389 lines
13 KiB
Rust
389 lines
13 KiB
Rust
use memorydb::*;
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use sha3::*;
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use hashdb::*;
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use hash::*;
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use nibbleslice::*;
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use bytes::*;
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use rlp::*;
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//use log::*;
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pub const NULL_RLP: [u8; 1] = [0x80; 1];
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pub const SHA3_NULL_RLP: H256 = H256( [0x56, 0xe8, 0x1f, 0x17, 0x1b, 0xcc, 0x55, 0xa6, 0xff, 0x83, 0x45, 0xe6, 0x92, 0xc0, 0xf8, 0x6e, 0x5b, 0x48, 0xe0, 0x1b, 0x99, 0x6c, 0xad, 0xc0, 0x01, 0x62, 0x2f, 0xb5, 0xe3, 0x63, 0xb4, 0x21] );
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pub trait Trie {
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fn root(&self) -> &H256;
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fn is_empty(&self) -> bool { *self.root() == SHA3_NULL_RLP }
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// TODO: consider returning &[u8]...
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fn contains(&self, key: &[u8]) -> bool;
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fn at(&self, key: &[u8]) -> Option<&[u8]>;
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fn insert(&mut self, key: &[u8], value: &[u8]);
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fn remove(&mut self, key: &[u8]);
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}
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enum Operation {
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New(H256, Bytes),
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Delete(H256),
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}
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struct Diff (Vec<Operation>);
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impl Diff {
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fn new() -> Diff { Diff(vec![]) }
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/// Given the RLP that encodes a node, append a reference to that node `out` and leave `diff`
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/// such that the reference is valid, once applied.
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fn new_node(&mut self, rlp: Bytes, out: &mut RlpStream) {
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if rlp.len() >= 32 {
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let rlp_sha3 = rlp.sha3();
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out.append(&rlp_sha3);
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self.0.push(Operation::New(rlp_sha3, rlp));
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}
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else {
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trace!("new_node: inline node {:?}", &rlp);
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out.append_raw(&rlp, 1);
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}
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}
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/// Given the RLP that encodes a now-unused node, leave `diff` in such a state that it is noted.
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fn delete_node_sha3(&mut self, old_sha3: H256) {
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self.0.push(Operation::Delete(old_sha3));
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}
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fn delete_node(&mut self, old: &Rlp) {
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if old.is_data() && old.size() == 32 {
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self.0.push(Operation::Delete(H256::decode(old)));
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}
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}
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fn replace_node(&mut self, old: &Rlp, rlp: Bytes, out: &mut RlpStream) {
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self.delete_node(old);
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self.new_node(rlp, out);
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}
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}
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pub struct TrieDB {
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db: Box<HashDB>,
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root: H256,
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}
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impl TrieDB {
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pub fn new_boxed(db_box: Box<HashDB>) -> Self { let mut r = TrieDB{ db: db_box, root: H256::new() }; r.set_root_rlp(&NULL_RLP); r }
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pub fn new<T>(db: T) -> Self where T: HashDB + 'static { Self::new_boxed(Box::new(db)) }
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pub fn new_memory() -> Self { Self::new(MemoryDB::new()) }
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pub fn db(&self) -> &HashDB { self.db.as_ref() }
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fn set_root_rlp(&mut self, root_data: &[u8]) {
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self.db.kill(&self.root);
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self.root = self.db.insert(root_data);
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trace!("set_root_rlp {:?} {:?}", root_data, self.root);
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}
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fn apply(&mut self, diff: Diff) {
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trace!("applying {:?} changes", diff.0.len());
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for d in diff.0.into_iter() {
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match d {
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Operation::Delete(h) => {
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trace!("TrieDB::apply --- {:?}", &h);
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self.db.kill(&h);
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},
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Operation::New(h, d) => {
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trace!("TrieDB::apply +++ {:?} -> {:?}", &h, &d);
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self.db.emplace(h, d);
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}
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}
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}
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}
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fn add(&mut self, key: &NibbleSlice, value: &[u8]) {
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trace!("ADD: {:?} {:?}", key, value);
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// determine what the new root is, insert new nodes and remove old as necessary.
