444 lines
14 KiB
Rust
444 lines
14 KiB
Rust
//! Simple Bloom Filter
|
|
use {
|
|
bv::BitVec,
|
|
fnv::FnvHasher,
|
|
rand::{self, Rng},
|
|
serde::{Deserialize, Serialize},
|
|
solana_sdk::sanitize::{Sanitize, SanitizeError},
|
|
std::{
|
|
cmp, fmt,
|
|
hash::Hasher,
|
|
marker::PhantomData,
|
|
sync::atomic::{AtomicU64, Ordering},
|
|
},
|
|
};
|
|
|
|
/// Generate a stable hash of `self` for each `hash_index`
|
|
/// Best effort can be made for uniqueness of each hash.
|
|
pub trait BloomHashIndex {
|
|
fn hash_at_index(&self, hash_index: u64) -> u64;
|
|
}
|
|
|
|
#[derive(Serialize, Deserialize, Default, Clone, PartialEq, Eq, AbiExample)]
|
|
pub struct Bloom<T: BloomHashIndex> {
|
|
pub keys: Vec<u64>,
|
|
pub bits: BitVec<u64>,
|
|
num_bits_set: u64,
|
|
_phantom: PhantomData<T>,
|
|
}
|
|
|
|
impl<T: BloomHashIndex> fmt::Debug for Bloom<T> {
|
|
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
|
|
write!(
|
|
f,
|
|
"Bloom {{ keys.len: {} bits.len: {} num_set: {} bits: ",
|
|
self.keys.len(),
|
|
self.bits.len(),
|
|
self.num_bits_set
|
|
)?;
|
|
const MAX_PRINT_BITS: u64 = 10;
|
|
for i in 0..std::cmp::min(MAX_PRINT_BITS, self.bits.len()) {
|
|
if self.bits.get(i) {
|
|
write!(f, "1")?;
|
|
} else {
|
|
write!(f, "0")?;
|
|
}
|
|
}
|
|
if self.bits.len() > MAX_PRINT_BITS {
|
|
write!(f, "..")?;
|
|
}
|
|
write!(f, " }}")
|
|
}
|
|
}
|
|
|
|
impl<T: BloomHashIndex> Sanitize for Bloom<T> {
|
|
fn sanitize(&self) -> Result<(), SanitizeError> {
|
|
// Avoid division by zero in self.pos(...).
|
|
if self.bits.is_empty() {
|
|
Err(SanitizeError::InvalidValue)
|
|
} else {
|
|
Ok(())
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<T: BloomHashIndex> Bloom<T> {
|
|
pub fn new(num_bits: usize, keys: Vec<u64>) -> Self {
|
|
let bits = BitVec::new_fill(false, num_bits as u64);
|
|
Bloom {
|
|
keys,
|
|
bits,
|
|
num_bits_set: 0,
|
|
_phantom: PhantomData::default(),
|
|
}
|
|
}
|
|
/// Create filter optimal for num size given the `FALSE_RATE`.
|
|
///
|
|
/// The keys are randomized for picking data out of a collision resistant hash of size
|
|
/// `keysize` bytes.
|
|
///
|
|
/// See <https://hur.st/bloomfilter/>.
