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Remove hashing hack.

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This commit is contained in:
Stephen Chung
2023-02-11 11:56:20 +08:00
parent 75718a5a8b
commit e177a5648a
4 changed files with 26 additions and 72 deletions
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53
src/func/hashing.rs
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@@ -13,25 +13,7 @@ pub type StraightHashMap<V> = hashbrown::HashMap<u64, V, StraightHasherBuilder>;
#[cfg(not(feature = "no_std"))]
pub type StraightHashMap<V> = std::collections::HashMap<u64, V, StraightHasherBuilder>;
/// 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;
/// A hasher that only takes one single [`u64`] and returns it as a non-zero hash key.
///
/// # Zeros
///
/// If the value is zero, it is mapped to `ALT_ZERO_HASH`.
/// A hasher that only takes one single [`u64`] and returns it as a hash key.
///
/// # Panics
///
@@ -81,15 +63,11 @@ pub fn get_hasher() -> ahash::AHasher {
}
}
/// Calculate a non-zero [`u64`] hash key from a namespace-qualified variable name.
/// Calculate a [`u64`] hash key from a namespace-qualified variable name.
///
/// Module names are passed in via `&str` references from an iterator.
/// Parameter types are passed in via [`TypeId`] values from an iterator.
///
/// # Zeros
///
/// If the hash happens to be zero, it is mapped to `ALT_ZERO_HASH`.
///
/// # Note
///
/// The first module name is skipped. Hashing starts from the _second_ module in the chain.
@@ -110,13 +88,10 @@ pub fn calc_var_hash<'a>(namespace: impl IntoIterator<Item = &'a str>, var_name:
count.hash(s);
var_name.hash(s);
match s.finish() {
0 => ALT_ZERO_HASH,
r => r,
}
s.finish()
}
/// Calculate a non-zero [`u64`] hash key from a namespace-qualified function name
/// Calculate a [`u64`] hash key from a namespace-qualified function name
/// and the number of parameters, but no parameter types.
///
/// Module names making up the namespace are passed in via `&str` references from an iterator.
@@ -124,10 +99,6 @@ pub fn calc_var_hash<'a>(namespace: impl IntoIterator<Item = &'a str>, var_name:
///
/// If the function is not namespace-qualified, pass [`None`] as the namespace.
///
/// # Zeros
///
/// If the hash happens to be zero, it is mapped to `ALT_ZERO_HASH`.
///
/// # Note
///
/// The first module name is skipped. Hashing starts from the _second_ module in the chain.
@@ -152,19 +123,12 @@ pub fn calc_fn_hash<'a>(
fn_name.hash(s);
num.hash(s);
match s.finish() {
0 => ALT_ZERO_HASH,
r => r,
}
s.finish()
}
/// Calculate a non-zero [`u64`] hash key from a base [`u64`] hash key and a list of parameter types.
/// Calculate a [`u64`] hash key from a base [`u64`] hash key and a list of parameter types.
///
/// Parameter types are passed in via [`TypeId`] values from an iterator.
///
/// # Zeros
///
/// If the hash happens to be zero, it is mapped to `ALT_ZERO_HASH`.
#[inline]
#[must_use]
pub fn calc_fn_hash_full(base: u64, params: impl IntoIterator<Item = TypeId>) -> u64 {
@@ -177,8 +141,5 @@ pub fn calc_fn_hash_full(base: u64, params: impl IntoIterator<Item = TypeId>) ->
});
count.hash(s);
match s.finish() {
0 => ALT_ZERO_HASH,
r => r,
}
s.finish()
}