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saving the header

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This commit is contained in:
bronku 2025-12-14 00:25:52 +01:00
parent 5bb846a53e
commit d54d86d948
2 changed files with 22 additions and 9 deletions
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29
src/btree.rs
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@ -5,7 +5,7 @@ use crate::storage::Storage;
pub struct BPlusTree<S> { pub struct BPlusTree<S> {
storage: S, storage: S,
root_loc: usize, header: HeaderNode,
} }
impl<S> BPlusTree<S> impl<S> BPlusTree<S>
@ -13,16 +13,25 @@ where
S: Storage, S: Storage,
{ {
pub fn open(mut storage: S) -> Self { pub fn open(mut storage: S) -> Self {
let root = Node::Leaf(LeafNode::new()); let header: HeaderNode = if storage.total_nodes() == 0 {
storage.write_node(0, &root); let header = HeaderNode { root: 1 };
storage.write_node(0, &Node::Header(header.clone()));
storage.write_node(1, &Node::Leaf(LeafNode::new()));
header
} else {
match storage.read_node(0).unwrap() {
Node::Header(n) => n,
_ => panic!("first node must be header"),
}
};
BPlusTree { BPlusTree {
storage, storage,
root_loc: 0, header: header,
} }
} }
pub fn find(&mut self, key: i32) -> Option<Record> { pub fn find(&mut self, key: i32) -> Option<Record> {
let mut current_loc = self.root_loc; let mut current_loc = self.header.root;
loop { loop {
let node = self.storage.read_node(current_loc)?; let node = self.storage.read_node(current_loc)?;
match node { match node {
@ -51,7 +60,7 @@ where
pub fn insert(&mut self, value: Record) { pub fn insert(&mut self, value: Record) {
let key = value[0]; let key = value[0];
let mut path = Vec::new(); let mut path = Vec::new();
let mut current_loc = self.root_loc; let mut current_loc = self.header.root;
let mut current_node = self.storage.read_node(current_loc).unwrap(); let mut current_node = self.storage.read_node(current_loc).unwrap();
while let Node::Internal(internal) = current_node { while let Node::Internal(internal) = current_node {
@ -122,7 +131,9 @@ where
}); });
let new_root_loc = self.storage.total_nodes(); let new_root_loc = self.storage.total_nodes();
self.storage.write_node(new_root_loc, &new_root); self.storage.write_node(new_root_loc, &new_root);
self.root_loc = new_root_loc; self.header.root = new_root_loc;
self.storage
.write_node(0, &Node::Header(self.header.clone()));
} else { } else {
self.insert_into_parent(new_key, new_leaf_loc, path); self.insert_into_parent(new_key, new_leaf_loc, path);
} }
@ -184,7 +195,9 @@ where
}); });
let new_root_loc = self.storage.total_nodes(); let new_root_loc = self.storage.total_nodes();
self.storage.write_node(new_root_loc, &new_root); self.storage.write_node(new_root_loc, &new_root);
self.root_loc = new_root_loc; self.header.root = new_root_loc;
self.storage
.write_node(0, &Node::Header(self.header.clone()));
} else { } else {
self.insert_into_parent(new_key, new_internal_loc, path); self.insert_into_parent(new_key, new_internal_loc, path);
} }

2
src/node.rs
View file

@ -12,7 +12,7 @@ pub enum Node {
#[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)] #[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)]
pub struct HeaderNode { pub struct HeaderNode {
pub root: i32, pub root: usize,
} }
#[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)] #[derive(Debug, Clone, Encode, Decode, PartialEq, Eq)]