|
|
pub fn random(num_items: usize, false_rate: f64, max_bits: usize) -> Self {
|
|
let m = Self::num_bits(num_items as f64, false_rate);
|
|
let num_bits = cmp::max(1, cmp::min(m as usize, max_bits));
|
|
let num_keys = Self::num_keys(num_bits as f64, num_items as f64) as usize;
|
|
let keys: Vec<u64> = (0..num_keys).map(|_| rand::thread_rng().gen()).collect();
|
|
Self::new(num_bits, keys)
|
|
}
|
|
fn num_bits(num_items: f64, false_rate: f64) -> f64 {
|
|
let n = num_items;
|
|
let p = false_rate;
|
|
((n * p.ln()) / (1f64 / 2f64.powf(2f64.ln())).ln()).ceil()
|
|
}
|
|
fn num_keys(num_bits: f64, num_items: f64) -> f64 {
|
|
let n = num_items;
|
|
let m = num_bits;
|
|
// infinity as usize is zero in rust 1.43 but 2^64-1 in rust 1.45; ensure it's zero here
|
|
if n == 0.0 {
|
|
0.0
|
|
} else {
|
|
1f64.max(((m / n) * 2f64.ln()).round())
|
|
}
|
|
}
|
|
fn pos(&self, key: &T, k: u64) -> u64 {
|
|
key.hash_at_index(k).wrapping_rem(self.bits.len())
|
|
}
|
|
pub fn clear(&mut self) {
|
|
self.bits = BitVec::new_fill(false, self.bits.len());
|
|
self.num_bits_set = 0;
|
|
}
|
|
pub fn add(&mut self, key: &T) {
|
|
for k in &self.keys {
|
|
let pos = self.pos(key, *k);
|
|
if !self.bits.get(pos) {
|
|
self.num_bits_set = self.num_bits_set.saturating_add(1);
|
|
self.bits.set(pos, true);
|
|
}
|
|
}
|
|
}
|
|
pub fn contains(&self, key: &T) -> bool {
|
|
for k in &self.keys {
|
|
let pos = self.pos(key, *k);
|
|
if !self.bits.get(pos) {
|
|
return false;
|
|
}
|
|
}
|
|
true
|
|
}
|
|
}
|
|
|
|
fn slice_hash(slice: &[u8], hash_index: u64) -> u64 {
|
|
let mut hasher = FnvHasher::with_key(hash_index);
|
|
hasher.write(slice);
|
|
hasher.finish()
|
|
}
|
|
|
|
impl<T: AsRef<[u8]>> BloomHashIndex for T {
|
|
fn hash_at_index(&self, hash_index: u64) -> u64 {
|
|
slice_hash(self.as_ref(), hash_index)
|
|
}
|
|
}
|
|
|
|
pub struct AtomicBloom<T> {
|
|
num_bits: u64,
|
|
keys: Vec<u64>,
|
|
bits: Vec<AtomicU64>,
|
|
_phantom: PhantomData<T>,
|
|
}
|
|
|
|
impl<T: BloomHashIndex> From<Bloom<T>> for AtomicBloom<T> {
|
|
fn from(bloom: Bloom<T>) -> Self {
|
|
AtomicBloom {
|
|
num_bits: bloom.bits.len(),
|
|
keys: bloom.keys,
|
|
bits: bloom
|
|
.bits
|
|
.into_boxed_slice()
|
|
.iter()
|
|
.map(|&x| AtomicU64::new(x))
|
|
.collect(),
|
|
_phantom: PhantomData::default(),
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<T: BloomHashIndex> AtomicBloom<T> {
|
|
fn pos(&self, key: &T, hash_index: u64) -> (usize, u64) {
|
|
let pos = key.hash_at_index(hash_index).wrapping_rem(self.num_bits);
|
|
// Divide by 64 to figure out which of the
|
|
// AtomicU64 bit chunks we need to modify.
|
|
let index = pos.wrapping_shr(6);
|
|
// (pos & 63) is equivalent to mod 64 so that we can find
|
|
// the index of the bit within the AtomicU64 to modify.
|
|
let mask = 1u64.wrapping_shl(u32::try_from(pos & 63).unwrap());
|
|
(index as usize, mask)
|
|
}
|
|
|
|
/// Adds an item to the bloom filter and returns true if the item
|
|
/// was not in the filter before.
