sombra 0.3.6

High-performance graph database with ACID transactions, single-file storage, and bindings for Rust, TypeScript, and Python
Documentation 
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

use std::path::{Path, PathBuf};
use std::sync::mpsc::{self, Receiver, Sender};
use std::sync::{Arc, Mutex};
use std::thread;
use std::time::Duration;

use crate::db::metrics::PerformanceMetrics;
use crate::error::Result;
use crate::pager::Pager;
use crate::storage::heap::RecordStore;

pub enum CompactionMessage {
    Trigger,
    Shutdown,
}

pub struct CompactionConfig {
    pub enabled: bool,
    pub interval_secs: Option<u64>,
    pub threshold_percent: u8,
    pub batch_size: usize,
}

impl Default for CompactionConfig {
    fn default() -> Self {
        Self {
            enabled: false,
            interval_secs: Some(300),
            threshold_percent: 50,
            batch_size: 100,
        }
    }
}

pub struct CompactionState {
    pub sender: Sender<CompactionMessage>,
    pub _compaction_thread: Option<thread::JoinHandle<()>>,
}

impl CompactionState {
    pub fn spawn(
        db_path: PathBuf,
        config: CompactionConfig,
        metrics: Arc<Mutex<PerformanceMetrics>>,
    ) -> Result<Arc<Mutex<Self>>> {
        if !config.enabled {
            let (sender, _receiver) = mpsc::channel();
            return Ok(Arc::new(Mutex::new(CompactionState {
                sender,
                _compaction_thread: None,
            })));
        }

        let (sender, receiver) = mpsc::channel();

        let compaction_thread = thread::spawn(move || {
            Self::compaction_loop(db_path, receiver, config, metrics);
        });

        Ok(Arc::new(Mutex::new(CompactionState {
            sender,
            _compaction_thread: Some(compaction_thread),
        })))
    }

    pub fn trigger_compaction(&self) -> Result<()> {
        self.sender
            .send(CompactionMessage::Trigger)
            .map_err(|_| crate::error::GraphError::Corruption("compaction channel closed".into()))
    }

    pub fn shutdown(&self) -> Result<()> {
        self.sender
            .send(CompactionMessage::Shutdown)
            .map_err(|_| crate::error::GraphError::Corruption("compaction channel closed".into()))
    }

    fn compaction_loop(
        db_path: PathBuf,
        receiver: Receiver<CompactionMessage>,
        config: CompactionConfig,
        metrics: Arc<Mutex<PerformanceMetrics>>,
    ) {
        let interval = Duration::from_secs(config.interval_secs.unwrap_or(300));

        loop {
            match receiver.recv_timeout(interval) {
                Ok(CompactionMessage::Trigger) => {
                    let _ = Self::perform_compaction(db_path.as_path(), &config, &metrics);
                }
                Ok(CompactionMessage::Shutdown) => {
                    break;
                }
                Err(mpsc::RecvTimeoutError::Timeout) => {
                    let _ = Self::perform_compaction(db_path.as_path(), &config, &metrics);
                }
                Err(mpsc::RecvTimeoutError::Disconnected) => {
                    break;
                }
            }
        }
    }

    fn perform_compaction(
        db_path: &Path,
        config: &CompactionConfig,
        metrics: &Arc<Mutex<PerformanceMetrics>>,
    ) -> Result<()> {
        let mut pager = Pager::open(db_path)?;
        let mut store = RecordStore::new(&mut pager);

        let candidates =
            store.identify_compaction_candidates(config.threshold_percent, config.batch_size)?;

        if candidates.is_empty() {
            return Ok(());
        }

        let mut total_bytes_reclaimed = 0;
        let mut pages_compacted = 0;

        for page_id in candidates {
            match store.compact_page(page_id) {
                Ok(bytes_reclaimed) => {
                    total_bytes_reclaimed += bytes_reclaimed;
                    pages_compacted += 1;
                }
                Err(_) => {
                    continue;
                }
            }
        }

        pager.flush()?;

        if let Ok(mut m) = metrics.lock() {
            m.compactions_performed += 1;
            m.pages_compacted += pages_compacted;
            m.bytes_reclaimed += total_bytes_reclaimed as u64;
        }

        Ok(())
    }
}