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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},
},
};
pub trait BloomHashIndex {
fn hash_at_index(&self, hash_index: u64) -> u64;
}
#[derive(Serialize, Deserialize, Default, Clone, PartialEq, 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> {
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(),
}
}
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;
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);
let index = pos.wrapping_shr(6);
let mask = 1u64.wrapping_shl(u32::try_from(pos & 63).unwrap());
(index as usize, mask)
}
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);
});
}
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() {
let bloom: Bloom<Hash> = Bloom::random(0, 0.1, 100);
assert_eq!(bloom.keys.len(), 0);
assert_eq!(bloom.bits.len(), 1);
let bloom: Bloom<Hash> = Bloom::random(10, 0.1, 100);
assert_eq!(bloom.keys.len(), 3);
assert_eq!(bloom.bits.len(), 48);
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);
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);
}
#[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);
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);
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));
}
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));
}
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);
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);
}
}