re_log_types/
hash.rs

1/// 64-bit hash.
2///
3/// 10^-12 collision risk with   6k values.
4/// 10^-9  collision risk with 190k values.
5/// 10^-6  collision risk with   6M values.
6/// 10^-3  collision risk with 200M values.
7#[derive(Copy, Clone, Eq, PartialOrd, Ord)]
8pub struct Hash64(u64);
9
10impl re_byte_size::SizeBytes for Hash64 {
11    #[inline]
12    fn heap_size_bytes(&self) -> u64 {
13        0
14    }
15}
16
17impl Hash64 {
18    pub const ZERO: Self = Self(0);
19
20    pub fn hash(value: impl std::hash::Hash) -> Self {
21        Self(hash(value))
22    }
23
24    /// From an existing u64. Use this only for data conversions.
25    #[inline]
26    pub fn from_u64(i: u64) -> Self {
27        Self(i)
28    }
29
30    #[inline]
31    pub fn hash64(&self) -> u64 {
32        self.0
33    }
34}
35
36impl std::hash::Hash for Hash64 {
37    #[inline]
38    fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
39        state.write_u64(self.0);
40    }
41}
42
43impl std::cmp::PartialEq for Hash64 {
44    #[inline]
45    fn eq(&self, other: &Self) -> bool {
46        self.0 == other.0
47    }
48}
49
50impl nohash_hasher::IsEnabled for Hash64 {}
51
52impl std::fmt::Debug for Hash64 {
53    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
54        f.write_str(&format!("Hash64({:016X})", self.0))
55    }
56}
57
58// ----------------------------------------------------------------------------
59
60pub const HASH_RANDOM_STATE: ahash::RandomState = ahash::RandomState::with_seeds(0, 1, 2, 3);
61
62/// Hash the given value.
63#[inline]
64fn hash(value: impl std::hash::Hash) -> u64 {
65    // Don't use ahash::AHasher::default() since it uses a random number for seeding the hasher on every application start.
66    HASH_RANDOM_STATE.hash_one(value)
67}
re_log_types/hash.rs

re_log_types/
hash.rs
