Adding upstream version 1.64.0+dfsg1.upstream/1.64.0+dfsg1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 126 insertions, 0 deletions

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+hashbrown
+=========
+
+[![Build Status](https://github.com/rust-lang/hashbrown/actions/workflows/rust.yml/badge.svg)](https://github.com/rust-lang/hashbrown/actions)
+[![Crates.io](https://img.shields.io/crates/v/hashbrown.svg)](https://crates.io/crates/hashbrown)
+[![Documentation](https://docs.rs/hashbrown/badge.svg)](https://docs.rs/hashbrown)
+[![Rust](https://img.shields.io/badge/rust-1.56.1%2B-blue.svg?maxAge=3600)](https://github.com/rust-lang/hashbrown)
+
+This crate is a Rust port of Google's high-performance [SwissTable] hash
+map, adapted to make it a drop-in replacement for Rust's standard `HashMap`
+and `HashSet` types.
+
+The original C++ version of SwissTable can be found [here], and this
+[CppCon talk] gives an overview of how the algorithm works.
+
+Since Rust 1.36, this is now the `HashMap` implementation for the Rust standard
+library. However you may still want to use this crate instead since it works
+in environments without `std`, such as embedded systems and kernels.
+
+[SwissTable]: https://abseil.io/blog/20180927-swisstables
+[here]: https://github.com/abseil/abseil-cpp/blob/master/absl/container/internal/raw_hash_set.h
+[CppCon talk]: https://www.youtube.com/watch?v=ncHmEUmJZf4
+
+## [Change log](CHANGELOG.md)
+
+## Features
+
+- Drop-in replacement for the standard library `HashMap` and `HashSet` types.
+- Uses [AHash](https://github.com/tkaitchuck/aHash) as the default hasher, which is much faster than SipHash.
+  However, AHash does *not provide the same level of HashDoS resistance* as SipHash, so if that is important to you, you might want to consider using a different hasher.
+- Around 2x faster than the previous standard library `HashMap`.
+- Lower memory usage: only 1 byte of overhead per entry instead of 8.
+- Compatible with `#[no_std]` (but requires a global allocator with the `alloc` crate).
+- Empty hash maps do not allocate any memory.
+- SIMD lookups to scan multiple hash entries in parallel.
+
+## Performance
+
+Compared to the previous implementation of `std::collections::HashMap` (Rust 1.35).
+
+With the hashbrown default AHash hasher:
+
+| name                    |  oldstdhash ns/iter | hashbrown ns/iter | diff ns/iter |  diff %  | speedup |
+|:------------------------|:-------------------:|------------------:|:------------:|---------:|---------|
+| insert_ahash_highbits       | 18,865      | 8,020         |               -10,845 | -57.49%  | x 2.35 |
+| insert_ahash_random         | 19,711      | 8,019         |               -11,692 | -59.32%  | x 2.46 |
+| insert_ahash_serial         | 19,365      | 6,463         |               -12,902 | -66.63%  | x 3.00 |
+| insert_erase_ahash_highbits | 51,136      | 17,916        |               -33,220 | -64.96%  | x 2.85 |
+| insert_erase_ahash_random   | 51,157      | 17,688        |               -33,469 | -65.42%  | x 2.89 |
+| insert_erase_ahash_serial   | 45,479      | 14,895        |               -30,584 | -67.25%  | x 3.05 |
+| iter_ahash_highbits         | 1,399       | 1,092         |                  -307 | -21.94%  | x 1.28 |
+| iter_ahash_random           | 1,586       | 1,059         |                  -527 | -33.23%  | x 1.50 |
+| iter_ahash_serial           | 3,168       | 1,079         |                -2,089 | -65.94%  | x 2.94 |
+| lookup_ahash_highbits       | 32,351      | 4,792         |               -27,559 | -85.19%  | x 6.75 |
+| lookup_ahash_random         | 17,419      | 4,817         |               -12,602 | -72.35%  | x 3.62 |
