iridium-db 0.4.0

A high-performance vector-graph hybrid storage and indexing engine
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#[derive(Debug, Clone)]
pub struct RunInfo {
    pub level: u32,
    pub run_id: u64,
    pub size_bytes: u64,
    pub max_delta_count: u32,
}

#[derive(Debug, Clone)]
pub struct GraphStats {
    pub hot_node_ids: Vec<u64>,
    pub max_pending_deltas: u32,
}

#[derive(Debug, Clone, PartialEq, Eq)]
pub struct CompactionDecision {
    pub source_level: u32,
    pub target_level: u32,
    pub run_ids: Vec<u64>,
    pub reason: String,
}

pub struct CompactionPolicy {
    pub max_deltas_per_node: u32,
    pub max_l0_runs: usize,
}

impl CompactionPolicy {
    pub fn new(max_deltas_per_node: u32, max_l0_runs: usize) -> Self {
        Self {
            max_deltas_per_node,
            max_l0_runs,
        }
    }

    pub fn select_compaction(
        &self,
        runs: &[RunInfo],
        stats: &GraphStats,
    ) -> Option<CompactionDecision> {
        if stats.max_pending_deltas >= self.max_deltas_per_node {
            let l0_runs: Vec<u64> = runs
                .iter()
                .filter(|r| r.level == 0)
                .map(|r| r.run_id)
                .collect();
            if !l0_runs.is_empty() {
                return Some(CompactionDecision {
                    source_level: 0,
                    target_level: 1,
                    run_ids: l0_runs,
                    reason: "max_pending_deltas exceeded".to_string(),
                });
            }
        }

        let l0_runs: Vec<u64> = runs
            .iter()
            .filter(|r| r.level == 0)
            .map(|r| r.run_id)
            .collect();
        if l0_runs.len() > self.max_l0_runs {
            return Some(CompactionDecision {
                source_level: 0,
                target_level: 1,
                run_ids: l0_runs,
                reason: "l0 run count exceeded".to_string(),
            });
        }

        None
    }
}

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

    #[test]
    fn compaction_triggers_on_pending_deltas() {
        let policy = CompactionPolicy::new(32, 4);
        let runs = vec![
            RunInfo {
                level: 0,
                run_id: 1,
                size_bytes: 1024,
                max_delta_count: 10,
            },
            RunInfo {
                level: 0,
                run_id: 2,
                size_bytes: 2048,
                max_delta_count: 50,
            },
        ];
        let stats = GraphStats {
            hot_node_ids: vec![7],
            max_pending_deltas: 40,
        };

        let decision = policy.select_compaction(&runs, &stats).unwrap();
        assert_eq!(decision.source_level, 0);
        assert_eq!(decision.target_level, 1);
        assert!(decision.run_ids.contains(&1));
        assert!(decision.run_ids.contains(&2));
    }

    #[test]
    fn compaction_triggers_on_l0_run_count() {
        let policy = CompactionPolicy::new(100, 2);
        let runs = vec![
            RunInfo {
                level: 0,
                run_id: 1,
                size_bytes: 100,
                max_delta_count: 1,
            },
            RunInfo {
                level: 0,
                run_id: 2,
                size_bytes: 100,
                max_delta_count: 1,
            },
            RunInfo {
                level: 0,
                run_id: 3,
                size_bytes: 100,
                max_delta_count: 1,
            },
        ];
        let stats = GraphStats {
            hot_node_ids: vec![],
            max_pending_deltas: 0,
        };

        let decision = policy.select_compaction(&runs, &stats).unwrap();
        assert_eq!(decision.run_ids.len(), 3);
    }
}