aHash
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tkaitchuck
Support specializing get_hash without nightly
Submitting as an alternative to #239. Benchmarks:
Before:
RUSTFLAGS='-Ctarget-cpu=native' cargo bench --bench ahash
aeshash/u8 time: [994.20 ps 995.35 ps 996.54 ps]
aeshash/u16 time: [994.81 ps 995.50 ps 996.21 ps]
aeshash/u32 time: [1.0140 ns 1.0169 ns 1.0204 ns]
aeshash/u64 time: [988.77 ps 989.85 ps 991.07 ps]
aeshash/u128 time: [501.29 ps 502.12 ps 503.08 ps]
aeshash/strings time: [57.541 ns 57.576 ns 57.615 ns]
cargo bench --bench ahash
fallbackhash/u8 time: [976.34 ps 977.16 ps 978.05 ps]
fallbackhash/u16 time: [982.23 ps 983.48 ps 984.79 ps]
fallbackhash/u32 time: [983.96 ps 986.30 ps 989.23 ps]
fallbackhash/u64 time: [976.09 ps 980.99 ps 987.61 ps]
fallbackhash/u128 time: [1.2632 ns 1.2644 ns 1.2657 ns]
fallbackhash/strings time: [129.09 ns 129.21 ns 129.33 ns]
RUSTFLAGS='-Zallow-features= -Ctarget-cpu=native' cargo bench --bench ahash
aeshash/u8 time: [551.31 ps 551.92 ps 552.62 ps]
aeshash/u16 time: [587.73 ps 588.50 ps 589.33 ps]
aeshash/u32 time: [548.83 ps 550.01 ps 551.29 ps]
aeshash/u64 time: [549.42 ps 550.84 ps 552.65 ps]
aeshash/u128 time: [557.69 ps 558.17 ps 558.70 ps]
aeshash/strings time: [57.197 ns 57.271 ns 57.355 ns]
RUSTFLAGS='-Zallow-features=' cargo bench --bench ahash
fallbackhash/u8 time: [1.1932 ns 1.1941 ns 1.1951 ns]
fallbackhash/u16 time: [1.2140 ns 1.2161 ns 1.2190 ns]
fallbackhash/u32 time: [1.2145 ns 1.2160 ns 1.2176 ns]
fallbackhash/u64 time: [1.2148 ns 1.2194 ns 1.2247 ns]
fallbackhash/u128 time: [1.4800 ns 1.4820 ns 1.4842 ns]
fallbackhash/strings time: [129.03 ns 129.26 ns 129.55 ns]
After:
RUSTFLAGS='-Zallow-features= -Ctarget-cpu=native' cargo bench --bench ahash
aeshash/u8 time: [990.82 ps 991.44 ps 992.03 ps]
aeshash/u16 time: [986.98 ps 988.56 ps 990.37 ps]
aeshash/u32 time: [995.33 ps 996.65 ps 998.35 ps]
aeshash/u64 time: [987.58 ps 988.99 ps 990.64 ps]
aeshash/u128 time: [506.18 ps 507.51 ps 509.45 ps]
aeshash/strings time: [57.803 ns 57.859 ns 57.923 ns]
RUSTFLAGS='-Zallow-features=' cargo bench --bench ahash
fallbackhash/u8 time: [973.12 ps 973.98 ps 974.93 ps]
fallbackhash/u16 time: [976.37 ps 977.22 ps 978.17 ps]
fallbackhash/u32 time: [984.10 ps 984.82 ps 985.56 ps]
fallbackhash/u64 time: [977.77 ps 978.66 ps 979.64 ps]
fallbackhash/u128 time: [1.2595 ns 1.2606 ns 1.2618 ns]
fallbackhash/strings time: [129.86 ns 130.00 ns 130.18 ns]
It's clear that we are now getting exactly the specialized behavior of both aeshash and fallbackhash, even without the use of unstable min_specialization.
@tkaitchuck If only 0.9 is fixed, then the abandoned unfixed 0.8 version will cause the same kind of pain that the abandoned unfixed 0.7 version has caused when only 0.8 had a fix.
I agree with https://github.com/tkaitchuck/aHash/pull/242#issuecomment-2316468766 — I was hoping to get this in an 0.8 patch.
I want to pull the generic type from the type of the map and type the builder to it rather than use that parameter. The advantage of this is we don't depend on having an implementation for the dereferenced type.