+| lookup_ahash_serial         | 15,254      | 3,606         |               -11,648 | -76.36%  | x 4.23 |
+| lookup_fail_ahash_highbits  | 21,187      | 4,369         |               -16,818 | -79.38%  | x 4.85 |
+| lookup_fail_ahash_random    | 21,550      | 4,395         |               -17,155 | -79.61%  | x 4.90 |
+| lookup_fail_ahash_serial    | 19,450      | 3,176         |               -16,274 | -83.67%  | x 6.12 |
+
+
+With the libstd default SipHash hasher:
+
+|name                     |  oldstdhash ns/iter | hashbrown ns/iter | diff ns/iter |  diff %  | speedup |
+|:------------------------|:-------------------:|------------------:|:------------:|---------:|---------|
+|insert_std_highbits       |19,216      |16,885           |            -2,331    |   -12.13%  | x 1.14 |
+|insert_std_random         |19,179      |17,034           |            -2,145    |   -11.18%  | x 1.13 |
+|insert_std_serial         |19,462      |17,493           |            -1,969    |   -10.12%  | x 1.11 |
+|insert_erase_std_highbits |50,825      |35,847           |            -14,978   |   -29.47%  | x 1.42 |
+|insert_erase_std_random   |51,448      |35,392           |            -16,056   |   -31.21%  | x 1.45 |
+|insert_erase_std_serial   |87,711      |38,091           |            -49,620   |   -56.57%  | x 2.30 |
+|iter_std_highbits         |1,378       |1,159            |            -219      |   -15.89%  | x 1.19 |
+|iter_std_random           |1,395       |1,132            |            -263      |   -18.85%  | x 1.23 |
+|iter_std_serial           |1,704       |1,105            |            -599      |   -35.15%  | x 1.54 |
+|lookup_std_highbits       |17,195      |13,642           |            -3,553    |   -20.66%  | x 1.26 |
+|lookup_std_random         |17,181      |13,773           |            -3,408    |   -19.84%  | x 1.25 |
+|lookup_std_serial         |15,483      |13,651           |            -1,832    |   -11.83%  | x 1.13 |
+|lookup_fail_std_highbits  |20,926      |13,474           |            -7,452    |   -35.61%  | x 1.55 |
+|lookup_fail_std_random    |21,766      |13,505           |            -8,261    |   -37.95%  | x 1.61 |
+|lookup_fail_std_serial    |19,336      |13,519           |            -5,817    |   -30.08%  | x 1.43 |
+
+## Usage
+
+Add this to your `Cargo.toml`:
+
+```toml
+[dependencies]
+hashbrown = "0.12"
+```
+
+Then:
+
+```rust
+use hashbrown::HashMap;
+
+let mut map = HashMap::new();
+map.insert(1, "one");
+```
+## Flags
+This crate has the following Cargo features:
+
+- `nightly`: Enables nightly-only features including: `#[may_dangle]`.
+- `serde`: Enables serde serialization support.
+- `rayon`: Enables rayon parallel iterator support.
+- `raw`: Enables access to the experimental and unsafe `RawTable` API.
+- `inline-more`: Adds inline hints to most functions, improving run-time performance at the cost
+  of compilation time. (enabled by default)
+- `bumpalo`: Provides a `BumpWrapper` type which allows `bumpalo` to be used for memory allocation.
+- `ahash`: Compiles with ahash as default hasher. (enabled by default)
+- `ahash-compile-time-rng`: Activates the `compile-time-rng` feature of ahash. For targets with no random number generator
+this pre-generates seeds at compile time and embeds them as constants. See [aHash's documentation](https://github.com/tkaitchuck/aHash#flags) (disabled by default)
+
+## License
+
+Licensed under either of:
+
+ * Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or https://www.apache.org/licenses/LICENSE-2.0)
+ * MIT license ([LICENSE-MIT](LICENSE-MIT) or https://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any
+additional terms or conditions.