2021-06-16 18:36:33 +08:00
|
|
|
//! Module containing utilities to hash functions and function calls.
|
|
|
|
|
|
|
|
#[cfg(feature = "no_std")]
|
|
|
|
use std::prelude::v1::*;
|
|
|
|
use std::{
|
|
|
|
any::TypeId,
|
|
|
|
hash::{BuildHasher, Hash, Hasher},
|
|
|
|
};
|
|
|
|
|
2022-09-05 19:22:30 +09:00
|
|
|
#[cfg(feature = "no_std")]
|
2022-09-12 23:08:38 +08:00
|
|
|
pub type StraightHashMap<V> = hashbrown::HashMap<u64, V, StraightHasherBuilder>;
|
2022-09-05 19:22:30 +09:00
|
|
|
|
|
|
|
#[cfg(not(feature = "no_std"))]
|
2022-09-12 23:08:38 +08:00
|
|
|
pub type StraightHashMap<V> = std::collections::HashMap<u64, V, StraightHasherBuilder>;
|
2022-09-05 13:13:06 +09:00
|
|
|
|
2021-12-06 10:34:13 +08:00
|
|
|
/// Dummy hash value to map zeros to. This value can be anything.
|
|
|
|
///
|
|
|
|
/// # Notes
|
|
|
|
///
|
|
|
|
/// Hashes are `u64`, and they can be zero (although extremely unlikely).
|
|
|
|
/// It is possible to hijack the zero value to indicate non-existence,
|
|
|
|
/// like [`None`] in [`Option<u64>`].
|
|
|
|
///
|
|
|
|
/// When a hash is calculated to be zero, it gets mapped to this alternate hash value.
|
|
|
|
/// This has the effect of releasing the zero value at the expense of causing the probability of
|
|
|
|
/// this value to double, which has minor impacts.
|
|
|
|
pub const ALT_ZERO_HASH: u64 = 42;
|
2021-12-05 17:05:19 +08:00
|
|
|
|
|
|
|
/// A hasher that only takes one single [`u64`] and returns it as a non-zero hash key.
|
|
|
|
///
|
|
|
|
/// # Zeros
|
|
|
|
///
|
2021-12-06 10:34:13 +08:00
|
|
|
/// If the value is zero, it is mapped to `ALT_ZERO_HASH`.
|
2021-06-16 18:36:33 +08:00
|
|
|
///
|
|
|
|
/// # Panics
|
|
|
|
///
|
|
|
|
/// Panics when hashing any data type other than a [`u64`].
|
|
|
|
#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash)]
|
2022-09-05 13:13:06 +09:00
|
|
|
pub struct StraightHasher(u64);
|
2021-06-16 18:36:33 +08:00
|
|
|
|
|
|
|
impl Hasher for StraightHasher {
|
|
|
|
#[inline(always)]
|
|
|
|
fn finish(&self) -> u64 {
|
|
|
|
self.0
|
|
|
|
}
|
2022-09-05 21:17:07 +08:00
|
|
|
#[inline(always)]
|
2022-09-05 13:13:06 +09:00
|
|
|
fn write(&mut self, _bytes: &[u8]) {
|
|
|
|
panic!("StraightHasher can only hash u64 values");
|
|
|
|
}
|
2022-09-05 21:17:07 +08:00
|
|
|
#[inline(always)]
|
2022-09-05 13:13:06 +09:00
|
|
|
fn write_u64(&mut self, i: u64) {
|
2022-09-05 19:22:30 +09:00
|
|
|
if i == 0 {
|
|
|
|
self.0 = ALT_ZERO_HASH;
|
|
|
|
} else {
|
|
|
|
self.0 = i;
|
|
|
|
}
|
2021-06-16 18:36:33 +08:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// A hash builder for `StraightHasher`.
|
|
|
|
#[derive(Debug, Clone, Copy, Eq, PartialEq, Ord, PartialOrd, Hash, Default)]
|
2022-09-05 13:13:06 +09:00
|
|
|
pub struct StraightHasherBuilder;
|
2021-06-16 18:36:33 +08:00
|
|
|
|
|
|
|
impl BuildHasher for StraightHasherBuilder {
|
|
|
|
type Hasher = StraightHasher;
|
|
|
|
|
|
|
|
#[inline(always)]
|
|
|
|
fn build_hasher(&self) -> Self::Hasher {
|
2021-12-06 10:34:13 +08:00
|
|
|
StraightHasher(ALT_ZERO_HASH)
|
2021-06-16 18:36:33 +08:00
|
|
|
}
|
|
|
|
}
|
|
|
|
|
|
|
|
/// Create an instance of the default hasher.