|
|
pub fn add(&self, key: &T) -> bool {
|
|
let mut added = false;
|
|
for k in &self.keys {
|
|
let (index, mask) = self.pos(key, *k);
|
|
let prev_val = self.bits[index].fetch_or(mask, Ordering::Relaxed);
|
|
added = added || prev_val & mask == 0u64;
|
|
}
|
|
added
|
|
}
|
|
|
|
pub fn contains(&self, key: &T) -> bool {
|
|
self.keys.iter().all(|k| {
|
|
let (index, mask) = self.pos(key, *k);
|
|
let bit = self.bits[index].load(Ordering::Relaxed) & mask;
|
|
bit != 0u64
|
|
})
|
|
}
|
|
|
|
pub fn clear_for_tests(&mut self) {
|
|
self.bits.iter().for_each(|bit| {
|
|
bit.store(0u64, Ordering::Relaxed);
|
|
});
|
|
}
|
|
|
|
// Only for tests and simulations.
|
|
pub fn mock_clone(&self) -> Self {
|
|
Self {
|
|
keys: self.keys.clone(),
|
|
bits: self
|
|
.bits
|
|
.iter()
|
|
.map(|v| AtomicU64::new(v.load(Ordering::Relaxed)))
|
|
.collect(),
|
|
..*self
|
|
}
|
|
}
|
|
}
|
|
|
|
impl<T: BloomHashIndex> From<AtomicBloom<T>> for Bloom<T> {
|
|
fn from(atomic_bloom: AtomicBloom<T>) -> Self {
|
|
let bits: Vec<_> = atomic_bloom
|
|
.bits
|
|
.into_iter()
|
|
.map(AtomicU64::into_inner)
|
|
.collect();
|
|
let num_bits_set = bits.iter().map(|x| x.count_ones() as u64).sum();
|
|
let mut bits: BitVec<u64> = bits.into();
|
|
bits.truncate(atomic_bloom.num_bits);
|
|
Bloom {
|
|
keys: atomic_bloom.keys,
|
|
bits,
|
|
num_bits_set,
|
|
_phantom: PhantomData::default(),
|
|
}
|
|
}
|
|
}
|
|
|
|
#[cfg(test)]
|
|
mod test {
|
|
use {
|
|
super::*,
|
|
rayon::prelude::*,
|
|
solana_sdk::hash::{hash, Hash},
|
|
};
|
|
|
|
#[test]
|
|
fn test_bloom_filter() {
|
|
//empty
|
|
let bloom: Bloom<Hash> = Bloom::random(0, 0.1, 100);
|
|
assert_eq!(bloom.keys.len(), 0);
|
|
assert_eq!(bloom.bits.len(), 1);
|
|
|
|
//normal
|
|
let bloom: Bloom<Hash> = Bloom::random(10, 0.1, 100);
|
|
assert_eq!(bloom.keys.len(), 3);
|
|
assert_eq!(bloom.bits.len(), 48);
|
|
|
|
//saturated
|
|
let bloom: Bloom<Hash> = Bloom::random(100, 0.1, 100);
|
|
assert_eq!(bloom.keys.len(), 1);
|
|
assert_eq!(bloom.bits.len(), 100);
|
|
}
|
|
#[test]
|
|
fn test_add_contains() {
|
|
let mut bloom: Bloom<Hash> = Bloom::random(100, 0.1, 100);
|
|
//known keys to avoid false positives in the test
|
|
bloom.keys = vec![0, 1, 2, 3];
|
|
|
|
let key = hash(b"hello");
|
|
assert!(!bloom.contains(&key));
|
|
bloom.add(&key);
|
|
assert!(bloom.contains(&key));
|
|
|
|
let key = hash(b"world");
|
|
assert!(!bloom.contains(&key));
|
|
bloom.add(&key);
|
|
assert!(bloom.contains(&key));
|
|
}
|
|
#[test]
|
|
fn test_random() {
|
|
let mut b1: Bloom<Hash> = Bloom::random(10, 0.1, 100);
|
|
let mut b2: Bloom<Hash> = Bloom::random(10, 0.1, 100);
|
|
b1.keys.sort_unstable();
|
|
b2.keys.sort_unstable();
|
|
assert_ne!(b1.keys, b2.keys);
|
|
}
|
|
// Bloom filter math in python
|
|
// n number of items
