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Onset: version control where nobody waits and nothing gets lost. The on command, its core and onset-server.
| 5 | use std::hash::{BuildHasherDefault, Hash, Hasher}; |
| 6 |
| 7 | use sha2::{Digest, Sha256}; |
| 8 |
| 9 | #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord)] |
| 10 | pub struct Id(pub [u8; 32]); |
| 11 |
| 12 | /// By its first bytes: an ID is a SHA-256, as good as random already. |
| 13 | impl Hash for Id { |
| 14 | fn hash<H: Hasher>(&self, state: &mut H) { |
| 15 | state.write_u64(u64::from_le_bytes(self.0[..8].try_into().unwrap())); |
| 16 | } |
| 17 | } |
| 18 |
| 19 | /// A hasher for IDs (see `Hash for Id`): their bytes, mixed once, rather |
| 20 | /// than SipHash over them, which a busy host spent a tenth of its landing in. |
| 21 | #[derive(Default, Clone, Copy)] |
| 22 | pub struct IdHasher(u64); |
| 23 |
| 24 | impl Hasher for IdHasher { |
| 25 | fn finish(&self) -> u64 { |
| 26 | self.0 |
| 27 | } |
| 28 | fn write(&mut self, bytes: &[u8]) { |
| 29 | for &b in bytes { |
| 30 | self.0 = (self.0.rotate_left(8) ^ u64::from(b)).wrapping_mul(0x9e37_79b9_7f4a_7c15); |
| 31 | } |
| 32 | } |
| 33 | fn write_u64(&mut self, n: u64) { |
| 34 | self.0 = (self.0 ^ n).wrapping_mul(0x9e37_79b9_7f4a_7c15); |
| 35 | } |
| 36 | } |
| 37 |
| 38 | /// Maps and sets keyed by ID. |
| 39 | pub type IdMap<V> = HashMap<Id, V, BuildHasherDefault<IdHasher>>; |
| 40 | pub type IdSet = HashSet<Id, BuildHasherDefault<IdHasher>>; |
| 41 |
| 42 | impl Id { |
| 43 | pub const ZERO: Id = Id([0; 32]); |
| 44 |
| 45 | /// The ID of an object of `kind` holding `data`. |
| 46 | pub fn of(kind: u8, data: &[u8]) -> Id { |
| 47 | let mut h = Sha256::new(); |
| 48 | h.update([kind]); |
| 49 | h.update(data); |
| 50 | Id(h.finalize().into()) |
| 51 | } |
| 52 |
| 53 | pub fn hex(&self) -> String { |
| 54 | let mut s = String::with_capacity(64); |
| 55 | for b in self.0 { |
| 56 | s.push(char::from_digit((b >> 4) as u32, 16).unwrap()); |
| 57 | s.push(char::from_digit((b & 15) as u32, 16).unwrap()); |
| 58 | } |
| 59 | s |
| 60 | } |
| 61 |
| 62 | pub fn parse(text: &str) -> Option<Id> { |
| 63 | if text.len() != 64 { |
| 64 | return None; |
| 65 | } |
| 66 | let mut out = [0u8; 32]; |
| 67 | for (i, chunk) in text.as_bytes().chunks(2).enumerate() { |
| 68 | let hi = (chunk[0] as char).to_digit(16)?; |
| 69 | let lo = (chunk[1] as char).to_digit(16)?; |
| 70 | out[i] = (hi * 16 + lo) as u8; |
| 71 | } |
| 72 | Some(Id(out)) |
| 73 | } |
| 74 |
| 75 | pub fn from_slice(bytes: &[u8]) -> Option<Id> { |
| 76 | Some(Id(bytes.try_into().ok()?)) |
| 77 | } |
| 78 |
| 79 | pub fn short(&self) -> String { |
| 80 | self.hex()[..12].to_string() |
| 81 | } |
| 82 | } |
| 83 |
| 84 | impl fmt::Display for Id { |
| 85 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| 86 | f.write_str(&self.hex()) |
| 87 | } |
| 88 | } |
| 89 |
| 90 | impl fmt::Debug for Id { |
| 91 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| 92 | write!(f, "Id({})", self.short()) |
| 93 | } |
| 94 | } |
| 95 |
| 96 | impl serde::Serialize for Id { |
| 97 | fn serialize<S: serde::Serializer>(&self, s: S) -> Result<S::Ok, S::Error> { |
| 98 | s.serialize_str(&self.hex()) |
| 99 | } |
| 100 | } |
| 101 |
| 102 | impl<'de> serde::Deserialize<'de> for Id { |
| 103 | fn deserialize<D: serde::Deserializer<'de>>(d: D) -> Result<Id, D::Error> { |
| 104 | let text = String::deserialize(d)?; |
| 105 | Id::parse(&text).ok_or_else(|| serde::de::Error::custom("not an object id")) |
| 106 | } |
| 107 | } |
| 108 |
| 109 | /// SHA-256 of arbitrary bytes, for version IDs. |
| 110 | pub fn sha256(parts: &[&[u8]]) -> Id { |
| 111 | let mut h = Sha256::new(); |
| 112 | for p in parts { |
| 113 | h.update(p); |
| 114 | } |
| 115 | Id(h.finalize().into()) |
| 116 | } |
| 117 |
| 118 | #[cfg(test)] |
| 119 | mod tests { |
| 120 | use super::*; |
| 121 |
| 122 | #[test] |
| 123 | fn hex_round_trip() { |
| 124 | let id = Id::of(1, b"hello\n"); |
| 125 | assert_eq!(Id::parse(&id.hex()), Some(id)); |
| 126 | assert_ne!(Id::of(1, b"x"), Id::of(2, b"x")); |
| 127 | } |
| 128 | } |
| 129 |