76 lines
2.4 KiB
Rust
76 lines
2.4 KiB
Rust
//! Key-value datastore with a modified Merkle tree.
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extern crate rand;
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use bytes::*;
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use sha3::*;
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use hash::*;
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/// Alphabet to use when creating words for insertion into tries.
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pub enum Alphabet {
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All,
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Low,
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Mid,
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Custom(Bytes),
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}
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/// Standard test map for profiling tries.
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pub struct StandardMap {
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alphabet: Alphabet,
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min_key: usize,
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journal_key: usize,
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count: usize,
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}
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impl StandardMap {
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/// Get a bunch of random bytes, at least `min_count` bytes, at most `min_count` + `journal_count` bytes.
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/// `seed` is mutated pseudoramdonly and used.
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fn random_bytes(min_count: usize, journal_count: usize, seed: &mut H256) -> Vec<u8> {
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assert!(min_count + journal_count <= 32);
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*seed = seed.sha3();
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let r = min_count + (seed.bytes()[31] as usize % (journal_count + 1));
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seed.bytes()[0..r].to_vec()
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}
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/// Get a random value. Equal chance of being 1 byte as of 32. `seed` is mutated pseudoramdonly and used.
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fn random_value(seed: &mut H256) -> Bytes {
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*seed = seed.sha3();
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match seed.bytes()[0] % 2 {
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1 => vec![seed.bytes()[31];1],
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_ => seed.bytes().to_vec(),
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}
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}
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/// Get a random word of, at least `min_count` bytes, at most `min_count` + `journal_count` bytes.
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/// Each byte is an item from `alphabet`. `seed` is mutated pseudoramdonly and used.
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fn random_word(alphabet: &[u8], min_count: usize, journal_count: usize, seed: &mut H256) -> Vec<u8> {
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assert!(min_count + journal_count <= 32);
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*seed = seed.sha3();
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let r = min_count + (seed.bytes()[31] as usize % (journal_count + 1));
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let mut ret: Vec<u8> = Vec::with_capacity(r);
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for i in 0..r {
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ret.push(alphabet[seed.bytes()[i] as usize % alphabet.len()]);
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}
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ret
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}
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/// Create the standard map (set of keys and values) for the object's fields.
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pub fn make(&self) -> Vec<(Bytes, Bytes)> {
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let low = b"abcdef";
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let mid = b"@QWERTYUIOPASDFGHJKLZXCVBNM[/]^_";
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let mut d: Vec<(Bytes, Bytes)> = Vec::new();
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let mut seed = H256::new();
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for _ in 0..self.count {
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let k = match self.alphabet {
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Alphabet::All => Self::random_bytes(self.min_key, self.journal_key, &mut seed),
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Alphabet::Low => Self::random_word(low, self.min_key, self.journal_key, &mut seed),
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Alphabet::Mid => Self::random_word(mid, self.min_key, self.journal_key, &mut seed),
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Alphabet::Custom(ref a) => Self::random_word(&a, self.min_key, self.journal_key, &mut seed),
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};
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let v = Self::random_value(&mut seed);
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d.push((k, v))
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}
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d
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}
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}
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