solana_program/
slot_hashes.rs

1//! A type to hold data for the [`SlotHashes` sysvar][sv].
2//!
3//! [sv]: https://docs.solana.com/developing/runtime-facilities/sysvars#slothashes
4//!
5//! The sysvar ID is declared in [`sysvar::slot_hashes`].
6//!
7//! [`sysvar::slot_hashes`]: crate::slot_hashes
8
9pub use crate::clock::Slot;
10use {
11    crate::hash::Hash,
12    std::{
13        iter::FromIterator,
14        ops::Deref,
15        sync::atomic::{AtomicUsize, Ordering},
16    },
17};
18
19pub const MAX_ENTRIES: usize = 512; // about 2.5 minutes to get your vote in
20
21// This is to allow tests with custom slot hash expiry to avoid having to generate
22// 512 blocks for such tests.
23static NUM_ENTRIES: AtomicUsize = AtomicUsize::new(MAX_ENTRIES);
24
25pub fn get_entries() -> usize {
26    NUM_ENTRIES.load(Ordering::Relaxed)
27}
28
29pub fn set_entries_for_tests_only(entries: usize) {
30    NUM_ENTRIES.store(entries, Ordering::Relaxed);
31}
32
33pub type SlotHash = (Slot, Hash);
34
35#[repr(C)]
36#[derive(Serialize, Deserialize, PartialEq, Eq, Debug, Default)]
37pub struct SlotHashes(Vec<SlotHash>);
38
39impl SlotHashes {
40    pub fn add(&mut self, slot: Slot, hash: Hash) {
41        match self.binary_search_by(|(probe, _)| slot.cmp(probe)) {
42            Ok(index) => (self.0)[index] = (slot, hash),
43            Err(index) => (self.0).insert(index, (slot, hash)),
44        }
45        (self.0).truncate(get_entries());
46    }
47    pub fn position(&self, slot: &Slot) -> Option<usize> {
48        self.binary_search_by(|(probe, _)| slot.cmp(probe)).ok()
49    }
50    #[allow(clippy::trivially_copy_pass_by_ref)]
51    pub fn get(&self, slot: &Slot) -> Option<&Hash> {
52        self.binary_search_by(|(probe, _)| slot.cmp(probe))
53            .ok()
54            .map(|index| &self[index].1)
55    }
56    pub fn new(slot_hashes: &[SlotHash]) -> Self {
57        let mut slot_hashes = slot_hashes.to_vec();
58        slot_hashes.sort_by(|(a, _), (b, _)| b.cmp(a));
59        Self(slot_hashes)
60    }
61    pub fn slot_hashes(&self) -> &[SlotHash] {
62        &self.0
63    }
64}
65
66impl FromIterator<(Slot, Hash)> for SlotHashes {
67    fn from_iter<I: IntoIterator<Item = (Slot, Hash)>>(iter: I) -> Self {
68        Self(iter.into_iter().collect())
69    }
70}
71
72impl Deref for SlotHashes {
73    type Target = Vec<SlotHash>;
74    fn deref(&self) -> &Self::Target {
75        &self.0
76    }
77}
78
79#[cfg(test)]
80mod tests {
81    use {super::*, crate::hash::hash};
82
83    #[test]
84    fn test() {
85        let mut slot_hashes = SlotHashes::new(&[(1, Hash::default()), (3, Hash::default())]);
86        slot_hashes.add(2, Hash::default());
87        assert_eq!(
88            slot_hashes,
89            SlotHashes(vec![
90                (3, Hash::default()),
91                (2, Hash::default()),
92                (1, Hash::default()),
93            ])
94        );
95
96        let mut slot_hashes = SlotHashes::new(&[]);
97        for i in 0..MAX_ENTRIES + 1 {
98            slot_hashes.add(
99                i as u64,
100                hash(&[(i >> 24) as u8, (i >> 16) as u8, (i >> 8) as u8, i as u8]),
101            );
102        }
103        for i in 0..MAX_ENTRIES {
104            assert_eq!(slot_hashes[i].0, (MAX_ENTRIES - i) as u64);
105        }
106
107        assert_eq!(slot_hashes.len(), MAX_ENTRIES);
108    }
109}
solana_program/slot_hashes.rs

solana_program/
slot_hashes.rs