|
|
|
|
#[inline(always)]
|
|
|
|
#[must_use]
|
|
|
|
pub fn get_hasher() -> ahash::AHasher {
|
2022-09-26 23:45:50 +08:00
|
|
|
if cfg!(feature = "stable_hash") {
|
|
|
|
ahash::RandomState::with_seeds(42, 999, 123, 0).build_hasher()
|
|
|
|
} else {
|
|
|
|
ahash::AHasher::default()
|
|
|
|
}
|
2021-06-16 18:36:33 +08:00
|
|
|
}
|
|
|
|
|
2021-12-05 17:05:19 +08:00
|
|
|
/// Calculate a non-zero [`u64`] hash key from a namespace-qualified variable name.
|
2021-06-30 16:28:37 +08:00
|
|
|
///
|
|
|
|
/// Module names are passed in via `&str` references from an iterator.
|
|
|
|
/// Parameter types are passed in via [`TypeId`] values from an iterator.
|
|
|
|
///
|
2021-12-05 17:05:19 +08:00
|
|
|
/// # Zeros
|
|
|
|
///
|
|
|
|
/// If the hash happens to be zero, it is mapped to `DEFAULT_HASH`.
|
|
|
|
///
|
2021-06-30 16:28:37 +08:00
|
|
|
/// # Note
|
|
|
|
///
|
|
|
|
/// The first module name is skipped. Hashing starts from the _second_ module in the chain.
|
|
|
|
#[inline]
|
|
|
|
#[must_use]
|
2022-09-21 11:46:23 +08:00
|
|
|
pub fn calc_var_hash<'a>(
|
2022-09-06 14:16:15 +09:00
|
|
|
modules: impl IntoIterator<Item = &'a str, IntoIter = impl ExactSizeIterator<Item = &'a str>>,
|
2022-06-11 16:01:15 +08:00
|
|
|
var_name: &str,
|
|
|
|
) -> u64 {
|
2021-06-30 16:28:37 +08:00
|
|
|
let s = &mut get_hasher();
|
|
|
|
|
|
|
|
// We always skip the first module
|
2022-09-06 14:16:15 +09:00
|
|
|
let iter = modules.into_iter();
|
|
|
|
let len = iter.len();
|
|
|
|
iter.skip(1).for_each(|m| m.hash(s));
|
2021-06-30 16:28:37 +08:00
|
|
|
len.hash(s);
|
2022-01-04 15:22:48 +08:00
|
|
|
var_name.hash(s);
|
2021-12-05 17:05:19 +08:00
|
|
|
|
|
|
|
match s.finish() {
|
2021-12-06 10:34:13 +08:00
|
|
|
0 => ALT_ZERO_HASH,
|
2021-12-05 17:05:19 +08:00
|
|
|
r => r,
|
|
|
|
}
|
2021-06-30 16:28:37 +08:00
|
|
|
}
|
|
|
|
|
2021-12-05 17:05:19 +08:00
|
|
|
/// Calculate a non-zero [`u64`] hash key from a namespace-qualified function name
|
2021-06-16 18:36:33 +08:00
|
|
|
/// and the number of parameters, but no parameter types.
|
|
|
|
///
|
2022-09-21 11:46:23 +08:00
|
|
|
/// Module names making up the namespace are passed in via `&str` references from an iterator.
|
2021-06-16 18:36:33 +08:00
|
|
|
/// Parameter types are passed in via [`TypeId`] values from an iterator.
|
|
|
|
///
|
2022-09-21 11:46:23 +08:00
|
|
|
/// If the function is not namespace-qualified, pass [`None`] as the namespace.
|
|
|
|
///
|
2021-12-05 17:05:19 +08:00
|
|
|
/// # Zeros
|
|
|
|
///
|
|
|
|
/// If the hash happens to be zero, it is mapped to `DEFAULT_HASH`.
|
|
|
|
///
|
2021-06-16 18:36:33 +08:00
|
|
|
/// # Note
|
|
|
|
///
|
|
|
|
/// The first module name is skipped. Hashing starts from the _second_ module in the chain.