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let mut todo: Diff = Diff::new();
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let root_rlp = self.augmented(self.db.lookup(&self.root).expect("Trie root not found!"), key, value, &mut todo);
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self.apply(todo);
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self.set_root_rlp(&root_rlp);
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trace!("---");
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}
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fn compose_leaf(partial: &NibbleSlice, value: &[u8]) -> Bytes {
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trace!("compose_leaf {:?} {:?} ({:?})", partial, value, partial.encoded(true));
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let mut s = RlpStream::new_list(2);
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s.append(&partial.encoded(true));
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s.append(&value);
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let r = s.out();
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trace!("compose_leaf: -> {:?}", &r);
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r
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}
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fn compose_raw(partial: &NibbleSlice, raw_payload: &[u8], is_leaf: bool) -> Bytes {
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println!("compose_raw {:?} {:?} {:?} ({:?})", partial, raw_payload, is_leaf, partial.encoded(is_leaf));
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let mut s = RlpStream::new_list(2);
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s.append(&partial.encoded(is_leaf));
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s.append_raw(raw_payload, 1);
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let r = s.out();
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println!("compose_raw: -> {:?}", &r);
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r
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}
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fn compose_extension(partial: &NibbleSlice, raw_payload: &[u8]) -> Bytes {
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Self::compose_raw(partial, raw_payload, false)
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}
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/// Return the bytes encoding the node represented by `rlp`. It will be unlinked from
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/// the trie.
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fn take_node<'a, 'rlp_view>(&'a self, rlp: &'rlp_view Rlp<'a>, diff: &mut Diff) -> &'a [u8] where 'a: 'rlp_view {
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if rlp.is_list() {
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trace!("take_node {:?} (inline)", rlp.raw());
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rlp.raw()
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}
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else if rlp.is_data() && rlp.size() == 32 {
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let h = H256::decode(rlp);
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let r = self.db.lookup(&h).expect("Trie root not found!");
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trace!("take_node {:?} (indirect for {:?})", rlp.raw(), r);
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diff.delete_node_sha3(h);
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r
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}
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else {
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panic!("Empty or invalid node given?");
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}
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}
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/// Transform an existing extension or leaf node to an invalid single-entry branch.
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///
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/// **This operation will not insert the new node nor destroy the original.**
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fn transmuted_extension_to_branch(orig_partial: &NibbleSlice, orig_raw_payload: &[u8], diff: &mut Diff) -> Bytes {
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trace!("transmuted_extension_to_branch");
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let mut s = RlpStream::new_list(17);
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assert!(!orig_partial.is_empty()); // extension nodes are not allowed to have empty partial keys.
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let index = orig_partial.at(0);
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// orig is extension - orig_raw_payload is a node itself.
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for i in 0..17 {
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if index == i {
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if orig_partial.len() > 1 {
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// still need an extension
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diff.new_node(Self::compose_extension(&orig_partial.mid(1), orig_raw_payload), &mut s);
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} else {
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// was an extension of length 1 - just redirect the payload into here.
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s.append_raw(orig_raw_payload, 1);
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}
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} else {
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s.append_empty_data();
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}
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}
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s.out()
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}
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fn transmuted_leaf_to_branch(orig_partial: &NibbleSlice, orig_raw_payload: &[u8], diff: &mut Diff) -> Bytes {
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trace!("transmuted_leaf_to_branch");
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let mut s = RlpStream::new_list(17);
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let index = if orig_partial.is_empty() {16} else {orig_partial.at(0)};
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// orig is leaf - orig_raw_payload is data representing the actual value.
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for i in 0..17 {
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if index == i {
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// this is our node.
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diff.new_node(Self::compose_raw(&orig_partial.mid(if i == 16 {0} else {1}), orig_raw_payload, true), &mut s);
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} else {
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s.append_empty_data();
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}
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}
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s.out()
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}
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/// Transform an existing extension or leaf node plus a new partial/value to a two-entry branch.
