233 lines
8.7 KiB
Rust
233 lines
8.7 KiB
Rust
//! Utility to deduplicate baches of incoming network packets.
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use {
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crate::packet::{Packet, PacketBatch},
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ahash::AHasher,
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rand::Rng,
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std::{
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hash::{Hash, Hasher},
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iter::repeat_with,
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sync::atomic::{AtomicU64, Ordering},
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time::{Duration, Instant},
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},
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};
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pub struct Deduper<const K: usize> {
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num_bits: u64,
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bits: Vec<AtomicU64>,
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seeds: [(u128, u128); K],
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clock: Instant,
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// Maximum number of one bits before the false positive
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// rate exceeds the specified threshold.
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capacity: u64,
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popcount: AtomicU64, // Number of one bits in self.bits.
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}
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impl<const K: usize> Deduper<K> {
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pub fn new<R: Rng>(rng: &mut R, false_positive_rate: f64, num_bits: u64) -> Self {
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assert!(0.0 < false_positive_rate && false_positive_rate < 1.0);
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let size = usize::try_from(num_bits.checked_add(63).unwrap() / 64).unwrap();
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let capacity = num_bits as f64 * false_positive_rate.powf(1f64 / K as f64);
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Self {
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num_bits,
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seeds: std::array::from_fn(|_| rng.gen()),
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clock: Instant::now(),
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bits: repeat_with(AtomicU64::default).take(size).collect(),
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capacity: capacity as u64,
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popcount: AtomicU64::default(),
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}
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}
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pub fn maybe_reset<R: Rng>(&mut self, rng: &mut R, reset_cycle: &Duration) {
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let popcount = self.popcount.load(Ordering::Relaxed);
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if popcount >= self.capacity || &self.clock.elapsed() >= reset_cycle {
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self.seeds = std::array::from_fn(|_| rng.gen());
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self.clock = Instant::now();
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self.bits.fill_with(AtomicU64::default);
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self.popcount = AtomicU64::default();
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}
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}
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// Returns true if the packet is duplicate.
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#[must_use]
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#[allow(clippy::integer_arithmetic)]
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fn dedup_packet(&self, packet: &Packet) -> bool {
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// Should not dedup packet if already discarded.
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debug_assert!(!packet.meta().discard());
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let mut out = true;
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for seed in self.seeds {
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let mut hasher = AHasher::new_with_keys(seed.0, seed.1);
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packet.data(..).unwrap_or_default().hash(&mut hasher);
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let hash: u64 = hasher.finish() % self.num_bits;
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let index = (hash >> 6) as usize;
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let mask: u64 = 1u64 << (hash & 63);
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let old = self.bits[index].fetch_or(mask, Ordering::Relaxed);
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if old & mask == 0u64 {
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self.popcount.fetch_add(1, Ordering::Relaxed);
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out = false;
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}
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}
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out
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}
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pub fn dedup_packets_and_count_discards(
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&self,
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batches: &mut [PacketBatch],
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mut process_received_packet: impl FnMut(&mut Packet, bool, bool),
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) -> u64 {
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batches
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.iter_mut()
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.flat_map(PacketBatch::iter_mut)
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.map(|packet| {
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if packet.meta().discard() {
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process_received_packet(packet, true, false);
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} else if self.dedup_packet(packet) {
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packet.meta_mut().set_discard(true);
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process_received_packet(packet, false, true);
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} else {
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process_received_packet(packet, false, false);
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}
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u64::from(packet.meta().discard())
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})
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.sum()
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}
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}
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#[cfg(test)]
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#[allow(clippy::integer_arithmetic)]
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mod tests {
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use {
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super::*,
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crate::{packet::to_packet_batches, sigverify, test_tx::test_tx},
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rand::SeedableRng,
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rand_chacha::ChaChaRng,
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solana_sdk::packet::{Meta, PACKET_DATA_SIZE},
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test_case::test_case,
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};
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#[test]
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fn test_dedup_same() {
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let tx = test_tx();
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let mut batches =
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to_packet_batches(&std::iter::repeat(tx).take(1024).collect::<Vec<_>>(), 128);
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let packet_count = sigverify::count_packets_in_batches(&batches);
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let mut rng = rand::thread_rng();
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let filter = Deduper::<2>::new(
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&mut rng, /*false_positive_rate:*/ 0.001, /*num_bits:*/ 63_999_979,
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);
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let mut num_deduped = 0;
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let discard = filter.dedup_packets_and_count_discards(
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&mut batches,
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|_deduped_packet, _removed_before_sigverify_stage, _is_dup| {
