Initial population of solana-program-sdk

sdk/program/src/slot_hashes.rs

@@ -0,0 +1,83 @@
+//! named accounts for synthesized data accounts for bank state, etc.
+//!
+//! this account carries the Bank's most recent bank hashes for some N parents
+//!
+use crate::hash::Hash;
+use std::{iter::FromIterator, ops::Deref};
+
+pub const MAX_ENTRIES: usize = 512; // about 2.5 minutes to get your vote in
+
+pub use crate::clock::Slot;
+
+pub type SlotHash = (Slot, Hash);
+
+#[repr(C)]
+#[derive(Serialize, Deserialize, PartialEq, Debug, Default)]
+pub struct SlotHashes(Vec<SlotHash>);
+
+impl SlotHashes {
+    pub fn add(&mut self, slot: Slot, hash: Hash) {
+        match self.binary_search_by(|(probe, _)| slot.cmp(&probe)) {
+            Ok(index) => (self.0)[index] = (slot, hash),
+            Err(index) => (self.0).insert(index, (slot, hash)),
+        }
+        (self.0).truncate(MAX_ENTRIES);
+    }
+    #[allow(clippy::trivially_copy_pass_by_ref)]
+    pub fn get(&self, slot: &Slot) -> Option<&Hash> {
+        self.binary_search_by(|(probe, _)| slot.cmp(&probe))
+            .ok()
+            .map(|index| &self[index].1)
+    }
+    pub fn new(slot_hashes: &[SlotHash]) -> Self {
+        let mut slot_hashes = slot_hashes.to_vec();
+        slot_hashes.sort_by(|(a, _), (b, _)| b.cmp(a));
+        Self(slot_hashes)
+    }
+}
+
+impl FromIterator<(Slot, Hash)> for SlotHashes {
+    fn from_iter<I: IntoIterator<Item = (Slot, Hash)>>(iter: I) -> Self {
+        Self(iter.into_iter().collect())
+    }
+}
+
+impl Deref for SlotHashes {
+    type Target = Vec<SlotHash>;
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::hash::hash;
+
+    #[test]
+    fn test() {
+        let mut slot_hashes = SlotHashes::new(&[(1, Hash::default()), (3, Hash::default())]);
+        slot_hashes.add(2, Hash::default());
+        assert_eq!(
+            slot_hashes,
+            SlotHashes(vec![
+                (3, Hash::default()),
+                (2, Hash::default()),
+                (1, Hash::default()),
+            ])
+        );
+
+        let mut slot_hashes = SlotHashes::new(&[]);
+        for i in 0..MAX_ENTRIES + 1 {
+            slot_hashes.add(
+                i as u64,
+                hash(&[(i >> 24) as u8, (i >> 16) as u8, (i >> 8) as u8, i as u8]),
+            );
+        }
+        for i in 0..MAX_ENTRIES {
+            assert_eq!(slot_hashes[i].0, (MAX_ENTRIES - i) as u64);
+        }
+
+        assert_eq!(slot_hashes.len(), MAX_ENTRIES);
+    }
+}