|
|
// p false rate
|
|
// m number of bits
|
|
// k number of keys
|
|
//
|
|
// n = ceil(m / (-k / log(1 - exp(log(p) / k))))
|
|
// p = pow(1 - exp(-k / (m / n)), k)
|
|
// m = ceil((n * log(p)) / log(1 / pow(2, log(2))));
|
|
// k = round((m / n) * log(2));
|
|
#[test]
|
|
fn test_filter_math() {
|
|
assert_eq!(Bloom::<Hash>::num_bits(100f64, 0.1f64) as u64, 480u64);
|
|
assert_eq!(Bloom::<Hash>::num_bits(100f64, 0.01f64) as u64, 959u64);
|
|
assert_eq!(Bloom::<Hash>::num_keys(1000f64, 50f64) as u64, 14u64);
|
|
assert_eq!(Bloom::<Hash>::num_keys(2000f64, 50f64) as u64, 28u64);
|
|
assert_eq!(Bloom::<Hash>::num_keys(2000f64, 25f64) as u64, 55u64);
|
|
//ensure min keys is 1
|
|
assert_eq!(Bloom::<Hash>::num_keys(20f64, 1000f64) as u64, 1u64);
|
|
}
|
|
|
|
#[test]
|
|
fn test_debug() {
|
|
let mut b: Bloom<Hash> = Bloom::new(3, vec![100]);
|
|
b.add(&Hash::default());
|
|
assert_eq!(
|
|
format!("{:?}", b),
|
|
"Bloom { keys.len: 1 bits.len: 3 num_set: 1 bits: 001 }"
|
|
);
|
|
|
|
let mut b: Bloom<Hash> = Bloom::new(1000, vec![100]);
|
|
b.add(&Hash::default());
|
|
b.add(&hash(&[1, 2]));
|
|
assert_eq!(
|
|
format!("{:?}", b),
|
|
"Bloom { keys.len: 1 bits.len: 1000 num_set: 2 bits: 0000000000.. }"
|
|
);
|
|
}
|
|
|
|
#[test]
|
|
fn test_atomic_bloom() {
|
|
let mut rng = rand::thread_rng();
|
|
let hash_values: Vec<_> = std::iter::repeat_with(|| solana_sdk::hash::new_rand(&mut rng))
|
|
.take(1200)
|
|
.collect();
|
|
let bloom: AtomicBloom<_> = Bloom::<Hash>::random(1287, 0.1, 7424).into();
|
|
assert_eq!(bloom.keys.len(), 3);
|
|
assert_eq!(bloom.num_bits, 6168);
|
|
assert_eq!(bloom.bits.len(), 97);
|
|
hash_values.par_iter().for_each(|v| {
|
|
bloom.add(v);
|
|
});
|
|
let bloom: Bloom<Hash> = bloom.into();
|
|
assert_eq!(bloom.keys.len(), 3);
|
|
assert_eq!(bloom.bits.len(), 6168);
|
|
assert!(bloom.num_bits_set > 2000);
|
|
for hash_value in hash_values {
|
|
assert!(bloom.contains(&hash_value));
|
|
}
|
|
let false_positive = std::iter::repeat_with(|| solana_sdk::hash::new_rand(&mut rng))
|
|
.take(10_000)
|
|
.filter(|hash_value| bloom.contains(hash_value))
|
|
.count();
|
|
assert!(false_positive < 2_000, "false_positive: {}", false_positive);
|
|
}
|
|
|
|
#[test]
|
|
fn test_atomic_bloom_round_trip() {
|
|
let mut rng = rand::thread_rng();
|
|
let keys: Vec<_> = std::iter::repeat_with(|| rng.gen()).take(5).collect();
|
|
let mut bloom = Bloom::<Hash>::new(9731, keys.clone());
|
|
let hash_values: Vec<_> = std::iter::repeat_with(|| solana_sdk::hash::new_rand(&mut rng))
|
|
.take(1000)
|
|
.collect();
|
|
for hash_value in &hash_values {
|
|
bloom.add(hash_value);
|
|
}
|
|
let num_bits_set = bloom.num_bits_set;
|
|
assert!(num_bits_set > 2000, "# bits set: {}", num_bits_set);
|
|
// Round-trip with no inserts.
