Function is_file_only_on_view

atomic-repository/src/repository/insert.rs:26–69

Check whether a file's creating change exists ONLY on the given view (and no other view). Returns `true` when it is safe to remove the file's TREE / INODES entries because no other view needs them. When the inode has no INODES position (not yet recorded) the function returns `true` — there is nothing to protect. # Complexity O(S × C) in the worst case, where S is the number of views and C is t

(
    txn: &T,
    inode: Inode,
    current_view: &str,
)

/// number of visible changes per view. Path deletion is uncommon, and using
/// the canonical inherited-view filter is required for correctness on drafts.
fn is_file_only_on_view<T: GraphTxnT + ViewTxnT + TreeTxnT>(
    txn: &T,
    inode: Inode,
    current_view: &str,
) -> bool {
    // Look up the position for this inode.  If there is no position the
    // file was never recorded, so removing from TREE is safe.
    let position = match txn.inode_position(inode) {
        Ok(Some(pos)) => pos,
        _ => return true,
    };

    let creating_change = position.change;
    if creating_change.is_root() {
        return true;
    }

    // Walk every view and check whether the creating change appears on
    // any view OTHER than `current_view`.
    let view_names = match txn.list_views() {
        Ok(names) => names,
        Err(_) => return true,
    };

    for name in view_names {
        if name == current_view {
            continue;
        }
        let view = match txn.get_view(&name) {
            Ok(Some(s)) => s,
            _ => continue,
        };
        if collect_visible_change_ids(txn, &view)
            .map(|ids| ids.contains(&creating_change))
            .unwrap_or(false)
        {
            // Another view still references this file — not safe to remove.
            return false;
        }
    }

    // No other view references the creating change.
    true
}

/// Timing details for the git-import fresh-write path.
#[derive(Debug, Clone, Copy, Default)]