use super::*;
#[derive(Default, Debug)]
pub struct BLinkMaterializer {
pub(super) roots: Mutex<Vec<(PageID, PageID)>>,
}
impl Materializer for BLinkMaterializer {
type PageFrag = Frag;
type Recovery = Vec<(PageID, PageID)>;
fn new(last_roots: &Option<Self::Recovery>) -> Self {
let roots: Vec<(PageID, PageID)> =
last_roots.clone().unwrap_or_else(|| vec![]);
BLinkMaterializer {
roots: Mutex::new(roots),
}
}
fn merge(&self, frags: &[&Frag]) -> Frag {
let (mut base_node, is_root) = match frags[0].clone() {
Frag::Base(base_node, is_root) => (base_node, is_root),
_ => panic!("non-Base in first element of frags slice"),
};
for &frag in &frags[1..] {
base_node.apply(frag);
}
Frag::Base(base_node, is_root)
}
fn recover(&self, frag: &Frag) -> Option<Vec<(PageID, PageID)>> {
match *frag {
Frag::Base(ref node, prev_root) => {
if let Some(prev_root) = prev_root {
let mut roots = self.roots.lock().unwrap();
if !roots.contains(&(node.id, prev_root)) {
roots.push((node.id, prev_root));
return Some(roots.clone());
}
}
}
_ => (),
}
None
}
}