|
|
|
|
#[inline]
|
|
|
|
#[must_use]
|
2022-09-21 11:46:23 +08:00
|
|
|
pub fn calc_fn_hash<'a>(
|
|
|
|
namespace: impl IntoIterator<Item = &'a str, IntoIter = impl ExactSizeIterator<Item = &'a str>>,
|
2022-01-04 15:22:48 +08:00
|
|
|
fn_name: &str,
|
2021-06-16 18:36:33 +08:00
|
|
|
num: usize,
|
|
|
|
) -> u64 {
|
|
|
|
let s = &mut get_hasher();
|
|
|
|
|
|
|
|
// We always skip the first module
|
2022-09-21 11:46:23 +08:00
|
|
|
let iter = namespace.into_iter();
|
2022-09-06 14:16:15 +09:00
|
|
|
let len = iter.len();
|
|
|
|
iter.skip(1).for_each(|m| m.hash(s));
|
2021-06-16 18:36:33 +08:00
|
|
|
len.hash(s);
|
2022-01-04 15:22:48 +08:00
|
|
|
fn_name.hash(s);
|
2021-06-16 18:36:33 +08:00
|
|
|
num.hash(s);
|
2021-12-05 17:05:19 +08:00
|
|
|
|
|
|
|
match s.finish() {
|
2021-12-06 10:34:13 +08:00
|
|
|
0 => ALT_ZERO_HASH,
|
2021-12-05 17:05:19 +08:00
|
|
|
r => r,
|
|
|
|
}
|
2021-06-16 18:36:33 +08:00
|
|
|
}
|
|
|
|
|
2021-12-05 17:05:19 +08:00
|
|
|
/// Calculate a non-zero [`u64`] hash key from a list of parameter types.
|
2021-06-16 18:36:33 +08:00
|
|
|
///
|
|
|
|
/// Parameter types are passed in via [`TypeId`] values from an iterator.
|
2021-12-05 17:05:19 +08:00
|
|
|
///
|
|
|
|
/// # Zeros
|
|
|
|
///
|
|
|
|
/// If the hash happens to be zero, it is mapped to `DEFAULT_HASH`.
|
2021-06-16 18:36:33 +08:00
|
|
|
#[inline]
|
|
|
|
#[must_use]
|
2022-09-06 14:16:15 +09:00
|
|
|
pub fn calc_fn_params_hash(
|
|
|
|
params: impl IntoIterator<Item = TypeId, IntoIter = impl ExactSizeIterator<Item = TypeId>>,
|
|
|
|
) -> u64 {
|
2021-06-16 18:36:33 +08:00
|
|
|
let s = &mut get_hasher();
|
2022-09-06 14:16:15 +09:00
|
|
|
let iter = params.into_iter();
|
|
|
|
let len = iter.len();
|
|
|
|
iter.for_each(|t| {
|
2022-07-27 18:04:59 +08:00
|
|
|
t.hash(s);
|
2022-07-27 16:04:24 +08:00
|
|
|
});
|
2021-06-16 18:36:33 +08:00
|
|
|
len.hash(s);
|
2021-12-05 17:05:19 +08:00
|
|
|
|
|
|
|
match s.finish() {
|
2021-12-06 10:34:13 +08:00
|
|
|
0 => ALT_ZERO_HASH,
|
2021-12-05 17:05:19 +08:00
|
|
|
r => r,
|
|
|
|
}
|
2021-06-16 18:36:33 +08:00
|
|
|
}
|
|
|
|
|
|
|
|
/// Combine two [`u64`] hashes by taking the XOR of them.
|
2021-12-05 17:05:19 +08:00
|
|
|
///
|
|
|
|
/// # Zeros
|
|
|
|
///
|
|
|
|
/// If the hash happens to be zero, it is mapped to `DEFAULT_HASH`.
|
2021-06-16 18:36:33 +08:00
|
|
|
#[inline(always)]
|
|
|
|
#[must_use]
|
2021-11-16 12:26:37 +08:00
|
|
|
pub const fn combine_hashes(a: u64, b: u64) -> u64 {
|
2021-12-05 17:05:19 +08:00
|
|
|
match a ^ b {
|
2021-12-06 10:34:13 +08:00
|
|
|
0 => ALT_ZERO_HASH,
|
2021-12-05 17:05:19 +08:00
|
|
|
r => r,
|
|
|
|
}
|
2021-06-16 18:36:33 +08:00
|
|
|
}
|