ve

More compact version of Vec, uses 2 bytes/characters instead of 3. Currently targeting only 64-bits machine and aim to be drop in replacement for Vec.

This crate is work in progress, requires nightly and is highly experimental. Porting is done by hand based on rust liballoc, String may be next target.

const WORD: usize = std::mem::size_of::<usize>();

assert_eq!(std::mem::size_of::<std::vec::Vec<u8>>(), 3 * WORD);
assert_eq!(std::mem::size_of::<ve::Vec<u8>>(), 2 * WORD);

How does it work?

                 +-----------+-----------+-----------+
std::vec::Vec    | Pointer   | Length    | Capacity  |
                 +-----------+-----------+-----------+

                 +-----------+-----------+
ve::Vec          | Pointer   | Cap | Len |
                 +-----------+-----------+

ve::Vec have capacity of 4294967295 compared to Vec 18446744073709551615. If you don't need that much digits, ve::Vec should be safe.

Inspired by https://github.com/maciejhirsz/beef.

Benchmarks

Work in progress, so far creation time is slower.

running 0 tests

test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

test bench_clone_0000                  ... bench:          17 ns/iter (+/- 9)
test bench_clone_0000_std              ... bench:          12 ns/iter (+/- 5)
test bench_clone_0010                  ... bench:          41 ns/iter (+/- 10) = 243 MB/s
test bench_clone_0010_std              ... bench:          29 ns/iter (+/- 1) = 344 MB/s
test bench_clone_0100                  ... bench:         119 ns/iter (+/- 5) = 840 MB/s
test bench_clone_0100_std              ... bench:         118 ns/iter (+/- 2) = 847 MB/s
test bench_clone_1000                  ... bench:         929 ns/iter (+/- 68) = 1076 MB/s
test bench_clone_1000_std              ... bench:         927 ns/iter (+/- 8) = 1078 MB/s
test bench_clone_from_01_0000_0000     ... bench:          23 ns/iter (+/- 0)
test bench_clone_from_01_0000_0000_std ... bench:          18 ns/iter (+/- 0)
test bench_clone_from_01_0000_0010     ... bench:          57 ns/iter (+/- 0) = 175 MB/s
test bench_clone_from_01_0000_0010_std ... bench:          43 ns/iter (+/- 0) = 232 MB/s
test bench_clone_from_01_0000_0100     ... bench:         149 ns/iter (+/- 1) = 671 MB/s
test bench_clone_from_01_0000_0100_std ... bench:         139 ns/iter (+/- 13) = 719 MB/s
test bench_clone_from_01_0000_1000     ... bench:       1,074 ns/iter (+/- 17) = 931 MB/s
test bench_clone_from_01_0000_1000_std ... bench:         980 ns/iter (+/- 23) = 1020 MB/s
test bench_clone_from_01_0010_0000     ... bench:          23 ns/iter (+/- 0)
test bench_clone_from_01_0010_0000_std ... bench:          18 ns/iter (+/- 1)
test bench_clone_from_01_0010_0010     ... bench:          57 ns/iter (+/- 0) = 175 MB/s
test bench_clone_from_01_0010_0010_std ... bench:          43 ns/iter (+/- 1) = 232 MB/s
test bench_clone_from_01_0010_0100     ... bench:         149 ns/iter (+/- 0) = 671 MB/s
test bench_clone_from_01_0010_0100_std ... bench:         139 ns/iter (+/- 1) = 719 MB/s
test bench_clone_from_01_0100_0010     ... bench:          57 ns/iter (+/- 3) = 175 MB/s
test bench_clone_from_01_0100_0010_std ... bench:          43 ns/iter (+/- 0) = 232 MB/s
test bench_clone_from_01_0100_0100     ... bench:         153 ns/iter (+/- 87) = 653 MB/s
test bench_clone_from_01_0100_0100_std ... bench:         139 ns/iter (+/- 0) = 719 MB/s
