2018-02-18 08:59:15 -08:00
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//! The `log` crate provides the foundational data structures for Proof-of-History,
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//! an ordered log of events in time.
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2018-02-15 09:13:56 -08:00
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2018-02-18 08:59:15 -08:00
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/// Each log entry contains three pieces of data. The 'num_hashes' field is the number
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2018-03-04 06:34:38 -08:00
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/// of hashes performed since the previous entry. The 'id' field is the result
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/// of hashing 'id' from the previous entry 'num_hashes' times. The 'event'
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/// field points to an Event that took place shortly after 'id' was generated.
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2018-02-15 09:13:56 -08:00
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///
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2018-02-15 09:48:30 -08:00
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/// If you divide 'num_hashes' by the amount of time it takes to generate a new hash, you
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2018-02-15 09:13:56 -08:00
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/// get a duration estimate since the last event. Since processing power increases
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2018-02-15 09:48:30 -08:00
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/// over time, one should expect the duration 'num_hashes' represents to decrease proportionally.
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2018-02-15 09:13:56 -08:00
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/// Though processing power varies across nodes, the network gives priority to the
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/// fastest processor. Duration should therefore be estimated by assuming that the hash
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/// was generated by the fastest processor at the time the entry was logged.
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2018-02-19 15:17:13 -08:00
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2018-03-06 16:31:17 -08:00
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use hash::Sha256Hash;
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2018-02-26 15:42:31 -08:00
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use serde::Serialize;
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2018-03-06 16:31:17 -08:00
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use entry::{create_entry_mut, next_tick, Entry};
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2018-03-06 11:26:39 -08:00
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use event::Event;
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2018-03-04 06:28:51 -08:00
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use rayon::prelude::*;
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2018-02-26 15:42:31 -08:00
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2018-02-15 09:13:56 -08:00
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/// Verifies the hashes and counts of a slice of events are all consistent.
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2018-02-26 14:37:33 -08:00
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pub fn verify_slice(events: &[Entry<Sha256Hash>], start_hash: &Sha256Hash) -> bool {
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2018-02-19 15:17:13 -08:00
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let genesis = [Entry::new_tick(Default::default(), start_hash)];
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2018-02-15 09:13:56 -08:00
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let event_pairs = genesis.par_iter().chain(events).zip(events);
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2018-03-06 11:35:12 -08:00
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event_pairs.all(|(x0, x1)| x1.verify(&x0.id))
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2018-02-15 09:13:56 -08:00
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}
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2018-02-28 17:04:35 -08:00
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/// Verifies the hashes and counts of a slice of events are all consistent.
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2018-03-05 16:29:32 -08:00
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pub fn verify_slice_i64(events: &[Entry<i64>], start_hash: &Sha256Hash) -> bool {
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2018-02-28 17:04:35 -08:00
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let genesis = [Entry::new_tick(Default::default(), start_hash)];
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let event_pairs = genesis.par_iter().chain(events).zip(events);
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2018-03-06 11:35:12 -08:00
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event_pairs.all(|(x0, x1)| x1.verify(&x0.id))
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2018-02-28 17:04:35 -08:00
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}
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2018-02-15 09:13:56 -08:00
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/// Verifies the hashes and events serially. Exists only for reference.
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2018-02-26 15:42:31 -08:00
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pub fn verify_slice_seq<T: Serialize>(events: &[Entry<T>], start_hash: &Sha256Hash) -> bool {
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2018-02-18 08:53:38 -08:00
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let genesis = [Entry::new_tick(0, start_hash)];
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2018-02-15 15:00:05 -08:00
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let mut event_pairs = genesis.iter().chain(events).zip(events);
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2018-03-06 11:35:12 -08:00
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event_pairs.all(|(x0, x1)| x1.verify(&x0.id))
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2018-02-15 09:13:56 -08:00
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}
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2018-02-26 15:42:31 -08:00
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pub fn create_entries<T: Serialize>(
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2018-02-26 14:31:01 -08:00
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start_hash: &Sha256Hash,
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2018-02-26 15:42:31 -08:00
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events: Vec<Event<T>>,
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) -> Vec<Entry<T>> {
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2018-03-04 06:34:38 -08:00
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let mut id = *start_hash;
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2018-02-26 10:01:19 -08:00
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events
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2018-02-26 15:42:31 -08:00
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.into_iter()
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2018-03-04 13:30:39 -08:00
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.map(|event| create_entry_mut(&mut id, &mut 0, event))
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2018-02-26 10:01:19 -08:00
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.collect()
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}
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2018-02-15 10:50:48 -08:00
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/// Create a vector of Ticks of length 'len' from 'start_hash' hash and 'num_hashes'.