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///
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/// **This operation will not insert the new node nor destroy the original.**
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fn transmuted_to_branch_and_augmented(&self, orig_is_leaf: bool, orig_partial: &NibbleSlice, orig_raw_payload: &[u8], partial: &NibbleSlice, value: &[u8], diff: &mut Diff) -> Bytes {
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trace!("transmuted_to_branch_and_augmented");
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let intermediate = match orig_is_leaf {
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true => Self::transmuted_leaf_to_branch(orig_partial, orig_raw_payload, diff),
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false => Self::transmuted_extension_to_branch(orig_partial, orig_raw_payload, diff),
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};
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self.augmented(&intermediate, partial, value, diff)
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// TODO: implement without having to make an intermediate representation.
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}
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/// Given a branch node's RLP `orig` together with a `partial` key and `value`, return the
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/// RLP-encoded node that accomodates the trie with the new entry. Mutate `diff` so that
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/// once applied the returned node is valid.
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fn augmented_into_branch(&self, orig: &Rlp, partial: &NibbleSlice, value: &[u8], diff: &mut Diff) -> Bytes {
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trace!("augmented_into_branch");
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let mut s = RlpStream::new_list(17);
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let index = if partial.is_empty() {16} else {partial.at(0) as usize};
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for i in 0usize..17 {
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match (index == i, i) {
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(true, 16) => // leaf entry - just replace.
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{ s.append(&value); },
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(true, i) if orig.at(i).is_empty() => // easy - original had empty slot.
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diff.new_node(Self::compose_leaf(&partial.mid(1), value), &mut s),
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(true, i) => { // harder - original has something there already
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let new = self.augmented(orig.at(i).raw(), &partial.mid(1), value, diff);
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diff.replace_node(&orig.at(i), new, &mut s);
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}
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(false, i) => { s.append_raw(orig.at(i).raw(), 1); },
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}
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}
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s.out()
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}
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/// Determine the RLP of the node, assuming we're inserting `partial` into the
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/// node currently of data `old`. This will *not* delete any hash of `old` from the database;
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/// it will just return the new RLP that includes the new node.
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///
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/// The database will be updated so as to make the returned RLP valid through inserting
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/// and deleting nodes as necessary.
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///
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/// **This operation will not insert the new node now destroy the original.**
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fn augmented(&self, old: &[u8], partial: &NibbleSlice, value: &[u8], diff: &mut Diff) -> Bytes {
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trace!("augmented ({:?}, {:?}, {:?})", old, partial, value);
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// already have an extension. either fast_forward, cleve or transmute_to_branch.
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let old_rlp = Rlp::new(old);
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match old_rlp.prototype() {
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Prototype::List(17) => {
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trace!("branch: ROUTE,AUGMENT");
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// already have a branch. route and augment.
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self.augmented_into_branch(&old_rlp, partial, value, diff)
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},
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Prototype::List(2) => {
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let existing_key_rlp = old_rlp.at(0);
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let (existing_key, is_leaf) = NibbleSlice::from_encoded(existing_key_rlp.data());
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match partial.common_prefix(&existing_key) {
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cp if partial.len() == existing_key.len() && cp == existing_key.len() && is_leaf => {
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// equivalent-leaf: replace
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trace!("equivalent-leaf: REPLACE");
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Self::compose_leaf(partial, value)
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},
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0 => {
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// one of us isn't empty: transmute to branch here
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trace!("no-common-prefix, not-both-empty (exist={:?}; new={:?}): TRANSMUTE,AUGMENT", existing_key.len(), partial.len());
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self.transmuted_to_branch_and_augmented(is_leaf, &existing_key, old_rlp.at(1).raw(), partial, value, diff)
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},
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cp if cp == existing_key.len() => {
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trace!("complete-prefix (cp={:?}): AUGMENT-AT-END", cp);
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// fully-shared prefix for this extension:
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// skip to the end of this extension and continue to augment there.
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let n = self.take_node(&old_rlp.at(1), diff);
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let downstream_node = self.augmented(n, &partial.mid(cp), value, diff);
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let mut s = RlpStream::new_list(2);
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s.append_raw(old_rlp.at(0).raw(), 1);
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diff.new_node(downstream_node, &mut s);
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s.out()
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},
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cp => {
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// partially-shared prefix for this extension:
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// split into two extensions, high and low, pass the
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// low through augment with the value before inserting the result
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// into high to create the new.
