Interface GraphTxnT

atomic-core/src/pristine/traits/graph.rs:30–273

Read-only graph operations This is the base trait that provides read access to the repository graph. All other transaction traits extend this one. # Graph Structure The graph consists of: - **Vertices**: Ranges of content within changes, identified by (change_id, start, end) - **Edges**: Connections between vertices with flags indicating relationship type # ID System Atomic uses two ID system

///
/// This trait provides methods to translate between these two systems.
pub trait GraphTxnT {
    /// Iterator type for adjacency lists
    ///
    /// This returns edges from a span. The iterator yields `Result` to handle
    /// potential storage errors during iteration.
    type Adj: Iterator<Item = Result<SerializedGraphEdge, PristineError>>;

    /// Get the external hash for an internal node ID.
    ///
    /// Translates a repository-local NodeId to the globally-unique content hash.
    ///
    /// # Returns
    ///
    /// * `Ok(Some(hash))` - The corresponding hash
    /// * `Ok(None)` - The NodeId is not registered
    /// * `Err(_)` - Database error
    fn get_external(&self, id: NodeId) -> Result<Option<Hash>, PristineError>;

    /// Get the internal node ID for an external hash.
    ///
    /// Translates a globally-unique content hash to a repository-local NodeId.
    /// This is the inverse of `get_external`.
    fn get_internal(&self, hash: &Hash) -> Result<Option<NodeId>, PristineError>;

    /// List registered normal changes as `(NodeId, Hash)` pairs.
    ///
    /// Implementations backed by pristine should filter out tags,
    /// attestations, and provenance nodes. The default is empty for tests and
    /// lightweight mocks that do not model registration tables.
    fn list_registered_changes(&self) -> Result<Vec<(NodeId, Hash)>, PristineError> {
        Ok(Vec::new())
    }

    /// Initialize an adjacency iterator for a span.
    ///
    /// Returns an iterator over edges from the given span that have flags
    /// within the specified range. This allows filtering edges by type.
    ///
    /// # Arguments
    ///
    /// * `node` - The source span
    /// * `min_flag` - Minimum edge flags (inclusive)
    /// * `max_flag` - Maximum edge flags (inclusive)
    ///
    /// # Example
    ///
    /// ```ignore
    /// // Get all non-deleted block edges
    /// let edges = txn.iter_adjacent(
    ///     span,
    ///     EdgeFlags::BLOCK,
    ///     EdgeFlags::BLOCK | EdgeFlags::PSEUDO,
    /// )?;
    ///
    /// for result in edges {
    ///     let edge = result?;
    ///     println!("Edge to {:?}", edge.dest());
    /// }