1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
#![allow(clippy::integer_arithmetic)]
//!
//! slot history
//!
pub use crate::clock::Slot;
use bv::BitVec;
use bv::BitsMut;

#[repr(C)]
#[derive(Clone, Serialize, Deserialize, PartialEq)]
pub struct SlotHistory {
    pub bits: BitVec<u64>,
    pub next_slot: Slot,
}

impl Default for SlotHistory {
    fn default() -> Self {
        let mut bits = BitVec::new_fill(false, MAX_ENTRIES);
        bits.set(0, true);
        Self { bits, next_slot: 1 }
    }
}

impl std::fmt::Debug for SlotHistory {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(f, "SlotHistory {{ slot: {} bits:", self.next_slot)?;
        for i in 0..MAX_ENTRIES {
            if self.bits.get(i) {
                write!(f, "1")?;
            } else {
                write!(f, "0")?;
            }
        }
        Ok(())
    }
}

pub const MAX_ENTRIES: u64 = 1024 * 1024; // 1 million slots is about 5 days

#[derive(PartialEq, Debug)]
pub enum Check {
    Future,
    TooOld,
    Found,
    NotFound,
}

impl SlotHistory {
    pub fn add(&mut self, slot: Slot) {
        if slot > self.next_slot && slot - self.next_slot >= MAX_ENTRIES {
            // Wrapped past current history,
            // clear entire bitvec.
            let full_blocks = (MAX_ENTRIES as usize) / 64;
            for i in 0..full_blocks {
                self.bits.set_block(i, 0);
            }
        } else {
            for skipped in self.next_slot..slot {
                self.bits.set(skipped % MAX_ENTRIES, false);
            }
        }
        self.bits.set(slot % MAX_ENTRIES, true);
        self.next_slot = slot + 1;
    }

    pub fn check(&self, slot: Slot) -> Check {
        if slot > self.newest() {
            Check::Future
        } else if slot < self.oldest() {
            Check::TooOld
        } else if self.bits.get(slot % MAX_ENTRIES) {
            Check::Found
        } else {
            Check::NotFound
        }
    }

    pub fn oldest(&self) -> Slot {
        self.next_slot.saturating_sub(MAX_ENTRIES)
    }

    pub fn newest(&self) -> Slot {
        self.next_slot - 1
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use log::*;

    #[test]
    fn slot_history_test1() {
        solana_logger::setup();
        // should be divisible by 64 since the clear logic works on blocks
        assert_eq!(MAX_ENTRIES % 64, 0);
        let mut slot_history = SlotHistory::default();
        info!("add 2");
        slot_history.add(2);
        assert_eq!(slot_history.check(0), Check::Found);
        assert_eq!(slot_history.check(1), Check::NotFound);
        for i in 3..MAX_ENTRIES {
            assert_eq!(slot_history.check(i), Check::Future);
        }
        info!("add 20");
        slot_history.add(20);
        info!("add max_entries");
        slot_history.add(MAX_ENTRIES);
        assert_eq!(slot_history.check(0), Check::TooOld);
        assert_eq!(slot_history.check(1), Check::NotFound);
        for i in &[2, 20, MAX_ENTRIES] {
            assert_eq!(slot_history.check(*i), Check::Found);
        }
        for i in 3..20 {
            assert_eq!(slot_history.check(i), Check::NotFound, "i: {}", i);
        }
        for i in 21..MAX_ENTRIES {
            assert_eq!(slot_history.check(i), Check::NotFound, "i: {}", i);
        }
        assert_eq!(slot_history.check(MAX_ENTRIES + 1), Check::Future);

        info!("add max_entries + 3");
        let slot = 3 * MAX_ENTRIES + 3;
        slot_history.add(slot);
        for i in &[0, 1, 2, 20, 21, MAX_ENTRIES] {
            assert_eq!(slot_history.check(*i), Check::TooOld);
        }
        let start = slot - MAX_ENTRIES + 1;
        let end = slot;
        for i in start..end {
            assert_eq!(slot_history.check(i), Check::NotFound, "i: {}", i);
        }
        assert_eq!(slot_history.check(slot), Check::Found);
    }

    #[test]
    fn slot_history_test_wrap() {
        solana_logger::setup();
        let mut slot_history = SlotHistory::default();
        info!("add 2");
        slot_history.add(2);
        assert_eq!(slot_history.check(0), Check::Found);
        assert_eq!(slot_history.check(1), Check::NotFound);
        for i in 3..MAX_ENTRIES {
            assert_eq!(slot_history.check(i), Check::Future);
        }
        info!("add 20");
        slot_history.add(20);
        info!("add max_entries + 19");
        slot_history.add(MAX_ENTRIES + 19);
        for i in 0..19 {
            assert_eq!(slot_history.check(i), Check::TooOld);
        }
        assert_eq!(slot_history.check(MAX_ENTRIES), Check::NotFound);
        assert_eq!(slot_history.check(20), Check::Found);
        assert_eq!(slot_history.check(MAX_ENTRIES + 19), Check::Found);
        assert_eq!(slot_history.check(20), Check::Found);
        for i in 21..MAX_ENTRIES + 19 {
            assert_eq!(slot_history.check(i), Check::NotFound, "found: {}", i);
        }
        assert_eq!(slot_history.check(MAX_ENTRIES + 20), Check::Future);
    }

    #[test]
    fn slot_history_test_same_index() {
        solana_logger::setup();
        let mut slot_history = SlotHistory::default();
        info!("add 3,4");
        slot_history.add(3);
        slot_history.add(4);
        assert_eq!(slot_history.check(1), Check::NotFound);
        assert_eq!(slot_history.check(2), Check::NotFound);
        assert_eq!(slot_history.check(3), Check::Found);
        assert_eq!(slot_history.check(4), Check::Found);
        slot_history.add(MAX_ENTRIES + 5);
        assert_eq!(slot_history.check(5), Check::TooOld);
        for i in 6..MAX_ENTRIES + 5 {
            assert_eq!(slot_history.check(i), Check::NotFound, "i: {}", i);
        }
        assert_eq!(slot_history.check(MAX_ENTRIES + 5), Check::Found);
    }

    #[test]
    fn test_older_slot() {
        let mut slot_history = SlotHistory::default();
        slot_history.add(10);
        slot_history.add(5);
        assert_eq!(slot_history.check(0), Check::Found);
        assert_eq!(slot_history.check(5), Check::Found);
        // If we go backwards we reset?
        assert_eq!(slot_history.check(10), Check::Future);
        assert_eq!(slot_history.check(6), Check::Future);
        assert_eq!(slot_history.check(11), Check::Future);
    }

    #[test]
    fn test_oldest() {
        let mut slot_history = SlotHistory::default();
        assert_eq!(slot_history.oldest(), 0);
        slot_history.add(10);
        assert_eq!(slot_history.oldest(), 0);
        slot_history.add(MAX_ENTRIES - 1);
        assert_eq!(slot_history.oldest(), 0);
        slot_history.add(MAX_ENTRIES);
        assert_eq!(slot_history.oldest(), 1);
    }
}