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// TODO: optimise by doing this without creating augmented_low.
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trace!("partially-shared-prefix (exist={:?}; new={:?}; cp={:?}): AUGMENT-AT-END", existing_key.len(), partial.len(), cp);
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// low (farther from root)
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let low = Self::compose_raw(&existing_key.mid(cp), old_rlp.at(1).raw(), is_leaf);
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let augmented_low = self.augmented(&low, &partial.mid(cp), value, diff);
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// high (closer to root)
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let mut s = RlpStream::new_list(2);
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s.append(&existing_key.encoded_leftmost(cp, false));
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diff.new_node(augmented_low, &mut s);
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s.out()
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},
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}
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},
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Prototype::Data(0) => {
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trace!("empty: COMPOSE");
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Self::compose_leaf(partial, value)
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},
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_ => panic!("Invalid RLP for node."),
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}
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}
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}
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impl Trie for TrieDB {
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fn root(&self) -> &H256 { &self.root }
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fn contains(&self, _key: &[u8]) -> bool {
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unimplemented!();
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}
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fn at(&self, _key: &[u8]) -> Option<&[u8]> {
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unimplemented!();
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}
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fn insert(&mut self, key: &[u8], value: &[u8]) {
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self.add(&NibbleSlice::new(key), value);
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}
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fn remove(&mut self, _key: &[u8]) {
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unimplemented!();
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}
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}
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#[cfg(test)]
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mod tests {
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use triehash::*;
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use super::*;
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use env_logger;
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#[test]
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fn playpen() {
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env_logger::init().unwrap();
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let mut t = TrieDB::new_memory();
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t.insert(&[0x01u8, 0x23], &[0x01u8, 0x23]);
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t.insert(&[], &[0x0]);
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assert_eq!(*t.root(), trie_root(vec![
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(vec![], vec![0x0]),
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(vec![0x01u8, 0x23], vec![0x01u8, 0x23]),
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]));
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}
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#[test]
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fn init() {
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let t = TrieDB::new_memory();
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assert_eq!(*t.root(), SHA3_NULL_RLP);
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assert!(t.is_empty());
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}
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#[test]
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fn insert_on_empty() {
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let mut t = TrieDB::new_memory();
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t.insert(&[0x01u8, 0x23], &[0x01u8, 0x23]);
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assert_eq!(*t.root(), trie_root(vec![ (vec![0x01u8, 0x23], vec![0x01u8, 0x23]) ]));
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}
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#[test]
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fn insert_replace_root() {
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let mut t = TrieDB::new_memory();
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t.insert(&[0x01u8, 0x23], &[0x01u8, 0x23]);
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t.insert(&[0x01u8, 0x23], &[0x23u8, 0x45]);
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assert_eq!(*t.root(), trie_root(vec![ (vec![0x01u8, 0x23], vec![0x23u8, 0x45]) ]));
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}
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#[test]
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fn insert_make_branch_root() {
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let mut t = TrieDB::new_memory();
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t.insert(&[0x01u8, 0x23], &[0x01u8, 0x23]);
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t.insert(&[0x11u8, 0x23], &[0x11u8, 0x23]);
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assert_eq!(*t.root(), trie_root(vec![
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(vec![0x01u8, 0x23], vec![0x01u8, 0x23]),
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(vec![0x11u8, 0x23], vec![0x11u8, 0x23])
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]));
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}
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#[test]
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fn insert_into_branch_root() {
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let mut t = TrieDB::new_memory();
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t.insert(&[0x01u8, 0x23], &[0x01u8, 0x23]);
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t.insert(&[0xf1u8, 0x23], &[0xf1u8, 0x23]);
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t.insert(&[0x81u8, 0x23], &[0x81u8, 0x23]);
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assert_eq!(*t.root(), trie_root(vec![
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(vec![0x01u8, 0x23], vec![0x01u8, 0x23]),
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(vec![0x81u8, 0x23], vec![0x81u8, 0x23]),
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(vec![0xf1u8, 0x23], vec![0xf1u8, 0x23]),
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]));
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}
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} |