Method parent_change_count

atomic-repository/src/repository/views.rs:512–540

Get the parent view's change count for a given view. Returns `Some((parent_name, parent_change_count))` if the view has a parent, or `None` if it is a root view. This is used by `atomic log` to determine the fork point: changes with sequence numbers `>= parent_change_count` are local to the draft view, while those below were inherited when the view was created.

(
        &self,
        view_name: &str,
    )

    /// draft view, while those below were inherited when the view was
    /// created.
    pub fn parent_change_count(
        &self,
        view_name: &str,
    ) -> Result<Option<(String, u64)>, RepositoryError> {
        let txn = self
            .pristine
            .read_txn()
            .map_err(|e| RepositoryError::Database(e.to_string()))?;

        let view = txn
            .get_view(view_name)
            .map_err(|e| RepositoryError::Database(e.to_string()))?
            .ok_or_else(|| RepositoryError::ViewNotFound {
                name: view_name.to_string(),
            })?;

        match view.parent {
            Some(parent_id) => {
                let parent = txn
                    .get_view_by_id(parent_id)
                    .map_err(|e| RepositoryError::Database(e.to_string()))?
                    .ok_or_else(|| RepositoryError::ViewNotFound {
                        name: format!("<parent id {}>", parent_id),
                    })?;
                Ok(Some((parent.name.clone(), parent.change_count)))
            }
            None => Ok(None),
        }
    }

    /// Get information about a view.
    ///