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num_deduped += 1;
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},
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) as usize;
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assert_eq!(num_deduped, discard + 1);
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assert_eq!(packet_count, discard + 1);
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}
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#[test]
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fn test_dedup_diff() {
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let mut rng = rand::thread_rng();
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let mut filter = Deduper::<2>::new(
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&mut rng, /*false_positive_rate:*/ 0.001, /*num_bits:*/ 63_999_979,
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);
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let mut batches = to_packet_batches(&(0..1024).map(|_| test_tx()).collect::<Vec<_>>(), 128);
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let discard = filter.dedup_packets_and_count_discards(&mut batches, |_, _, _| ()) as usize;
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// because dedup uses a threadpool, there maybe up to N threads of txs that go through
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assert_eq!(discard, 0);
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filter.maybe_reset(&mut rng, /*reset_cycle:*/ &Duration::from_millis(0));
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for i in filter.bits {
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assert_eq!(i.load(Ordering::Relaxed), 0);
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}
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}
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#[test]
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#[ignore]
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fn test_dedup_saturated() {
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let mut rng = rand::thread_rng();
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let filter = Deduper::<2>::new(
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&mut rng, /*false_positive_rate:*/ 0.001, /*num_bits:*/ 63_999_979,
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);
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let mut discard = 0;
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assert!(filter.popcount.load(Ordering::Relaxed) < filter.capacity);
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for i in 0..1000 {
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let mut batches =
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to_packet_batches(&(0..1000).map(|_| test_tx()).collect::<Vec<_>>(), 128);
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discard += filter.dedup_packets_and_count_discards(&mut batches, |_, _, _| ()) as usize;
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trace!("{} {}", i, discard);
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if filter.popcount.load(Ordering::Relaxed) >= filter.capacity {
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break;
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}
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}
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assert!(filter.popcount.load(Ordering::Relaxed) >= filter.capacity);
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}
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#[test]
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fn test_dedup_false_positive() {
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let mut rng = rand::thread_rng();
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let filter = Deduper::<2>::new(
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&mut rng, /*false_positive_rate:*/ 0.001, /*num_bits:*/ 63_999_979,
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);
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let mut discard = 0;
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for i in 0..10 {
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let mut batches =
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to_packet_batches(&(0..1024).map(|_| test_tx()).collect::<Vec<_>>(), 128);
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discard += filter.dedup_packets_and_count_discards(&mut batches, |_, _, _| ()) as usize;
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debug!("false positive rate: {}/{}", discard, i * 1024);
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}
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//allow for 1 false positive even if extremely unlikely
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assert!(discard < 2);
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}
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#[test_case(63_999_979, 0.001, 2_023_857)]
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#[test_case(622_401_961, 0.001, 19_682_078)]
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#[test_case(622_401_979, 0.001, 19_682_078)]
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#[test_case(629_145_593, 0.001, 19_895_330)]
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#[test_case(632_455_543, 0.001, 20_000_000)]
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#[test_case(637_534_199, 0.001, 20_160_601)]
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#[test_case(622_401_961, 0.0001, 6_224_019)]
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#[test_case(622_401_979, 0.0001, 6_224_019)]
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#[test_case(629_145_593, 0.0001, 6_291_455)]
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#[test_case(632_455_543, 0.0001, 6_324_555)]
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#[test_case(637_534_199, 0.0001, 6_375_341)]
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fn test_dedup_capacity(num_bits: u64, false_positive_rate: f64, capacity: u64) {
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let mut rng = rand::thread_rng();
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let deduper = Deduper::<2>::new(&mut rng, false_positive_rate, num_bits);
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assert_eq!(deduper.capacity, capacity);
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}
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#[test_case([0xf9; 32], 3_199_997, 101_192, 51_414, 70, 101_125)]
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#[test_case([0xdc; 32], 3_200_003, 101_192, 51_414, 71, 101_132)]
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#[test_case([0xa5; 32], 6_399_971, 202_384, 102_828, 127, 202_157)]
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#[test_case([0xdb; 32], 6_400_013, 202_386, 102_828, 145, 202_277)]
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#[test_case([0xcd; 32], 12_799_987, 404_771, 205_655, 289, 404_434)]
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#[test_case([0xc3; 32], 12_800_009, 404_771, 205_656, 309, 404_278)]
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fn test_dedup_seeded(
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seed: [u8; 32],
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num_bits: u64,
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capacity: u64,
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num_packets: usize,
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num_dups: usize,
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popcount: u64,
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) {
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let mut rng = ChaChaRng::from_seed(seed);
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let deduper = Deduper::<2>::new(&mut rng, /*false_positive_rate:*/ 0.001, num_bits);
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assert_eq!(deduper.capacity, capacity);
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let mut packet = Packet::new([0u8; PACKET_DATA_SIZE], Meta::default());
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let mut dup_count = 0usize;
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for _ in 0..num_packets {
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let size = rng.gen_range(0, PACKET_DATA_SIZE);
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packet.meta_mut().size = size;
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rng.fill(&mut packet.buffer_mut()[0..size]);
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if deduper.dedup_packet(&packet) {
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dup_count += 1;
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}
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assert!(deduper.dedup_packet(&packet));
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}
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assert_eq!(dup_count, num_dups);
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assert_eq!(deduper.popcount.load(Ordering::Relaxed), popcount);
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}
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}
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