db.rs refactor

crates/pdfs-core/src/db/cache.rs

@@ -0,0 +1,126 @@
+//! The content-cache index: one row per cached blob, carrying the access stamp
+//! the LRU eviction pass sorts on.
+
+use rusqlite::params;
+
+use super::Db;
+use crate::Result;
+
+pub struct CacheEntryInput<'a> {
+    /// On-disk filename of the blob or block.
+    pub key: &'a str,
+    /// `'blob'` or `'block'` — the two byte budgets are counted separately.
+    pub kind: &'a str,
+    pub size: u64,
+    /// Initial LRU key, in unix milliseconds.
+    pub last_accessed: i64,
+}
+
+impl Db {
+    pub fn cache_touch(&self, key: &str, kind: &str, size: u64, now: i64) -> Result<()> {
+        let conn = self.conn.lock();
+        conn.execute(
+            "INSERT INTO cache_entries (cache_key, kind, size_bytes, last_accessed)
+             VALUES (?1, ?2, ?3, ?4)
+             ON CONFLICT(cache_key) DO UPDATE SET
+               kind          = excluded.kind,
+               size_bytes    = excluded.size_bytes,
+               last_accessed = excluded.last_accessed",
+            params![key, kind, size as i64, now],
+        )?;
+        Ok(())
+    }
+
+    /// Bump only `last_accessed` on a cache hit (LRU ordering). A missing row is
+    /// a no-op — best effort, mirroring the old best-effort mtime touch.
+    pub fn cache_accessed(&self, key: &str, now: i64) -> Result<()> {
+        let conn = self.conn.lock();
+        conn.execute(
+            "UPDATE cache_entries SET last_accessed = ?2 WHERE cache_key = ?1",
+            params![key, now],
+        )?;
+        Ok(())
+    }
+
+    /// Drop a single cache-entry row (one evicted blob or block).
+    pub fn cache_remove(&self, key: &str) -> Result<()> {
+        let conn = self.conn.lock();
+        conn.execute(
+            "DELETE FROM cache_entries WHERE cache_key = ?1",
+            params![key],
+        )?;
+        Ok(())
+    }
+
+    /// Drop the whole-file blob row for `key` plus every block row for the same
+    /// uid (`<key>.b<idx>`). Called by `ContentCache::evict`, which removes the
+    /// blob and all of a uid's cached blocks at once.
+    pub fn cache_remove_all(&self, key: &str) -> Result<()> {
+        let conn = self.conn.lock();
+        conn.execute(
+            "DELETE FROM cache_entries WHERE cache_key = ?1 OR cache_key LIKE ?2",
+            params![key, format!("{key}.b%")],
+        )?;
+        Ok(())
+    }
+
+    /// Every cache entry of `kind`, ordered least-recently-accessed first, as
+    /// `(cache_key, size_bytes)`. The budget enforcer sums the sizes and evicts
+    /// from the front until the cache fits.
+    pub fn cache_entries_by_kind(&self, kind: &str) -> Result<Vec<(String, u64)>> {
+        let conn = self.conn.lock();
+        let mut stmt = conn.prepare(
+            "SELECT cache_key, size_bytes FROM cache_entries
+             WHERE kind = ?1 ORDER BY last_accessed ASC",
+        )?;
+        let rows = stmt.query_map(params![kind], |r| {
+            Ok((r.get::<_, String>(0)?, r.get::<_, i64>(1)?.max(0) as u64))
+        })?;
+        let mut out = Vec::new();
+        for r in rows {
+            out.push(r?);
+        }
+        Ok(out)
+    }
+
+    /// Replace the whole cache index with `entries`, as one transaction. The
+    /// daemon calls this on open, so a crash or an external file deletion can
+    /// never leave a phantom row inflating the budget total.
+    ///
+    /// The clear and the refill are the same commit deliberately: they are one
+    /// operation — "the index now describes what is on disk" — and a crash
+    /// between them would otherwise leave an empty index against a full cache
+    /// directory, i.e. a budget total of zero and nothing eviction can see.
+    ///
+    /// One commit also matters for speed. A mount is the only caller and it runs
+    /// on the open path, so a cache of thousands of blobs used to pay thousands
+    /// of autocommit fsyncs before the mountpoint appeared.
+    pub fn cache_rebuild(&self, entries: &[CacheEntryInput<'_>]) -> Result<()> {
+        let mut conn = self.conn.lock();
+        let tx = conn.transaction()?;
+        tx.execute("DELETE FROM cache_entries", [])?;
+        {
+            let mut stmt = tx.prepare(
+                "INSERT INTO cache_entries (cache_key, kind, size_bytes, last_accessed)
+                 VALUES (?1, ?2, ?3, ?4)
+                 ON CONFLICT(cache_key) DO UPDATE SET
+                   kind          = excluded.kind,
+                   size_bytes    = excluded.size_bytes,
+                   last_accessed = excluded.last_accessed",
+            )?;
+            for e in entries {
+                stmt.execute(params![e.key, e.kind, e.size as i64, e.last_accessed])?;
+            }
+        }
+        tx.commit()?;
+        Ok(())
+    }
+
+    // --- Pins (P5) --------------------------------------------------------
+    //
+    // The pin registry, formerly `pins.json`. One row per directly-pinned node,
+    // keyed by uid display string. `recursive` marks a folder pin: its whole
+    // subtree counts as pinned, resolved against `nodes` via a CTE so a new
+    // descendant is covered the moment it lands in the node cache.
+
+}