapped`] (https://doc.rust-lang.org/stable/core/net/struct.Ipv6Addr.html#method.to_ipv4_mapped) - [`MaybeUninit::assume_init_read`] (https://doc.rust-lang.org/stable/core/mem/union.MaybeUninit.html#method.assume_init_read) - [`MaybeUninit::zeroed`] (https://doc.rust-lang.org/stable/core/mem/union.MaybeUninit.html#method.zeroed) - [`mem::discriminant`] (https://doc.rust-lang.org/stable/core/mem/fn.discriminant.html) - [`mem::zeroed`] (https://doc.rust-lang.org/stable/core/mem/fn.zeroed.html) Cargo ----- - [Add new packages to `[workspace.members]` automatically.] (rust-lang/cargo#12779) - [Allow version-less `Cargo.toml` manifests.] (rust-lang/cargo#12786) - [Make browser links out of HTML file paths.] (rust-lang/cargo#12889) Rustdoc ------- - [Accept less invalid Rust in rustdoc.] (rust-lang/rust#117450) - [Document lack of object safety on affected traits.] (rust-lang/rust#113241) - [Hide `#[repr(transparent)]` if it isn't part of the public ABI.] (rust-lang/rust#115439) - [Show enum discriminant if it is a C-like variant.] (rust-lang/rust#116142) Compatibility Notes ------------------- - [FreeBSD targets now require at least version 12.] (rust-lang/rust#114521) - [Formally demote tier 2 MIPS targets to tier 3.] (rust-lang/rust#115238) - [Make misalignment a hard error in `const` contexts.] (rust-lang/rust#115524) - [Fix detecting references to packed unsized fields.] (rust-lang/rust#115583) - [Remove support for compiler plugins.] (rust-lang/rust#116412)

Implement BufRead for VecDeque<u8>

a9ece12

rustbot assigned Mark-Simulacrum Apr 20, 2023

rustbot added S-waiting-on-review Status: Awaiting review from the assignee but also interested parties. T-libs Relevant to the library team, which will review and decide on the PR/issue. labels Apr 20, 2023

rustbot assigned joshtriplett and unassigned Mark-Simulacrum Apr 24, 2023

workingjubilee added the T-libs-api Relevant to the library API team, which will review and decide on the PR/issue. label Jul 26, 2023

rustbot assigned BurntSushi and unassigned joshtriplett Jul 31, 2023

rustbot assigned dtolnay and unassigned BurntSushi Sep 7, 2023

dtolnay removed the T-libs Relevant to the library team, which will review and decide on the PR/issue. label Sep 7, 2023

dtolnay approved these changes Sep 7, 2023

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rfcbot added proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. disposition-merge This issue / PR is in PFCP or FCP with a disposition to merge it. labels Sep 7, 2023

rfcbot added final-comment-period In the final comment period and will be merged soon unless new substantive objections are raised. and removed proposed-final-comment-period Proposed to merge/close by relevant subteam, see T-<team> label. Will enter FCP once signed off. labels Oct 5, 2023

dtolnay approved these changes Oct 15, 2023

View reviewed changes

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-review Status: Awaiting review from the assignee but also interested parties. labels Oct 15, 2023

bors added the merged-by-bors This PR was explicitly merged by bors. label Oct 15, 2023

bors merged commit f70779b into rust-lang:master Oct 15, 2023
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rustbot added this to the 1.75.0 milestone Oct 15, 2023

estebank pushed a commit to estebank/rust that referenced this pull request Oct 16, 2023

Auto merge of rust-lang#110604 - a1phyr:vecdeque_buf_read, r=dtolnay

b1cd526

Implement `BufRead` for `VecDeque<u8>` Note: it would become insta-stable

Veykril mentioned this pull request Oct 17, 2023

Pull upstream master 2023 10 17 ferrocene/ferrocene#54

Merged

apiraino removed the to-announce Announce this issue on triage meeting label Oct 19, 2023

a1phyr deleted the vecdeque_buf_read branch March 12, 2024 17:12

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Implement `BufRead` for `VecDeque<u8>` #110604

Implement `BufRead` for `VecDeque<u8>` #110604

a1phyr commented Apr 20, 2023 •

edited

rustbot commented Apr 20, 2023

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Mark-Simulacrum commented Apr 24, 2023

workingjubilee commented Jul 31, 2023

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rfcbot commented Sep 7, 2023 •

edited by BurntSushi

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rust-timer commented Oct 16, 2023

wiseaidev commented Jan 11, 2024 •

edited

Implement BufRead for VecDeque<u8> #110604

Implement BufRead for VecDeque<u8> #110604

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a1phyr commented Apr 20, 2023 • edited

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rust-timer commented Oct 16, 2023

Overall result: no relevant changes - no action needed

Instruction count

Max RSS (memory usage)

Cycles

Binary size

wiseaidev commented Jan 11, 2024 • edited

Implement `BufRead` for `VecDeque<u8>` #110604

Implement `BufRead` for `VecDeque<u8>` #110604

a1phyr commented Apr 20, 2023 •

edited

rfcbot commented Sep 7, 2023 •

edited by BurntSushi

wiseaidev commented Jan 11, 2024 •

edited