solana_slot_hashes/
lib.rs

1//! A type to hold data for the [`SlotHashes` sysvar][sv].
2//!
3//! [sv]: https://docs.solanalabs.com/runtime/sysvars#slothashes
4//!
5//! The sysvar ID is declared in [`solana_program::sysvar::slot_hashes`].
6//!
7//! [`solana_program::sysvar::slot_hashes`]: https://docs.rs/solana-program/latest/solana_program/sysvar/slot_hashes/index.html
8#![cfg_attr(docsrs, feature(doc_cfg))]
9
10#[cfg(feature = "sysvar")]
11pub mod sysvar;
12
13use {
14    solana_hash::Hash,
15    std::{
16        iter::FromIterator,
17        ops::Deref,
18        sync::atomic::{AtomicUsize, Ordering},
19    },
20};
21
22pub const MAX_ENTRIES: usize = 512; // about 2.5 minutes to get your vote in
23
24// This is to allow tests with custom slot hash expiry to avoid having to generate
25// 512 blocks for such tests.
26static NUM_ENTRIES: AtomicUsize = AtomicUsize::new(MAX_ENTRIES);
27
28pub fn get_entries() -> usize {
29    NUM_ENTRIES.load(Ordering::Relaxed)
30}
31
32pub fn set_entries_for_tests_only(entries: usize) {
33    NUM_ENTRIES.store(entries, Ordering::Relaxed);
34}
35
36pub type SlotHash = (u64, Hash);
37
38const LEN_PREFIX: usize = size_of::<u64>();
39const SLOT_HASH_SERIALIZED_SIZE: usize = size_of::<u64>() + size_of::<Hash>();
40
41/// Serialized size of the `SlotHashes` sysvar account.
42pub const SIZE: usize = LEN_PREFIX + MAX_ENTRIES * SLOT_HASH_SERIALIZED_SIZE;
43const _: () = assert!(SIZE == 20_488);
44
45#[repr(C)]
46#[cfg_attr(
47    feature = "serde",
48    derive(serde_derive::Deserialize, serde_derive::Serialize)
49)]
50#[cfg_attr(feature = "wincode", derive(wincode::SchemaWrite, wincode::SchemaRead))]
51#[derive(PartialEq, Eq, Debug, Default)]
52pub struct SlotHashes(Vec<SlotHash>);
53
54impl SlotHashes {
55    pub fn add(&mut self, slot: u64, hash: Hash) {
56        match self.binary_search_by(|(probe, _)| slot.cmp(probe)) {
57            Ok(index) => (self.0)[index] = (slot, hash),
58            Err(index) => (self.0).insert(index, (slot, hash)),
59        }
60        (self.0).truncate(get_entries());
61    }
62    pub fn position(&self, slot: &u64) -> Option<usize> {
63        self.binary_search_by(|(probe, _)| slot.cmp(probe)).ok()
64    }
65    #[allow(clippy::trivially_copy_pass_by_ref)]
66    pub fn get(&self, slot: &u64) -> Option<&Hash> {
67        self.binary_search_by(|(probe, _)| slot.cmp(probe))
68            .ok()
69            .map(|index| &self[index].1)
70    }
71    pub fn new(slot_hashes: &[SlotHash]) -> Self {
72        let mut slot_hashes = slot_hashes.to_vec();
73        slot_hashes.sort_by(|(a, _), (b, _)| b.cmp(a));
74        Self(slot_hashes)
75    }
76    pub fn slot_hashes(&self) -> &[SlotHash] {
77        &self.0
78    }
79}
80
81impl FromIterator<(u64, Hash)> for SlotHashes {
82    fn from_iter<I: IntoIterator<Item = (u64, Hash)>>(iter: I) -> Self {
83        Self(iter.into_iter().collect())
84    }
85}
86
87impl Deref for SlotHashes {
88    type Target = Vec<SlotHash>;
89    fn deref(&self) -> &Self::Target {
90        &self.0
91    }
92}
93
94#[cfg(test)]
95mod tests {
96    use {super::*, solana_sha256_hasher::hash};
97
98    #[test]
99    fn test_size_of() {
100        let slot_hashes = SlotHashes(vec![(0, Hash::default()); MAX_ENTRIES]);
101        assert_eq!(
102            wincode::serialized_size(&slot_hashes).unwrap() as usize,
103            SIZE,
104        );
105    }
106
107    #[test]
108    fn test() {
109        let mut slot_hashes = SlotHashes::new(&[(1, Hash::default()), (3, Hash::default())]);
110        slot_hashes.add(2, Hash::default());
111        assert_eq!(
112            slot_hashes,
113            SlotHashes(vec![
114                (3, Hash::default()),
115                (2, Hash::default()),
116                (1, Hash::default()),
117            ])
118        );
119
120        let mut slot_hashes = SlotHashes::new(&[]);
121        for i in 0..MAX_ENTRIES + 1 {
122            slot_hashes.add(
123                i as u64,
124                hash(&[(i >> 24) as u8, (i >> 16) as u8, (i >> 8) as u8, i as u8]),
125            );
126        }
127        for i in 0..MAX_ENTRIES {
128            assert_eq!(slot_hashes[i].0, (MAX_ENTRIES - i) as u64);
129        }
130
131        assert_eq!(slot_hashes.len(), MAX_ENTRIES);
132    }
133}
solana_slot_hashes/lib.rs

solana_slot_hashes/
lib.rs