test bench_clone_from_01_0100_1000     ... bench:       1,072 ns/iter (+/- 17) = 932 MB/s
test bench_clone_from_01_0100_1000_std ... bench:         980 ns/iter (+/- 323) = 1020 MB/s
test bench_clone_from_01_1000_0100     ... bench:         149 ns/iter (+/- 2) = 671 MB/s
test bench_clone_from_01_1000_0100_std ... bench:         139 ns/iter (+/- 2) = 719 MB/s
test bench_clone_from_01_1000_1000     ... bench:       1,073 ns/iter (+/- 33) = 931 MB/s
test bench_clone_from_01_1000_1000_std ... bench:         978 ns/iter (+/- 7) = 1022 MB/s
test bench_clone_from_10_0000_0000     ... bench:         133 ns/iter (+/- 6)
test bench_clone_from_10_0000_0000_std ... bench:          84 ns/iter (+/- 1)
test bench_clone_from_10_0000_0010     ... bench:         345 ns/iter (+/- 6) = 289 MB/s
test bench_clone_from_10_0000_0010_std ... bench:         225 ns/iter (+/- 10) = 444 MB/s
test bench_clone_from_10_0000_0100     ... bench:       1,114 ns/iter (+/- 23) = 897 MB/s
test bench_clone_from_10_0000_0100_std ... bench:       1,046 ns/iter (+/- 22) = 956 MB/s
test bench_clone_from_10_0000_1000     ... bench:       8,589 ns/iter (+/- 223) = 1164 MB/s
test bench_clone_from_10_0000_1000_std ... bench:       8,029 ns/iter (+/- 208) = 1245 MB/s
test bench_clone_from_10_0010_0000     ... bench:         134 ns/iter (+/- 9)
test bench_clone_from_10_0010_0000_std ... bench:          85 ns/iter (+/- 2)
test bench_clone_from_10_0010_0010     ... bench:         346 ns/iter (+/- 58) = 289 MB/s
test bench_clone_from_10_0010_0010_std ... bench:         223 ns/iter (+/- 13) = 448 MB/s
test bench_clone_from_10_0010_0100     ... bench:       1,114 ns/iter (+/- 23) = 897 MB/s
test bench_clone_from_10_0010_0100_std ... bench:       1,046 ns/iter (+/- 23) = 956 MB/s
test bench_clone_from_10_0100_0010     ... bench:         344 ns/iter (+/- 6) = 290 MB/s
test bench_clone_from_10_0100_0010_std ... bench:         225 ns/iter (+/- 22) = 444 MB/s
test bench_clone_from_10_0100_0100     ... bench:       1,113 ns/iter (+/- 21) = 898 MB/s
test bench_clone_from_10_0100_0100_std ... bench:       1,046 ns/iter (+/- 20) = 956 MB/s
test bench_clone_from_10_0100_1000     ... bench:       8,616 ns/iter (+/- 242) = 1160 MB/s
test bench_clone_from_10_0100_1000_std ... bench:       8,030 ns/iter (+/- 414) = 1245 MB/s
test bench_clone_from_10_1000_0100     ... bench:       1,115 ns/iter (+/- 19) = 896 MB/s
test bench_clone_from_10_1000_0100_std ... bench:       1,046 ns/iter (+/- 21) = 956 MB/s
test bench_clone_from_10_1000_1000     ... bench:       8,587 ns/iter (+/- 373) = 1164 MB/s
test bench_clone_from_10_1000_1000_std ... bench:       8,012 ns/iter (+/- 146) = 1248 MB/s
test bench_extend_0000_0000            ... bench:          26 ns/iter (+/- 0)
test bench_extend_0000_0000_std        ... bench:          25 ns/iter (+/- 0)
test bench_extend_0000_0010            ... bench:          83 ns/iter (+/- 2) = 120 MB/s
test bench_extend_0000_0010_std        ... bench:          65 ns/iter (+/- 1) = 153 MB/s
test bench_extend_0000_0100            ... bench:         178 ns/iter (+/- 4) = 561 MB/s
test bench_extend_0000_0100_std        ... bench:         168 ns/iter (+/- 4) = 595 MB/s
test bench_extend_0000_1000            ... bench:       1,164 ns/iter (+/- 32) = 859 MB/s
test bench_extend_0000_1000_std        ... bench:       1,170 ns/iter (+/- 73) = 854 MB/s
