mdql_core/
cache.rs

1//! Per-file mtime-based caching for parsed rows.
2
3use std::collections::HashMap;
4use std::path::Path;
5use std::time::SystemTime;
6
7use crate::model::Row;
8
9/// Cached row with its file mtime at parse time.
10#[derive(Debug)]
11struct CachedRow {
12    mtime: SystemTime,
13    row: Row,
14}
15
16/// Per-table cache that tracks file mtimes to avoid re-parsing unchanged files.
17#[derive(Debug)]
18pub struct TableCache {
19    rows: HashMap<String, CachedRow>,
20    table_mtime: Option<SystemTime>,
21}
22
23impl TableCache {
24    pub fn new() -> Self {
25        TableCache {
26            rows: HashMap::new(),
27            table_mtime: None,
28        }
29    }
30
31    /// Get a cached row if the file hasn't been modified since caching.
32    pub fn get(&self, path: &str, current_mtime: SystemTime) -> Option<&Row> {
33        self.rows.get(path).and_then(|cached| {
34            if cached.mtime == current_mtime {
35                Some(&cached.row)
36            } else {
37                None
38            }
39        })
40    }
41
42    /// Store a row in the cache with its file mtime.
43    pub fn put(&mut self, path: String, mtime: SystemTime, row: Row) {
44        self.rows.insert(path, CachedRow { mtime, row });
45    }
46
47    /// Remove a cached entry (e.g., after delete).
48    pub fn remove(&mut self, path: &str) {
49        self.rows.remove(path);
50    }
51
52    /// Check if the table directory has been modified since last cache update.
53    pub fn is_stale(&self, table_dir: &Path) -> bool {
54        let current = dir_mtime(table_dir);
55        match (self.table_mtime, current) {
56            (Some(cached), Some(now)) => cached != now,
57            (None, _) => true, // Never cached
58            (_, None) => true, // Can't read dir mtime
59        }
60    }
61
62    /// Update the cached table-directory mtime.
63    pub fn set_table_mtime(&mut self, table_dir: &Path) {
64        self.table_mtime = dir_mtime(table_dir);
65    }
66
67    /// Clear all cached entries.
68    pub fn invalidate_all(&mut self) {
69        self.rows.clear();
70        self.table_mtime = None;
71    }
72
73    /// Number of cached rows.
74    pub fn len(&self) -> usize {
75        self.rows.len()
76    }
77
78    /// Whether the cache is empty.
79    pub fn is_empty(&self) -> bool {
80        self.rows.is_empty()
81    }
82
83    /// All cached paths.
84    pub fn cached_paths(&self) -> Vec<&str> {
85        self.rows.keys().map(|s| s.as_str()).collect()
86    }
87}
88
89impl Default for TableCache {
90    fn default() -> Self {
91        Self::new()
92    }
93}
94
95fn dir_mtime(path: &Path) -> Option<SystemTime> {
96    std::fs::metadata(path)
97        .and_then(|m| m.modified())
98        .ok()
99}
100
101/// Get the mtime of a file, returning None if it can't be read.
102pub fn file_mtime(path: &Path) -> Option<SystemTime> {
103    std::fs::metadata(path)
104        .and_then(|m| m.modified())
105        .ok()
106}
107
108#[cfg(test)]
109mod tests {
110    use super::*;
111    use crate::model::Value;
112    use std::time::Duration;
113
114    #[test]
115    fn test_cache_hit_and_miss() {
116        let mut cache = TableCache::new();
117        let mtime = SystemTime::UNIX_EPOCH + Duration::from_secs(1000);
118        let row = Row::from([
119            ("path".into(), Value::String("test.md".into())),
120            ("title".into(), Value::String("Hello".into())),
121        ]);
122
123        cache.put("test.md".into(), mtime, row);
124
125        // Hit: same mtime
126        assert!(cache.get("test.md", mtime).is_some());
127
128        // Miss: different mtime
129        let later = mtime + Duration::from_secs(1);
130        assert!(cache.get("test.md", later).is_none());
131    }
132
133    #[test]
134    fn test_remove() {
135        let mut cache = TableCache::new();
136        let mtime = SystemTime::UNIX_EPOCH + Duration::from_secs(1000);
137        let row = Row::from([("path".into(), Value::String("test.md".into()))]);
138        cache.put("test.md".into(), mtime, row);
139        assert_eq!(cache.len(), 1);
140
141        cache.remove("test.md");
142        assert_eq!(cache.len(), 0);
143    }
144
145    #[test]
146    fn test_invalidate_all() {
147        let mut cache = TableCache::new();
148        let mtime = SystemTime::UNIX_EPOCH;
149        cache.put("a.md".into(), mtime, Row::new());
150        cache.put("b.md".into(), mtime, Row::new());
151        assert_eq!(cache.len(), 2);
152
153        cache.invalidate_all();
154        assert!(cache.is_empty());
155    }
156}
mdql_core/cache.rs

mdql_core/
cache.rs