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2018-03-04 13:30:39 -08:00
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pub fn next_ticks(start_hash: &Sha256Hash, num_hashes: u64, len: usize) -> Vec<Entry<Sha256Hash>> {
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2018-03-04 06:34:38 -08:00
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let mut id = *start_hash;
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2018-03-04 13:30:39 -08:00
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let mut ticks = vec![];
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for _ in 0..len {
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let entry = next_tick(&id, num_hashes);
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id = entry.id;
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ticks.push(entry);
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}
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ticks
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2018-02-15 09:13:56 -08:00
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}
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2018-02-15 16:47:05 -08:00
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#[cfg(test)]
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mod tests {
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use super::*;
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2018-03-06 11:48:26 -08:00
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use signature::{generate_keypair, get_pubkey};
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2018-03-06 15:34:14 -08:00
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use transaction::Transaction;
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2018-03-06 16:31:17 -08:00
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use hash::hash;
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2018-02-15 16:47:05 -08:00
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2018-02-26 14:37:33 -08:00
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fn verify_slice_generic(verify_slice: fn(&[Entry<Sha256Hash>], &Sha256Hash) -> bool) {
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2018-02-19 15:17:13 -08:00
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let zero = Sha256Hash::default();
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let one = hash(&zero);
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assert!(verify_slice(&vec![], &zero)); // base case
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assert!(verify_slice(&vec![Entry::new_tick(0, &zero)], &zero)); // singleton case 1
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assert!(!verify_slice(&vec![Entry::new_tick(0, &zero)], &one)); // singleton case 2, bad
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2018-03-04 13:30:39 -08:00
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assert!(verify_slice(&next_ticks(&zero, 0, 2), &zero)); // inductive step
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2018-02-19 15:17:13 -08:00
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2018-03-04 13:30:39 -08:00
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let mut bad_ticks = next_ticks(&zero, 0, 2);
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2018-03-04 06:34:38 -08:00
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bad_ticks[1].id = one;
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2018-02-19 15:17:13 -08:00
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assert!(!verify_slice(&bad_ticks, &zero)); // inductive step, bad
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2018-02-16 08:14:42 -08:00
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}
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#[test]
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fn test_verify_slice() {
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verify_slice_generic(verify_slice);
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2018-02-15 16:47:05 -08:00
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}
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2018-02-16 08:14:42 -08:00
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#[test]
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fn test_verify_slice_seq() {
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2018-02-26 15:42:31 -08:00
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verify_slice_generic(verify_slice_seq::<Sha256Hash>);
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2018-02-16 08:14:42 -08:00
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}
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2018-02-20 13:46:36 -08:00
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#[test]
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fn test_reorder_attack() {
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let zero = Sha256Hash::default();
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let one = hash(&zero);
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2018-03-02 09:58:43 -08:00
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// First, verify entries
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2018-03-01 16:01:55 -08:00
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let keypair = generate_keypair();
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2018-03-06 15:34:14 -08:00
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let tr0 = Transaction::new(&keypair, get_pubkey(&keypair), zero, zero);
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let tr1 = Transaction::new(&keypair, get_pubkey(&keypair), one, zero);
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let events = vec![Event::Transaction(tr0), Event::Transaction(tr1)];
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2018-03-04 13:30:39 -08:00
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let mut entries = create_entries(&zero, events);
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2018-02-24 05:53:36 -08:00
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assert!(verify_slice(&entries, &zero));
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2018-02-20 13:46:36 -08:00
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2018-03-02 09:58:43 -08:00
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// Next, swap two events and ensure verification fails.
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2018-02-20 13:46:36 -08:00
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let event0 = entries[0].event.clone();
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let event1 = entries[1].event.clone();
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entries[0].event = event1;
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entries[1].event = event0;
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2018-02-24 05:53:36 -08:00
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assert!(!verify_slice(&entries, &zero));
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2018-02-20 13:46:36 -08:00
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}
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2018-02-15 16:47:05 -08:00
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}
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2018-02-15 09:13:56 -08:00
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#[cfg(all(feature = "unstable", test))]
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mod bench {
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extern crate test;
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use self::test::Bencher;
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2018-02-18 08:59:15 -08:00
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use log::*;
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2018-02-15 09:13:56 -08:00
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#[bench]
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fn event_bench(bencher: &mut Bencher) {
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2018-02-19 15:17:13 -08:00
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let start_hash = Default::default();
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2018-03-04 13:30:39 -08:00
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let events = next_ticks(&start_hash, 10_000, 8);
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2018-02-16 09:38:12 -08:00
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bencher.iter(|| {
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2018-02-19 15:17:13 -08:00
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assert!(verify_slice(&events, &start_hash));
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2018-02-16 09:38:12 -08:00
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});
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}
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#[bench]
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fn event_bench_seq(bencher: &mut Bencher) {
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2018-02-19 15:17:13 -08:00
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let start_hash = Default::default();
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2018-03-04 13:30:39 -08:00
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let events = next_ticks(&start_hash, 10_000, 8);
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2018-02-15 09:13:56 -08:00
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bencher.iter(|| {
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2018-02-26 16:03:50 -08:00
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assert!(verify_slice_seq(&events, &start_hash));
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2018-02-15 09:13:56 -08:00
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});
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}
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}
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