test bench_extend_0010_0010            ... bench:         171 ns/iter (+/- 3) = 58 MB/s
test bench_extend_0010_0010_std        ... bench:         151 ns/iter (+/- 14) = 66 MB/s
test bench_extend_0100_0100            ... bench:         370 ns/iter (+/- 9) = 270 MB/s
test bench_extend_0100_0100_std        ... bench:         350 ns/iter (+/- 9) = 285 MB/s
test bench_extend_1000_1000            ... bench:       2,920 ns/iter (+/- 75) = 342 MB/s
test bench_extend_1000_1000_std        ... bench:       3,015 ns/iter (+/- 134) = 331 MB/s
test bench_from_elem_0000              ... bench:           5 ns/iter (+/- 0)
test bench_from_elem_0000_std          ... bench:           4 ns/iter (+/- 0)
test bench_from_elem_0010              ... bench:          35 ns/iter (+/- 0) = 285 MB/s
test bench_from_elem_0010_std          ... bench:          32 ns/iter (+/- 1) = 312 MB/s
test bench_from_elem_0100              ... bench:         111 ns/iter (+/- 2) = 900 MB/s
test bench_from_elem_0100_std          ... bench:         111 ns/iter (+/- 2) = 900 MB/s
test bench_from_elem_1000              ... bench:         798 ns/iter (+/- 33) = 1253 MB/s
test bench_from_elem_1000_std          ... bench:         795 ns/iter (+/- 16) = 1257 MB/s
test bench_from_fn_0000                ... bench:           5 ns/iter (+/- 0)
test bench_from_fn_0000_std            ... bench:           5 ns/iter (+/- 0)
test bench_from_fn_0010                ... bench:          33 ns/iter (+/- 0) = 303 MB/s
test bench_from_fn_0010_std            ... bench:          33 ns/iter (+/- 0) = 303 MB/s
test bench_from_fn_0100                ... bench:         121 ns/iter (+/- 2) = 826 MB/s
test bench_from_fn_0100_std            ... bench:         119 ns/iter (+/- 3) = 840 MB/s
test bench_from_fn_1000                ... bench:         948 ns/iter (+/- 23) = 1054 MB/s
test bench_from_fn_1000_std            ... bench:         951 ns/iter (+/- 18) = 1051 MB/s
test bench_from_iter_0000              ... bench:          18 ns/iter (+/- 0)
test bench_from_iter_0000_std          ... bench:          12 ns/iter (+/- 0)
test bench_from_iter_0010              ... bench:          72 ns/iter (+/- 1) = 138 MB/s
test bench_from_iter_0010_std          ... bench:          34 ns/iter (+/- 2) = 294 MB/s
test bench_from_iter_0100              ... bench:         172 ns/iter (+/- 4) = 581 MB/s
test bench_from_iter_0100_std          ... bench:         124 ns/iter (+/- 4) = 806 MB/s
test bench_from_iter_1000              ... bench:       1,168 ns/iter (+/- 70) = 856 MB/s
test bench_from_iter_1000_std          ... bench:         955 ns/iter (+/- 20) = 1047 MB/s
test bench_from_slice_0000             ... bench:          18 ns/iter (+/- 0)
test bench_from_slice_0000_std         ... bench:          17 ns/iter (+/- 0)
test bench_from_slice_0010             ... bench:          53 ns/iter (+/- 2) = 188 MB/s
test bench_from_slice_0010_std         ... bench:          51 ns/iter (+/- 1) = 196 MB/s
test bench_from_slice_0100             ... bench:         163 ns/iter (+/- 4) = 613 MB/s
test bench_from_slice_0100_std         ... bench:         153 ns/iter (+/- 5) = 653 MB/s
test bench_from_slice_1000             ... bench:       1,170 ns/iter (+/- 25) = 854 MB/s
test bench_from_slice_1000_std         ... bench:       1,192 ns/iter (+/- 188) = 838 MB/s
test bench_new                         ... bench:           7 ns/iter (+/- 0)