|
|
let bloom: AtomicBloom<_> = bloom.into();
|
|
assert_eq!(bloom.num_bits, 9731);
|
|
assert_eq!(bloom.bits.len(), (9731 + 63) / 64);
|
|
for hash_value in &hash_values {
|
|
assert!(bloom.contains(hash_value));
|
|
}
|
|
let bloom: Bloom<_> = bloom.into();
|
|
assert_eq!(bloom.num_bits_set, num_bits_set);
|
|
for hash_value in &hash_values {
|
|
assert!(bloom.contains(hash_value));
|
|
}
|
|
// Round trip, re-inserting the same hash values.
|
|
let bloom: AtomicBloom<_> = bloom.into();
|
|
hash_values.par_iter().for_each(|v| {
|
|
bloom.add(v);
|
|
});
|
|
for hash_value in &hash_values {
|
|
assert!(bloom.contains(hash_value));
|
|
}
|
|
let bloom: Bloom<_> = bloom.into();
|
|
assert_eq!(bloom.num_bits_set, num_bits_set);
|
|
assert_eq!(bloom.bits.len(), 9731);
|
|
for hash_value in &hash_values {
|
|
assert!(bloom.contains(hash_value));
|
|
}
|
|
// Round trip, inserting new hash values.
|
|
let more_hash_values: Vec<_> =
|
|
std::iter::repeat_with(|| solana_sdk::hash::new_rand(&mut rng))
|
|
.take(1000)
|
|
.collect();
|
|
let bloom: AtomicBloom<_> = bloom.into();
|
|
assert_eq!(bloom.num_bits, 9731);
|
|
assert_eq!(bloom.bits.len(), (9731 + 63) / 64);
|
|
more_hash_values.par_iter().for_each(|v| {
|
|
bloom.add(v);
|
|
});
|
|
for hash_value in &hash_values {
|
|
assert!(bloom.contains(hash_value));
|
|
}
|
|
for hash_value in &more_hash_values {
|
|
assert!(bloom.contains(hash_value));
|
|
}
|
|
let false_positive = std::iter::repeat_with(|| solana_sdk::hash::new_rand(&mut rng))
|
|
.take(10_000)
|
|
.filter(|hash_value| bloom.contains(hash_value))
|
|
.count();
|
|
assert!(false_positive < 2000, "false_positive: {}", false_positive);
|
|
let bloom: Bloom<_> = bloom.into();
|
|
assert_eq!(bloom.bits.len(), 9731);
|
|
assert!(bloom.num_bits_set > num_bits_set);
|
|
assert!(
|
|
bloom.num_bits_set > 4000,
|
|
"# bits set: {}",
|
|
bloom.num_bits_set
|
|
);
|
|
for hash_value in &hash_values {
|
|
assert!(bloom.contains(hash_value));
|
|
}
|
|
for hash_value in &more_hash_values {
|
|
assert!(bloom.contains(hash_value));
|
|
}
|
|
let false_positive = std::iter::repeat_with(|| solana_sdk::hash::new_rand(&mut rng))
|
|
.take(10_000)
|
|
.filter(|hash_value| bloom.contains(hash_value))
|
|
.count();
|
|
assert!(false_positive < 2000, "false_positive: {}", false_positive);
|
|
// Assert that the bits vector precisely match if no atomic ops were
|
|
// used.
|
|
let bits = bloom.bits;
|
|
let mut bloom = Bloom::<Hash>::new(9731, keys);
|
|
for hash_value in &hash_values {
|
|
bloom.add(hash_value);
|
|
}
|
|
for hash_value in &more_hash_values {
|
|
bloom.add(hash_value);
|
|
}
|
|
assert_eq!(bits, bloom.bits);
|
|
}
|
|
}
|