Method scan_ids

atomic-core/src/pristine/txn/pristine.rs:239–279

Scan existing tables for the next available IDs. Shared implementation for `open_existing` and `open_readonly` — both skip the table-init write transaction and only need a read pass to discover the max allocated node, view, and inode IDs.

(db: Database)

    /// skip the table-init write transaction and only need a read pass to
    /// discover the max allocated node, view, and inode IDs.
    fn scan_ids(db: Database) -> PristineResult<Self> {
        let read_txn = db.begin_read()?;

        let next_node_id = {
            let table = read_txn.open_table(EXTERNAL)?;
            let mut max_id = 0u64;
            for result in table.iter()? {
                let (k, _) = result?;
                max_id = max_id.max(k.value());
            }
            AtomicU64::new(next_id(max_id)?)
        };

        let next_view_id = {
            let table = read_txn.open_table(VIEWS)?;
            let mut max_id = 0u64;
            for result in table.iter()? {
                let (_, value) = result?;
                let state = deserialize_view_state(value.value())?;
                max_id = max_id.max(state.id);
            }
            AtomicU64::new(next_id(max_id)?)
        };

        let next_inode = {
            let table = read_txn.open_table(INODES)?;
            let mut max_id = 0u64;
            for result in table.iter()? {
                let (k, _) = result?;
                max_id = max_id.max(k.value());
            }
            AtomicU64::new(next_id(max_id)?)
        };

        Ok(Self {
            db,
            next_node_id,
            next_view_id,
            next_inode,
        })
    }

    /// Begin a read-only transaction
    ///