test bench_new_std                     ... bench:           2 ns/iter (+/- 0)
test bench_push_all_0000_0000          ... bench:          17 ns/iter (+/- 1)
test bench_push_all_0000_0000_std      ... bench:          15 ns/iter (+/- 0)
test bench_push_all_0000_0010          ... bench:          43 ns/iter (+/- 1) = 232 MB/s
test bench_push_all_0000_0010_std      ... bench:          41 ns/iter (+/- 1) = 243 MB/s
test bench_push_all_0000_0100          ... bench:         130 ns/iter (+/- 3) = 769 MB/s
test bench_push_all_0000_0100_std      ... bench:         129 ns/iter (+/- 3) = 775 MB/s
test bench_push_all_0000_1000          ... bench:         957 ns/iter (+/- 27) = 1044 MB/s
test bench_push_all_0000_1000_std      ... bench:         956 ns/iter (+/- 35) = 1046 MB/s
test bench_push_all_0010_0010          ... bench:         116 ns/iter (+/- 2) = 86 MB/s
test bench_push_all_0010_0010_std      ... bench:         114 ns/iter (+/- 3) = 87 MB/s
test bench_push_all_0100_0100          ... bench:         292 ns/iter (+/- 5) = 342 MB/s
test bench_push_all_0100_0100_std      ... bench:         287 ns/iter (+/- 6) = 348 MB/s
test bench_push_all_1000_1000          ... bench:       1,926 ns/iter (+/- 60) = 519 MB/s
test bench_push_all_1000_1000_std      ... bench:       1,923 ns/iter (+/- 42) = 520 MB/s
test bench_push_all_move_0000_0000     ... bench:          26 ns/iter (+/- 5)
test bench_push_all_move_0000_0000_std ... bench:          25 ns/iter (+/- 2)
test bench_push_all_move_0000_0010     ... bench:          70 ns/iter (+/- 3) = 142 MB/s
test bench_push_all_move_0000_0010_std ... bench:          65 ns/iter (+/- 4) = 153 MB/s
test bench_push_all_move_0000_0100     ... bench:         164 ns/iter (+/- 5) = 609 MB/s
test bench_push_all_move_0000_0100_std ... bench:         175 ns/iter (+/- 3) = 571 MB/s
test bench_push_all_move_0000_1000     ... bench:       1,165 ns/iter (+/- 25) = 858 MB/s
test bench_push_all_move_0000_1000_std ... bench:       1,182 ns/iter (+/- 24) = 846 MB/s
test bench_push_all_move_0010_0010     ... bench:         144 ns/iter (+/- 3) = 69 MB/s
test bench_push_all_move_0010_0010_std ... bench:         134 ns/iter (+/- 10) = 74 MB/s
test bench_push_all_move_0100_0100     ... bench:         335 ns/iter (+/- 10) = 298 MB/s
test bench_push_all_move_0100_0100_std ... bench:         331 ns/iter (+/- 8) = 302 MB/s
test bench_push_all_move_1000_1000     ... bench:       2,906 ns/iter (+/- 60) = 344 MB/s
test bench_push_all_move_1000_1000_std ... bench:       2,975 ns/iter (+/- 85) = 336 MB/s
test bench_with_capacity_0000          ... bench:           3 ns/iter (+/- 0)
test bench_with_capacity_0000_std      ... bench:           3 ns/iter (+/- 0)
test bench_with_capacity_0010          ... bench:          17 ns/iter (+/- 1) = 588 MB/s
test bench_with_capacity_0010_std      ... bench:          30 ns/iter (+/- 0) = 333 MB/s
test bench_with_capacity_0100          ... bench:          17 ns/iter (+/- 0) = 5882 MB/s
test bench_with_capacity_0100_std      ... bench:          30 ns/iter (+/- 1) = 3333 MB/s
test bench_with_capacity_1000          ... bench:          38 ns/iter (+/- 5) = 26315 MB/s
test bench_with_capacity_1000_std      ... bench:          39 ns/iter (+/- 0) = 25641 MB/s

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://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.